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25 February 2023, Volume 44 Issue 4
Food Chemistry
Physical Characteristics and Stability of pH-Shifted Soybean Oil Body-Curcumin Composite Emulsion
KANG Mengxue, SUN Yufan, SONG Hanyu, ZHONG Mingming, WANG Shuai, QI Baokun
2023, 44(4):  1-8.  doi:10.7506/spkx1002-6630-20220430-401
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A curcumin delivery system was prepared by using the pH-shift method to load curcumin into the oil phase core of soybean oil body, which has a natural oil-in-water structure. The encapsulation characteristics of the emulsion were studied in terms of its encapsulation efficiency, particle size, zeta potential, and microstructure. The structural changes were analyzed by endogenous fluorescence spectroscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the storage stability, pH stability and oxidation stability were evaluated. The results showed that curcumin was successfully encapsulated with soybean oil body by the pH-shift method. At pH 1.0, the highest encapsulation efficiency of 65.55% was observed, and the lipid droplets were regular in shape and uniform in size, with an average particle size of 590.5 nm. The oxidative stability was good, but the storage stability and pH stability were poor. Protein structure was not changed significantly compared to untreated oil body. This study may provide a reference for future research on natural oil body to carry lipophilic polyphenols such as curcumin.
Reactive Oxygen Species Accelerates Energy Metabolism by Activating Hypoxia-Inducible Factor-1α in Bovine Muscle at the Initial Stage of Postmortem Aging
GUO Yuxuan, CHEN Cheng, SHI Xixiong, GUO Zhaobin, MA Guoyuan, MA Jibing, YU Qunli
2023, 44(4):  9-16.  doi:10.7506/spkx1002-6630-20220407-072
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This study aimed to investigate the effect of reactive oxygen species (ROS) on early postmortem energy metabolism in bovine muscle via regulating the expression of hypoxia-inducible factor-1α (HIF-1α). The muscle samples were treated with hydrogen peroxide (H2O2), N-acetyl-L-cysteine (NAC), and normal saline (control), separately. The ROS content, proline hydroxylase (PHD) activity, phosphoinositide-3 kinase/protein kinase B (PI3K/AKT) and HIF-1α expression levels, energy metabolism, and pH were determined at 0.5, 6, 12, 24 and 48 h postmortem. The results revealed that the H2O2-treated group showed a significantly higher ROS content than the other two groups at 0.5 h postmortem (P < 0.05) and remained at a high level within 48 h, while NAC inhibited the accumulation of ROS for a short period of time (during 0.5–12 h) postmortem. The PHD activity in the H2O2-treated group was significantly lower than that in the other two groups during 0.5–48 h (P < 0.05). Meanwhile, the expression levels of PI3K from 0.5 to 12 h and phosphorylated AKT (p-AKT) from 0.5 to 6 h were significantly higher than those in the other groups (P < 0.05). Consequently, the expression level of HIF-1α in the H2O2-treated group was significantly higher than that of the other two groups during 6–48 h (P < 0.05), the rate of glycogenolysis and the rate of increase in R value were significantly faster in the H2O2-treated group during 6–24 h (P < 0.05), and the pH of the H2O2-treated group reached the limit value earlier (at 12 h). In conclusion, ROS can activate the stable expression of HIF-1α by reducing the activity of PHD and up-regulating the PI3K/AKT signaling pathway and consequently accelerate energy metabolism dominated by glycolysis and the decrease in pH in bovine muscle at the initial stage of postmortem aging, which may have a crucial impact on meat quality.
Mechanism of Reduction of Allergenicity of Silver Carp Parvalbumin by Glycation Combined with Phosphorylation
CHEN Wenmei, ZHOU Houze, SHAO Yanhong, LIU Jun, TU Zongcai
2023, 44(4):  17-23.  doi:10.7506/spkx1002-6630-20220406-062
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The changes in antigenic epitopes and allergenicity of silver carp parvalbumin (PV) after glycation and phosphorylation were investigated by spectroscopy, mass spectrometry and KU812 cell assay. The results showed that glycation combined with phosphorylation increased the molecular mass, reduced the free amino acid content, and changed the secondary structure and conformation of PV. The modified PV had eight glycation sites (K33, K46, K55, K65, K84, K88, K97 and K108) and one phosphorylation site (S56). The modification significantly reduced the ability of PV to bind IgG and IgE, and decreased histamine and interleukin-6 release from KU812 cells. Thus, glycation combined with phosphorylation reduced PV allergencity by masking the linear epitopes and damaging the conformational epitopes at the glyclation and phosphorylation sites. The results of this study may provide an important theoretical basis for the development of hypoallergenic fish products.
Effect of the Interaction between Wheat Starch and Gluten on Oil Distribution in Deep-Fried Battered and Breaded Fish Nuggets from Silver Carp Surimi
FENG Jiaqi, CHEN Jiwang, YUAN Zijun, LIAO E, PENG Lijuan, XIA Wenshui
2023, 44(4):  24-31.  doi:10.7506/spkx1002-6630-20220328-349
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In the present study, the effect of the interaction between wheat starch and gluten on oil distribution in deep-fried battered and breaded fish nuggets (BBFNs) from silver carp surimi was investigated. Deep-fried BBFNs were prepared using batters consisting of wheat starch (WS) and gluten (WG) blends (at mass ratios of 15:1, 13:1, 11:1, 9:1 and 7:1), and then the surface hydrophobicity (H0), free sulfydryl content, disulfide bond content, secondary structure of WG and the crystalline structure of WS in the crust, as well as the surface oil and penetrated surface oil contents of deep-fried BBFNs were evaluated. The microstructure and oil distribution in the crust were also observed. The results showed that as the WS/WG ratio decreased, the H0 value increased firstly then decreased, and the free sulfydryl and disulfide bond contents gradually decreased and increased, respectively. Meanwhile, the β-turn structure of WG was gradually converted into β-sheet, and the surface oil and penetrated surface oil contents of deep-fried BBFNs as well as the relative crystallinity of WS decreased firstly then increased. The size of pores in the crust and oil distribution decreased at first and then increased. Among the tested WS/WG ratios, deep-fried BBFNs with a WS/WG ratio of 11:1 had the highest H0 (8 990), and the lowest surface oil (2.1%) and penetrated surface oil contents (5.8%), and the lowest relative crystallinity of WS (17.8%), and the crust exhibited the most compact microstructure and the least oil distribution. Therefore, the interaction between WS and WG is affected by changes in WS/WG ratio, which can in turn affect oil distribution in deep-fried BBFNs.
Effects of Combined Plasma and Polyphenol Modification on Properties of Banana Starch
SUN Ying, ZHENG Lili, ZHENG Xiaoyan, YANG Yang, XIAO Dao, AI Binling, ZHANG Zhengke, SHENG Zhanwu
2023, 44(4):  32-41.  doi:10.7506/spkx1002-6630-20211011-104
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The purpose of this study was to explore the effect of treatment with dielectric barrier discharge (DBD) plasma followed by complexation with resveratrol on the physicochemical properties and digestibility of green banana starch. The results showed that DBD plasma treatment improved the complexation between banana starch and resveratrol. Compared with unmodified banana starch, the solubility, retrogradation properties, oil-holding capacity, gelatinization temperature (the onset gelatinization temperature (To), peak gelatinization temperature (Tp) and conclusion gelatinization temperature (Tc) increased from 64.10, 71.14 and 73.92 ℃ to 70.18, 75.79 and 82.53 ℃, respectively) and digestibility of the complex were significantly improved, while the swelling power and freeze-thaw stability were reduced. Scanning electron microscopy (SEM) showed that DBD plasma treatment produced more starch fragments and etched the starch surface. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that resveratrol combined with banana starch through CH-π bond, which made the structure of the complex more compact and orderly, forming a non V-type inclusion complex with high crystallinity. Therefore, plasma treatment and then complexation with polyphenols can improve the processing properties of banana starch, which will contribute to the development of new health foods.
Effect of Peony Stamen Protein on Dough and Gluten Protein Properties
LUO Lei, XIA Yingli, YANG Haokun, ZHAO Yifan, LI Hanshu, MA Xiao
2023, 44(4):  42-47.  doi:10.7506/spkx1002-6630-20220314-155
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In order to realize the resource utilization of peony stamens, the effects of peony stamen protein on the texture, dynamic rheological properties, disulfide bonds, surface microstructure and secondary structure of dough and gluten proteins were studied using soybean protein isolate (SPI) as a reference. The results showed that peony stamen protein could significantly improve the hardness, stickiness and chewiness of dough, and the effect of addition of less than 6% of peony stamen protein was more pronounced than that of SPI. Addition of peony stamen protein increased the storage and loss moduli and consequently the viscoelasticity of dough. The effect of peony stamen protein on the formation of gluten protein network structure was basically the same as that of SPI. Under scanning electron microscopy (SEM), gluten proteins added with 6% of peony stamen protein exhibited a compact network structure consisting of many deep pores. In the presence of peony stamen protein, the total proportion of the relative stable secondary structures of α-helix and β-sheet reached the maximum value of 59.32%, and the content of disulfide bonds increased by 89% compared with the blank group. In conclusion, peony stamen protein can effectively promote the formation of gluten protein network structure and improve the quality of dough, and therefore can be used in the production of flour products with high viscoelasticity requirements.
Effects of Mesona chinensis Benth Polysaccharide on the Physicochemical Properties and Structural Characteristics of Myosin
ZHOU Xinyi, YOU Gang,, GAO Ke’an, DONG Shiyu, MA Shutian, CHEN Shangli, LIU Xiaoling
2023, 44(4):  48-56.  doi:10.7506/spkx1002-6630-20220507-094
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The effects of different concentrations (0–0.10 mg/mL) of Mesona chinensis Benth polysaccharide (MCP) on the physicochemical properties (potential, particle size, surface hydrophobicity, and sulfhydryl groups), structural properties (determined by ultraviolet-visible spectroscopy, fluorescence spectroscopy, Fourier transformation infrared spectroscopy, circular dichroism spectroscopy, and electrophoresis) and microstructure of myosin were investigated. The interaction mechanism between myosin and MCP was elucidated. The results showed that the interaction force between myosin and MCP changed with increasing MCP, and myosin-MCP complexes and myosin-myosin aggregates were formed mainly through electrostatic interaction force and hydrophobic interaction, thereby increasing the turbidity of the myosin-MCP mixed system, decreasing the potential and surface hydrophobicity, widening the range of particle size distribution, and reducing the average particle size (D50). Besides, ultraviolet-visible spectroscopy, fluorescence spectroscopy, and circular dichroism spectroscopy also confirmed that myosin structure changed with increasing MCP concentration.
Effect of Alkaline pH Extraction on the Stability and Digestive Properties of Soybean Oil Bodies
SONG Hanyu, ZHONG Mingming, KANG Mengxue, MAN hui, WANG Zhenxiao, QI Baokun
2023, 44(4):  57-63.  doi:10.7506/spkx1002-6630-20220403-036
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The purpose of this study was to understand the stability of natural emulsions formed from soybean oil bodies (SOB) extracted at alkaline pH (8.0–11.0) and their digestive properties in the gastrointestinal tract. The stability of SOB was evaluated in terms of its basic composition, particle size, zeta potential and rheology, and the digestive properties were evaluated in terms of fatty acid release from SOB and the microstructure of SOB. The results showed that with an increase in extraction pH, the water and protein contents of SOB decreased and the particle size decreased from (471.57 ± 8.53) nm to (424.77 ± 12.21) nm, while the lipid content increased. In addition, the oxidative stability of SOB showed a similar trend. Specifically, the peroxide value (POV) decreased with increasing extraction pH and the thiobarbituric acid reactive substances (TBARS) value increased with an increase in storage time. The apparent viscosity decreased with increasing shear rate. SOB emulsions showed shear thinning behavior with G’ being greater than G” for all samples, and the release percentage of free fatty acids from SOB significantly increased with increasing extraction pH (P < 0.05). This study provides theoretical support for the wide application of highly stable natural SOB.
Preparation of Tamarind Seed Globulin-EGCG Covalent Complex and Its Application in Emulsified Sausages
YANG Yang, WANG Mengju, WANG Yue, BIAN Xin, FAN Jing, MA Chunmin, SHI Yanguo, LI Xiaomei, ZHANG Na
2023, 44(4):  64-70.  doi:10.7506/spkx1002-6630-20220421-266
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In this study, a covalent complex between tamarind seed globulin (TSG) and epigallocatechin-3-gallate (EGCG) was prepared by alkali treatment. UV-visible spectroscopy was used to analyze the binding rate of TSG-EGCG covalent complex and the binding conditions were optimized. The effects of adding different amounts of TSG-EGCG covalent complex on the cooking loss, water-holding capacity and texture of emulsified sausages were studied using a color difference meter, a texture analyzer and a scanning electron microscope (SEM). The results showed that reaction at pH 9.5 and 30 ℃ with a mass ratio of TSG to EGCG of 1:0.1 gave the maximum binding rate. Compared with TSG, the microstructure of emulsified sausages added with TSG-EGCG complex was more compact, the three-dimensional gel network was more uniform and clear, and the cooking loss, water-holding capacity and texture properties were significantly improved. In conclusion, TSG-EGCG complex can improve the sensory quality of emulsified sausages, and the quality of emulsified sausages can be significantly improved by adding 2% of TSG-EGCG complex.
Myofibrillar Protein Oxidation in Immersion-Frozen Red Shrimp (Solenocera crassicornis) during Frozen Storage: Analysis Based on Changes of Endogenous Enzyme Activity
XU Dan, Han Yue, Zheng Bin, Deng Shanggui, Chen Xuechang, Zhang Xiaojun
2023, 44(4):  71-77.  doi:10.7506/spkx1002-6630-20220708-083
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A comparative analysis of the changes in indicators of myofibrillar protein oxidation and the activities of cathepsins B, H and in red shrimp during frozen storage after immersion freezing (?18 and ?30 ℃) and refrigerator freezing (?18 and ?30 ℃) was conducted. Microstructural observation of myofibrillar protein was carried out to analyze the effect of cathepsin activity on myofibrillar protein hydrolysis and its correlation with muscle tissue structure was explored. The results showed that the contents of salt-soluble protein in the immersion freezing groups at ?18 and ?30 ℃ were 92.7 and 97.8 mg/g, respectively, significantly higher than those in the refrigerator freezing groups at ?18 and ?30 ℃ (72.40 and 77.90 mg/g, respectively). The surface hydrophobicity in the immersion freezing group at ?30 ℃ was the lowest =(400.6 μg), and Ca2+-ATPase activity was higher at ?30 ℃ than at ?18 ℃ for both freezing methods. The trend of change in total sulfhydryl content was consistent with that of Ca2+-ATPase activity. At the early stage of storage (0–60 days), immersion freezing at lower temperature could better inhibit cathepsin activity and maintain myofibrillar protein structure. At the late stage of storage (60–120 days), the cathepsin inhibitory effect decreased. Based on the above results, it was clear that during a certain storage period, immersion freezing could better attenuate the oxidation of myofibrillar protein and cathepsin activity of Solenocera crassicornis than refrigerator freezing, and lower freezing temperature of antifreeze liquid resulted in higher freezing rate, weaker cathepsin activity and lower extent of myofibrillar protein oxidation, which was more conducive to the maintenance of myofibrillar protein structure.
Physicochemical, Functional and Microstructural Changes during the Emulsification Process of Processed Cheese
LI Hongjuan, LI Mengfan, YUAN Yujing, CHEN Ziyang, ZHU Guangchao, LI Dan, LI Hongbo, YU Jinghua
2023, 44(4):  78-84.  doi:10.7506/spkx1002-6630-20220502-014
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In this study, we investigated the changes in the functional properties (meltability and fat precipitation), texture, rheological properties, and microstructure of processed cheese during emulsification (5–30 min) at different temperatures (80 and 85 ℃). The results showed that as the emulsification time increased, the meltability and fat precipitation showed a decreasing trend, and the fat precipitation at 85 ℃ was significantly higher than that at 80 ℃ during the emulsification process (P < 0.05). The gumminess and chewiness increased significantly (P < 0.05) with the increase in emulsification time, and the hardness, gumminess and chewiness at 85 ℃ were greater than those at 80 ℃. The storage modulus (G’) of processed cheese was greater than the loss modulus (G”) at the same degree of emulsification for both temperatures and both G’ and G” showed an upward trend with increasing frequency from 0.1 to 10 Hz. The microstructure of processed cheese showed that the number of fat globules was greatly reduced, the diameter was decreased, the distribution of fat globules became more uniform, the protein matrix became smoother and the cheese structure became denser at 5–15 min of emulsification. However, the microstructure of processed cheese was honeycomb-like at 20–30 min of emulsification, suggesting excessive creaming reaction. Therefore, a short emulsification time during the processing of processed cheese will result in inadequate creaming reaction; too long emulsification time will cause adverse changes in cheese texture. During the emulsification process, the protein-protein and protein-fat interactions were enhanced, thereby improving the functional properties of the product. In conclusion, the emulsification process of processed cheese is closely related to its physicochemical and functional properties and microstructure. This study provides some theoretical guidance for future process development of processed cheese production.
Physicochemical Properties of Deacetylated Konjac Glucomannan and Its Effects on the Quality and in Vitro Digestion Characteristics of Cold Noodles
GE Zhenzhen, XU Mingyue, JIN Xueyuan, GAO Shanshan, ZHAO Guangyuan, ZONG Wei
2023, 44(4):  85-90.  doi:10.7506/spkx1002-6630-20220628-317
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In this work, the structures of deacetylated konjac glucomannan (DKGM) with different degrees of deacetylation were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and their viscosity, water-holding capacity (WHC) and thermal stability were evaluated and compared. The effects of DKGM with high degree of deacetylation (72.70%) on the texture and in vitro digestion characteristics of cold noodles were analyzed. The results showed that the characteristic absorption peak of acetyl group at 1 735 cm?1 in DKGM decreased, the surface became rough, the crystallinity and the thermal stability increased, and the viscosity and WHC decreased with the increase in the degree of deacetylation when compared with konjac glucomannan (KGM) (P < 0.05). After adding DKGM with high degree of deacetylation, the hardness, chewiness and cohesiveness of cold noodles showed a downward trend, and its in vitro digestibility decreased. In conclusion, addition of DKGM with high degree of deacetylation can improve the mouthfeel and digestion resistance of cold noodles, which may provide a theoretical basis for the application of DKGM and starch blends in low glycemic index foods.
Binding Mechanism and Conformation and Functional Changes of Soybean Protein-Baicalein Complexes
YAN Xinyue, JIA Yijia, SUN Shiyan, ZHANG Dongmeng, GENG Mengjie, YANG Jinjie, Stanislav Sukhikh, Olga Babich, QI Baokun, LI Yang
2023, 44(4):  91-98.  doi:10.7506/spkx1002-6630-20220519-255
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This study aimed to explore the binding mechanism of soybean β-conglycinin (7S)/glycinin (11S) with baicalein, and to investigate the changes in the conformational and functional properties of the complexes. Fourier transform infrared (FT-IR) spectroscopy indicated that baicalein could induce the transformation of β-sheets into α-helices and random coils. Intrinsic fluorescence spectra confirmed that the addition of baicalein made the structure of 7S and 11S more compact. The reaction of baicalein with the proteins took place spontaneously and quenched the protein fluorescence in a static manner. The 7S and 11S proteins bound to baicalein by hydrogen bonds and hydrophobic interactions, respectively. Molecular docking results showed that the affinity of baicalein to 11S was higher than that to 7S. Scanning electron microscopy (SEM) showed microstructure differences between 7S and 11S and their complexes. In addition, the surface hydrophobicity of 7S and 11S was decreased and the functional properties such as thermal stability were improved after combining with baicalein.
Effect of Partial Acid Hydrolysis on the Structure and Emulsifying Function of Peach Gum Polysaccharide
ZHANG Hongyuan, QIAN Jiajun, LI Zheyuan, ZHANG Shendong, YANG Xiaochen, AI Lianzhong, LAI Fengxi, ZHANG Hui
2023, 44(4):  99-106.  doi:10.7506/spkx1002-6630-20220519-259
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In order to investigate the key structural features of peach gum polysaccharide (PGP) responsible for its emulsifying function, partial acid hydrolysis of PGP with 0.1 mol/L trifluoroacetic acid was conducted, yielding hydrolysates 30P, 60P, 120P and 180P with different degrees of hydrolysis at different hydrolysis times. The effects of partial acid hydrolysis on the monosaccharide composition and molecular mass of PGP were analyzed by high performance anion-exchange chromatography (HPAEC) and high performance size-exclusion chromatography with a multi-angle laser light scattering detector (HPSEC-MALLS) and the effect of partial acid hydrolysis on the emulsifying function of PGP was investigated by using an oil in water (O/W) emulsion system. Results showed that PGP was an acidic arabinogalactan composed of arabinose, galactose, xylose, mannose, galacturonic acid and glucuronic acid conjugated with a small amount of protein. PGP, whose average molecular mass of 10 980 kU, presented a flexible coil-like chain in 0.1 mol/L NaNO3 solution. As acid hydrolysis progressed, the contents of uronic acid and protein in PGP gradually increased, the molecular mass and degree of branching gradually decreased, and the molecular conformation of the hydrolysates changed from a flexible coil-like to a rigid rod-like structure. The stability of the O/W emulsion prepared using 60P as an emulsifier was significantly improved compared to the other hydrolysates. It was speculated that 60P, whose molecular mass was 1 188 kU and which had reduced degree of branching and higher contents of glycuronic acid-protein conjugate and exhibited a flexible chain-like structure, may be the key structural feature responsible for of the emulsifying function PGP. This study will be helpful to further explain the mechanism action of PGP as an emulsifier.
Effect of Chuzhou Chrysanthemum Powder on Dough Properties and Flavor and Antioxidant Activity of Bread
BAO Yuting, SUN Yue, LI Xueling, LIANG Jin
2023, 44(4):  107-114.  doi:10.7506/spkx1002-6630-20220403-034
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In order to explore the effect of Chuzhou chrysanthemum powder application in bread processing on dough characteristics and bread flavor and antioxidant activity, the thermal and mechanical properties of dough with added Chuzhou chrysanthemum powder were measured using Mixolab 2, and the volatile flavor compounds in the resulting bread were analyzed by gas chromatography-ion mobility spectrometry (GC-IMS). In addition, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) cation radical scavenging capacity and the total flavonoid content of the bread were determined. The results showed that the water absorption rate of dough significantly increased while the peak viscosity and setback of starch decreased upon addition of Chuzhou chrysanthemum powder. Compared with the control bread, the content of flavor components in Chuzhou chrysanthemum incorporated bread was higher, and d-camphor was found to be the characteristic flavor component of Chuzhou chrysanthemum. The volatile flavor components in the samples with and without Chuzhou chrysanthemum were obviously different according to principal component analysis (PCA). The total flavonoid content of Chuzhou chrysanthemum incorporated bread was 260.47 mg/100 g, which was significantly higher than that of the control bread, and the DPPH and ABTS cation radical scavenging activities were higher than those of the control bread. In conclusion, addition of Chuzhou chrysanthemum powder to bread can enrich the flavor components and improve the antioxidant activity of bread, which provides a reference for the application of Chuzhou chrysanthemum in bakery foods.
Effects of Amylose and Protein Contents on Visual Appearance and Eating Quality of Proso Millet
LI Dongmei, WANG Honglu, GONG Yao, CAO Ziwei, LI Jiayu, FENG Baili
2023, 44(4):  115-121.  doi:10.7506/spkx1002-6630-20220406-063
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In this study, four proso millet varieties with significantly different amylose and protein contents were used to explore the effects of amylose and protein contents on the visual appearance and eating quality of proso millet. The results showed that the viscosity, gelatinization time and gelatinization temperature of whole proso millet flour, as well as the water absorption percentage, volume expansion percentage and hardness of cooked proso millet were significantly higher for the varieties with higher amylose content than those with lower amylose content, while the gelatinization enthalpy was lower than that of the varieties with lower amylose content. For the varieties with higher protein content, whole proso millet flour had lower paste viscosity, and cooked proso millet had lower water absorption percentage and volume expansion percentage but higher harness. Proso millet with higher amylose and protein contents had poorer cooking quality, higher energy consumption and longer cooking time. In conclusion, appropriately reducing the amylose and protein contents of proso millet can improve the palatability.
Screening and Structural Characterization of Auricularia auricula Polysaccharides for Their Ability to Improve Rehydration Characteristics of Dehydrated White Radish
SU Xin, WANG Bixiang, JIAO Xuan, ZHANG Chi, WEN Liankui, HE Yang,
2023, 44(4):  122-130.  doi:10.7506/spkx1002-6630-20211214-157
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Polysaccharides from Auricularia auricula (AAP) were extracted by hot water extraction and fractionated by sequential precipitation with 10% and 80% (final concentration) ethanol into two fractions (named AAP-10 and AAP-80, respectively). Each fraction was further separated into three subfractions: AP-10-I, AAP-10-II, AAP-10-III, AAP-80-I, AAP-80-II and AAP-80-III. Each of the six polysaccharides was vacuum infiltrated into white radish before dehydration and rehydration. The effects of these polysaccharides on the rehydration characteristics of white radish were investigated by measuring the rehydration ratio, expansibility, water-holding capacity (WHC), color and texture parameters. Polysaccharides that greatly differed in their ability to improve the rehydration characteristics of dehydrated radish were selected for structural characterization. The results showed that compared with dehydrated radish without osmotic treatment, treatment with AAP could improve the rehydration characteristics of dehydrated radish in varying degrees. The effect of AAP-80-III was most pronounced among the six polysaccharides. The rehydration ratio of radish treated with AAP-80-III was 7.32, the expansibility was 3.22 mL/g, and the water-holding capacity was 87.2%; it had better color (L* value of 62.68 ± 0.17, a* value of ?1.06 ± 0.02, and b* value of 4.23 ± 0.09), hardness (1 746.14 ± 11.9) N and chewiness (1 207.09 ± 9.39) N. AAP-10-I could also improve the rehydration characteristics of dehydrated radish, but the difference was not significant. AAP-10-I and AAP-80-III contained neither protein nor nucleic acid, and both had hydrophilic functional groups. But the molecular mass of AAP-80-III was less than that AAP-10-I, and so AAP-80-III could more easily penetrate into radish tissue. Moreover, arabinose accounted for a larger proportion in the monosaccharide composition of AAP-80-III, which increased the water-holding capacity of radish tissue. Based on the above results, AAP-80-III can effectively improve the rehydration characteristics of dehydrated radish.
Maillard Reaction between Rice Bran Polysaccharide and Whey Protein Isolate and Characterization of the Reaction Product
WU Shuang, WANG Han, WANG Zhan, SHEN Wangyang, HU Zhongze, ZHOU Jian, HUANG Wenjing
2023, 44(4):  131-138.  doi:10.7506/spkx1002-6630-20211221-245
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Objective: The purpose of this study was to explore the impact of dry heating time on the Maillard reaction between rice bran polysaccharide (RBP) and whey protein isolate (WPI) in order to develop a new emulsifier for the preparation of nanoemulsions encapsulating lipid-soluble substances. Methods: The changes in absorbance at 294 nm (A294 nm), browning degree, color and free amino acid content were monitored during the Maillard reaction under dry heating condition, and the molecular mass, particle size, emulsifying activity and emulsion stability, and microstructure of the reaction product were characterized. Meanwhile, the Maillard reaction product was used to prepare soybean oil nanoemulsion. Results: As indicated by the changes in A294 nm, browning degree, color difference and free amino acid content, the Maillard reaction took place, and the color of the product became darker with an increase in reaction time. The molecular mass of the reaction product was 17 kDa, and a uniform particle size distribution was observed at 12 h of reaction. The Maillard reaction significantly improved the emulsifying activity and emulsion stability of WPI (P < 0.05). Nanoemulsion containing WPI-RBP complex at 12 h of reaction was more stable than the one containing WPI and showed uniform particle size distribution, and it could resist the negative impact of acid and salt ions. Conclusion: The Maillard reaction between WPI and RBP effectively improve the emulsifying properties of WPI, and the reaction product can be used as a new emulsifier in the food field.
Preparation and Physicochemical Properties of Coix Seed Starch Nanoparticles
ZENG Muhua, HUANG Minli, CHEN Wenjing, JIA Ru, LIAO Jun, YAO Shihan, LI Jin, ZHENG Baodong, GUO Zebin
2023, 44(4):  139-145.  doi:10.7506/spkx1002-6630-20220408-097
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In this study, coix seed starch nanoparticles were prepared by nano-precipitation method using three different systems (alkali solution, water-ethanol system and dimethyl sulfoxide (DMSO)-ethanol system). The structures and physicochemical properties of the three nanoparticles were investigated by analysis of their particle characteristics, molecular characteristics, crystallization characteristics and thermal characteristics. The results showed that the nanoparticles prepared using alkaline solution had the highest proportion of nanoparticles (85.65%). Both the nanoparticles prepared using alkaline solution and water-ethanol system had an A-type crystalline structure, while the crystalline structure of the nanoparticles prepared using DMSO-ethanol system changed from A-type to amorphous. The nanoparticles prepared using alkali solution at 45 ℃ had the smallest particle size (348 nm), the highest polydispersity, higher degree of order, relative crystallinity and thermal stability, indicating that alkali solution was the most suitable to prepare coix seed starch nanoparticles. This study may provide a theoretical basis for the preparation of starch nanoparticles and the study of their structural properties as well as the expansion of the application of coix seed starch.
Effect of Activated Carbon or Hydrogen Peroxide Decolorization on the Structure and Application Properties of Polysaccharides from Thesium chinense Turcz.
SHAO Lijun, JU Feilong, ZHONG Yang, ZHOU Yingdi, LI Beibei, LING Yifan, SUN Yue, LIANG Jin, LI Xueling
2023, 44(4):  146-151.  doi:10.7506/spkx1002-6630-20220712-125
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Hydrogen peroxide and activated carbon were separately used for decolorization of Thesium chinense Turcz polysaccharides. The physical characteristics of the two decolorized samples were analyzed by X-ray diffractometry (XRD), thermogravimetry, laser particle size analyzer and rheometer, and their inhibitory activities against the proliferation of liver cancer cells were compared, as well as their effects on the gelation temperature of κ-carrageenan. The results showed that the crystalline structure of the activated carbon-treated sample was more obvious in the XRD pattern. Its apparent viscosity was higher than that of the hydrogen peroxide-treated sample at the same concentration. The thermogravimetric curve showed that the thermal decomposition degree of the hydrogen peroxide-treated sample was higher than that of the activated carbon-treated sample (mass loss percentage of 59.33% and 53.21%, respectively). At concentrations of 6–10 mg/mL, the activated carbon-treated sample showed inhibitory activity against the proliferation of HepG2 cells, while the hydrogen peroxide-treated samples did not have any inhibitory effect in the concentration range of 1–10 mg/mL. Furthermore, the increase in temperature hysteresis of blends of the activated carbon-treated-treated polysaccharides with κ-carrageenan was greater than that in blends of the HTP-treated polysaccharides with κ-carrageenan. Therefore, different decolorization methods can affect the structure and application characteristics of Thesium chinense Turcz. polysaccharides.
Influence of Sheeting Gap on the Quality of Fresh Wheat Noodles from the Perspective of Water Migration
LIU Ling, MA Xinxin, SHI Zhaojian, HU Xinzhong
2023, 44(4):  152-161.  doi:10.7506/spkx1002-6630-20211219-217
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This study was conducted to analyze the moisture characteristics, microstructure and macroscopic quality of fresh wheat noodles processed at three sheeting gaps: 0.9, 1.5 and 2.2 mm. The results showed that water affected the macroscopic quality of fresh noodles mainly through two ways: directly and indirectly. In the direct way, as the sheeting gap decreased from 2.2 to 0.9 mm, the activity, freezability and freedom of water molecules within noodles reduced, limiting microbial utilization of nutrients and inhibiting microbial growth. In the indirect way, as the sheeting gap decreased, the binding strength between water molecules and flour components was enhanced. When the sheeting gap was 1.5 mm, the water molecules in a stronger bonding state prompted the formation of more stable and orderly β-sheets and α-helices in noodles through hydrogen bonding, solidifying the secondary structure and disulfide bonds of gluten and consequently resulting in the formation of a uniform and coherent gluten network manifested by a higher branching rate and a lower end-point rate, ultimately leading to a lower cooking loss rate.
Comparative Studies on Interaction Mechanism of Hesperidin and Naringin with Casein
LIU Xuemei, WANG Huamin, ZHAO Li, BAI Chunqing
2023, 44(4):  162-170.  doi:10.7506/spkx1002-6630-20211205-056
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The interaction and mechanism of casein (CA) with hesperidin (HES) and naringin (NAR) were investigated using fluorescence spectroscopy, synchronous fluorescence spectroscopy, thermodynamic analysis, and molecular docking in this study. The results showed that both polyphenols quenched CA in a static manner, but HES had stronger fluorescence quenching effect and binding affinity to CA and had more binding sites. According to thermodynamic parameters, the binding of CA to HES and NAR was spontaneous and mainly driven by hydrophobic forces. According to synchronous fluorescence spectra, introduction of the two polyphenols caused changes in the hydrophobic environment of amino acid residues in CA. The binding process was mostly driven by hydrophobic forces according to molecular docking, and more hydrogen bonds were formed between HES and CA, making the binding between them more stable. The results of this study can be used as a reference for future studies on polyphenol-protein interactions as well as the feasibility of CA as a carrier of flavonoid polyphenols.
Bioengineering
Effect of Fermentation Method on Quality and Flavor Characteristics of Maize Flour
HAN Cuiping, DUAN Jiayu, CAO Chen, LI Ge, YANG Xue, JIANG Lianzhou, YU Dianyu
2023, 44(4):  171-176.  doi:10.7506/spkx1002-6630-20220401-015
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The quality of naturally fermented maize flour, unfermented maize flour and maize flour fermented with Lactobacillus plantarum (Lp) and/or Saccharomyces cerevisiae (Sc) was analyzed by using unfermented maize flour as the control. The results showed that the contents of crude protein, crude fat, crude fiber and crude ash in fermented maize flour were significantly lower (P < 0.05) and the content of total starch was significantly higher (P < 0.05) when compared with unfermented maize flour. Fermentation increased the pasting temperature of maize flour significantly (P < 0.05), the breakdown and setback values of naturally fermented and Lp + Sc fermented maize flour were significantly lower than those of unfermented maize flour (P < 0.05), and the stability and anti-retrogradation ability of maize flour were improved. Moreover, fermentation with Lp and Lp + Sc had a pronounced effect on the structure of maize flour, while during fermentation with Sc and Lp + Sc, aroma compounds and metabolites which could improve the off-odor of fermented maize flour were produced. The fermentation periods of maize flour with Lp, Sc and their combination were 72, 18?and 48?hours, respectively compared to 13 days for natural fermentation. Maize flour fermented with Lp + Sc had better quality, flavor and processing properties.
Purification, Identification, and Characterization of Surfactin from Bacillus velezensis 1-3
ZHANG Jun, ZHANG Liang, TANG Wei, SUN Xiaowen, TANG Tao, QIAO Xiaoni, LIANG Meng, HE Zengguo
2023, 44(4):  177-184.  doi:10.7506/spkx1002-6630-20220326-326
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The antimicrobial substances produced by Bacillus velezensis 1-3, a strain with antibacterial activity isolated from oral samples, were separated and purified by ammonium sulfate precipitation, gel filtration chromatography and thin-layer chromatography and were analyzed by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS). These substances were identified as surfactin consisting of three cyclic lipopeptides with 14–16 carbon atoms, whose molecular masses were 1 030.642, 1 044.660 and 1 058.677 Da, respectively. Surfactin could function as a surfactant and exhibited good antimicrobial activity against common pathogenic bacteria in the food, medical and livestock industries. Meanwhile, the minimal inhibitory concentration (MIC) of surfactin against Listeria monocytogenes ATCC 19115 was 4 μg/mL. Surfactin did not show hemolytic activity against mouse red blood cells within the effective antibacterial concentration range. It could endure temperatures at 20–100 ℃ and withstand a wide pH range of 2.0–10.0. Hence, surfactin produced by B. velezensis 1-3 has great potential for applications in the food, medical, and livestock fields .
Correlation between Microorganisms and Volatile Flavor Compounds Stage of Chopped Pepper with Ginger Shreds during Post-Ripening
TIAN Yexin, MU Yingchun, SU Wei, YIN Xuedong
2023, 44(4):  185-193.  doi:10.7506/spkx1002-6630-20220316-187
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The microbial community structure and volatile flavor compounds in chopped pepper with ginger shreds at the post-ripening stage were analyzed by high-throughput sequencing and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively, and the relationship between them was analyzed multivariate statistical analysis. The results showed that Proteobacteria, Firmicutes and Bacteroidetes were identified as the dominant bacterial phyla, and Ascomycetes and Basidiomycetes as the dominant fungal phyla. At the genus level, nine core bacterial genera and 11 core fungal genera were identified. The major bacterial genera identified were Ralstonia, Acinetobacter and Enterobacter, and the major fungal genera identified were Colletotrichum, Penicillium and Fusarium. A total of 87 volatile compounds were identified, including 15 hydrocarbons, 10 acids, 28 alcohols, 3 aldehydes, 11 esters, 5 ketones, 5 phenols, 3 ethers, 2 terpenes and 5 other compounds. Based on Pearson’s correlation coefficient, the correlation between 36 differential volatile flavor substances (P < 0.05, variable importance in the projection (VIP) value greater than 1) and dominant microorganisms was analyzed. It was found that the changes of many flavor substances were significantly correlated with the genera Debaryomyces, Enterobacter and Erwinia. This study will provide data support for improving the quality of chopped pepper with shredded ginger.
Isolation, Purification and Structure Identification of Salty Peptides from Wheat Gluten
WEN Qingyu, ZHANG Yu, Li Tianqi, ZHANG Kangyi
2023, 44(4):  194-199.  doi:10.7506/spkx1002-6630-20220624-278
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The salty enzymatic hydrolysate of wheat gluten was desalted and fractionated into four fractions (F1–F5). F4, which had the highest salty taste and proportion of peptides with molecular mass below 1 000 Da among these fractions, was further fractionated by Sephadex G-15 gel filtration chromatography into five subfractions (P1–P5). Among these subfractions, P2 was found to have the highest content of salty peptides and the strongest salty taste. By liquid chromatography tandem mass spectrometry (LC-MS/MS), the amino acid sequences of P2 were identified as PFGQQ, PFSPQ, QPFP, PDFP and FDDP, with molecular masses of 576.28, 575.28, 488.25, 475.22 and 493.21 Da, respectively. The results provide a theoretical basis for the development of salty peptides from gluten protein.
Breeding of a High-Yield Glutathione-Producing Strain by Atmospheric and Room Temperature Plasma Mutagenesis and Microbial Microdroplet Culture System
LING Siyu, WANG Zhou, ZHANG Huimin, LI Chuang, LIU Qingtao, LIU Yan, XUE Zhenglian
2023, 44(4):  200-208.  doi:10.7506/spkx1002-6630-20220302-040
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In order to improve the ability of a wild-type strain (BY-1) of Pichia pastoris to produce glutathione (GSH), a mutant strain designated BY-1-26 was obtained by atmospheric and room temperature plasma (ARTP) mutagenesis. To further improve the production of glutathione by the mutant during shake flask culture, 1,2,4-triazole was added to the culture medium. Finally, adaptive evolution of the mutant strain was carried out on a microbial microdroplet culture system (MMC) using 1,2,4-triazole as a screening factor. As a result, a high-yield glutathione-producing mutant strain BY-2-24 was obtained, and its genetic stability was investigated. The results showed that a high-yield glutathione-producing mutant strain could be obtained using the wild-type strain BY-1 by ARTP mutagenesis, primary resistance screening on gradient plates, adaptive evolution on MMC and shake-flask secondary screening. The yield of glutathione produced by BY-2-24 in shake flask culture was (312.13 ± 2.62) mg/L, which was 134.26% higher than that produced by the original strain, and this mutant still had good genetic stability after seven passages. Meanwhile, the biomass was increased by 118.33%, indicating that the growth ability of the mutant strain was improved compared to the original strain. The result of this study show that the combination of ARTP and MMC can be used as a simple and effective screening method for excellent mutant strains, which provides a reference for high throughput selection of target strains.
Purification, Identification and Antioxidant Activity of Antioxidant Peptides from Chickpea Protein Hydrolysate
LIANG Xuerong, LU Zhenkang, MAO Xiaoying, WU Qingzhi, ZHANG Jian
2023, 44(4):  209-216.  doi:10.7506/spkx1002-6630-20211214-165
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In this study, an antioxidant peptide was purified from the protein hydrolysate of germinated chickpea by Sephadex column chromatography, and its antioxidant activities were evaluated by determining free radical scavenging capacity, reducing power, lipid oxidation inhibitory effect and protective effect against free radical-induced damage to proteins and DNA. The purified peptide was identified and synthesized to verify its antioxidant activities, and the safety of the synthetic peptide was predicted. The results showed that the antioxidant peptide had good free radical scavenging ability and reducing power, significantly inhibited the autooxidation of linoleic acid, and protected against protein and DNA damage induced by free radicals. It was predicted that the synthetic peptide had no toxicity or allergenicity. In conclusion, the protein hydrolysate of germinated chickpea has antioxidant capacity and can be used to prepare antioxidant peptides, which will improve the utilization value of chickpea.
Component Analysis
Sensory-Guided Analysis and Recombination of Characteristic Flavor Compounds in Vanilla planifolia Andrews
LI Ruili, TIAN Shu, GUO Chunsheng, LI Liqun, CHEN Kang, LIANG Miao, ZHANG Junsong
2023, 44(4):  217-223.  doi:10.7506/spkx1002-6630-20220421-270
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Headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile aroma components of vanilla extract. The characteristic flavor compounds of vanilla extract were analyzed by a sensory-guided approach based on olfactory threshold and odor activity value (OAV) and reconstituted by aroma recombination test. The results showed that 83 aroma compounds were detected in vanilla extract, and 34 aroma components contributing to creamy, sweet, sour, acidic aroma, balsamic, burnt, bean-like and spicy aroma notes were found to be closely related to the characteristic flavor of vanilla extract. According to their OAV values, 14 aroma compounds including vanillin, 4-(ethoxymethyl) phenol, 2-methoxy-phenol, acetic acid, 4-vinyl guaiacol, and vanillin ethyl ether were identified as the key components contributing to the characteristic flavor of vanilla extract. The aroma recombination sample of these characteristic flavor compounds had vanilla-like creamy, sweet, smoked and sour aromas, and could be used to identify the characteristic aroma of vanilla with a sensory similarity of 92.33%, indicating that the 14 characteristic flavor compounds can be used as key indicators for quality control of natural perfumes with the characteristic flavor of vanilla and provide a material basis for the reconstitution of food additives with the characteristic flavor of vanilla.
Changes in Viability and Taste Compounds of Crassostrea gigas during Depuration and Waterless Live Storage
LIN Hengzong, GAO Jialong, LIANG Zhiyuan, QIN Xiaoming, FAN Xiuping, LIN Haisheng, CAO Wenhong, HUANG Yanping
2023, 44(4):  224-231.  doi:10.7506/spkx1002-6630-20211231-366
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To explore the changes in the viability and taste compounds of Crassostrea gigas at different circulation stages after harvesting, the oysters were sampled at different times of depuration, induced dormancy and waterless live storage for evaluation of viability changes in terms of adenosine triphosphate (ATP) related compounds, adenylate energy charge (AEC) and free amino acids and evaluation of flavor quality changes with respect to contents and taste activity values (TAV) of taste compounds. The results showed that the viability and taste compounds of C. gigas were significantly influenced by postharvest transportation and environmental stress. All viability indicators were significantly restored by 24 h depuration, with ATP, AEC and the content of total free amino acids being significantly higher than before depuration (P < 0.05), indicating that the viability reached new levels. During the process from induced dormancy to waterless live storage, more energy substances were required to maintain the balance of the organism under low temperature and hypoxia stress, so all viability indicators were significantly lower than before depuration (P < 0.05) and remained stable at a lower level. Among the taste compounds, the content of umami amino acids increased and the content of bitter amino acids decreased in C. gigas after depuration, and the content of taste amino acids decreased slowly as the waterless live storage time increased. The umami?nucleotides inosine 5’-monphosphate (IMP) and adenosine 5’-monophosphate (AMP) were accumulated throughout the circulation process (P < 0.05); the total amount of organic acids showed a fluctuant downward trend, with the amount of lactic acid being significantly higher after than before depuration (P < 0.05) and showing a decreasing trend from dormancy to the end of waterless live storage (P < 0.05), while the amounts of succinic acid and malic acid showed an increasing trend during waterless live storage (P < 0.05). The levels of Na+ and K+, which play an auxiliary role in the umami taste of C. gigas, were higher after 9 days of waterless live storage than before depuration. The total amount of taste substances did not change overall. The TAV of taste compounds showed that Asp, Glu, Arg, Ala, IMP, lactic acid, succinic acid, Na+ and K+ contributed significantly to the taste of C. gigas. In conclusion, the viability and taste substances of C. gigas can be maintained at a high level by depuration for 24 hours + gradient cooling to induce dormancy + ecological ice temperature waterless live storage for 9 days after harvesting.
Differential Analysis of Aroma Components of Huangguanyin Oolong Tea from Different Geographical Origins Using Electronic Nose and Headspace Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry
SHAO Shuxian, XU Mengting, LIN Yanping, CHEN Xiaomin, FANG Deyin, CAI Jieying, WANG Jinhuan, JIN Shan, YE Naixing
2023, 44(4):  232-239.  doi:10.7506/spkx1002-6630-20220413-160
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To investigate the differences in the quality of Huangguanyin oolong tea from different geographical origins, the aroma composition of Huangguanyin oolong tea produced in Yunxiao and Wuyishan was analyzed by using electronic nose and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The electronic nose data showed that orthogonal partial least squares-discriminant analysis (OPLS-DA) could distinguish Huangguanyin oolong tea from different geographical origins. By HS-SPME-GC-MS, a total of 79 aroma components were identified, of which 17 aroma components were found to be significantly different between the two production regions and therefore could be used to distinguish the geographical origin of Huangguanyin oolong tea. According to odor activity values (OAV), methyl jasmonate, indole, jasmonone, E-nerolidol and jasmonolacton contributed greatly to the floral aroma of Yunxiao Huangguanyin tea, while linalool, decanal, laurelene, isovaleraldehyde and hexanal contributed greatly to the floral and fruit aroma of Wuyi Huangguanyin tea. The results of geographical origin authentication showed that the discrimination accuracy of the support vector machine (SVM) model based on the 17 differential aroma compounds was only 83.33%, compared to 100% based on five important aroma components (linalool, E-lactone, jasmonolactone, methyl jasmonate and indole). Our results will provide useful information for elucidating the quality characteristics of Huangguanyin oolong tea from Yunxiao and Wuyishan.
Effects of Different Cooking Processes on Nutrients and Flavor Substances of Fotiaoqiang, Steamed Abalone with Shark’s Fin and Fish Maw in Broth
LIN Ruirong, YUAN Hongfei, ZHONG Xiaoqing, TANG Shengchun, WU Juanjuan, GUO Zebin
2023, 44(4):  240-246.  doi:10.7506/spkx1002-6630-20220420-252
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In this study, the nutrients and flavor substances of Fotiaoqiang cooked by the traditional and modern cooking processes were evaluated by analysis of physicochemical indicators and the contents of free amino acids and taste nucleotides as well as using an electronic tongue, gas chromatography-ion mobility chromatography (GC-IMS) and principal component analysis (PCA). The results showed that different cooking processes had a significant impact on the fat content of Fotiaoqiang (P < 0.05). Taste-active nucleotides in Fotiaoqiang cooked by the traditional process could better combine with umami amino acids, imparting a better umami taste to Fotiaoqiang. The electronic tongue results showed that Fotiaoqiang cooked by the two processes were different mainly in bitterness and astringency. The GC-IMS results showed that Fotiaoqiang cooked by the traditional process contained more volatile flavor substances than that cooked by the modern process. PCA showed that there were great differences in the composition of volatile compounds between the two cooking processes. The findings of this study can provide a theoretical reference for the development and application of Fotiaoqiang products.
Identification of Characteristic Odorants in Duck Meat by Headspace-Gas Chromatography-Ion Mobility Spectrometry
ZHAO Gaiming, WANG Sen, ZHU Chaozhi, SUN Lingxia, WANG Zhuangzhuang, WANG Xinghui, XIE Wei
2023, 44(4):  247-255.  doi:10.7506/spkx1002-6630-20220420-257
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The characteristic odorants in duck breast, leg and clavicle meat cooked at 60 and 90 ℃ were analyzed by headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and were identified by sensory evaluation, electronic nose measurement and flavor substance evaluation. The results showed that duck breast, leg and clavicle meat cooked at 90 ℃ had a stronger odor than at 60 ℃, and there were differences in the odor characteristics of different groups of duck meat samples, which was also confirmed by electronic nose analysis. A total of 61 volatile flavor compounds were identified by HS-GC-IMS. The types of volatile substances in different groups of duck meat samples were basically the same, but there were differences in their relative contents. Based on the sensory evaluation results and the relative odor activity values (ROAV) of flavor substances, a total of 12 characteristic odorants were identified, including nonanal, octanal, heptanal, decanal, pentanal, hexanal, (E)-2-octenal, (E)-2-heptenal, 2-methyl-butanal, 3-methyl-butanal, 2-heptanone and 1-octene-3-ol. The interaction between these substances contributed significantly to the formation of the odor of duck meat. Due to the differences in the types and contents of odorants, duck meat samples cooked at 60 and 90 ℃ had distinct odor characteristics.
Determination of 11 Water-Soluble Organic Acids in Plants by Online Solid-Phase Extraction Coupled with High Performance Liquid Chromatography-High Resolution Mass Spectrometry
ZHAN Nan, SUN Qing, HAO Ruixia, GUO Feng
2023, 44(4):  256-264.  doi:10.7506/spkx1002-6630-20220328-345
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An analytical method for the determination of 11 water-soluble organic acids (lactic acid, fumaric acid, malic acid, tartaric acid, coumaric acid, gallic acid, citric acid, vanillic acid, ferulic acid, and neochlorogenic acid) in plants by online solid-phase extraction (SPE) coupled with high performance liquid chromatography-quadrupole orbitrap high resolution mass spectrometry (HPLC-Q-Orbitrap-HRMS) was developed. Samples were homogenized, ultrasonically extracted, filtrated, diluted, and purified on an Oasis MAX column (20 mm × 2.1 mm, 30 μm). The analytes were separated on separated on a BEH C18 AX column (100 mm × 2.1 mm, 1.7 μm) by gradient elution using a mobile phase consisting of 0.9% formic acid solution containing 10 mmol/L ammonium formate and 0.9% formic acid in acetonitrile. The MS analysis was performed by full MS/dd-MS2 scanning in the negative ion mode. Quantitation was performed using the internal standard method. Under the optimum conditions, the 11 organic acids were well separated within 9 minutes, and the accurate mass deviation for each compound was less than 5.00 × 10-6. The developed method showed good linearity in the range of 1–100 μg/L with correlation coefficients (R2) greater than 0.999. The limits of detection (LOD) and quantification (LOQ) ranged from 0.1 to 3.2 μg/kg and from 0.3 to 9.6 μg/kg, respectively. The average recoveries of the 11 organic acids in Euryale ferox seeds and pakchoi spiked at two concentration levels were 92.2%–111% and 94.2%–110% with intraday relative standard deviations (RSDs) of 1.4%–4.9% and 0.8%–5.6%, respectively. The method was successfully applied to the analysis of organic acids in white radish, carrot, potato, pakchoi, banana, pear, grape, and E. ferox seeds. This method is simple, fast, accurate, and reliable, and can be used as a new approach for the rapid analysis of water-soluble organic acids in plants.
Safety Detection
Nondestructive Detection of Vegetable Moisture Content and Storage Time Using Microwave Free-Space Reflection Method
LI Chenxiao, REN Yuan, ZHAO Chenyu, HE Xian, YU Xiaoting, XU Yanlei
2023, 44(4):  265-271.  doi:10.7506/spkx1002-6630-20220329-354
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In this study, a radar traveling-standing wave detection device for the rapid and nondestructive detection of the moisture content and storage time of vegetables was designed based on the microwave free-space reflection method. Spatial traveling-standing waves generated by microwave free-space reflection and superposition were explored and the changes in standing wave ratio and the coordinate of antinode as a function of the moisture content and storage time of vegetables were investigated. The results showed that the proposed models had good prediction accuracy. The goodness of fit (R2) of the moisture content prediction models for lettuce and leaf lettuce were 0.979 and 0.959, and the standard errors of prediction (SEP) were 0.310% and 0.641%, respectively. The R2 values of the storage time prediction models for lettuce and leaf lettuce were 0.992 and 0.951, and the SEP values were 0.173 and 0.285 days, respectively. This study provides a new method for nondestructive testing of vegetable quality.
Detection of the Degree of Natural Mildew of Camellia oleifera Fruit Using Visible/Near Infrared, Mid- and Short-Wave Near Infrared Spectroscopy
JIANG Hongzhe, YANG Xuesong, LI Xingpeng, JIANG Xuesong, ZHOU Hongping, SHI Minghong
2023, 44(4):  272-277.  doi:10.7506/spkx1002-6630-20211226-293
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This study explored the feasibility of applying visible and near-infrared (400?1 000 nm), and mid- and short-wave near infrared (900?1 700 nm) spectroscopy for detecting Camellia oleifera fruit with different degrees of natural mildew. The near infrared spectra of the equatorial shady and sunny sides, and the junction surfaces of samples with different degrees of mildew were collected in two wavelength bands. The average spectra were analyzed by principal component analysis (PCA), revealing that samples with different mildew degrees could be clustered into different groups, and the first and second principal components (PC1 and PC2) were effective in distinguishing the samples in each category. The full-spectrum partial least squares-discriminant analysis (PLS-DA) model based on the original spectra performed better than of its counterpart based on the preprocessed spectra. In the selection of characteristic wavelengths, successive projections algorithm (SPA) was found to be superior to PC loadings in establishing the simplified models for both spectral ranges. The correct classification rate and kappa coefficient were 84.4% and 0.766 7 for the prediction set, respectively. Based on the observation of confusion matrices for the prediction set, the specificities of the two optimal simplified models for the prediction of each degree of mildew were equivalent to each other and above 0.84. However, mid- and short-wave near infrared spectra in the wavelength range of 900–1 700 nm provided slightly higher sensitivity (0.72) in classifying samples with moderate degree of mildew. Our study showed that near-infrared spectroscopy could be used to detect the degree of natural mildew of C. oleifera fruit, and visible and near-infrared spectroscopy showed comparable results to mid- and short-wave near infrared spectroscopy. Considering its lower cost, visible and near-infrared spectroscopy has a better application prospect for real-time detection.
Mechanisms for Simultaneous Removal of Formaldehyde and Glyoxal by Amino Acids and Cytotoxicity of Their Products
LIN Jiayu, HUANG Caihuan, ZHENG Jie, LIU Fu, OU Juanying, ZHOU Hua, HU Jiaman, OU Shiyi
2023, 44(4):  278-285.  doi:10.7506/spkx1002-6630-20220224-201
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This study aimed to investigate the mechanisms by which amino acids simultaneously remove formaldehyde and glyoxal and to evaluate the cytotoxicity of their products. γ-Aminobutyric acid or L-alanine was reacted with formaldehyde and glyoxal at a molar ratio of 5:1:1 for 95 ℃, 4 h. The amounts of residual formaldehyde and glyoxal were tested by the 2,4-dinitrophenyl hydrazine (2,4-DNPH) derivatization method. Formaldehyde was found to promote the removal of glyoxal by γ-aminobutyric acid, increasing the removal rate from 55.8% to 70.6%. Similarly, glyoxal could promote the removal of formaldehyde by L-alanine, increasing the removal rate from 2% to 41.3%. The major products were identified as imidazole salts using high-resolution mass spectrometry (HR-MS) and nuclear magnetic resonance spectroscopy (NMR). The reaction mechanism was that the dehydration reaction between one molecule of amino acid and one molecule of formaldehyde took place to form Mannich base, which reacted with one molecule of amino acid to produce an immediate product with two imine groups, attacking glyoxal via nucleophilic addition and finally resulting in the formation of imidazole salts by dehydration reaction. The imidazole salts formed with γ-aminobutyric acid or L-alanine significantly attenuated the cytotoxicity of formaldehyde and glyoxal. Both imidazole salts were detected in commercial and home-made potato chips and biscuits, and their contents could be greatly increased by addition of L-alanine and γ-aminobutyric acid to the raw materials. The results of this study indicated that γ-aminobutyric acid and L-alanine have potential application in the reduction and control of formaldehyde and glyoxal in thermally processed foods.
Comparative Differential Scanning Calorimetric Analysis of Thermal Properties of Bovine and Goat Milk Powder and Identification of Goat Milk Powder Adulteration with Bovine Milk Powder
ZHANG Haoyang, XIAO Yu, QIAO Chunyan, HAO Guo, LI Yan, LIU Yongfeng
2023, 44(4):  286-291.  doi:10.7506/spkx1002-6630-20220412-138
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The thermal characteristics of whole goat and bovine milk powder, prepared by vacuum freeze drying, and goat milk powder adulterated with different proportions (75%, 50%, 25%, 10%, 5%, 3% and 1%) of bovine milk powder were analyzed by differential scanning calorimetry (DSC). The results showed that there were differences in DSC thermal characteristics between whole goat and bovine milk powder. Compared with whole goat milk powder, whole milk powder lacked the characteristic melting endothermic peak (b) of fat, and had lower protein melting endothermic peak (c) temperature and enthalpy value but higher enthalpy value for lactose melting decomposition peak (e). According to the presence or absence of endothermic peak b and its enthalpy value, we could judge whether goat milk powder was adulterated with bovine milk powder at levels below 25% and determine adulteration levels. In conclusion, DSC can be used for the analysis and evaluation of the thermal properties of goat milk powder and milk powder and can also be used as a potential tool for quality assurance and authenticity identification in the dairy industry.
Determination of Chlorpromazine in Livestock and Poultry Meat by Polydopamine@nanosilver Modified Glassy Carbon Electrode Based on Square Wave Voltammetry
ZOU Yuting, DUAN Ningxin, GU Feiyan, HUANG Hongkai, ZHAO Xiaojuan, LIU Gongliang, LUO Zhongrun
2023, 44(4):  292-299.  doi:10.7506/spkx1002-6630-20220411-125
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Based on the self-polymerization reaction of dopamine (DA), a polydopamine (PDA) film was formed on the surface of silver nanoparticles (AgNPs) and glassy carbon electrode (GCE), which could result in uniform dispersion of AgNPs on the surface of GCE. As a result, PDA@AgNPs/GCE modified electrode was obtained. The self-polymerization time of DA and the electrochemical test method and conditions for chlorpromazine were investigated and optimized to establish a rapid method for the detection of chlorpromazine based on square wave voltammetry. The modified electrode was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Under the optimal conditions, the oxidation peak current of chlorpromazine on PDA@AgNPs/GCE had a good linear relationship with its concentration in the range of 5.0 × 10-8–1.0 × 10-5 mol/L (R2 = 0.991). The detection limit (RSN = 3) was 1.7 × 10-8 mol/L. The recoveries of chlorpromazine in spiked pork, chicken and beef samples were 84.9%–88.8%, 79.8%–93.8% and 80.6%–93.9%, respectively. The instrument used in the method was light and portable, and the preparation method of the modified electrode was simple, easy, cheap, and convenient for batch preparation of modified electrodes, and could be used for the rapid detection of chlorpromazine in livestock and poultry meat.
Multiplex Ligation-Dependent Probe Amplification for Simultaneous Detection of Six Allergenic Ingredients in Foods
WANG Mingqiu, LIU Yan, LI Shiyao, DONG Wanting, ZHANG Tao, LIN Jin, ZHU Biting, ZHANG Li
2023, 44(4):  300-305.  doi:10.7506/spkx1002-6630-20220127-283
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A multiplex ligation-dependent probe amplification (MLPA) technique was developed for simultaneous detection of six food allergens: soy, sesame, peanut, almond, hazelnut and walnut. Six pairs of species-specific MLPA probes targeting the internal transcribed spacer (ITS) sequences were designed and synthesized. The probes were hybridized with the target DNA, ligated and amplified by polymerase chain reaction (PCR) and the amplicons were detected using capillary electrophoresis, revealing that they could clearly discriminate the six food allergens. Good specificity of the MLPA system was observed for more than 20 plants, animals and bacteria. The limit of detection (LOD) of the assay was determined to be 5 mg/kg for model cookie spiked with different concentrations of the target species. The applicability of the MLPA assay was demonstrated through the analysis of 30 different commercial products, evidencing good performance in practical applications. Therefore, the MLPA technique is highly specific and sensitive and can provide technical support for the assessment, label management and risk control of food allergens.
A Fluorescent Probe Based on Cu,Fe-N-C Nanozyme with Oxidase-like Activity for Detection of Phthalate Esters
LI Hong, SHI Qiao, CHEN Junfei, WANG Xinrui, TANG Huihua, LI Qiulan, YANG Dezhi, YANG Yaling
2023, 44(4):  306-312.  doi:10.7506/spkx1002-6630-20211213-143
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A simple and sensitive fluorescent probe for the determination of phalic acid ester (PAEs) in fermented foods was developed based on the fact that the oxidase-like activity of Cu,Fe-N-C nanozyme can be regulated by PAEs. After PAEs were adsorbed on the surface of Cu,Fe-N-C, the catalytic oxidation of the substrate o-phenylenediamine (OPD) was accelerated, thus increasing the fluorescence intensity of the generated 2,3-diaminophenazine (DAP). The calibration curve for PAEs showed a good linear relationship in the concentration range of 1.25–50 μg/L. The detection limit of the proposed method was 0.76 μg/L. The recoveries of spiked samples ranged from 88.0% to 104.6%, which meet the detection requirements of the national standard GB 5009.271-2016. This method is simple, stable and rapid, and its detection limit is lower than the national limit for PAEs content in foods.
A Fluorescent Aptasensor Based on Fe3+ Doped Polydopamine Nanospheres for Detection of Deoxynivalenol in Wheat
LU Nian, MA Ji,, CHENG Junhu, SUN Da-wen
2023, 44(4):  313-320.  doi:10.7506/spkx1002-6630-20220228-241
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Objective: A fluorescent aptasensor based on fluorescence resonance energy transfer (FRET) was constructed for the detection of deoxynivalenol (DON) in wheat. The ability of polydopamine nanospheres (PDANS) in the sensor to quench 6-carboxyuorescein (FAM) was improved by doping with Fe3+. Methods: FAM labeled DON aptamer (PDON) was adsorbed on the surface of PDANS (Fe-PDANS) doped with Fe3+ via π-π stacking non-covalent interactions, and Fe-PDANS quenched the fluorescence of FAM through FRET. In the presence of DON, PDON could specifically combine with DON, changing the conformation of PDON, making it difficult to adsorb onto Fe-PDANS, and finally enhancing the fluorescence signal of the sensor for the detection of DON. Results: The aptasensor exhibited a linear range from 0.266 7 to 133.3 ng/mL for DON, and the detection limit was 0.118 2 ng/mL. The results of this aptasensor for DON in positive wheat samples were not significantly different (P > 0.05) from those obtained by enzyme-linked immunosorbent assay (ELISA). Conclusion: The fluorescent aptasensor is characterized by rapid detection, excellent sensitivity, high specificity and good repeatability, which will provide a new method for the detection of DON in wheat.
Grade Identification of Huangjincha Tea 2 by Aroma Fingerprinting Combined with Multivariate Chemometric Analysis
CHAO Jin, ZHOU Lingxin, YIN Feiyan, LUO Qian, ZHAO Mengmeng, YUAN Yong, WU Haoren, LI Pao, JIANG Liwen
2023, 44(4):  321-328.  doi:10.7506/spkx1002-6630-20211202-019
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The aroma components of two grades of Huangjincha tea 2 were investigated by using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) to establish their aroma fingerprints. The results were analyzed using chemometrics. Totally 81 aroma components were identified, 41 of which were common to both. Based on these common aroma components, the two grades could be discriminated by orthogonal partial least squares-discrimination analysis (OPLS-DA), and nine differential aroma components between them were identified including heptanal, limonene, trans-β-ocimene, 1-octanol, (E)-4,8-dimethylnona-1,3,7-triene, trans-nerolidol, 1,10-diepicubenol, epicubenol, and methyl hexadecanoate. A linear discriminant model to distinguish the two grades was established using the differential aroma components as independent variables. The self-validation and cross-validation accuracy of this model were 100%. These results may provide an objective and quantitative reference for the classification of Huangjincha 2.
Detection of Cashew Allergens in Foods by Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry
NING Yawei, YANG Zheng, MA Junmei, LIU Zhuo, CHEN Jia, LI Qiang
2023, 44(4):  329-336.  doi:10.7506/spkx1002-6630-20220411-119
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A quantitative method for the detection of cashew allergens in foods was established based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Cashew samples were extracted, trypsinized, purified, and separated using an Easy nLC 1000 nano-liquid chromatograph, and then data were collected in the full-scan acquisition mode by quadrupole/orbitrap high-resolution mass spectrometry. The scanning results were analyzed by ProteinPilot software search against the UniProt protein database, and the peptide specificity was verified using the basic local alignment search tool (BLAST). Finally, six cashew specific peptides were selected, and actual samples were detected by UPLC-quadrupole/orbitrap MS in the multi-reaction monitoring (MRM) mode. The results showed that the proposed method had good linearity in the range of 0.005–10 mg/mL with correlation coefficients (R2) greater than 0.99. The quantitation limit was 2.5–5 mg/kg and 0.005–0.01 mg/mL for solid-state and beverage matrices, respectively. The average recoveries were 82.5%–109.9%, and the relative standard deviation (RSD) was not more than 8.9%. This method has high sensitivity and specificity, and it can be used for the detection of cashew allergens in six food substrates including biscuit, bread, cake, walnut cookie, chocolate and beverage.
Gold Core@Platinum Shell-Nanozyme-Mediated Magnetic Relaxation Immunosensor for the Rapid Detection of Foodborne Salmonella
DONG Yongzhen, CHEN Rui, WU Zijing, CHEN Yiping, PAN Hui, LIU Mingjun
2023, 44(4):  337-343.  doi:10.7506/spkx1002-6630-20220224-202
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In this study, a magnetic relaxation immunosensor based on gold core@platinum shell (Au@Pt) nanozyme-mediated paramagnetic ion valence transition was constructed and used for the rapid detection of Salmonella in foods. Pt@Au nanozyme with high stability and good catalytic performance was synthesized by a microwave-assisted hydrothermal (MAH) method, and its catalase-like activity was used to catalyze hydrogen peroxide (H2O2). The remaining H2O2 could convert MnO4- into Mn2+ through a redox reaction. The significant difference in magnetic signals between MnO4? and Mn2+ allowed the quantitative analysis of hydrogen peroxide. In the immunoreaction, the concentration of Salmonella was directly proportional to the content of “detection antibody-Pt@Au”. Au@Pt could regulate the H2O2-mediated MnO4?/Mn2+ conversion system and consequently control the change of magnetic signal, ultimately allowing the quantitative analysis of Salmonella. The detection limit of this method for Salmonella was 50 CFU/mL, and the linear range was 1 × 102–5 × 107 CFU/mL. The results of this method for Salmonella in eggs were in good agreement with those of fluorescence quantitative polymerase chain reaction (PCR). This method has the advantages of high sensitivity, good stability, simple operation and low cost, thus having a good application prospect in the rapid detection of foodborne pathogens.