The purpose of this research was to determine the feasibility of milk protein concentrate (MPC), inulin, dextran and their mixtures MPC-inulin (M-I) and MPC-dextran (M-D) as fat replacers for producing low-fat ice cream by instrumental analyses and sensory evaluation. The results showed that no significant differences in the pH, titrable acidity or overrun of ice cream were found between the control and experimental groups. The use of inulin and dextran increased the stability of ice cream mixes, and MPC increased the viscosity and decreased the melting rate. The particle size distribution of ice cream in the dextran group was similar to that of the control group whereas the MPC, inulin and M-D groups showed smaller particle size with narrower range distribution. Dynamic rheological parameters at both frequency and temperature sweeps showed that the M-I and M-D groups were closer to that of the control. Sensory evaluation showed that the M-I and M-D groups had better fat-like mouthfeel. The regression model obtained by regression analysis based on overall mouthfeel and temperature-dependent dynamic rheological parameters will be useful for evaluation of the applicability of fat replacers in low-fat soft ice cream.

Oleogels were formed by adding cinnamic acid to canola oil, corn oil and flaxseed oil, followed by heating, stirring and cooling. Our aim was to analyze the effect of oil type on the critical concentration, oil binding capacity (OBC), hardness, solid fat content (SFC), X-ray diffraction (XRD) pattern as well as microstructure of oleogels. The results showed that oil type had no significant effect on the critical concentration of oleogels (4%, regardless of oil type) but influenced OBC; for each of the oils, OBC increased with increasing concentration of cinnamic acid. The different oils had a significant effect on the hardness of oleogels and among them, canola oil and flaxseed oil oleogels had the lowest and highest hardness, respectively. The SFC of three oleogels was in the increasing order of canola oil < corn oil < flaxseed oil. At the same time, crystallographic analysis showed that the major crystalline forms of all three oleogels were β and β’. Significant differences in the microstructure and crystal distribution of these oleogels were characterized by polarized light microscope, indicating that oil type had a significant effect on the microstructure of oleogels.

The specific volume and texture properties of steamed bread and the secondary structure of gluten were determined by a volume meter, a texture analyzer and Fourier transform infrared (FTIR) spectroscopy, respectively. The effects of fermentation time on bread quality and gluten protein structure were investigated. The results showed that β-sheet was the dominant secondary structure for both the glutenin and gliadin in steamed bread. The contents of β-sheet and α-helix in the gliadin did not significantly change with fermentation time, whereas random coil gradually decreased and β-turn increased; the intensity of the hydroxyl absorption band was gradually increased, and the hydration of the gliadin was enhanced. For the glutenin, the contents of α-helix and random coil changed little; β-sheet content increased first and then decreased while the opposite was observed for β-turn. The intensity of the hydroxyl absorption band gradually declined. The peaks at 1 082 cm-1 and 1 155 cm-1 in the FTIR spectrum of the glutenin disappeared at 80 min of fermentation, which may be attributed to the weakened C–C vibration of the protein ring structure

The heteroaggregation and transglutaminase-induced aggregation of whey protein isolate (WPI) and lactoferrin (LF) emulsions were investigated in order to improve the rheological properties of the system. WPI and LF emulsions were prepared by microfluidization and the heteroaggregation of emulsion droplets occurred when they were mixed together. After addition of transglutaminase, aggregates were formed by cross-linking, which led to a specific three-dimensional network structure. The mixed 50% LF-50% WPI emulsions showed the greatest degree of aggregation and highest physical stability. Compared with the single WPI and LF emulsions, heteroaggregation enhanced the rheological properties of 50% LF-50% WPI aggregates to 3.72 and 2.2 times, respectively. Notably, the viscosity was increased to 11.4 times through transglutaminase cross-linking. Therefore, it was of great value to improve the rheological properties of food systems by combing heteroaggregation and enzymatic cross-linking. The results of this study will lay a theoretical foundation for developing food lipid substitutes.

Abalone muscle polysaccharide (AMP) was prepared from the muscle of Haliotis discus hannai Ino by protease hydrolysis combined with fractional precipitation with gradient concentrations of ethanol. Three fractions (AMP-1, AMP-2 and AMP-3) were obtained by DEAE-52 column chromatography. Their physicochemical properties and antitumor activity were investigated. The results of chemical composition suggested that the total sugar content of AMP was 83.9%, while the total sugar content of AMP-1 was 83.8%, which was higher than that of AMP-2 (62.5%) and AMP-3 (31.6%). Monosaccharide composition analysis suggested that AMP was mainly composed of Glc, AMP-1 was almost exclusively composed of Glc, and AMP-2 and AMP-3 were mainly composed of Glc and Gal together with hexosamine. Based on the results of chemical composition as well as ultraviolet spectroscopic and Fourier transform infrared spectroscopic analyses, AMP-1 was α-pyranose with high purity, while AMP-2 and AMP-3 might be glycoprotein. The results of iodine staining indicated that AMP-1 was a non-starch glucan. Scanning electron microscopy showed that AMP and AMP-1 had a lamellar structure, while AMP-2 and AMP-3 contained many spherical particles. Furthermore, AMP and AMP-1 showed a strong inhibitory activity against both human breast cancer cell line MDA-MB-231 and human liver cancer cell line HepG2.

In this paper, non-covalent binding (pH 7.4, 2 h) and covalent cross-linking (pH 9, 24 h) were used to analyze the variations of protein conformations in soybean protein isolate (SPI)-anthocyanins complexes. The changes in protein structure in the composite systems were studied by turbidity measurement, binding capacity, gel electrophoresis analysis, fluorescence spectroscopy and infrared spectroscopy. The results of gel electrophoresis showed the formation of macromolecular derivatives in complexes 4, 5 and 6 (SPI/anthocyanins ratio = 20:1, 10:1, 5:1, m/m) by covalent cross-linking. The turbidity values of the covalently cross-linked complexes were lower than that of the non-covalently bound ones (1, 2 and 3), and the affinity of the anthocyanins in the covalently cross-linked complexes were stronger. The fluorescence intensity of the proteins was decreased with the increase of anthocyanins in complexes and tryptophan residues were exposed to a more hydrophilic environment. This finding suggested that the fluorescence quenching effect of the covalently cross-linked complexes were obvious. Covalent cross-linking was greater than non-covalent binding; the infrared absorption intensities of the proteins in complexes 1 and 4 were significantly decreased, indicating that the secondary structure of the proteins is changed. In addition, the contents of β-turn and irregular structure in sample 4 were higher, indicating that the covalent cross-linking mechanism of anthocyanins in the complex reveals a stronger ability to unfold the proteins.

This study was implemented to investigate the effect of heat treatment under acidic condition on the rheological and structural characteristics of pectin and to unravel the underlying mechanism. After heat treatment under acidic condition, changes in the apparent viscosity and rheological properties of high-molecular-mass pectin from pomelo peel were examined as well as changes in some physicochemical measurements such as galacturonic acid content, degree of esterification and molecular mass distribution. We also investigated the structural changes of the pectin molecule using an atomic force microscope (AFM). The results obtained showed that the apparent viscosity and consistency coefficient of the pectin declined significantly during 0–100 min of heat treatment at 85 ℃ and pH 3.7 (P < 0.05), while the flow behavior index n increased significantly (P < 0.05). Nonetheless, there was no significant change in galacturonic acid content, degree of esterification or molecular mass distribution (P > 0.05). Moreover, the pectin molecule was changed from a dispersive and unfolded state to an aggregate state, altering the spatial structure and consequently the apparent viscosity and rheological properties and attenuating the thickening effect of the pectin.

The glutelin from litchi juice was purified using the Osborne sequential protein extraction method, and its molecular mass distribution, thermal stability and secondary structures were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), differential scanning calorimetry (DSC) and infrared (IR) spectroscopy, respectively. The results showed that the glutelin had a large molecular mass and contained approximately 10 bands, most of which had a molecular mass of 50 kDa or above. After reduction, a few bands with higher molecular mass disappeared and new bands with smaller molecular mass (mostly including 50 kDa) appeared. The surface hydrophobicity was evaluated by SDS-binding capacity. The glutelin could bind (74.25 ± 5.26) μg of SDS per mg sample, and its contents of free sulphydryl group, total sulphydryl group and disulfide bond were (29.83 ± 1.72), (40.59 ± 2.04) and (5.38 ± 0.18) μmol/g, respectively. Its denaturation peak temperature was 105.24 ℃. The major secondary structures were β-sheet and β-turn, accounting for 33.92% and 64.7%, respectively. Hence, we can infer preliminarily that the composition of glutelin in litch juice is complex, mainly containing high-molecular-weight glutelins, which have strong surface hydrophobicity, low disulfide bond content and good thermal stability.

The purpose of this study was to investigate the influence of antifreeze proteins (AFPs) on protein characteristics and the states of water in frozen dough during frozen storage and freeze-thaw cycles by using Ellman’s colorimetric method, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Results showed that the free sulphur content in frozen dough rose while the disulfide bond content decreased after frozen storage and freeze-thaw cycles. Adding AFPs had no effect on the protein subunits. With increasing frozen storage time, the content of intermolecular β-sheet increased whereas the content of β-turn structure dropped. Freeze-thaw cycles decreased the content of α-helix structure. Frozen dough with added AFPs showed smaller changes in all protein characteristics compared with the control sample with no added AFPs. The water loss rate in the control sample remarkably increased; the relaxation time T21 became greater with frozen storage time and the bound water content decreased. These findings illustrate that AFPs could inhibit disulfide bond rupture and changes in protein secondary structure, restrain the recrystallization of ice crystals, prevent water loss from the dough, and maintained the water-holding capacity of the dough.

This experiment aimed to study the effect of partially replacing nitrate with mixed fruit and vegetable slurries on the formation of N-nitrosamines in fermented sausages for the purpose of exploring its feasibility in fermented sausage production. In this study, four groups of fermented sausages, negative control group (NCG, blank group), positive control group (PCG, 0.3 g/kg nitrate and 0.55 g/kg sodium ascorbate without fresh fruit or vegetable slurry), celery plus cherry group (CCG), and cabbage plus tomato group (CTG), were set up. The changes in nitrite, nitrosamines and biogenic amines during fermentation and maturation were investigated. The results obtained were as follows: 1) During the fermentation process, the nitrite content in CCG, CTG and PCG increased firstly and then decreased, and the maximum value (65.52 mg/kg) of nitrite in CTG was significantly lower than that (105.31 mg/kg) in PCG. N-nitrosodiethylamine (NDEA) was detected in all four fermented sausages, while the NDEA content in CCG and CTG (1.23 μg/kg and undetectable) was significantly lower than that (3.72 μg/kg) in PCG; 2) The nitrite content in CTG (36.45 mg/kg) and CCG (47.97 mg/kg) was significantly higher than that in NCG (24.49 mg/kg) and PCG (31.40 mg/kg) at the early ripening stage but decreased to below 30 mg/kg (the national standard limit) in CCG and CTG after 3 days of ripening. The total biogenic amine content in four groups was in the following decreasing order: NCG > PCG > CCG > CTG. Histamine and tyramine were not detected in CTG. The contents of NDMA (N-nitrosodimethylamine) and NDEA in all groups with the exception of PCG increased gradually during the ripening process. The contents of NDMA (0.16 and 0.11 μg/kg) and NDEA (4.33 and 4.13 μg/kg) in CCG and CTG were lower than those (1.73 and 9.50 μg/kg) in NCG, but were equivalent to those (0 and 4.74 μg/kg) in PCG at the end of the ripening process. Hence, our results confirmed the feasibility of partial replacement of nitrate with mixed fruit and vegetable slurries to reduce the contents of N-nitrosamines and biogenic amine in fermented sausage.

In this study, the emulsion formed during enzyme-assisted aqueous extraction of soybean oil was investigated at different hydrolysis times (1, 2, and 3 h) and enzyme dosages (1% and 2%). The mechanism of action of oil droplets in the emulsion was elucidated to explore the structural features and intermolecular interactions. The degree of hydrolysis (DH), microscopic observation, zeta-potential, fluorescence spectroscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles were determined. The results showed that the DH of the emulsion was about 7%. As a result, the protein in the emulsion was broken down into small peptides, resulting in reduced affinity between oil and protein, droplet aggregation and decreased absolute value of zeta potential. Large protein aggregates linked by disulfide bonds appeared on the SDS-PAGE. In addition, the fluorescence intensity of the emulsion was obviously weakened as compared to soybean protein isolate (SPI) under the same hydrolysis conditions, which may be attributed to the presence of phospholipids, the interaction between tryptophan residue and oil and the disulfide-linked aggregates.

In this research, the interaction between anthocyanin extracted from black bean coats and iron ions [Fe(II) and Fe(III)] was investigated by UV-visible absorption and fluorescence quenching spectrocopy. The effects of anthocyanin extract on the stability and solubility of iron ion were studied. The presence of iron ions changed the UV-visible absorption spectra of anthocyanins at the experimental pH values. Fluorescence quenching spectra showed the complexes formed between anthocyanins and iron ions. Anthocyanins were capable of protecting Fe(II) from being oxidized and improving the solubility of Fe(III).

This study aimed to verify the impact of moisture distribution status on thermal characteristics of starch from newly harvested maize. Two maize cultivars in northeast China, Zhengdan 958 and Xianyu 335, were used in this study. Low field nuclear magnetic resonance (LF-NMR) and differential scanning calorimeter (DSC) were applied to study changes in water migration and distribution status in maize kernels during 60 days of postharvest storage and changes in thermal characteristics of maize starch were also examined. The results showed that the relaxation time (T2) and water distribution changed significantly (P < 0.05) during the postharvest storage period. For both cultivars, the melting enthalpy of maize starch gels reached a maximum value of 18.54 and 15.06 J/g at 40 d after harvest, respectively. There was a significantly negative correlation between the relative area (A21) and the relaxation time (T21) of bound water and moisture content of maize grains (P < 0.01). In addition, A21 was significantly correlated with endothermic enthalpy (ΔH) of starch gels (P < 0.05). Accordingly, changes in the crystal structure of starch may be partly related to water migration and distribution status. LF-NMR can effectively analyze the dynamic changes of moisture during the postharvest storage of maize and its effect on the functional properties of starch.

The effect of lowering levels of NaCl addition (2.5%, 2.0%, 1.5%, and 1.0%) on the physicochemical and quality characteristics of Harbin dry sausages was investigated by measuring moisture content, water distribution, salt content, color, shear force, thiobarbituric acid reactive substances (TBARS) and total bacterial count as a function of fermentation time. Our aim was to produce reduced salt sausages. The results showed that the moisture content, water activity (Aw), L* value, TBARS value and total bacterial count of the sausages with lower levels of NaCl addition were significantly higher (P < 0.05) during the initial fermentation (0–6 d), whereas a* value, pH value and shear force were significantly lower (P < 0.05). During the late fermentation stage (6–12 d), the moisture content, Aw, pH value and L* value of the sausages with lower levels of NaCl addition were significantly lower (P < 0.05) while the shear force, TBARS value and total bacterial count were significantly higher (P < 0.05). There was no significant difference in a* value among all sausages (P > 0.05). Additionally, low field nuclear magnetic resonance (LF-NMR) analysis showed that the relaxation time (T21) of immobilized water in all sausages were faster with fermentation time, and the relaxation time of sausages with lower levels of NaCl addition was significantly faster (P < 0.05). Finally, sensory evaluation showed that the sausage with 2% NaCl presented the best overall acceptance with a moderate salinity. To sum up the optimal level NaCl addition to Harbin air-dried sausages was 2.0%.

The use of one-factor-at-a-time method in conjunction with response surface methodology was investigate to optimize the process parameters of ultrasonic-assisted bromelain treatment for tenderizing duck meat. Moreover, the mechanism underlying meat tenderization was explored. The optimized conditions were obtained as follows: temperature 45 ℃, pH 7.2; bromelain concentration, 350 U/g, ultrasonic power 80 W and tenderization time 15 min. Under these conditions, the predicted and measured shear force were 20.208 and 21.110 N, respectively. The tenderized meat presented a significant increase in pH, water-holding capacity and myofibrillar fragmentation index (MFI) and a significant decrease in shear force, myofibrillar protein solubility and insoluble collagen content compared with the untreated meat (P < 0.05), but the color was not significantly changed (P > 0.05). SDS-PAGE results indicated that macromolecular proteins of the treated duck muscle were hydrolyzed into small peptides and/or amino acids. Transmission electron microscopy (TEM) revealed that myofibrillar Z lines were broken and dissolved, sarcomeres were deformed and shortened, with the I and A bands becoming blurred, and myofibrillar fragmentation occurred. Ultrasonic-assisted bromelain treatment had a significant effect on tenderizing duck meat and greatly reduced the tenderization time, and the tenderized meat was juicy and elastic and had greatly improved quality.

Acidic and enzymatic extraction methods were separately used to extract collagen from yak bone and the physicochemical properties of the obtained collagens were compared. Their amino acid compositions were analyzed and their structures were determined by using UV spectroscopy, Fourier transform infrared spectroscopy (FTIR), heat shrinkage temperature, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscopy (SEM). The extracts were characterized as collagens, showing maximum UV absorption peak at 230 nm. The heat shrinkage temperatures of acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) were 40.12 and 40.94 ℃, respectively, and their denaturation enthalpies were 0.25 and 0.22 J/g, respectively. FTIR and SDS-PAGE analyses demonstrated that ASC and PSC were mainly composed of α, β and γ subunit components, which both belonged to type I collagen with a complete three-strand helical structure. SEM revealed that ASC and PSC retained a relatively complete fibrous network structure, but the structure of ASC was more evenly distributed. There was no significant difference in the physiochemical properties of the two collagens, while the enzymatic extraction method gave a higher yield of collagen but was more expensive than acidic extraction.

In this paper, the effect of three different treatments: atmospheric pressure cooking, high pressure cooking and sequential enzymatic hydrolysis with cellulase followed by flavorzyme on the release of flavor compounds from the edible straw mushroom Volvariella volvacea. Soluble sugar, organic acid, 5’-nucleotide, free amino acid composition and molecular mass distribution of peptides in the hydrolysates were measured. The results showed that the total amount of soluble sugar in the mushroom homogenate was significantly decreased after atmospheric pressure cooking, while high pressure cooking hardly altered the total content of soluble sugar and sugar alcohol. The enzymatic treatment significantly increased the soluble sugar content. The total organic acid content was significantly increased after cooking, but significantly decreased after enzymatic hydrolysis. All three treatments especially high pressure cooking could elevate the total free amino acid content; the contents of umami amino acids, sweet amino acids and bitter amino acids were all significantly after high pressure cooking, and the amount of peptides higher than 3 000 Da was reduced after both cooking treatments. The high pressure cooked sample contained the highest content of peptides lower than 3 000 Da and was an important source of taste peptides. Thus different treatments showed significant differences in the release of taste compounds from the mushroom, and proper treatment should be used depending on the desired flavor substances.

The objective of this study was to investigate the effects of coumarin at various concentrations (0, 0.03, 0.06, 0.09, 0.12, and 0.15 g/100 mL) on physical properties and microstructure of edible films from tilapia scale gelatin. The results showed that the addition of coumarin did not affect the thickness and water content of the gelatin film, but significantly decreased the water vapor permeability (WVP). When coumarin was added at 0.09 g/100 mL, the WVP was lowest. The tensile strength (TS) and elongation at break (EAB) increased first, reaching the maximum at a coumarin concentration of 0.09 g/100 mL, and then decreased with the increase of coumarin addition. Differential scanning calorimetry (DSC) analysis showed that coumarin had good compatibility with the gelatin film, and could remarkably improve its glass transition temperature (Tg). The results of scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) showed that the cross-linking effect of coumarin and gelatin increased with increasing concentration of coumarin in the range of 0–0.09 g/100 mL, making the film surface smoother and more compact. With further increasing coumarin, the performance and structure of the gelatin composite film were deteriorated. Addition of coumarin effectively reduced the UV and visible light transmittance of the gelatin film. These results showed that coumarin at 0.09 g/100 mL holds promise for the development of packaging materials with better moisture resistance, higher mechanical properties and smoother surface.

The objective of this work was to explore the inhibitory effect of oligomeric procyanidins of lotus seedpod (LSOPC) on the formation of advanced?glycation?end?products?(AGEs) in a simulated physiological environment. The percentage inhibition of AGEs by LSOPC in the presence of metal ions, high glucose and high protein concentration was determined and the inhibitory effect of LSOPC complexes with epigallocatechin gallate (EGCG) on the formation of AGEs was evaluated. The?results?showed?that?the?optimal?incubation time to obtain the highest inhibitory effect of LSOPC was 35 d. Inhibitory effects on AGEs formation varied depending on the type and concentration of metal irons added. Cu2+ and Fe2+ had the highest promoting effects on AGEs formation and could work together with LSOPC. Five other metal irons had different inhibitory or promoting effects on AGEs formation but hardly influenced the effect of LSOPC. We also found that LSOPC had the lowest inhibitory effect at high concentrations of both BSA and glucose or at high concentrations of BSA. Additionally, LSOPC in combination with EGCG showed a potent synergistic inhibitory effect and the optimal effect was obtained at a ratio of 2:1.

In this paper, soybean protein isolate (SPI) and oligosaccharides (raffinose and stachyose) were used to prepare a mixed aqueous solution. The phase behavior and microstructure of the composite system were studied at varying pH from 3.0 to 10.0 in order to determine the generation conditions of soluble electrostatic complex and its influence on the emulsifying properties of SPI. The results of zeta potential, confocal laser scanning microscope and turbidity measurement showed that SPI and oligosaccharides could form an electrostatic complex under acidic conditions. Moreover, the isoelectric point of the complex shifted toward acidity compared to SPI. The intrinsic fluorescence spectra illustrated that the fluorescence intensity of the complex was lower than that of SPI, and it showed a more significant decrease with stronger electrostatic interaction. This research also indicated that SPI and oligosaccharides could form soluble electrostatic complexes at pH 6.0, whose functional properties were improved compared to SPI. The emulsifying capacity of SPI-stachyose and SPI-raffinose complexes were increased by 50.66% and 39.69% compared to that of SPI.

The objective of this study was to evaluate the effect of potato starch and transglutaminase (TG) on the functional properties (gelling and emulsifying properties) of myofibrillar protein from common carp muscle. potato starch was added at 0%, 1%, 2%, 3%, and 4%, and transglutaminase (TG) at 0%, 0.10%, 0.30%, 0.50%, and 0.70%. Heat-induced gels were formed at different temperatures (60 and 70 ℃). Changes in protein profiles were measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as well. Results indicated that gel hardness and springiness significantly increased with potato starch and transglutaminase content at the same temperature (P < 0.05). No significant difference in gel whiteness was observed at different temperatures (P > 0.05). Water holding capacity of gels was increased at higher temperature. The additives markedly affected the emulsion stability but not the emulsifying activity of myofibrillar protein, which initially increased and then decreased with increasing contents of the additives. When potato starch and transglutaminase were added at 2% and 0.5%, respectively, emulsifying stability index (ESI) reached a maximum value of 94.5%. SDS-PAGE showed that the addition of potato starch and TG could weaken the intensity of myosin heavy chain and actin band, thereby significantly affecting protein structure and functional properties.

In order to explore the effects of different emulsifiers on moisture migration and thermodynamics in fresh noodles during shelf-life, fresh noodles with sodium stearyl lactate (SSL), β-cyelodextrin (β-CD) and no emulsifier (control) were examined for water distribution and migration, microstructure and thermodynamic properties by low-field nuclear magnetic resonance (LF-NMR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results showed that the bound water content (A21) and immobilized water content (A22) of fresh noodles diminished, while the free water content (A23) increased during 7 d of storage at 4 ℃. The addition of SSL and β-CD increased A21 and A22 (P < 0.05), decreased A23 (P < 0.05) and elevated the T21 (bound water) and T22 (immobilized water) relaxation time compared with the control group; SSL showed a greater increase in both T21 and T22 than β-CD. Both emulsifiers decreased the T2 relaxation time in fresh noodles after 7 d storage (P < 0.05) and their effects were significantly different (P < 0.05). The recrystallization melting onset temperature (T0), peak temperature (Tp) and aging enthalpy (ΔH) increased during the 7 d storage period. The emulsifiers slowed the rate of increase in T0, Tp and ΔH (P < 0.05), and they decreased ΔH from (1.81 ± 0.05) J/g to (1.37 ± 0.12) and (1.31 ± 0.04) J/g, respectively. Noodles with SSL and β-CD showed a smooth microstructure and a uniform water distribution, and exhibited more stable gluten structure than the control group. SSL was closely bound to protein, and β-CD was incorporated into starch.

In the study, we investigated the effect of addition of five different clarifying agents: soy protein, gelatin, bentonite, casein and polyvinylpolypyrrolidone (PVPP) after natural clarification of sparkling base wine (Chardonnay) on its clarity, physicochemical parameters, flavor compounds and sensory quality. The results showed that the clarification treatments could significantly increase the transmittance and decrease the color intensity of wine (P < 0.05). While alcohol content in the treated wine was not significantly changed, volatile acids, total acid, residual?sugar and total phenols were decreased by 0.18–0.30, 0–0.09, 0.25–1.20 and 0.05–0.21 g/L, respectively. No significant differences in the contents of total acids, volatile acids and total phenols were found among all the treatments except that bentonite and casein had a greater effect on total sugar content. In addition, the types and amounts of aroma components in the wine samples were decreased after clarification. However the amount of volatile compounds in the wine treated with soy protein was obviously higher than in other groups, which was testified by principal component analysis. The wine treated with soy proteins at 200 mg/L exhibited good visual appearance and aroma and its sensory evaluation score was closest to that of the control, indicating that soy protein, a new type of plant protein clarifying agent, can be used for the clarification of sparkling base wine.

The extraction of crude polysaccharides (YP) from the tubers of Habenaria ciliolaris Kranzl was performed by hot water extraction and alcohol precipitation. DEAE cellulose 52 ion exchange column and Toyopearal HW-65 gel filtration column chromatographies were successively used to separate and purify the crude polysaccharides, yielding four fractions: YP1-1, YP2-1, YP2-2 and YP3-1. The purities and molecular masses of the purified polysaccharides were determined by high performance liquid chromatography (HPLC) with evaporative light-scattering detection and their structures were investigated by Fourier transform infrared (FT-IR) spectroscopy, ultraviolet (UV) spectroscopy, and HPLC. The monosaccharide composition was determined by HPLC with precolumn derivatization. The in vitro bile acid-binding capacity of these polysaccharides was evaluated in a simulated intestinal environment. The results showed that the yield of YP was 2.41% and the total sugar content of YP was 96.35%. YP1-1, YP2-1, YP2-2 and YP3-1 were purified to homogeneity and did not contain nuclear acid or protein. Their molecular masses were 3.52 × 106, 3.08 × 106, 1.93 × 106 and 3.35 × 106 Da, respectively. The four polysaccharides mainly contained pyranose rings connected through β-glucoside bonds. Monosaccharide composition analysis demonstrated that YP1-1 and YP3-1 were composed of rhamnose, arabinose, mannose, glucose, and galactose while YP2-1 and YP2-2 were composed of rhamnose, arabinose, mannose, glucose, galactose, and fucose. All four polysaccharides exhibited strong ability to bind bile acid.

Bifidocin A is a novel bacteriocin produced by Bifidobacterium animalis BB04 with antimicrobial activity against a wide range of foodborne bacteria. The objective of this study was to investigate the quorum-sensing regulation behavior of bifidocin A production in B. animalis BB04. The correlation between cell density and bacteriocin production was analyzed by monitoring the cell growth and bacteriocin antimicrobial activity during the fermentation process. Using a low bacteriocin culture model system, the presence of auto-inducing peptide and quorum-sensing system related to bacteriocin production were analyzed. The auto-inducing peptide was purified by ultrafiltration, Sephadex G25 chromatography and HPLC, and its molecular mass was determined by matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF-MS). Results showed that bifidocin A began to be synthesized when the cell density reached 7.31 (lg (CFU/mL)), and the bacteriocin production depended on cell density. In the low bacteriocin culture model system, the culture temperature was 37 ℃, the initial pH value of culture medium was 5, the concentration of culture medium was 1/10 modified MRS, the inoculum quantity was 1%, and the incubation time was 24 h. The auto-inducing peptide was detected in the fermentation supernatant and it mediated the regulation of bacteriocin production by the quorum-sensing system. The molecular mass of the purified auto-inducing peptide was 3 587.253 Da.

In this study, Zygosaccharomyces rouxii was cultured in hypertonic medium (80% sugar content) and basic medium, respectively. Optical density was monitored by a UV-Vis spectrophotometer for examining the growth of Z. rouxii. The intracellular materials were identified by silylation derivatization-gas chromatography-mass spectrometry (GC-MS). The extracellular substances were identified by head-space solid phase micro-extraction (HS-SPME) coupled to GC-MS. The data were analyzed by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The results showed that the OD value of Z. rouxii increased logarithmically with culture time in high glucose medium. Thirty-six and 47 extracellular substances were identified from Z. rouxii at the logarithmic phase in high glucose medium and basic medium, respectively, and 45 extracellular substances were produced by Saccharomyces cerevisiae at the logarithmic phase in basic medium. Under hyperosmotic conditions, Z. rouxii mainly produced alcohols and esters, but did not produce ketones. The three samples were clearly discriminated by PCA, indicating significant differences among them. Both the R2 and Q2 of the PLS-DA model were close to 1, indicating high reliability. The characteristic substances of Z. rouxii under hypertonic condition including 7-octenoic acid ethyl ester, 3-(methylthio) propyl acetate, 2-tridecanol, pentadecanoic acid 3-methylbutyl ester, 9-decenoate, 3-(methylthio)-1-propanol, 2-decanol were selected based on variable importance in the projection (VIP) value. 83 intracellular components were identified, and 23 of these compounds were detected to present in both cultures. A total of 27 intracellular substances were found to exhibit significant differences between these two cultures, suggesting that Z. rouxii is able to withstand high osmotic pressure by producing some sugars, alcohols, acids and other substances involved in sugar metabolism and energy metabolism. The results of this study can provide a theoretical basis for further insights into the resistance of Z. rouxii to osmotic pressure.

An analytical method for cysteine sulfonate by high performance liquid chromatography (HPLC) was established and applied to determine the activity of cysteine dioxygenase in different marine organism tissues. Cysteine sulfinate was subjected to 3 min pre-column derivatization with o-phthalaldehyde (OPA) at a molar ratio of 1:2. The separation was performed on an Agilent Eclipse XDB-C18 using a mobile phase composed of methanol and sodium acetate (8:2, V/V) at a flow rate of 1 mL/min. The analyte was detected at 315 nm. The calibration curve showed a good linearity (R2 > 0.99) in the concentration range of 10–400 μg/mL. The relative standard deviations (RSDs) for parallel samples were 0.9%–6.4% and the retention time was 1.46 min. Using this method, cysteine dioxygenase activity was detected to be present in marine shellfish, crab, shrimp and fish, with the highest activity being observed in Penaeus vannamei. Among different tissues of fish, the highest activity of cysteine dioxygenase was detected in the liver, while the lowest was found in the gill.

According to the codon preference of Escherichia coli, the β2 adrenergic receptor (β2AR) gene sequence was designed and synthesized. Then the E. coli-based cell-free protein synthesis (CFPS) system and MagneHis? Ni-Particles were used for efficient expression and purification. The purified receptor was identified by SDS-PAGE analysis and enzyme-linked receptor assays (ELRA). The results indicated that the codon adaptation index (CAI) of the optimized β2AR gene was 0.96 and its GC content was decreased from 58% to 46.17%, favoring its expression in E. coli. The optimal Mg2+ concentration in the expression system was 22 mmol/L, leading to the maximum protein expression of 1 250 μg/mL. SDS-PAGE revealed the specific band of the purified protein of 47 kDa with a purity of over 90% as expected. The results of direct ELRA showed that when the plates were coated with the receptor at 1:500 dilution, the OD values of the purified receptor binding to three horse radish peroxidase (HRP)-β-agonists decreased in the following order: clenbuterol, salbutamol, and ractopamine, which were 0.976, 0.836 and 0.728, respectively. β2AR was successfully synthesized by using the CFPS system, which will provide a theoretical and practical foundation for the rapid multi-residue determination of β-agonists based on the receptor.

In this study, 15 strains of endophytic bacteria were isolated from healthy Dangshan pear. Out of these, one isolate, designated DSL-9, was screened for its strong inhibitory activity against Colletotrichum gloeosporioides. This strain was tentatively identified as Bacillus subtilis based on its morphological characteristics and 16S rDNA sequence. The results showed that the antifungal effect of strain DSL-9 was mediated mainly by the extracellular compounds secreted by it. A crude protein extract from DSL-9 was obtained by ammonium sulfate precipitation. The antifungal activity of the extract was not significantly changed at 30–60 ℃ but was decreased at temperatures higher than 60 ℃. In the pH range of 7 to 10, high antifungal activity was obtained without significant changes. Ultraviolet (UV) light had no significant influence on the antifungal extract. After protease treatment, the antifungal activity was declined. DSL-9 could improve resistance to C. gloeosporioides in Dangshan pear as reflected by its effect on defense enzyme activities in infected pear fruits. B. subtilis DSL-9 will have potential application in biological control of C. gloeosporioides in Dangshan pear.

A precise method for the determination of changes in the molecular mass of dextran and the quantification of sucrose, fructose and glucose concentration during the dextransucrase-catalyzed reaction of sucrose was presented in this paper. High performance gel filtration chromatography (HPGFC) with one column and with two tandem columns were compared for their efficiencies in the determination of dextran standard and the catalytic reaction products in order to develop a robust method to measure the molecular mass of dextran. By dextransucrase combined with two-stage membrane treatment, we investigated the mechanism underlying dextran synthesis. It was found that the synthesis process was continuous aggregation of glucosyl group at the active site of dextransucrase until reaching a specific molecular mass (> 106 Da) before detachment rather than stepwise aggregation and then detachment.

The contents of taste components in the belly, dorsal meat and red meat of grass carp frozen by different methods: quick freezing at ?40 ℃, liquid alcohol freezing at ?20 ℃, and static air freezing at ?20 ℃ were determined and compared by high performance liquid chromatography (HPLC), amino acid auto-analyzer and electronic tongue. The lactic acid content of fish meat was also determined. The results were obtained as follows. The freezing methods had an influence on fish freshness and taste components. The freezing rate was positively correlated with the contents of inosine monphosphate (IMP), adenosine monophosphate (AMP) and total free amino acids, whereas it was inversely correlated with lactic acid, insoine (HxR) and hypoxanthine (Hx). Fish samples frozen by the first and third freezing methods showed the lowest and highest K values (freshness index) after 3 d of frozen storage at ?20 ℃, respectively. Of the three meats, red meat contained the highest contents of IMP and AMP but lowest contents HxR and Hx, which led to poor taste and freshness. The K values of red meat frozen by three freezing methods were 28.99%, 40.92%, and 46.58%, respectively. The contents of free amino acids in belly meat were similar to those of dorsal meat, but higher than those of red meat. Notably, red meat was significantly richer in asparagic acid and glutamate as well as lactic acid than belly meat and dorsal meat, and the lactic acid content of red meat was greatly affected by the freezing methods. The different parts of fish meat and fish samples frozen by the different freezing methods were clearly distinguished with an electronic tongue.

The volatile components of steamed pork with rice obtained at 4 different steaming times were investigated by purge and trap thermal desorption (P&T-TD) combined with gas chromatography-mass spectrometry-olfactometry (GC-MS-O). The results showed that a total of 77 volatile compounds were identified, 69, 43, 50 and 56 of which were detected after 0, 30, 60 and 90 min of steaming, respectively. Thirty-three volatile compounds were common to the four samples. The total content of volatile components increased gradually from 1 646.39 to 2 657.10 μg/kg during the process of steaming, and the types of volatile compounds also increased gradually. The analysis of odor activity value (OAV) showed that the contents of all the flavor compounds (OAV > 0.1) increased firstly and then decreased, and the highest OAV value was observed after steaming for 60 min. Furthermore, methyl nonaldehyde, decyl aldehyde and methyl cinnamate made the greatest contribution to the characteristic flavor of streamed pork with rice. Principal component analysis (PCA) showed that the 60 min steamed sample was clearly discriminated from other samples and exhibited a greater cumulative variance contribution rate of the first and second principal components. In summary, better flavor of the product was obtained after steaming for 60 min.

In this study, the contents of phenolic compounds in five commercial brands of pickled and dried mustard were analyzed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), and their antioxidant activity was evaluated by four antioxidant capacity assays. The five brands were Xianhong (XH), Guguxian (GGX), Guanhuawang (GHW), and homemade products A and B (JTA and JTB). The results showed that the total phenol contents, the proportions of different phenolic classes and antioxidant activity were significantly different among five pickled and dried mustard brands. The total phenol content of GGX was 14.18 mg GAE/g, the total flavonoid content was 7.10 mg RE/g, and the antioxidant activity was 28.09, 31.72, 32.88 and 445.55 μmol TE/g as measured by 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonate (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) assays, respectively, which was significantly higher than that of the other four brands. A total of 17 phenolic compounds, including 9 flavonoids and 8 phenolic acids, were identified by HPLC-MS/MS. Among these, the major flavonoids were identified as rhoifolin, kaempferol, isorhamnetin, and naringenin, ferulic acid, p-coumaric acid and t-cinnamic acid were the main phenolic acids. In addition, among the four antioxidant capacity assays, the correlation between ABTS and FRAP was the highest with a correlation coefficient of 0.967; the antioxidant capacity of pickled and dried mustard evaluated by the ORAC method was significantly higher than those by three other methods; the ABTS method exhibited the highest correlation coefficient with antioxidants, which was the most suitable for evaluating the total antioxidant capacity of pickled and dried mustard. In summary, the total phenol contents and antioxidant capacities of different brands of commercially available pickled and dried mustard were different. Among them, GGX had the highest total phenol content and strongest antioxidant capacity.

This study aimed to examine the characteristics of lipid oxidation during sauced duck processing. Low-temperature air drying was introduced to the processing of traditional sauced duck. Changes in pH, phospholipids, free fatty acid (FFA), peroxide values (POV), thiobarbituric acid reactive substances (TBARS) and total volatile base nitrogen (TVB-N) values were investigated during processing. The results showed that the pH value of raw duck meat increased from 5.81 to 6.09 after sterilization. Analysis of the intramuscular phospholipid composition indicated that C16:0/C20:4, C16:0/C18:1, C16:0/C22:5, C16:0/C22:4 and C16:0/C22:6 were the primary phosphatidylethanolamines (PE). Both POV and TBARS values increased firstly and then decreased. TVB-N values significantly decreased during salting, marination and sterilization, but increased during air-drying significantly (P < 0.05). Total FFA showed a significantly positive correlation with monounsaturated fatty acids (MUFA) (R = 0.92, P < 0.01), and we also found a significantly positive correlation between PUFA and pH values (R = 0.90, P < 0.01), between PUFA and TBARS values (R = 0.80, P < 0.01), between TBARS and POV (R = 0.89, P < 0.01), and between POV and TVB-N values (R = 0.81, P < 0.01), but phosphatidylcholine (PC) was significantly negatively correlated with PE (R = ?1.00, P < 0.01). These results may provide a theoretical basis for understanding the mechanism of lipid oxidation during the processing of low-temperature air-dried sauced duck.

This study investigated the effects of low-concentration calcium lactate on phytic acid degradation and the contents of macronutrients during soybean germination. After being sprayed with calcium lactate at 0.27 mmol/L for 4 days, the phytic acid in soybean sprouts was degraded significantly, and the bioavailability of zinc and iron was improved. In addition, the contents of other macronutrients, including soluble proteins and soluble sugars, were decreased continuously, while the content of free amino acids was increased. The contents of total proteins and amino acids were maintained steadily or decreased slightly, while the amino acids composition varied greatly. The contents of Asp and His were increased with germination time, whereas the contents of 15 other amino acids were decreased. Calcium lactate enhanced the accumulation of Asp and Val but decreased the content of other amino acids. Spraying soybean sprouts with low-concentration calcium lactate as a good calcium supplement could promote phytic acid degradation, and enhance the nutritional quality of soybean sprouts.

The purpose of this work was to obtain good quality and high microencapsulation efficiency of onion essential oil microcapsules by spray drying method. Arabic gum, β-cyclodextrin and maltodextrin were evaluated for their use as wall materials. The effect of wall material type, core to wall material (C/M) ratio and solid content on microencapsulation efficiency was investigated. The morphology under scanning electron microscopy (SEM), sensory attributes, encapsulation degree (ratio between microencapsulated oil and wall material), water content, solubility, bulk density and storage stability of microcapsules were measured. The results showed that the maximum microencapsulation efficiency of 92.35% was achieved under the following conditions: arabic gum and β-cyclodextrin mixture (4:3, m/m) as wall material, C/M ratio 1:4 (mL/g), and solid content 20%. SEM examination showed that the obtained microcapsules were spherical in shape with smooth and continuous surfaces. The microcapsules had good sensory properties, and were homogenous in size and non-sticky, which could effectively hide the pungent odor of onion essential oil, making the product acceptable to consumers. Moreover, the encapsulation degree, water content, solubility, bulk density and glass transition temperature (Tg) of the microcapsules were 21.32%, 3.69%, 97.56%, 0.786 g/cm3 and 46.35 ℃, respectively indicating good solubility, a low water content and a Tg higher than general storage temperature. Therefore, high-quality microcapsules were obtained under the optimized conditions, which had good storage stability and were acceptable to the market.

This study aimed to optimize the ultrasonic-assisted extraction of anthocyanins from Aronia melanocarpa and to determine the antioxidant capacity and constituents of the obtained extract. The optimization was carried out by response surface methodology. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) radical (ABTS+·) scavenging capacity and Fe3+ reducing ability of plasma (FRAP) assays were used to evaluate the antioxidant capacity. The anthocyanin components were analyzed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The results showed that the optimum extraction conditions were as follows: extraction temperature 60 ℃, ultrasonic power 100 W, solid-to-liquid 1:30 (g/mL), ultrasonic time 31 min, ethanol concentration 64%, and pH 2.0. Under these conditions, the content of anthocyanins was determined to be (3.61 ± 0.01) mg/g. The in vitro antioxidant activity of the anthocyanin extract was significantly higher than that of vitamin C at the same concentration. Six anthocyanins including two new compounds, dimer of cyanidin-3-hexoside and cyanidin-3,5-dihexoside, were detected in the extract.

Ultrasonic was applied to assist the Maillard reaction between zein and dextran. The reaction conditions were optimized using one-factor-at-a-time and orthogonal array design methods and the reaction products were characterized for structural and functional properties. The results indicated that the maximum degree of grating (DG) of 18.28% was obtained under the following conditions: 50.15 min ultrasonic irradiation, ultrasonic power 300 W and sugar concentration 0.025 g/mL, which increased by 44.58% compared with that obtained by water bath heating. Fourier transform infrared (FTIR) analysis showed that zein covalently bound to dextran confirming the occurrence of glycosylation. Functional characterization showed that the solubility, emulsifying capacity, emulsion stability, foaming ability and foam stability of zein-dextran conjugate produced under ultrasonic irradiation were improved significantly compared with zein and hot water bath, which indicated that ultrasonic irradiation could promote the efficiency of glycosylation and improve the structure and properties of the products, broadening the scope of application of zein.

In this paper, composite powders of walnut peptide, buckwheat and quinoa at different ratios were prepared. The optimal ratio was determined by evaluating their protein nutritional value based on the calculated score of ratio coefficient of amino acid (SRCAA). The conditions for liquefaction and saccharification of buckwheat and quinoa before being blended with walnut peptide were optimized by one-factor-at-a-time and orthogonal array design methods. The composite powder of walnut peptide, buckwheat and quinoa was obtained by spray drying and its digestbility and antioxidant activity in vitro were studied. The results showed that the optimal ratio of walnut peptide to buckwheat to quinoa was 0.7:13:5 (m/m), and the SRCAA of this combination was 95.15%, which was closed to the reference protein pattern. The optimal liquefaction conditions were α-amylase 7 U/g, 60 ℃, and digestion time 50 min, and the optimal saccharification conditions were β-amylase 150 U/g, 55 ℃, and digestion time 2.5 h. Under these conditions, the concentration of reducing sugar was 20.03 mg/mL. The contents of peptide, reducing sugar, flavonoid and polyphenol were increased during simulated in vitro digestion; especially during simulated intestinal digestion, the content of rapidly digestible starch (RDS) was 64.19% and the content of slowly digestible starch (SDS) was 27.12%, while the content of resistant starch (RS) was only 8.70%, which indicated that starch was more thoroughly hydrolyzed after gastrointestinal digestion. The antioxidant activities in vitro of the composite powder was proved by its reducing power (IC50 = 5.04 mg/mL), scavenging activity against DPPH radical (IC50 = 0.67 mg/mL), hydroxyl radical (IC50 = 62.32 mg/mL) and superoxide anion radical (IC50 = 13.07 mg/mL) and total antioxidant capacity (27.63 U/mL). To conclude, the composite powder of walnut peptide, buckwheat and quinoa was not only easy to digest and absorb but also had antioxidant activity.

In this experiment, phage JS25 was microencapsulated with sodium alginate, and the structure of the microcapsule powder was characterized in order to determine its size distribution. In addition, the stability at different temperatures was analyzed by using planktonic phage as a control. The release characteristics of microencapsulated phage in four different food simulant systems were evaluated as well. The results showed that the phage was effectively microencapsulated with sodium alginate and CaCl2. The results of optimization by response surface methodology (RSM) indicated that the maximum microencapsulation efficiency of 88.38% was obtained when the concentrations of sodium alginate and CaCl2 were 3.72 and 2.55 g/100 mL, respectively. The size of the prepared microcapsules showed a normal distribution in the range of 20–90 μm. The microcapsules were stable for 35 d at 4 and 20 ℃, having improved stability compared with the control. The phage microcapsule powder was rapidly released in the tested food simulation systems and the release rate increased and then remained stable, reaching higher than 75% at 8 min. Therefore, this process can be used for microencapsulation of phage JS25 to improve its stability with little impact on its titer.

This study aimed to optimize and compare the ultrasonic assisted extraction (UAE) and the microwave assisted extraction (MAE) of proanthocyanidins from fresh flowers and essential oil extraction residue of Kushui rose. The optimization was performed using one-factor-at-a-time (OFAT) method and response surface methodology (RSM). The results of OFAT experiments showed that the optimal ultrasonic irradiation temperature and time to obtain the maximum yield of proanthocyanidins were 60 ℃ and 20 min and the optimal microwave irradiation temperature and time were 60 ℃ and 40 s, respectively. When the extraction was carried out for 1.5 h using 60% ethanol as extraction solvent at 75 ℃ with a solid-to-solvent ratio of 1:20 (g/mL), 17 min ultrasonic irradiation at 59 ℃ and 44 s microwave irradiation at 61 ℃ were found to be optimal to obtain a higher yield of proanthocyanidins of 96.94 and 100.81 mg/g from fresh rose flowers, respectively, while in the case of the oil extraction residue, 20 min ultrasonic irradiation at 60 ℃ and 42 s microwave irradiation at 60 ℃ were the optimal conditions to obtain a higher yield of proanthocyanidins of 57.74 and 58.74 mg/g, respectively. It is suggested that both ultrasonic and microwave assisted extraction were efficient to extract proanthocyanidins from fresh flowers and essential oil extraction resident of Kushui rose, and microwave assisted extraction showed better extraction efficiency.

The effect of fat content on the quality of butter and cocoa butter replacer-based whipping cream was investigated. Further, we evaluated the effect of fat content, butter to cocoa butter replacer ratio and homogenization pressure on the overrun, texture characteristics, partial coalescence rate of fat globules and crystalline characteristics of whipping cream using an orthogonal array design. It was shown that a fat content of 30%, a butter to cocoa butter replacer ratio of 2:3 and a homogenization pressure of 60 MPa allowed partial coalescence rate of fat globules and maintained the sensory characteristics, overrun and crystalline characteristics of the whipping cream. Homogenization at 60 MPa maintained the stability of the system and produced a large amount of free fat globules, promoting the partial coalescence of fat globules. The results of crystal formation analysis showed that under the optimized conditions, the X-ray diffraction patterns of the initial emulsions were broadened and changed from being sharp to being moderate, and the β’ crystal was significantly increased. Whipping cream emulsions produced fat crystals at low temperatures, and the size of fat crystals was larger than that at high temperature.

The effects of nano zinc oxide on the degradation of Irgafos 168 in nano zinc oxide-polypropylene (PP) films under sunlight exposure, ultraviolet (UV) irradiation and microwave irradiation were studied by using gas chromatography-mass spectrometry (GC-MS). The results indicated that the degradation rate of Irgafos 168 in nano zinc oxide-polypropylene composite films was increased gradually during sunlight exposure and UV irradiation until reaching equilibrium. The presence of nano zinc oxide in PP films began to accelerate the degradation of Irgafos 168 after 12 days of sunlight exposure. Furthermore, addition of the coupling agent also affected it. Compared to sunlight exposure, UV irradiation resulted in higher degradation of Irgafos 168 and the content of 2,4-di-tert-butylphenol, one of the degradation products, was increased to a maximum value at 24 h and decreased afterwards. Nano zinc oxide in PP films began to hinder the degradation of Irgafos 168 after 13 h of UV irradiation, and addition of the coupling agent only affected the generation of tris (2,4-di-tert-butylphenyl) phosphate, another degradation product, but had little impact on the degradation of Irgafos 168. Higher microwave power could accelerate the degradation of Irgafos 168, which was not significantly related with the number of microwave irradiation cycles, nano zinc oxide or the coupling agent.

In this work, trypsin-catalyzed 18O labeling combined with high performance liquid chromatography-linear ion trap/Orbitrap high-resolution mass spectrometry (HPLC-LTQ/Orbitrap MS/MS) was used to study the 18O labeling characteristics of marker peptides in donkey-hide gelatin. Moreover, the method was applied to quantify donkey-hide gelatin and bovine-hide gelatin in their mixtures. Under trypsin catalysis, all the marker peptides of donkey-hide gelatin were labeled by two 18O atoms. The measured ratios for 18O-labeled and 16O-labeled peptide mixtures at ratios of 20:1, 10:1, 5:1, 1:1 and 1:5 were 19.66, 10.24, 5.01, 1.00 and 0.20, respectively. The measured ratios for mixtures of donkey-hide gelatin and bovine-hide gelatin at ratios of 1:10, 1:1 and 10:1 using 18O-labeled characteristic peptides as the internal standard were 0.10, 1.02 and 9.72, respectively. The results showed that trypsin-catalyzed 18O labeling combined with HPLC-LTQ/Orbitrap MS/MS should be a promising method to quantify the target gelatin and control the quality of donkey-hide gelatin product.

In this study, a line-scanning Raman hyperspectral imaging system was built to quantify sodium thiocyanate illegally added in skim milk powders with large sample areas. Firstly, the penetration depth of Raman signal produced by sodium thiocyanate in skim milk powders was measured. Then, ten milk powder mixtures with different concentrations of sodium thiocyanate were prepared and their hyperspectral images were also collected. The Gaussian filter smoothing and the airPLS baseline correction methods were used to preprocess the Raman spectra. The corrected images at 2 068.48 cm-1 waveband were extracted to determine the presence of sodium thiocyanate particles. The concentration and spatial distribution of the sodium thiocyanate particles were finally obtained using a simple binarization method. The results showed that the average Raman intensity of all the pixels in the region of interest increased linearly with the increase of sodium thiocyanate particles, and the determination coefficient was 0.991 5. In the binary images, the sum of all sodium thiocyanate pixels in the region of interest increased exponentially. The limit of detection (LOD) for sodium thiocyanate concentration was estimated as 0.01% without using any chemical reagents. This system could expand the area of milk powder samples to 80 mm × 80 mm at a time in a non-invasive and non-contact way. In our research, the sodium thiocyanate particles could be fast, non-destructively and extensively detected using the line-scanning Raman hyperspectral imaging system. Both the concentration and the spatial distribution of the sodium thiocyanate particles in skim milk powder could be acquired at the same time. This method has a great potential for practical application.

This paper presents a method to detect nitrate and nitrite simultaneously in fruits, vegetables and meat products using high performance capillary electrophoresis (HPCE). We focused on optimizing the detection conditions and eliminating the interfering ions. The separation was carried out in a capillary column with an internal diameter (ID) and an effective length of 30 cm (total length = 40 cm) and the analytes were detected by capillary zone electrophoresis-direct UV detection at 214 nm. The effects of buffer pH and concentration, the electroosmotic flow modifier cetyl trimethyl ammonium bromide (CTAB), elimination of chloride ion interference and separation voltage on separation efficiency were investigated. The method was validated in terms of recovery, linearity, limit of detection (LOD) and precision. Results showed that NO3- and NO2- at concentrations below 500 mmol/L were separated well in 6 min. The recoveries of this method were in the range of 81.82%–100.91%, and it showed a wide linear range with a correlation coefficient above 0.99. The LODs for nitrate and nitrite were 0.69 and 0.50 μg/mL, respectively, and the precision (expressed as relative standard deviation) was less than 3.2% for both salts. This method proved to simple, fast, accurate and environmental friendly and would provide a scientific basis for rapid monitoring of nitrate and nitrite residues in fruits, vegetables and meat products.

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of six illegal water-retaining drugs, atropine, lidocaine, procaine, anisodamine, scopolamine and salbutamol, in frozen meat. The samples were extracted with phosphate buffer, and the extract was cleaned up on an HLB cartridge. The analytes were detected in the multiple reaction monitoring mode and quantified by the external standard method. The results indicated that good linearity over the concentration range of 0.25–50 ng/mL was observed for all analytes with correlation coefficients greater than 0.99. The limits of detection (LOD) and quantification (LOQ) were 0.5 and 2.0 μg/kg, respectively. The average recoveries of the six drugs ranged from 78.07% to 96.76% with relative standard deviations (RSDs) of 0.4%–2.1% (n = 6). The method is sensitive, simple, rapid and accurate and can meet the requirements of practical analysis.

A method using a new online purifying pretreatment system and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established for the determination of ergosterol and ergotsterone in food flavors and spices. The pretreatment method in combination with matrix solid-phase dispersion and column chromatography was used for sample extraction and purification, followed by concentration and analysis by HPLC-MS/MS. The analysis was performed on a C18 column with gradient elution with a mobile phase consisting of water and methanol at a flow rate of 0.4 mL/min. The mass spectrometer with an?atmospheric pressure chemical ionization (APCI) source in the positive ion mode was operated using multiple reaction monitoring (MRM) and an internal standard method was used for quantification. The results showed that the pretreatment method was simple and stable with solvent recycle, integrating extraction, purification and concentration. The two analytes could be separated in 5 min with good linearity in the concentration range of 1.5–250 μg/mL with correlation coefficients larger than 0.999. The limits of detection (LODs) were 0.32 μg/mL for ergosterol and 0.35 μg/mL for ergotsterone. The mean recoveries of the target compounds at three different spiked levels were 86%–96% with relative deviations (RSDs) of 3.1%–3.6%. This method is suitable for the analysis of ergosterol and ergotsterone in food flavors and spices.

Adenosine triphosphate (ATP) and its degradation products, which are related to freshness K value, can absorb terahertz (THz) waves due to molecular rotation and vibration and overall vibration of molecular clusters. Thus, THz spectroscopy can be used to detect the K value of pork non-destructively. However, water can strongly absorb THz waves as well, which will affect the accuracy of the obtained results. In this study, different spectral preprocessing methods were compared for their efficiencies in weakening water interference and improving the performance of predictive models in the detection of pork K value by THz spectroscopy. Four spectral preprocessing methods, including multiple scatter correction (MSC), standard normal variate transformation (SNVT), first derivative (FD) and second derivative (SD), were employed to preprocess the original attenuated total reflectance (ATR) infrared spectra. Predictive models were established by back-propagation artificial neural network (BP-ANN) regression algorithm, and their precisions?were compared. The results showed that the FD pretreatment method was the most effective in eliminating baseline drift and improving the spectral quality. Compared with the predictive model without pretreatment, the correlation coefficient of prediction set (Rp) of the FD model was increased from 0.34 to 0.75, and the root mean square error of prediction set (RMSEP) was reduced from 20.24% to 14.36%. This study highlighted the importance of selecting the appropriate spectral pretreatment method to improve the predictive accuracy of models. The BP-ANN model based on FD pretreatment of THz spectra can be used to non-destructively detect pork freshness K value.