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    FOOD SCIENCE 2013 Vol.34
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    Effect of Olestra on Microstructure, Rheological Properties and Baking Properties of Snack Cake
    FOOD SCIENCE    2013, 34 (1): 1-7.  
    Abstract1894)   HTML7)    PDF(pc) (968KB)(620)       Save
    The effect of partial fat substitution with olestra in different proportions (25%, 50% and 75%) on paste density, microstructure and rheological properties and physiochemical parameters, texture and sensory characteristics of snack cakes was studied. At a fat substitution level of 25%, only little differences in rheological properties of flour paste and the quality of snack cakes were observed compared with control group. Fat substitution at a level of 50% resulted in an obvious increase in paste density and a decrease in the number of gas bubbles and the specific volume of snack cakes. TPA showed that the hardness and chewiness of snack cakes could be markedly improved by fat substitution with olestra.
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    Effect of Dietary Supplementation with Low Molecular Weight Chitosan on Growth and Digestive Enzyme Activities in Common Carp (Cyprinus carpio)
    FOOD SCIENCE    2013, 34 (1): 8-12.  
    Abstract1447)   HTML5)    PDF(pc) (703KB)(416)       Save
    This study aimed to examine the effect of dietary supplementation with low molecular weight chitosan (LMWC) on common carp growth and digestive enzyme activities. Basal diet group was used as control and LMWC groups at increasing gradient concentrations (0.25%, 0.50%, 0.75% and 1.0%) were established. Body weight gain, feed coefficient and the activities of amylase, lipase and trypsin in the hepatopancreas and gut were analyzed after feeding for 30, 45 d and 60 d. When compared with control group, body weight gain and the activities of amylase, lipase and trypsin showed a gradual upward trend, whereas an opposite trend was observed for feed coefficient with increasing dietary LMWC supplementation and feeding time. After 45 d and 60 d of feeding, a more striking increase in body weight gain and the activities of amylase, lipase and trypsin was found for 0.75% LMWC group compared with control group and 0.25%, 0.50% and 1.0% LMWC groups. For 1.0% LMWC group, the increasing trend of body weight gain and digestive enzyme activities gradually slowed down with increasing feeding time. Dietary LMWC supplementation in different proportions had different effects on digestive enzyme activities in common carps and the optimal dosage was 0.75%.
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    Construction of Lowly Toxic Liquid Crystals as Curcumin Delivery System
    zhong-Ni WANG Wu ZHOU Zhen LI
    FOOD SCIENCE    2013, 34 (1): 13-17.  
    Abstract1201)   HTML2)    PDF(pc) (765KB)(387)       Save
    The phase diagram of oleyl polyoxyethylene (20) ether/butyl acetate/water was determined at 25 ℃, and the influence of the biosurfactant sodium deoxycholate (NaDC) on the phase behavior and rheological properties of the system was investigated. Furthermore, the protection and in vitro release behavior of curcumin in the liquid crystals were studied. Hexagonal and cubic crystals were found in the ternary system. When adding NaDC, the area of hexagonal phase became smaller and the cubic phase disappeared. All investigated samples followed a shear-thinning behavior under steady shear. The cubic crystals showed high elasticity with tan δ values less than 0.1, while the hexagonal crystals demonstrated typical visco-elasticity with tan δ values between 0.47 and 0.54. The characteristic relaxation time of the hexagonal crystals increased after adding NaDC. Curcumin could be protected by the liquid crystals against sun light. Surcumin solved in the liquid crystals exhibited slow release behavior. Moreover, the protection effect was enhanced and the equilibrium time of release was extended in NaDC containing systems.
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    Extraction and Functional Properties of Four Proteins from Rice Bran
    Min ZHANG
    FOOD SCIENCE    2013, 34 (1): 18-21.  
    Abstract1987)   HTML13)    PDF(pc) (774KB)(711)       Save
    Four protein isolates including albumin, globulin, gliadin and glutenin were extracted from rice bran using the Osbron method and their functional properties were evaluated. Albumin, globulin, gliadin and glutenin accounted for 56.93%, 20.84%, 3.167% and 19.06% of total proteins in rice bran, respectively, and their isoelectric points were 4.0, 4.0, 5.0 and 4.6, respectively. Comparative evaluation of functional properties showed that albumin possessed the highest water-binding capacity but the weakest foaming capacity at the isoelectric point, and glutenin had the highest emulsibility. SDS-PAGE suggested that the subunit molecular weights were 95.43, 76.51 kD and 52.85 kD for albumin, 103.12 kD and 76.51 kD for globulin, 14 kD for gliadin, and 36.29, 20.00 kD and 14.00 kD for glutenin, respectively.
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    Effect of Sorbitol on Water Holding Capacity and Texture of Fermented Sausages as Determined by NMR
    Xiao-Lei YAN
    FOOD SCIENCE    2013, 34 (1): 22-26.  
    Abstract1459)   HTML2)    PDF(pc) (667KB)(592)       Save
    Low-field NMR was used to study the distribution and changes of constitutional water, immobilized water and free water during the production of fermented sausages and the effect of sorbitol on the three types of water. The activity of the three kinds of water descended gradually during fermentation and drying. Addition of sorbitol reduced the activity of immobilized water and free water. The activity of constitutional water also declined in the presence of a high level of sorbitol (10%). Addition of 12% sorbitol shortened the drying time from 25.8 h to 8.8 h when final water activity was controlled to be 0.87. The TPA results showed that sorbitol effectively improved the quality and taste of fermented sausages.
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    Adsorption Efficiency of Ethylene Glycol Maleic Rosinate Acrylate-Acrylamide Copolymer for Puerarin
    LI Xiao-Yan
    FOOD SCIENCE    2013, 34 (1): 27-32.  
    Abstract1697)   HTML2)    PDF(pc) (954KB)(371)       Save
    In this study, a copolymer was synthesized using suspension polymerization from ethylene glycol maleic rosinate acrylate (EGMRA) and acrylamide (AM), and its thermodynamic and kinetic characteristics for adsorbing puerarin and mechanism for controlling puerarin adsorption were analyzed. The prepared copolymer showed good adsorption performance towards puerarin. The optimum static adsorption conditions were obtained as follows: 40% ethanol as solvent for puerarin at a concentration of 6.0 mg/mL, adsorbent particle size 20—40 mesh, and equilibrium adsorption at a temperature between 25 ℃ and 50 ℃ with shaking at a speed of 80 r/min. Under these conditions, the equilibrium adsorption capacity (Qe) was 23.01 mg/g. A pseudo second-order equation that could well describe the adsorption process was established. Film diffusion and particle diffusion were found to be key steps in the adsorption system, and the diffusion coefficients were calculated using the Fick equation to be 5.22 × 10-8 cm2/s and 3.20 × 10-8 cm2/s, respectively.
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    Comparative Application of ESR and Spectrophotometry to Evaluate the Antioxidant Activity of Grape Seed Proanthocyanidins
    FOOD SCIENCE    2013, 34 (1): 33-37.  
    Abstract1193)   HTML2)    PDF(pc) (1779KB)(627)       Save
    Electron spin resonance (ESR) spectroscopy was used to investigate the antioxidant activity of four proanthocyanidin extracts from wine grape seeds (designated as GSP0, GSP1, GSP2 and GSP3, respectively) and compared with spectrophotometry as a control. GSP3 had the strongest DPPH radical scavenging activity as determined by both methods. After 30 min of reaction at concentrations below 40 mg/L, a positive correlation between scavenging rate and GSP3 concentration was observed. At concentrations above 40 mg/L, the DPPH radical scavenging activity of GSP3 tended to be stable. Higher scavenging rates were obtained for all four proanthocyanidin extracts using ESR than spectrophotometry. After 30 min of reaction, the DPPH radical scavenging rates of GSP0 and GSP3 at various concentrations were determined using ESR to be in the range of 35.99%—99% and 52.45%—99%, respectively, whereas those obtained using spectrophotometry were in the range of 7.06%—78% and 29%—95%, respectively.
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    Quantitative Descriptive Analysis of Sensory Characteristics of Musalais from A’wati, Xinjiang
    FOOD SCIENCE    2013, 34 (1): 38-44.  
    Abstract1487)   HTML3)    PDF(pc) (1063KB)(579)       Save
    In the present study, 10 Musalais samples from different producers in A’wati, Xinjiang were subjected to quantitative descriptive evaluation and multivariable statistical analysis. Besides, factors that influence the appearance, taste and aroma characteristics of Musalais were analyzed. The results of analysis of variance (ANOVA), average flavor wheel chart and principal component analysis indicated significant differences in sensory characteristics of different Musalais samples, which were dominated by a brown color and a good sweet-sour balance with a light bitterness, abundant aroma (prominent caramel and alcoholic aroma) and good representativeness. The traditional production procedure was the main factor underlying the basic color, body and typical aroma of Musalais, but grape variety and storage time were also important affecting factors. The traditional production procedure and Hetain Red grape ensured the quality of Musalaism, whereas the introduction of modern technologies and the use of other grape varieties had negative effects on the taste and aroma of Musalais. After storage for 1–2 years, the rough and bitter taste of fresh Musalais was improved and became mellow and full, and the fragrant aroma and long lingering aftertaste were attenuated and became light. In spite of this, ageing time did not notably affect the sensory quality of Musalais. Partial least square regression and cluster analysis suggested highly dispersive distribution of Musalais samples. This indicates that sensory characteristics of Musalais varies complicatedly and lack stability. 
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    Antibacterial Activity of Pyrrolyl Amino Acids as Precursors of Laba Garlic Pigment
    FOOD SCIENCE    2013, 34 (1): 45-48.  
    Abstract1231)   HTML3)    PDF(pc) (504KB)(507)       Save
    The inhibitory effects of four pyrrolyl amino acids (P-Leu, P-Gly, P-Ala and P-Val) as precursors of Laba garlic pigment, in vitro synthesized by Paal-Knorr method, were examined against Escherichia coli and Bacillus subtilis. All four pigment precursors had antibacterial activity in a dose-dependent manner, and Bacillus subtilis was more effectively inhibited by them than Escherichia coli. In addition, pigment precursors with different structures had different antibacterial activities.
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    Comparative Evaluation of Four Homogenization Machines
    FOOD SCIENCE    2013, 34 (1): 49-52.  
    Abstract1058)   HTML1)    PDF(pc) (391KB)(285)       Save
    Microbiological examination of foods involves sample preparation and subsequent homogenization. This paper addresses the effectiveness of Stomacher™, Pulsifier™, Bagmixer™ and Smasher™ instruments in terms of: 1) viable cell counts/g for 10 kinds of foods, 2) noise level of four instruments associated with human operation and decibel meter at 5 ft from each instrument, 3) convenience for cleaning instruments after use, and 4) ergonomics. Aliquots of 25 g for 10 kinds of foods were placed individually in a sample bag containing 224.5 mL of 0.1% peptone water plus 0.5 mL of Escherichia coli inoculum. Each food was homogenized for 60 s. Ease of cleaning and ergonomics when using Stomacher™ were determined as a reference. All 4 instruments revealed a similar performance regarding viable cell counts. As for noise level, Smasher™ and Bagmixer™ were the quietest, followed by Stomacher™ and Pulsifier™. Smasher™ ranked highest in ease of cleaning and ergonomics, followed by Bagmixer™, Stomacher™, and Pulsifier™.
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    Effect of Fish Paste Content on Surimi Gel Properties
    FOOD SCIENCE    2013, 34 (1): 53-56.  
    Abstract1222)   HTML4)    PDF(pc) (430KB)(528)       Save
    Whole fish paste and bone paste from sliver carps were analyzed for basic chemical composition and their effects on gel properties of surimi were investigated. Meanwhile, we examined whether microbial transglutaminase (MTGase) could improve gel properties of surimi. Both pastes were rich in total ash content and had a protein content exceeding 12%. For each fish paste, two-stage heating (40 ℃, 1 h/90 ℃, 0.5 h) resulted in an increase in gel properties and water-holding capacity compared with one-stage heating (121 ℃, 0.5 h). Moreover, breaking strength and gel strength of two-stage heat-induced surimi gel initially increased and then decreased with increasing fish paste content. The proper amount of whole fish paste (10%) was higher than that of bone paste (5%). MTGase could enhance gel properties and water-holding capacity of surimi and was more effective in improving the water-holding capacity of surimi gel induced by one-stage heating compared with two-stage heating.
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    Characteristics of Starch from Quercus fabric Hance
    FOOD SCIENCE    2013, 34 (1): 57-60.  
    Abstract1210)   HTML2)    PDF(pc) (563KB)(309)       Save
    The structure and properties of starch extracted from Quercus fabric Hance were systematically studied using X-ray diffraction (XRD) spectroscopy, laser scattering spectroscopy, differential scanning calorimetry (DSC), spectrophotometry and texture analysis and were compared with those of corn starch. The results indicated that Quercus fabric Hance starch had quite small granules with an average size of 3.15 μm. This starch contained 18.90% of amylase and had a gelatinization temperature ranging from 72.3 to 84.7 ℃. The X-ray pattern indicated that it belonged to crystal structure type A. The solubility and swelling power were bigger than those of corn starch. Quercus fabric Hance starch paste showed low transparency, strong retrogradation, poor freeze-thaw stability, small viscosity and high enzymatic hydrolyzability. Furthermore, texture analysis indicated its high gel strength and good texture and taste.
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    in situ SEM Observation of Ultrastructural Morphology of Edible Starch Granules
    王绍清,范文浩,王琳琳,曹?红,曹宝森
    FOOD SCIENCE    2013, 34 (1): 61-64.  
    Abstract1185)   HTML2)    PDF(pc) (632KB)(1045)       Save
    In this study, the ultrastructural morphology of starch granules from 25 kinds of crops was in situ observed by scanning electron microscopy (SEM) and compared with starch granules extracted from potato and corn by the classical method. The classic extraction procedure had hardly any effect on the ultrastructural morphology of starch granules. In addition, spatial effects played a vital role in the morphological formation of starch granules in mature cereal grains with the exception of wheat, but had no impact on beans and root crops.
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    Effect of Color, Thickness and Part on Free Amino Acid Contents in Asparagus
    FOOD SCIENCE    2013, 34 (1): 65-68.  
    Abstract1379)   HTML2)    PDF(pc) (481KB)(293)       Save
    This work presents a reversed phase high-performance liquid chromatography (RP-HPLC) method for the determination of free amino acids in asparagus after precolumn derivatization. The effects of different colors, thicknesses and parts on free amino acid contents in asparagus were investigated by non-parametric tests. At least 15 free amino acids with were detected and their contents showed differences among three different parts of asparagus (bottom, middle and top). All investigated samples were highest in asparagine and glutamine, glutamic acid and aspartic acid were in the middle, the contents of cysteine, trytophan, leucine and isoleucine were the lowest, and methionine was not detected. Different colors, thicknesses and parts had significant effects on free amino acid contents in asparagus.
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    Effect of Microwave Sterilization on Quality Properties of Stewed Pork Liver
    FOOD SCIENCE    2013, 34 (1): 69-72.  
    Abstract1288)   HTML7)    PDF(pc) (205KB)(376)       Save
    This study explored the effect of microwave sterilization on quality properties of stewed pork liver such as microbiological indexes, moisture content, texture, color and vitamin A content. After microwave sterilization, the moisture content and tenderness of stewed pork liver decreased, and the toughness increased. When the surface temperature reached 70 ℃, similar sterilization efficiency to that obtained by high temperature treatment was obtained. Moreover, after microwave sterilization, the color of stewed pork liver became dark, and vitamin A content declined, but only minor quality change was observed when compared with high temperature sterilization.
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    Effect of Ultra High Pressure (UHP) on Polyphenol Content and Antioxidant Activity in Kiwifruit Juice from Different Cultivars
    FOOD SCIENCE    2013, 34 (1): 73-77.  
    Abstract1739)   HTML2)    PDF(pc) (1064KB)(337)       Save
    Ultra high pressure (UHP) (500 MPa, 20 min) was used for the treatment of kiwifruit juice from four species (yellow kiwifruit, green kiwifruit, Hongyang kiwifruit and Juxiang kiwifruit) for evaluating the content and antioxidant activity of polyphenols. Results indicated that UHP could significantly improve polyphenol (free phenol and bound phenol) contents (P<0.05). Especially, the content of free phenol from yellow kiwifruits revealed an improvement of 78.68 μg/mL; the content of bound phenol from Juxiang kiwifruits revealed an improvement of 15.58 μg/mL. The antioxidant activities of four cultivars of kiwifruits were evaluated by DPPH radical scavenging method, reducing power method and ABTS radical scavenging method. Results indicated that antioxidant activity of free polyphenols was higher than that of bound polyphenols. Therefore, UHP treatment can improve the antioxidant activity of four kinds of kiwifruit pulp, but not significantly.
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    Correlation between Antioxidant Activity and Contents of VC, Polyphenols and Polysaccharides in Pumpkin Wine
    FOOD SCIENCE    2013, 34 (1): 78-82.  
    Abstract1250)   HTML1)    PDF(pc) (597KB)(398)       Save
    The antioxidant potential of pumpkin wine was evaluated by measuring its scavenging activity against DPPH, hydroxyl and superoxide anion radicals and analyzed for its correlation with the contents of VC, polyphenols and polysaccharides. Pumpkin wine had strong scavenging activity against DPPH, hydroxyl and superoxide anion radicals in a dose-dependent fashion, and its radical scavenging activity was better than that of pumpkin extract at the same dose. Meanwhile, our results suggested that VC, polyphenols and polysaccharides were the dominant antioxidant components in pumpkin wine.
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    Effect of Salt on Properties of Salted Yolk Protein
    FOOD SCIENCE    2013, 34 (1): 83-87.  
    Abstract1357)   HTML1)    PDF(pc) (582KB)(761)       Save
    The effect of salt on properties of yolk protein during salting was investigated. The soluble protein content was 1.95 g/100 g in fresh egg yolk (on a wet basis) and increased to 4.30 g/100 g after salting for 15 weeks. The sulfhydryl content of fresh egg yolk was 0.057 mmol/g protein, and reached a peak level of 0.102 mmol/g protein after 3 weeks of salting. DSC results showed that salting promoted the heat tolerance of egg yolk protein. The thermal transition temperature of fresh yolk protein was 79.06 ℃, and increased to 80 ℃ after 15 weeks of salting. SDS-PAGE showed that salt did not affect the structure of peptide chains. Salt could result in a significant change in the secondary structure of yolk protein. The major secondary structures of fresh egg yolk protein were α-helix and β-sheet, accounting for 74.67% of all secondary structures. After salting, parts of α-helix and β-sheet turned into T turn.
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    Antioxidant Effects of α-Tocopherol, Ascorbyl Palmitate and Quercetin on Structured Lipid Containing Pinolenic Acid
    FOOD SCIENCE    2013, 34 (1): 88-92.  
    Abstract1367)   HTML2)    PDF(pc) (573KB)(504)       Save
    The antioxidant effects of α-tocopherol (TOH), ascorbyl palmitate (AP), quercetin (Qu) on structured lipid (SL) were investigated through oven oxidation at 60 ℃. Polyunsaturated fatty acids (PUFA) revealed an obvious decrease, and the functional pinolenic acid decreased from 7.10% to 4.60% after 30 days of oven oxidation. AP and Qu could effectively protect PUFA from oxidation and significantly reduce the peroxide, acid, and TBARS values. AP and Qu showed a dose-dependent antioxidant capability. Compared to a low concentration (100 mg/kg), TOH at a high concentration (500 mg/kg) revealed a slight promotion effect on oxidation, thus increasing acid and TBARS values. Besides, not only chemical characteristics including fatty acid composition and acid, peroxide and TBARS values, but also the melting and crystal profiles of SL were affected by oxidation and added antioxidants.
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    Changes in Main Nutrients of Bamboo Shoots during Pickling
    FOOD SCIENCE    2013, 34 (1): 93-96.  
    Abstract1535)   HTML3)    PDF(pc) (407KB)(315)       Save
    Bamboo shoots (Dendrocalamus latiflorus) were analyzed for changes in main nutrients including protein, soluble sugar, cellulose, vitamin C and minerals during pickling by 4 different methods. The results showed that the contents of protein, soluble sugar, cellulose, vitamin C and minerals significantly changed during pickling. After 90 d of pickling, the contents of protein, soluble sugar, vitamin C and cellulose decreased by 87.01%, 98.17%, 71.29% and 39.27% for fermentative pickling, and 77.36%, 86.63%, 90.87% and 45.01% for non-fermentative pickling, respectively. However, the contents of calcium and potassium in pickled samples increased by 26.00% and 3.15%, respectively, while the contents of phosphorus, iron and zinc decreased by 94.31%, 62.53% and 29.17%, respectively, when compared to fresh samples.
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    Evaluation of Quality Characteristics of Popular Imported Cheese in Nanning, Guangxi
    FOOD SCIENCE    2013, 34 (1): 97-100.  
    Abstract1200)   HTML1)    PDF(pc) (207KB)(318)       Save
    In order to investigate the consumer preference of cheeses, six samples of different types of popular imported cheese in Nanning, Guangxi were tested for nutrient composition, texture and sensory characteristics. The relationship between cheese textural properties and sensory properties was also studied by simple correlation and canonical correlation analysis. The results showed that Cheddar with moderate water content, better flavor and excellent texture was preferred by most consumers. The correlation coefficient was higher than 0.7 for firmness, gumminess and texture, whereas other correlation coefficients were lower than 0.7, indicating that the relationship between cheese textural properties and sensory properties arises from an obvious correlation with chewiness, guminess and texture patterns.
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    Effect of Corn Flour on Textural Properties of Wheat Dough and Chinese Steamed Bread
    FOOD SCIENCE    2013, 34 (1): 101-104.  
    Abstract1697)   HTML4)    PDF(pc) (310KB)(558)       Save
    The objective of this study is to investigate the effect of corn flour on textural properties of dough and Chinese steamed bread (CSB). Corn flour was added to wheat flour at ratios of 0:100, 5:100, 10:100, 15:100 and 20:100. Textural properties were studied using texture profile analysis, and the ultrastructure of gluten was examined by scanning electron microscopy (SEM). Results revealed a significant difference in textural properties of dough at a ratio of 20:100 and no significant difference at levels lower than 20:100 was observed. Adding more corn flour led to a significant decrease in hardness and gumminess and an obvious increase in springiness; however, no significant change in cohesiveness, chewiness and adhesiveness was observed. As the hardening rate of CSB increased, the effect of corn flour on anti-retrogration became bad and corn flour could hinder the formation of gluten network. Therefore, addition of corn flour can alter the ultrastructure of gluten and textural properties of dough and CSB.
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    Effect of Cooking on Nutritional Quality and Fatty Acid Pattern of Fat Duck Liver with Different Fatty Acid Profiles
    FOOD SCIENCE    2013, 34 (1): 105-108.  
    Abstract1254)   HTML1)    PDF(pc) (196KB)(291)       Save
    The objective of this study was to investigate the effect of cooking on general nutrients, fatty acid composition, and lipid oxidation in fat livers of ducks fed corn alone or in combination with fish oil or soybean oil. The results showed that cooking increased the contents of C12:0, total lipid and MDA, and decreased the contents of moisture and protein while no effect was observed on hepatin content in fat duck liver. After cooking, the contents of SFA, PUFA, n-6PUFA, n-3PUFA, EPA and DHA in livers of fish oil-fed ducks were significantly higher than those observed for soybean oil-fed ducks (P<0.05) and extremely significantly higher than those observed for corn control (P<0.01). The contents of SFA and MUFA decreased significantly (P<0.05) with a concomitant increase in PUFA, n-6PUFA and n-3PUFA (P<0.05) in duck livers of corn control after cooking, only minor changes in these fatty acids were observed for livers of soybean oil-fed ducks, whereas livers of fish oil-fed ducks showed an increase in the levels of these fatty acids, particularly a significant increase in n-6PUFA (P<0.05). For each group of fat duck livers, cooking could cause a decrease in the levels of EPA and DHA, and corn control group and soybean oil group showed the biggest decrease in EPA and DHA, respectively. The above results suggest that fat livers of fish oil-fed ducks have the highest nutritional value.
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    Physico-chemical Properties and Structural Analysis of Modified Potato Starch
    FOOD SCIENCE    2013, 34 (1): 109-113.  
    Abstract1608)   HTML3)    PDF(pc) (500KB)(662)       Save
    Modified starches were prepared from native potato starch through introducing acetic ester groups and their structural characteristics were analyzed by FT-IR and SEM. Oxidized potato starch, potato starch acetate and oxidized potato starch acetate exhibited better transparency, adhesiveness and spreadability when compared to native potato starch. FT-IR analysis revealed the presence of characteristic absorption peak of carboxyl groups in oxidized potato starch and the formation of acetate groups in oxidized potato starch acetate. SEM observation showed the spherical or ellipsoidal shape and smooth surface of oxidized potato starch, no detectable change in the shape of potato starch acetate granules, but with poor regularity, and intact oxidized potato starch acetate granules with a low degree of substitution as a result of estertification on their rough surfaces.
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    Enzymatic Modification and Antioxidant Activity of Polysaccharides from Cordyceps militaris Fruit Bodies
    FOOD SCIENCE    2013, 34 (1): 114-120.  
    Abstract1636)   HTML3)    PDF(pc) (1080KB)(370)       Save
    Polysaccharides were extracted from Cordyceps militaris fruit bodies and modified using α-amylase for enhanced antioxidant activity. Response surface methodology was employed to optimize conditions for the enzymatic modification of polysaccharides based on DPPH radical scavenging activity. In addition, modified polysaccharides were tested for DPPH radical scavenging activity, ferrous ion chelating capacity and reducing power as well as triple-helical conformation. The optimized hydrolysis parameters were in decreasing order of their effects on DPPH radical scavenging activity of modified polysaccharides: enzyme dosage, temperature and pH and their optimal conditions were 259.5 U/g, 48.5 ℃ and 5.8, respectively. Under these conditions, the maximum predicted and experimental DPPH radical scavenging rates of modified polysaccharides were 81.4% and (81.6 ± 1.6)%. The results of the validation experiments showed good reproducibility and thus, the fitted prediction model is applicable in practice. The antioxidant tests showed that the EC50 values of modified polysaccharides for scavenging DPPH radical and chelating ferrous ions were 0.0247 mg/mL and 1.0120 mg/mL, respectively, which were 55.1% and 39.8% higher than before the modification, respectively. Meanwhile, the reducing power of polysaccharides significantly increased (P<0.05) after the modification (P<0.05), and the triple-helical conformation was well maintained but slightly damaged.
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    Effect of Microwave Radiation on Physico-chemical Properties of Native and Modified Corn Starch
    FOOD SCIENCE    2013, 34 (1): 121-126.  
    Abstract1383)   HTML3)    PDF(pc) (852KB)(605)       Save
    Native corn starch containing 30% moisture and octenyl succinate modified starch were treated by microwave for different periods of time to investigate the effect of microwave radiation on their physico-chemical properties. The moisture content of native starch and modified starch showed a downward trend with increasing microwave radiation time and reached normal levels after 4 min. Partial or even complete rupture on the surface of both starch granules was observed by SEM after microwave radiation. Moreover, their crystallinity basically remained stable before and after microwave radiation. Both starches and their gelatinization products were found to be pseudoplastic non-Newton fluids. Power law model could well fit shear force as a function of shear rate. The viscosity of native corn starch decreased, but octenyl succinate modified starch showed a trend to initially increase and then decrease with increasing microwave radiation time. The storage modulus of native corn starch initially increased and then decreased, and the loss modulus exhibited only minor changes, whereas an opposite changing trend to storage modulus was observed for loss factor. Octenyl succinate modified starch revealed only minor changes in viscoelasticity. For octenyl succinate modified starch, microwave radiation for a period of lower than 6 min resulted in only very minor changes in viscoelasticity when compared to control group (not receiving microwave radiation) and a decrease in storage and loss moduli but a significant increase in loss factor when compared to 6 min microwave radiation.
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    Fingerprinting Analysis of Quality Change of Deep Frying Edible Oil
    FOOD SCIENCE    2013, 34 (1): 127-130.  
    Abstract1038)   HTML1)    PDF(pc) (717KB)(254)       Save
    Infrared spectroscopy and electronic nose were used to detect functional groups in used edible oil. Infrared spectroscopic analysis showed that soybean oil revealed changes in some absorption peak areas due to the formation of aldehydes and ketone after thermal oxidation. The results of electronic nose detection demonstrated that no obvious changes in chemical components were observed at heating temperatures lower than 150 ℃ despite significant differences when compared with control group. The same results were obtained when the continuous heating time exceeded 3 h. Hence, both techniques allow the identification of quality changes of edible oil during high temperature heating.
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    Purification and Identification of Nucleoside Components in Cordyceps cicadae Fruit Bodies
    FOOD SCIENCE    2013, 34 (1): 131-134.  
    Abstract1790)   HTML3)    PDF(pc) (566KB)(475)       Save
    The aim of this study was to extract, purify and identify nucleoside components of Cordyceps cicadae fruit bodies. Samples were extracted with 65% ethanol by ultrasonic-assisted extraction, and a supernatant was obtained from the resulting extract by centrifugation at 10000 r/min for 5 min and separated by RP-HPLC using 0—100% methanol as a mobile phase through gradient elution at a flow rate of 15 mL/min (1 mL injection volume, 260 nm detection wavelength). As a result, 6 final products were obtained and identified as cytosine, uridine, inosine,guanosine, adenosine and cordycepin, respectively, with a purify exceeding 95%. This study demonstrates that RP-HPLC is a feasible, simple and accurate technique for separating and preparing nucleoside components of Cordyceps cicadae fruit bodies.
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    Influence of Microbial Transglutaminase on the Quality of Wheat Flour
    FOOD SCIENCE    2013, 34 (1): 135-139.  
    Abstract1173)   HTML1)    PDF(pc) (667KB)(437)       Save
    The influence of microbial transglutaminase (MTG) on the rheological properties of dough and gluten was investigated by farinograph and extensograph measurement and HPLC analysis. When 5 U/g MTG was added to wheat flour, the dough stability time increased by 18%, the degree of softening decreased about 15%, and the farinograph index also ascended. Addition of 5 U/g MTG had more significant effects on extensograph properties, and the longer the standing time, the better extensograph properties were improved. In addition, the contents of ω5-gliadin and ωb-gliadin in flour suspension declined by 99% and 88%, respectively, as opposed to 42% and 25% observed when 10 U/g MTG was added. MTG could improve the quality of gluten by catalyzing the intermolecular and intramolecular interactions of various components and producing more macromolecular proteins. In conclusion, MTG is effective in improving the quality of flour and therefore has wide prospects for applications in baked foods.
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    Grading Method for Beef Marbling Based on Improved Watershed Algorithm and Hopfield Network
    Xiang-Yan MENG
    FOOD SCIENCE    2013, 34 (1): 140-145.  
    Abstract1667)   HTML1)    PDF(pc) (765KB)(444)       Save
    Beef images were pretreated based on the hue component of the HSV color space, and an improved watershed algorithm was proposed to separate the rib-eye and beef marbling region from the images. Meanwhile, the correlations of characteristics parameters from U.S., Chinese and Japanese standard grading graphs were analyzed. Five characteristic parameters were selected for beef marbling distribution. A new automatic grading method based on improved watershed method and Hopfield network was proposed, and the results indicated that the accuracy of this method was 87.23%.
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    Effect of Monoglycerides on Physico-chemical Properties of Potato Starch
    CHEN Cong-Gui
    FOOD SCIENCE    2013, 34 (1): 146-149.  
    Abstract1083)   HTML1)    PDF(pc) (373KB)(511)       Save
    The effect of monoglycerides (MON) on paste rheological properties and gel syneresis and hardness of potato starch (PS) was investigated. In addition, thermal properties and gel microstructure of PS alone or with added MON were analyzed by differential scanning calorimetry and scanning electron microscopy (SEM). Addition of MON caused a significant increase in the onset gelatinization temperature, temperature for maximum viscosity and gelatinization enthalpy of PS, and a significant decrease in the maximum viscosity of starch paste and gel syneresis after retrogradation (P<0.05). Moreover, the gel structural compactness was significantly enhanced and as a result, the gel hardness after retrogradation was improved (P<0.05).
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    Benzoic Acid Formation Mechanism in Traditional Fermented Douchi
    FOOD SCIENCE    2013, 34 (1): 150-154.  
    Abstract1491)   HTML6)    PDF(pc) (742KB)(416)       Save
    To explore the mechanism of benzoic acid formation during production of traditional fermented douchi and discover the reason for natural existence of benzoic acid without adding it, changes in the contents of benzoic acid, phenylalanine and β-cinnamic acid and phenylalanine ammonia lyase (PAL) activity were determined by HPLC at different stages of fermentation. After 2 days of incubation, the benzoic acid content of the koji was 2.43 mg/kg and then gradually increased with increasing incubation time, reaching 37.23 mg/kg after 215 days of post-fermentation. Similarly, the phenylalanine content of the starting raw material (soybean) was 4.89 mg/100 g and increased to 272.23 mg/100 g after 215 days of post-fermentation. β-cinnamic acid showed a high level during the koji making stage, resulting in an obvious increase in benzoic acid level, but gradually declined during the post-fermentation stage, without considerably increasing benzoic acid level. Moreover, the PAL activity, which catalyzes the transformation of phenylalanine into β-cinnamic acid, was stronger during the koji making stage, but gradually became weaker during the post-fermentation stage. The contents of benzoic acid and β-cinnamic acid increased and decreased, respectively, due to addition of β-cinnamic acid during the post-fermentation stage. Hence, we conclude that the mechanism of benzoic acid formation during production of traditional fermented douchi may partial hydrolysis of proteins into peptides in the staring raw material, subsequent PAL-catalyzed transformation of phenylalanine into β-cinnamic acid and final oxidization of β-cinnamic acid into benzoic acid under required conditions.
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    Effect of Dissolved Oxygen Controlling Conditions on Production of Extracellular Polysaccharides by Agaricus bisporus MJ-0811
    FOOD SCIENCE    2013, 34 (1): 155-159.  
    Abstract1329)   HTML2)    PDF(pc) (628KB)(363)       Save
    Agaricus bisporus MJ-0811 was cultured in a 5 L automatic fermenter to explore the effect of dissolved oxygen controlling conditions (stirring speed and aeration) on mycelial biomass, extracellular polysaccharide production, dissolved oxygen concentration, and residual glucose concentration. The results showed that stirring speed and aeration rate had significant impact on the growth of Agaricus bisporus MJ-0811 and the production of extracellular polysaccharides. The highest mycelial biomass (20.81 g/L) and extracellular polysaccharides (3.75 g/L) were obtained when Agaricus bisporus MJ-0811 was cultured for 5 d at 25 ℃ with a stirring speed of 160 r/min and an aeration rate of 0.9 vvm.
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    Isolation and Identification of Bacteria Causing Discoloration in Red Pepper Fruits (Capsicum annuum L.)
    FOOD SCIENCE    2013, 34 (1): 160-165.  
    Abstract1271)   HTML5)    PDF(pc) (521KB)(440)       Save
    Five dominant bacteria causing the discoloration of red pepper fruits (Capsicum annuum L.) were isolated from red pepper fruits following the traditional bacterial isolation procedures. Meanwhile, they were identified based on morphological observation, physiological and biochemical properties, 16S rDNA sequences and BLAST homology alignment as two Bacillus subtilis strains, one Lysinibacillus sphaericus strain, one Bacillus amyloliquefaciens strain, and one Bacillus pumilus strain, respectively.
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    Optimization of Enzymatic Preparation of Rapeseed Peptides
    Li-Feng WANG
    FOOD SCIENCE    2013, 34 (1): 166-170.  
    Abstract2288)   HTML2)    PDF(pc) (558KB)(228)       Save
    Rapeseed protein was extracted from defatted rapeseeds and hydrolyzed by alcalase. Response surface methodology was employed to optimize enzymatic hydrolysis conditions based on degree of hydrolysis (DH) and rapeseed peptide yield. The optimum conditions for enzymatic preparation of rapeseed peptides were found to be hydrolysis at 55 ℃ and pH 8.45 for 180 min with a substrate concentration of 4.49% and an enzyme concentration of 5000 U/g protein. Under these conditions, the theoretical value of degree of hydrolysis was 15.00%, while the actual value was 14.71%.
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    Analysis of Antibiotics Related Genes from Antagonistic Bacillus amyloliquefaciens against Aeromonas hydrophila
    Hai-Peng Cao
    FOOD SCIENCE    2013, 34 (1): 171-174.  
    Abstract1466)   HTML1)    PDF(pc) (409KB)(421)       Save
    The antibiotics related genes of antagonistic Bacillus amyloliquefaciens G1 against Aeromonas hydrophila isolated from sturgeons were amplified by PCR and sequenced. Meanwhile, the amino acid sequence, transmembrane heices, domains and secondary structure of their encoded products were determined. The results showed that only the gene essential for iturin synthetase was present in strain G1, which was naturally clustered with the iturin gene family from Bacillus sp. in GenBank, including iturin A, bacillomycin D, mycosubtilin, and showed 98% similarity to the iturin A gene sequences of B. subtilis strain MH25 and strain RB14. The amino acid sequence of the encoded product of the iturin synthetase gene exhibited high similarity to that of iturin, iturin A, bacillorin and bacillomycin D, and was close relative to the iturin A synthetase B of B. subtilis strain MH25 (GenBank accession No.ABY89499). In addition, no obvious transmembrane structure was present in the encoded product of the iturin synthetase gene of strain G1. However, both AMP-binding site and PP-binding site were present in its domains. Alpha helix, beta turn, random coil and extended strand were also present in its secondary structure.
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    Optimization of Process Parameters for Alcoholic Fermentation of Jujube Juice
    Zhou-Min LU
    FOOD SCIENCE    2013, 34 (1): 175-179.  
    Abstract1476)   HTML1)    PDF(pc) (682KB)(403)       Save
    Process parameters for the alcoholic fermentation of jujube juice prepared from Mu jujubes collected from Qingjian county such as initial solid content, yeast inoculum size, temperature and fermentation time were optimized using response surface methodology. Alcohol production was extremely significantly influenced by initial solid content, temperature and fermentation time (P<0.01) and no significantly influenced by inoculum size (P>0.05). Four process parameters were in descending order of their effects on alcohol production: fermentation time > temperature > initial solid content > inoculum size. Their optimum conditions were determined to be 43 h, 31 ℃, 17% and 0.8%, respectively. Under these conditions, the alcohol concentration in fermented jujube juice was over 9.6%. The results of validation experiments demonstrated that the developed mathematical prediction model is applicable for practical production.
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    Synthesis and Characterization of Ractopamine Antigen Linked by 4-Methylbenzoic Acid
    FOOD SCIENCE    2013, 34 (1): 180-184.  
    Abstract1159)   HTML1)    PDF(pc) (572KB)(396)       Save
    The mixed anhydride method was used to prepare artificial antigen through the conjugation between ractopamine (RAC) and bovine serum albumin (BSA) in the presence of 4-chloromethyl benzoic acid (CBA). The prepared artificial antigen was identified by IR, UV and SDS-PAGE. RAC-CBA was also conjugated with OVA to form a coating antigen. The affinity and inhibitory activity of the coating antigen were measured. This study suggests that CBA can be used to prepare artificial RAC antigens. Meanwhile, CBA conjugated with RAC to form coating agent improves the sensitivity of ELISA.
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    Screening of Optimal Strain for Microbial Preparation of ACE Inhibitory Peptides from Soybean Protein Isolate
    FOOD SCIENCE    2013, 34 (1): 185-188.  
    Abstract1301)   HTML4)    PDF(pc) (572KB)(466)       Save
    To screen the optimal strain for microbial preparation of ACE inhibitory peptides from soybean protein isolate (SPI), the effects of different strains including 5 Lactobacillus strains, 3 mould strains and 1 Bacillus subtilis strain on ACE inhibitory rate and peptide concentration were investigated. Lactobacillus bulgaricus was found to be the best of five 5 Lactobacillus strains for the preparation of ACE inhibitory peptides from SPI, providing an ACE inhibitory rate of 57.93% and a peptide concentration of 3.27 mg/mL. A. oryzae was the best mould, providing an ACE inhibitory rate of 41.23% and a peptide concentration of 2.17 mg/mL. Bacillus subtilis fermented SPI showed an ACE inhibitory rate of 45.02% and a peptide concentration of 2.25 mg/mL. Comparing the fermentation characteristics of 9 strains, Lactobacillus bulgaricus was an excellent strain for the preparation of ACE inhibitory peptides from SPI.
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    Screening of Protease-Producing Bacterium from Octopus vulgaris Intestine, Fermentation Conditions and Enzymatic Properties
    Jin Yu Lan mei-zi PIAO
    FOOD SCIENCE    2013, 34 (1): 189-193.  
    Abstract1309)   HTML1)    PDF(pc) (679KB)(333)       Save
    A protease-producing bacterial strain was isolated and screened from the intestine of Octopus vulgaris by detecting hydrolysis circle of protease and its activity and identified as QDV-3. The optimal fermentation conditions for protease production and its enzymatic properties were also investigated. The highest protease production was achieved when strain QDV-3 was cultured at 30 ℃ for 3.5 d under shaking conditions in a medium at pH 8.0 with fructose as the carbon source and peptone as the nitrogen source. Meanwhile, protease production was improved in the presence of Mn2+ and Ba2+. At least five proteases were identified by SDS-PAGE, with molecular weights between 32.4 kD and 124.2 kD. The optimal reaction temperature and pH for the fermentation supernatant were 50—60 ℃ and 9—11, respectively. The fermentation supernatant exhibited high thermal stability, and 95% of its initial activity was retained after 1 h incubation at 50 ℃.
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