Abstract:Cultured meat is meat produced from animal stem cells cultured in vitro, which is different from conventional meat production through farming. In recent years, cultured meat is becoming a subversive future food production technology. In this review, the progress in cell sources, stemness maintenance, serum-free culture conditions, large-scale proliferation and differentiation, food processing, safety evaluation and regulatory requirements for cultured meat industrialization were summarized. As a prospect, the challenges and potential solutions were also discussed.
Abstract:To investigate the generation and occurrence mechanism of viable but non-culturable(VBNC) in Salmonella enterica serovar Typhimurium artificially inoculated in BPY broth during thermosonication (TS), RT-qPCR and plate counting methods were used to detect the viable and VBNC state S. Typhimurium, ESR was used to detect free radicals generation. The relationship between free radicals generation and VBNC state incidence index was analyzed. Generally, higher intensity of TS treatment promoted S. Typhimurium into VBNC state and produced more free radicals. Three kinds of free radicals were detected, including C-centered radicals, hydroxyl radicals and hydrogen radicals. There was a correlation between the intensity of free radicals and the VBNC state incidence index during TS treatment, which can be fitted and validated using the Boltzmann model. Sodium pyruvate, as a free radical scavenger, was used to confirm that free radicals play an key role in inducting VBNC state microbial cells. These obtained results may help to facilitate application of TS processing.
Abstract:Objective: To investigate the effect of phosphorylation on nutritional value and digestion and absorption of whey protein isolate(WPI). Methods: Phosphorylation of WPI by sodium tripolyphosphate(STP) was carried out. The emulsifying and emulsifying stability, foaming and foam stability, gel hardness and amino acid composition before and after modification were compared. In vitro simulated digestion model and Caco-2 cell absorption model were used to simulate digestion and absorption experiments. The digestion and absorption rate and amino acid composition of WPI before and after modification were determined and compared. Results: When the content of STP increased from 1% to 7%, the degree of modification increased with the increase of the amount of addition, and the functional properties of WPI increased significantly (P<0.05). Threonine (Thr) and lysine (Lys) decreased with the increase of the degree of modification, but there was no significant difference in SRCAA among the modified groups. The digestion and absorption rate of WPI before and after phosphorylation modification was not significant difference(P>0.05). Comparing the amino acid composition of WPI before and after phosphorylation modification, glutamic acid (glutamine) content was significantly decreased (P<0.05), suggesting that glutamine may be a phosphorylation site other than lysine. Conclusion: Phosphorylation of WPI improve the functional properties of the same time, does not affect the nutritional value of protein and digestion and utilization.
Abstract:The probiotic potential of four Lactobacillus from breast-fed infants faeces: Lactobacillus rhamnosus BF-1, Lactobacillus plantarum BF-15, Lactobacillus salivarius BF-29 and Lactobacillus paracasei BF-55 was evaluated by a series of in vitro assays: resistance to simulated gastrointestinal juice and bile, adhesion to Caco-2 cells, the safety and the effect on proliferative capacity of the spleen lymphocytes in th-e mice. Results showed that it was indicated that: Lactobacillus plantarum BF-15 has stronger tolerance toartificial digestive juice and bile salts. The adhesion to Caco-2 cells [(7.10 ± 0.30)CFU/cell] of BF-15 was significantly higher than the positive control strain LGG [(3.90 ± 0.30) CFU/cell](P<0.05). In addition, Lactobacillus plantarum BF-15 was resistant not only to aminoglycoside inherently,but also to oxacillin and cephalothin without plasmid. In a certain concentration range(1×106-107 CFU/mL), viable or heat-killed Lactobacillus both could promote lymphocyte proliferation of the mice in vitro and showed a dose-dependent relationship. Under the same bacterium concentration, there was no significant difference in immunoregulation ability between the two strains (P>0.05). Lactobacillus plantarum BF-15 presents favorable strain-specific properties, which could provide probiotic resources for developping new infants and young children formula milk powderin and new probiotic products in the future.
Abstract:In this study, the turbidimetry and viable count methods were used to study the growth of Lactobacillus rhamnosus AS 1.2466T / Lactobacillus bulgaricus ATCC 11842 in basic medium / Jerusalem artichoke juice base medium with different amounts of xylo-oligosaccharides, oligosaccharides, red ginseng liquid and its acid hydrolyzate. The results showed that the enrichment effect of different additives on Lactobacillus rhamnosus AS 1.2466T is red ginseng liquid medicine> red ginseng acid hydrolyzate> xylo-oligosaccharide> oligofructose. The OD600 value of Lactobacillus rhamnosus AS 1.2466T was 1.172 when the amount of red ginseng was 12.50%; and the number of viable cells was 2.72 × 108 CFU / mL, which was an order of magnitude higher than that of the basic medium 7.75 × 107 CFU / mL. The enrichment effect of prebiotics on Lactobacillus bulgaricus ATCC 11842 is red ginseng liquid medicine> xylo-oligosaccharides> red ginseng acid hydrolyzate> oligofructose. The OD600 value of Lactobacillus bulgaricus ATCC 11842 was 0.627 when the amount of red chemical solution was 6.25%; and the number of viable cells was 4.43 × 108 CFU / mL, which was an order of magnitude higher than the maximum viable count of 1.48 × 107 CFU / mL in the basal medium of Jerusalem artichoke. In summary, we found that red ginseng has a better enrichment effect than xylo-oligosaccharides or oligofructose. It can be used as a prebiotics to further study its prebiotics function, which can provide a basis on the study of the effect of red ginseng on intestinal microbes.
Abstract:Tyr-Phe-Cys-Leu-Thr(YFCLT), a corn peptide identified from corn gluten meal, was used as the research object. Through the in vitro anti-oxidation test and cell model test, the protective effects on HepG2 cells were studied from two aspects of oxidative stress and lipid metabolism. The results of antioxidant test in vitro showed that Tyr-Phe-Cys-Leu-Thr had DPPH radical scavenging ability, ABTS radical scavenging rate, iron chelating ability and oxygen radical absorbing ability (ORAC) at a lower concentration of 1 μmol/L. Alcohol was used as the inducer to induce the alcoholic injury model of human hepatocarcinoma cells (HepG2). The optimal concentration of alcohol was 500 mmol/L for 24 hours. The results showed that Tyr-Phe-Cys-Leu-Thr could protect the HepG2 cells from oxidative stress injury by reducing the leakage of ALT and AST, the activity of SOD, cat and GSH, and the release of ROS and TNF-α. Tyr-Phe-Cys-Leu-Thr can also reduce the content of TG in cells and the accumulation of fat, thus play a protective role in lipid metabolism. In conclusion, Tyr-Phe-Cys-Leu-Thr can protect HepG2 cells from alcohol induced injury.
Abstract:Selenium-chelating porn oligopeptide were prepared by using pea oligopeptide and sodium selenite. The properties of moisture, acid soluble protein, total nitrogen and molecular weight distribution were analyzed. Taking scavenging effects on DPPH, OH free radicals and reducing power as indicators, the antioxidant function of raw materials and chelates were evaluated and compared in vitro. The results showed that the yield was 27.87%, the moisture content of the product was (14.17 ± 1.12)%, the acid soluble protein accounted for 97.28% of the crude protein, and the molecular weight below 1 000 u was 93.45%. For raw materials, sodium selenite only had strong OH radicals scavenging ability; for pea oligopeptides, the median inhibitory concentrations (IC50 values) of DPPH radical and OH radical scavenging activities were (3.39 ± 0.02) mg/mL and(23.55 ± 0.07) mg/mL, respectively, and the pea oligopeptides showed some reducing power. While for selenium-chelating pea oligopeptides, IC50 of DPPH radical and OH radical scavenging activities were (1.77 ± 0.01) mg/mL and (3.28 ± 0.04) mg/mL, and showed certain reducing power, better than pea oligopeptides。
Abstract:Pepsin was used for in vitro simulated digestion of heat-treated soybean protein isolate (SPI). The subunit composition, protein secondary structure and molecular weight distribution of digestion products were researched. The degree of hydrolysis increased firstly and then decreased with the increase of heat treatment temperature and time, which indicated that proper heat treatment conditions could promote the digestion and degradation of SPI by pepsin. The heat treatment was able to change in vitro digestion mode of SPI, reducing the digestion degree of 11S subunit, leading to the digestion and degradation of 7S subunits, which formed the component with the molecular weight lower than 17 ku. Heat treatment mainly resulted in the increase of α-helix content and the decrease of β-sheet content in the secondary structure of digestion products. The molecular weight distribution of SPI digestion products was also changed. As rising of heat treatment temperature, the α-helix content increased firstly and then decreased, whereas the opposite trend was noted for β-sheet content. However, the heat treatment time had no significant effect on the content of all secondary structures. For the SPI digestion products, high temperature or heat treatment for long time could increase the distribution in the range of more than 100 ku and 3-10 ku, while decrease the distribution in the range of 10-100 ku and less than 3 ku.
Abstract:By using spectrophotometric method, enzymatic methods and cylinder-plate method, the biological characteristics on of Bacillus subtilis HJD.A32 which was screened from the fresh cupei of Shanxi vinegar and produced bacteriocine was researched. The research showed that B. subtilis HJD.A32. had the ability of produceing liquefaction, glucoamylase and protease. The activity of enzymes by B. subtilis HJD.A32 in the solid-state fermentation was better than that in the liquid fermentation. The activity of those enzymes was respectively 1 874.23, 4.43 U/g and 181.91 U/g. B. subtilis HJD.A32 had tolerance to the NaCl and cholate, the highest resistant concentration of them was respectively 6% and 1%; B. subtilis HJD.A32 had the tolerance to the surfactant or emulsifier, e.g SDS, LAS, AES, Towen 20, Towen 80. B. subtilis HJD.A32 had the tolerennce to the temperature. It could grow and reproduction when it was deal with for 5 min under the temperature 100℃. B. subtilis HJD.A32 had tolerance to the artificial gastric solution and intestinal solution. B. subtilis HJD.A32 could grow and reproduction under the condition of the artificial gastric solution and intestinal solution. B. subtilis HJD.A32 was sensitive to many antibiotics. It could grow with acetobacter. All the character above of B. subtilis HJD.A32 establish the foundation for its development and utilization as probiotic preparations.
Abstract:Objective: By analyzing the polyphenol composition, antioxidant capacity and their correlation of 15 not from concentrate (NFC) apple juice, the contribution of polyphenol composition to antioxidant capacity is studied, providing reference for the juice industry in the selection of raw fruit. Method: Fifteen varieties of NFC apple juice were prepared, and the composition and antioxidant capacity of polyphenols (DPPH and ABTS free radical scavenging capacity) were analyzed by ultra-high performance liquid chromatography and antioxidant experiment in vitro, and the results were obtained by one-way ANOVA and correlation analysis. Results: Among the 15 kinds of monomer phenols in NFC apple juice, chlorogenic acid content was the highest and epicatechin gallate content was the lowest. The main polyphenols were proanthocyanidins, phenolic acids and flavonoids. The content of phenolic acids was the highest (102-331 g/mL) and the flavonoids were the lowest (5-30 μg/mL). Among the 15 apple varieties, the DPPH free radical scavenging ability of Jonagold was the highest at 89.1%, and the ABTS free radical scavenging ability of Qiuxiang was the highest at 92.6%. Conclusion: Procyanidines are major contributors to the antioxidant capacity of NFC apple juice in vitro. Three monomeric phenols, procyanidins B2, epicatechin and epicatechin gallate, have strong DPPH radical scavenging ability, while ABTS radical scavenging ability is more dependent on the total phenol content.
Abstract:Malondialdehyde was selected as a representative of reactive aldehydes produced in the process of polyunsaturated fatty acids lipid peroxidation catalyzed by lipoxygenase, and the aim of this work was to investigate the effect of malondialdehyde oxidation on the emulsifying properties of walnut protein isolates. The results indicated that as concentration of malondialdehyde increased from 0 to 10 mmol/L, carbonyl content of walnut protein isolates increased from 3.12 nmol/mg to 20.61 nmol/mg; Surface hydrophobicity(H0) showed the trend of first increase and then decrease (P<0.05); Intrinsic fluorescence of emulsion decreased from 419.97 to 109.86 and maximum emission wavelength moved in the short wave direction; Droplet size distributions and creaming rate firstly decreased then increased; Zeta potential and emulsion stability of the test emulsions firstly increased then decreased; but emulsifying activity decreased form 46.57 m2/g to 26.26 m2/g. When malondialdehyde concentration was 0.1 mmol/L, droplet size distributions and creaming rate reached the minimum value; and zeta potential and emulsion stability reached the maximum value. The analysis of the results showed lower level oxidation could generate emulsion stability of walnut protein isolates, while higher level oxidation had a negative effect on the emulsifying properties.
Abstract:In the present study, the enzymatic hydrolysis resistance of gelatin, modified by transglutaminase, was investigated by single factor test and uniform design. Results showed that the enzymatic hydrolysis resistance of modified gelatin was affected by transglutaminase concentration, treatment pH value, treatment temperature, and treatment time. The optimal treatment conditions for the enzymatic hydrolysis resistance of modified gelatin were as follows: transglutaminase concentration 0.20 g/L, treatment pH 6.0, treatment temperature 44 °C, and treatment time 35 min. The enzymatic hydrolysis resistance of modified gelatin increased 14.44% compared to unmodified gelatin. This study confirmed that the enzymatic hydrolysis resistance of gelatin can be enhanced by transglutaminase modified.
刘功良;朱宝生;高苏娟;刘锐;白卫东;费永涛;艾连中;俞剑燊;郭波;
Abstract:Metabolic characteristics and metabolic flow of Zygosacharomyces mellis LGL-1 under high- glucose stress were studied. Metabolites accumulated under 100 g/L and 400 g/L glucose concentration, such as alcohol, trehalose, glycerin, malic acid, α-ketoglutarate, citric acid, and lactic acid were determined. Metabolic flow distribution of key nods were analyzed through construction of metabolic matrix equations, MATLAB software and normalization method. The results showed that the carbon flow of Z. mellis LGL-1 was towards the metabolism branch of trehalose, glycerol, alcohol synthesis and TCA cycle. Compared with the normal cultivation, the metabolic flux of trehalose, glycerol and TCA under high-glucose stress was increased by 50.00%, 17.73% and 4.79%, respectively. But the metabolic flux of ethanol showed little difference. Trehalose and glycerin accumulation, flux change of TCA cycle under high-glucose stress reflected the important protective function to Z. mellis LGL-1.
张宇;姜毓君;党芳芳;潘瑞丽;陈思涵;林官根;张雅硕;满朝新;张微;
Abstract:The objective of this study was to evaluate hypoglycemic effects of Lactobacillus paracasei TD062 on the type 2 diabetes mice treated with the strain at 109, 108 and 107 CFU/mL. Meanwhile, the expression levels of glycogen synthase kinase 3β(GSK-3β) were determined to explore the hypoglycemic mechanism. The results demonstrated that L. paracasei TD062 could ameliorate glucose levels, organ coefficient and body weight. In addition, glucose tolerance and antioxidant capacity were elevated by oral administration of L. paracasei TD062. Furthermore, it was revealed that L. paracasei TD062 downregulated the relative expression levels of GSK-3β, regulated glucose metabolic disorders and ameliorated insulin resistance, thus delaying the development of diabetes. Therefore, L. paracasei TD062 might be applied as a new type of hypoglycemic agent in functional foods.
Abstract:Licorice is the root and rhizome of the legumes. Glycyrrhetinic acid, bioactive ingredient in licorice, has great application value. By preliminary screening and rescreening from ediblestrains, this study selected Aspergillus niger, which hasstrong ability toproduce glycyrrhetinic acid. Based on the research of the Response Surface Method, this research optimized the fermentation conditions for Aspergillus niger (A) transforming glycyrrhetinic acid, the factors include content of licorice, content of concentrated apple juice, content of wheat bran and the fermentation time. The results showed these four factors havegreat effect on transformation of glycyrrhetinic acid, and the optimum fermentation conditions were as following: content of licorice was 9.83%, content of concentrated apple juice was 8.05%, content of wheat bran was 9.76%, the fermentation time was 6.79 days and the expected conversion rate of 18-α-glycyrrhetinic acid was 0.9256, the result of verification experiment matched the predicted value.
Abstract:On the basis of single factor experiments,the paper deals with the optimization of the synthesis conditions for the fructose glucose and glycine reaction synthesis of 1- deoxy -1-L- glycine -D- (Fructosyl-Glycine, Fru-Gly) using response surface methodology. Fru-Gly compounds were synthesized under different reaction time, reaction temperature and molar ratio of glucose to amino acid. The antioxidant capacity was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging capacity, and reducing power. The results showed that, the concentration of Fru-Gly compound in the condition which was reacting for 0.9 h at the reaction temperature 79 ℃ after the molar ratio of glucose to glycine controlled to 3.25 ∶ 1 was the highest. And at this time the antioxidant activity of the sample was the strongest. The correlation analysis showed that the concentration of Fru-Gly compounds was significantly correlated with DPPH radical scavenging force, ABTS radical scavenging force and reduction force, and the correlation coefficient was greater than 0.96.
Abstract:Saccharomyces cerevisiae was embedded in calcium alginate to produce immobilized yeast. The difference between physical and chemical indexes and aroma substances in yellow rice wine fermentation process between free yeast and immobilized yeast was investigated. The results showed that after primary fermentation 5 d (28 ℃), after fermentation 15 d (15 ℃), there was no significant difference in alcohol content, total sugar and total acid change curve between immobilized yeast and free fermentation process, indicating that fermentation performance of immobilized yeast was stable and the contamination of heteromyces was controlled. The characteristic aroma compounds of 9 kinds of rice wine, such as ethyl acetate, were analyzed by gas chromatography (GC), it was found that the total alcohol content of n-propanol, isobutanol, isoamyl alcohol and beta benzoyl alcohol in yellow wine with free fermentation was 680.91 mg/L, and the total higher alcohols content of the first to fifth batch of immobilized fermentation in yellow rice wine was 633.63, 649.79, 658.17, 637.63 mg/L and 614.68 mg/L. It was suggested that immobilized fermentation was beneficial to control the content of higher alcohols in yellow wine. And the total amount of esters in the fermentation products of immobilized yeast was higher than free yeast, with the increase of the number of immobilized yeast fermentation, the total amount of esters increased: The fifth (115.90 mg/L) > the fourth(90.81 mg/L) > the first to three batch of immobilized fermentation (80.10-81.81 mg/L) > free yeast fermentation(55.66 mg/L). It showed that immobilized fermentation made the aroma of ester of yellow wine stronger. According to the calculation of the aroma threshold, the aroma of the yellow wine obtained by the immobilized fermentation was no worse than the yellow wine produced by the free yeast. Therefore, the production of yellow wine by immobilized yeast has the prospect of commercial application.
Abstract:A fungal strain was isolated with the capability for efficient production of ethyl hexanoate. The strain was identified as Monascus purpureus by ITS and beta-tubulin sequence analysis after morphological identification, and numbered as YJX-8. The culture conditions of YJX-8 for enzyme production were optimized for enhanced production of ethyl hexanoate, and the substrate specificity was also investigated. The results showed that the optimal culture medium components were sucrose 90 g/L, soybean cake powder 25 g/L, MgSO4 1 g/L, NaH2PO4 1 g/L. The optimal culture conditions were pH 4.5, 30 ℃, 180 r/min, 6 d. Under the optimized conditions, the esterifying enzymes activity was(1.177 ± 0.009)U/mL, which enhanced by 4.56 folds. The esterifying enzyme had an obvious substrate specificity to hexanoic acid.
Abstract:Super-pulverized fish bone was used as amino source to produce Maillard reaction with glucose. The optimal preparation processing of the solid-phase Maillard reaction were explored by response surface experiments on the basis of single factor experimental results using electronic nose and sensory evaluation as the index. The results showed that the primary factor of the Maillard reaction sensory evaluation is the glucose addition > reaction time > reaction time > initial pH value, and the optimal processing of Maillard reaction were 9.79% of glucose addition, 103.25 ℃, 70 min and initial pH is 7.21. The flavor of cod bone and fishbone flavorings can be distinguished by the electronic nose principal component analysis (PCA). And the sensory evaluation score of fish bone seasoning powder was higher and the flavor was better. It can not only provide the theoretical basis and method guidance for the development of natural seafood seasonings, but also provide a reference for the comprehensive processing and utilization on the scraps of the pollock.
Abstract:In this study, strawberry was used as raw material to ferment into jiaosu. The total sugar, total titratable acidity, citric acid, L-malic acid, acetic acid, lactic acid, total phenols and antioxidant properties (scavenging activities against DPPH radical, hydroxyl radical, ABTS radical and reducing power) were investigated. The relationship between metabolites and the antioxidant indicators was studied. Besides, principal component analysis was used to establish the change of comprehensive index in the fermentation process of strawberry jiaosu. The results showed that during the initial fermentation time (the first 20 days), the content of total sugar decreased little, and the content of total phenolic, total titratable acidity, citric acid and L-malic acid decreased. The scavenging ability of strawberry jiaosu against DPPH free radical and ABTS free radical was low, and the reducing power was less than 0.5. Meanwhile, the promoting effects against the hydroxyl radical was observed. In the mid-fermentation (20 d to 30 d), the content of total sugar decreased obviously, and the content of total titratable acidity, citric acid, L-malic acid, acetic acid and lactic acid and total phenols increased obviously, with scavenging activities against DPPH radical, hydroxyl radical, ABTS radical and reducing power increasing significantly. During the later phase of fermentation (30 d to 75 d), the content of each metabolites tended to be stable, and the content of citric acid and L-malic acid decreased slightly. The reducing power of strawberry jiaosu increased in the entire fermentation process, and the reduction rate against reducing power slowed down. After fermentation of 30 d, the total sugar, total titratable acidity, organic acids, total phenolic and antioxidant activity tends to be stable. The comprehensive evaluation index(CEI) of strawberry jiasu has the highest comprehensive score at 75 d, which can be used as the reference end point of fermentation or the basis of adding syrup or yeast. The establishment of comprehensive indexes in the fermentation process of strawberry jiaosu provides a theoretical basis for the precise fermentation of strawberry jiaosu.
Abstract:The effects of microwave apple whole fruit pretreatment on browning and quality of apple juice were investigated in this paper, compared with traditional enzyme inactivation process. The browning index, total phenolic and polyphenol oxidase activity, soluble quinone, pH, ascorbic acid content and antioxidant activity of apple juice were analyzed. Phenolic compounds were quantified using high performance liquid chromatography. The microstructure of the apple flesh was observed using scanning electron microscopy and transmission electron microscopy. The results indicated that with the microwave power of 800 W and time of 140 s, microwave preprocess can significantly retard the browning, increase the total phenol content, antioxidant capacity and stability of apple Juice(P<0.05). Microwave process pretreatment is a potential approach for apple juice processing.
Abstract:Foxtail millet was used as raw material to prepare food borne active peptides with angiotensin I converting enzyme(ACE) inhibition. The foxtail millet flour was processed by extrusion and fermentation, and its effect on digestibility of protein was studied. At the same time, ACE inhibitory activity and antioxidant capacity of foxtail millet polypeptide under pepsin-trypsin hydrolysis conditions were analyzed. The results showed, compared with the untreated foxtail millet flour, that extrusion and fermentation had significant effects on ACE inhibitory activity and antioxidant capacity of foxtail millet peptides(P<0.01). In general, the peptide of foxtail millet with extrusion treatment obtained by pepsin-trypsin hydrolysis has strong ACE inhibitory activity (IC50 = 0.057 mg peptide/mL), DPPH radical scavenging ability (10.99 μmol/g peptide) and iron ion reducing ability (82.92 μmol/g peptide).
Abstract:The combination of soluble polysaccharide and black soybean protein could change many functional properties of protein. In this experiment, black soybean protein was mixed with soluble polysaccharide with different time of ultrasonic treatment, which had the effect on physical properties and structure. The results showed that the stability of emulsification and emulsification was the best when the soy protein isolate was mixed with soluble polysaccharide at the ratio of 1 ∶ 2. When treated the compound of 1 ∶ 2 with ultrasonic, the emulsions of the composites treated for 16 min were the best, and the emulsions with 8 min were the best. Meanwhile with the prolongation of ultrasonic time, there was an increase in the α-helix and a decrease in the β-sheet, which indicated the structure and functional properties of proteins were closely related to each other. Therefore, proper ultrasonic treatment can influence the degree of compounding of soy protein isolates with soluble polysaccharides, and improved some properties.
Abstract:The optimum conditions for the preparation of kidney bean resistant starch by ultrasonic-microwave synergistic enzymatic method and the structural characteristics of kidney bean resistant starch were investigated. Purple round kidney bean starch was used as experimental material, and RS3-type resistant starch was prepared by ultrasonic-microwave and pullulan enzymatic hydrolysis method. The effects of different levels of starch suspension mass fraction, ultrasonic time, pullulanase addition and microwave power on the yield of resistant starch were investigated, and the response conditions were used to optimize the process conditions, and the structures of kidney bean starch and resistant starch were analyzed by gel permeation chromatography, scanning electron microscopy and infrared spectroscopy characteristic. The results showed that the highest yield of the resistant starch of alfalfa was(24.37 ± 0.41)% when the mass fraction of starch suspension was 16%, the amount of pullulanase was 12.5 ASPU/g(dry basis), the microwave power was 300 W, and the ultrasonic-microwave synergistic treatment for 20 min. Compared with the original starch, the resistant starch granules of kidney bean were broken and showed different shapes and sizes like a block of gravel structure. There was no new characteristic absorption peak of resistant starch. The average polymerization degree of resistant starch in kidney bean was decreased after treatment, the weight average and number average molecular weight increased, and the polydispersity coefficient decreased. Ultrasound-microwave synergistic enzymatic hydrolysis could increase the yield of resistant starch in kidney bean. The starch functional group unchanged during the formation of resistant starch, and the other structural characteristics changed.
Abstract:Different cooking methods can change the fat content and fatty acid composition in pork. Therefore, this assay use the longissimus dorsi muscle as the raw material, through four common cooking methods: steaming, boiling, microwave, baking, to explore the fatty acid changes, and then guide people’s cooking methods. Extraction of fat from cooked pork by improved Folch method, NH2 solid phase extraction cartridge was used to separate triglycerides and phospholipids from fat. The fatty acid composition was analyzed by gas chromatography with methyl thirteen methyl ester as the internal standard. The results showed that there was no significant effect of steaming, microwave, cooking and baking on fatty acid composition of triglyceride in pork fat compared with the control group. However, the composition of fatty acids in phospholipids was significantly changed by microwave, cooking and baking, the contents of saturated fatty acids (SFA) and trans fatty acids(TFA) in phospholipids were increased while the content of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) were significantly reduced, the most obvious change is baking; the steaming has the least influence on the fatty acid composition of phospholipid, but only SFA and PUFA change to a certain extent. The total fatty acid composition are significantly different, its change is mainly caused by the changes of phospholipids. Conclusion: cooking has a significant effect on phospholipids. Steaming is the best protection for fatty acids of pork fat, and roasting is easy to destroy fatty acids, thereby reducing nutritional value.
Abstract:The composite coatings of sodium alginate (SA) and konjac glucomannan (KGM) with different mass ratio were prepared by tape casting, and the physicochemical properties were measured. The preservation properties of the coatings on the ginger are researched. The results show that KGM makes the tensile strength and elongation at break of the SA coating increase significantly, and makes the water permeability and gas/ light permeability improve. Compared with the single SA coating, the SA/KGM composite coatings make the weight loss rate and respiration rate of the ginger decrease, the content decrease of total phenolics and flavonoids delay, the activity of PPO, POD and PAL restrain, the decrease of AsA, TA and the total soluble sugar content delay in the store process. So the qualities of the ginger are kept by the SA/KGM composite coatings. All KGM/SA composite coatings with different mass ratio can make the ginger keep fresh, and the preservation property of the KGM ∶ SA=2 ∶ 1 composite coating is the optimal.
Abstract:Rice bran (BR) was treated by superheated steam(SS) at the temperature of 120-160 ℃ for 1-5 min, Lipase activity was used as an index to select rice bran samples with good passivation lipase activity. The effects of SS treatment on the nutritional properties (Total phenolic content, total antioxidant capacity, phenolic acid composition changes, α-tocopherol content, γ-oryzanol content) and storage stability (fatty acid value, peroxide value, carbonyl value) of rice bran were evaluated. The results showed that the activity of lipase in rice bran had no significant changes after treated with SS at 120 ℃, 4 min; 130 ℃, 4 min; 140 ℃, 3 min; 150 ℃, 3 min; 160 ℃, 2 min. Rice bran at this time known as the best passivation lipase point rice bran, and its lipase activity decreased to 30.99%-13.41%. Compared with the rice bran, the total phenolics content, the total antioxidant capacity and the total phenolic acid content of the rice bran with the best passivation lipase point rice bran are significantly increased, The main contribution is the significant increase of ferulic acid and p-hydroxybenzoic acid; α-tocopherol and γ-oryzanol content decreased insignificantly. SS treatment significantly increased the stability of rice bran. At the 25th week, the fatty acid value, peroxide value and carbonyl value of rice bran at the best passivation lipase point rice bran were 36.0%-21.87%, 50.0%-44.3% and 30.3%-22.1% of BR, respectively, which effectively extended the storage period of rice bran. Considering the nutritional properties and storage stability of rice bran, rice bran obtained under the condition of 130 ℃, 4 min was the best.
Abstract:In order to investigate the effect of microencapsulation on the quality of fish oil, we made microcapsule by spray drying method, which was composed of chitosan as shell material, tuna oil as core material. The physicochemical properties, fatty acid composition and volatile ingredients were detected, and the accelerated storage tests were used to examine changes in these indicators above. The results showed that the fish oil microcapsules had higher peroxide value, lower unsaturated fat content, more key volatile components related to the fishy smell, and lower quality relatively. During the storage, fish oil microcapsules can significantly inhibit the increase of peroxide value and the increase of the content of key volatile components, and little effect on retention rate of DHA and EPA. Although the fish oil microcapsule preparation process will reduce the quality of fish oil to a certain degree, but to delay the oxidation of fish oil and masking bad taste does have a certain effect.
Abstract:This study designed two pairs of primers and probes and established a duplex digital PCR method for the quantitative detection of GM rice TT51-1 event based on the sequence of sucrose phosphate synthase gene of rice and TT51-1 event-specific gene, respectively. The absolute sensitivity and relative sensitivity were 2 copies/μL and 0.1% respectively. The relative standard deviation (RSD) was among 7.30% to 18.63% while the deviation was among - 8.77% to 9.62% in 6 replicates, even the content of GM rice TT51-1 event was as low as 0.1%, met the requirements of standardized detection of GMO. The relative sensitivity of real-time PCR method established with the same pairs of primers and probes could reach only 1%. In order to promote the standardization the application of this method, an intra-laboratory repeatability validation was performed on the chip-based digital PCR platform by different operators to verify the quantitative detection method established on the droplet digital PCR platform, and the results showed that the precision and accuracy of the assay still met the quantitative requirements. It was proved that this method could be applied to the quantitative detection of TT51-1 GM rice ingredients in rice and its preliminary processing products.
Abstract:Clustered regularly interspaced short palindromic repeats(CRISPR) are the genetic structures existing in most bacteria and archaea. They can effectively prevent the invasion of exogenous DNA (plasmids, phages, etc.), and then prevent the horizontal transfer of foreign genes. Object: Shigella boydii, Shigella dysenteriae, Shigella flexneri and Shigella flexneri which are common in Shigella spp. 40 strains were studied to explore the structural differences of CRISPR loci and the relationship between CRIPSR and the plasmid in different species. Method: The bioinformatics methods were used to compare the homology of spacers and insert sequences and the relationship between the CRISPR locus and RNA secondary structure stability. Result: The results showed that there were CRISPR structures in all 40 Shigella strains, including 241 CRISPR loci and 6 loci. Repeat sequence and cas3 gene can not be used as a classification basis for these four types of bacteria. Conclusion: Although we found there was no statistical relationship between the number of CRISPR loci and the number of spacers, the original genetic motifs of spacer sequence integron and drug resistance gene had some homology, indicating that Shigella in the evolutionary process in the constant invasion by exogenous genes.
Abstract:Objective: To study the abundance and diversity of microorganisms in different periods before, during and after fermentation of mulberry ferment by metagenome technology. Methods: To take mulberry ferment fermentation early stage (18 d), medium-term (42 d), late (60 d) samples and a series of metagenome sequencing steps, such as genomic DNA extraction, PCR amplification and product purification, fluorescence quantification, Illumina PE library preparation and Illumina high-throughput sequencing. After optimizing the sequencing data, the changes of bacteria and fungi composition and diversity in the fermentation process of mulberry jiaosu were studied. Results: The bacterical diversity of mulberry jiaosu was larger than that of fungal diversity by metagenome technique, and the analysis of microbial diversity in the genus level showed that the Lactobacillus was the dominant bacterium in the fermentation process of mulberry jiaosu. The yeast was the predominant bacterium(92.16%) in the prophase of fermentation. Conclusion: The dynamic changes and diversity mechanism of mulberry jiaosu in the process of natural fermentation were clarified, which provided practical guidance and theoretical basis for the subsequent development of a new type of artificial controllable mulberry jiaosu.
张露;胡红美;李铁军;徐开达;孙秀梅;应忠真;金衍健;杨承虎;郭远明;
Abstract:A simple, efficienct, sensitive method for the determination of phthalates(PAEs) in seafood using GC-MS was proposed. Moreover, the contents of PAEs in different seafoods were determined, and their health risk assessment was evaluated, simultaneously. Under optimized condition, the linearity of this method and detection limits (3S/N) were in the range of 1-1 000 μg/L and 0.15-0.30 μg/kg, respectively. The recoveries of spiked 16 PAEs at low, medium and high three gradient levels were in the ranges of 73%-117%, with relative standard deviations of 2.8%-7.5% (n=5). The results showed that there was no significant difference in contents of PAEs among different type of seafood, and the∑PAEs ranged from 80.0 μg/kg to 438 μg/kg. diisobutyl phthalate (DIBP), di-n-butyl phthalate (DBP) and di-2-Ethylhexyl phthalate (DEHP) were the predominant compounds in all detected seafood, accounts for 83.01%-94.18% of the total PAEs. Based on health risk assessment, all detected seafoods were considered safe for consumption, and children’s health risk was slightly higher than adults.
李婷婷;任丽琨;王当丰;宋敏杰;于海凤;励建荣;谢晶;沈琳;牟伟丽;黄建联;
Abstract:For identifying the content of purine in different parts of sea fish. In this paper, a high-performance liquid chromatogram (HCLP) method was developed in order to determinate the contents of guanine, hypoxanthine, xanthine and adenine in edible parts and internal organs of seawater fish. Purine bases were separated using Agilent ZORBAX Eclipse XDB-C18 (4.6 mm × 250 mm, 5 μm) chromatographic column with water-methanol-ice acetic acid-20% tetrabutyl ammonium hydroxide(V/V/V/V = 879/100/15/6) as mobile phase, the flow rate was set at 0.8 mL/min, column temperature was 30 ℃, and wavelength of UV detection was at 254 nm. The sample volume was 10 μL. Four kinds of purines had a good linear relation between the concentration and peak area in the range of 0.1-400 mg/L. The correlation coefficient was 0.9998-1.0000, the limit of detection (LOD) was between 0.0465-0.1056 mg/L, method precision of RSD% was between 0.0200%-0.7000%. The repeatability of sample treatment adenine, guanine, hypoxanthine, xanthine is 1.2421%, 0.9711%, 0.8836%, 1.9727% respectively. The recovery rate was between 94.2888%-102.9188%. So the method was suitable for the determination of four purines in marine fish. The test results showed that the total purine contents of edible part (eye, belly of fish, the back of the fish, fish skin) in sea bass were the highest, which was followed by turbot, golden hamster, yellow croaker, sciaenops ocellatus, Pedal fish and gadus in oeder.
Abstract:Methods of solid phase extraction and liquid chromatography with ultraviolet detection (SPE-HPLC-UV) for simultaneous determination in meat products of 9 kinds of N-nitrosoamines (NDMA, NMEA, NDEA, NDPA, NDBA, NPIP, NPYR, NMOR and NDpheA) were established. Using dichloromethane as extraction reagent to investigate the effect of extraction consisting of extraction time, solvent amount and extraction power, compared the purification effect of C18, neutral alumina and activated carbon for ultrasonic extraction of sample. The results showed that using 40 mL dichloromethane, 400 W, extract 20 min, the peak area of N-nitrosamines reached the maximum. And finally through the recovery experiment selected activated carbon solid-phase extraction as sample purification. The recovery of the method was 86%-99%, and the precision was 1.19%-3.42%, the method is simple and rapid, with good sensitivity, repeatability, and can be applied to simultaneous determination of content in meat products of 9 kinds of N-nitrosamines compounds.
Abstract:To identify the volatiles and aroma-active components of different pomelo varieties, five kinds of pomelo varieties from Zhejiang, Jiangxi and Fujian were tested. Solid phase microextraction(SPME) combining with gas chromatography-mass spectrometer-olfactometry(GC-MS-O) were used in this research. The chemometric methods, such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), were used to distinguish different pomelo varieties and explain the differences. According to the analysis of volatiles by GC-MS-O, terpenes, alcohols, aldehyde, ketones, esters et al. were identified to be the main classes of volatile components. The content of these classes were different in five pomelo varieties. There are 38 aroma-active components identified in these varieties presenting the aroma properties of citrus, turpentine, balsamic, grass, wood et al. PCA can distinguish different varieties and determine the contribution of volatile components amongthem. PLS-DA has achieved to descriminate aroma characteristics among different varieties, and given the result that the flavor of grass, flower, mint and turpentine could be recognised as the main characteristics to distinguish different varieties. The results showed that the GC-MS-O coupling PCA and PLS-DA could be successfully used to identify and distinguish these five kinds of pomelo in China. This study provides the basis forthe comparison of variety characteristics, the processing of pomelo and the localization of origin.
Abstract:Compared with traditional thermal process pasteurization, high hydrostatic pressure sterilization technology can achieve good sterilization effect and ensure the original flavor and nutritional value in food as well. Therefore, in order to guarantee the reliability and safety of high hydrostatic pressure sterilization technology, it is necessary to study the factors that affect the sterilization performance thoroughly. Previous studies have focused on the pressure holding stage to obtain optimal conditions for sterilization, including pressure level, pressure holding time and temperature etc. However, a series of studies have shown that pressurization and depressurization will also affect the sterilization performance. In this paper, the main factors affecting the sterilization performance of high hydrostatic pressure were introduced briefly, and the effects of pressurization and depressurization on sterilization were introduced with special efforts. This review aims to promote the application of high hydrostatic pressure sterilization technology in food processing industry in China.
Abstract:Objective: "Scientific Consensus on Probiotics(2020)" will be formed by Probiotics Society of the Chinese Institute of Food Science and Technology in 2020 based on the latest research progress of probiotics. Method: The article was written according experts’ speeches, communications and records in special seminars. Results: The safety of probiotics has been recognized by authoritative institutions at home and abroad. And the improvement of probiotics standard regulations requires a solid scientific foundation. In addition, probiotics were characterized by adequate amounts, live microorganisms and health benefits. Finally, it was a long-term, rigorous and scientific process for human to explore and evaluate the efficacy of probiotics. Public science education should be strengthened to guide scientific and rational consumption of probiotics products. Conclusion: The Consensus will play an important guiding role in the scientific development and innovation of probiotics industry.
Abstract:For a better understanding of the existing condition of food science discipline, a bibliometrics approach was used to analyze the publication amount, countries/ territories, institutes, source journals and the research hotspots of highly cited papers from 2009 to 2018. The results showed that China’s highly cited papers had been ranked first in the world, but judging from the total cited times and average cited times, the influence and quality of Chinese papers still lagged far behind that of the United States. China’s influence in the formation of international science and technology cooperation network was also far less than that of the United States. Among the top 20 research institutes with highly cited papers, Chinese institutes had occupied the largest number of seats, reaching five seats, but each of them had the phenomenon of low total cited times and average cited times. At present, the development of food science shows a trend of interdisciplinary integration, and the research hotspots around the world mainly focus on the bioactivity and mechanism of food effective components, new nutrient delivery systems (microcapsules, nanocapsules and emulsion systems), intestinal microbes, stability of ingredients, food packaging and shelf life. The research fields between China and the USA, as well as China’s five superiority research institutions, are distinctive and distinctly different.