• Volume 41,Issue 6,2017 Table of Contents
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    • Comparison of flavor compounds in meat and head of Litopenaeus vannamei

      2017, 41(6):907-918. DOI: 10.11964/jfc.20170410820

      Abstract (2065) HTML (699) PDF 586.40 K (2662) Comment (0) Favorites

      Abstract:In order to make full use of Litopenaeus vannamei's shrimp head,increase the economic value and discuss the influence of cooking on the flavor, the shirimp meat and heads were detected for amino acids, flavor nucleotides, volatile flavor compounds and the nutrients by the method of amino acid analyzer, high performance liquid chromatography (HPLC) and gas chromatography-mass spectrography (GC/MS). The results showed that the protein content of head was significantly higher than that of meat, while the crude protein content decreased in cooked shrimp, but the difference was not significant. The contents of essential amino acid (EAA) and total free amino acid (TFAA) in head were significantly higher than those in meat and the main free amino acids were same (glycine, arginine, proline, alanine, threonine), and amino acids that contribute to flavor were more abundant in head; IMP had the highest content in meat and head, AMP took second place, and the taste activity values (TAV) of them were more than 1, which made a great contribution to umami flavor. Totally 88 volatile compounds were identified by GC/MS and compared for significant differences, the numbers of unique compounds in meat and head were 29 and 18 respectively. The differences of kinds and quantity led to special smell, and cooking produced mass aldehyde, ketone and aromatic compounds. Preliminary results showed that significant differences in the composition and content of amino acids, flavor nucleotides, volatile flavor compounds and nutrients observed between meat and head lead to different flavors.

    • Kinetics of lipopeptides production of tilapia processing byproduct fermentation by Bacillus natto NT-6 in solid state

      2017, 41(6):817-826. DOI: 10.11964/jfc.20161010585

      Abstract (2048) HTML (852) PDF 1.22 M (1898) Comment (0) Favorites

      Abstract:A 60 h solid state fermentation experiment was conducted to investigate the production technology of tilapia sp. byproduct as an antimicrobial product and source of nutritious feed. Crushed tilapia sp. byproduct and water was put in a triangular flask and then inoculated with 5% Bacillus Natto NT-6 with fermentation temperature at 30 ℃. Studies on changes in pH, temperature, ratio of water and enzymatic activity during the fermentation process was conducted. In addition to this, modelling of the antimicrobial concentration of the biomass and protein concentration was done. Analysis of the relationship between these parameters and lipopeptide yield was also made. The results showed that during fermentation the biomass increased for 48 h, then stabilized, the maximum growth rate was 0.2355×108 cfu/h. The production trend of lipopeptide is same as the biomass, the maximum yield was 7.3 g/kg and the maximum generation rate was 0.1112 g/h. The bacteria (B. Natto NT-6) secreted a high amount of enzymes, extraordinarily,the protease enzymatic activity was as highly as 30 304.56 U/g. During the process, the temperature, pH and water content of the substrate was fluctuating slightly. On the bases of Logistic and material balance equation, the model of bacteria growth kinetics, comprehensive product generation and substrate consumption were set up and the non-linear fitting was employed to model the kinetics of fermentation by the software Origin 8.5. At the time,the models and the experimental data were well fitted and the relative error non-significant. The model developed in this study could predict the concentration of surfactin in biomass, substrate consumption and also help to determine whether the fermentation process was normal or not. This would enable a sound scientific control of surfactin fermentation process in real-time. This is of great significance to antimicrobial lipopeptides at large-scale production and application.

    • Preparation of peptone by ultrasonic-assisted enzymatic hydrolysis of skipjack tuna (Katsuwonus pelamis) by-products

      2017, 41(6):919-927. DOI: 10.11964/jfc.20161210637

      Abstract (1965) HTML (794) PDF 1.19 M (1700) Comment (0) Favorites

      Abstract:Katsuwonus pelamis processing by-products, including viscera, fish head, fish gills and fish skin, contain protein, fat and other nutrients. Ineffective utilization of these by-products will lead to the waste of nutritious resources and serious environmental pollution. In order to provide a practical method to improve the utilization of by-products, the peptone was prepared by ultrasonic-assisted enzymatic hydrolysis of K. pelamis by-products by trypsin. The effects of time, temperature and power of ultrasonic on the changes of protease activity, degree of hydrolysis, nitrogen recovery, TCA-soluble nitrogen recovery and molecular weight distribution of the hydrolysate were investigated during the ultrasonic-assisted enzymatic hydrolysis of K. pelamis by-products. The conditions of peptone preparation were optimized by single factor experiment. The results showed that the enzymatic activity of trypsin was significantly changed by ultrasound treatment, and the activity of trypsin increased within 30 min under the ultrasonic power 120 W. However, after 30 min, the activity of trypsin decreased obviously, until 4 h later the enzyme activity tended to decrease gently. The power of ultrasonic and the temperature of enzymatic hydrolysis all affect the enzymatic efficiency of enzymatic hydrolysis of K. pelamis by-products. Under the conditions of ultrasonic power 240 W and 50 ℃, the recovery of nitrogen increased by 18.66%, the degree of hydrolysis increased by 30.43% and the recovery of TCA-soluble nitrogen increased by 33.20%, compared with non-ultrasound group. And ultrasound also can effectively improve the small molecule peptide in the enzymatic solution. The optimum conditions were temperature 55 ℃, ultrasonic power 240 W, hydrolytic time 4 h. Under these conditions, the recovery of nitrogen was 81.40% and the recovery of TCA-soluble nitrogen was 40.75%.

    • Separation of phospholipids and fish oil from fishery by-products followed by lipidomics study

      2017, 41(6):827-835. DOI: 10.11964/jfc.20170310748

      Abstract (2008) HTML (498) PDF 2.16 M (1527) Comment (0) Favorites

      Abstract:For full utilization of the fishery wastes, the aim of this study was to establish a method for extracting the phospholipids and fish oil simultaneously from wastes, followed by the analysis of phospholipid and fatty acid composition on the basis of multi-dimensional tandem mass spectrometry and gas chromatography. Phospholipids and fish oil were extracted simultaneously by modified Folch method and precipitation method with acetone. The extracting efficiency of five different extracts was compared, and the mixture of CH2Cl2-MeOH (1∶2, V/V) performed best, whose extracting rates of phospholipids and fish oil were 0.97%和28.05%, respectively. Afterwards, the obtained fish oil was esterified and analyzed by gas chromatography, and the obtained phospholipids were injected directly by a syringe pump and identified and quantified by tandem mass spectrometry in the precursor-ion scan (PreIS) and neutral-loss scan (NLS) modes. The results show that fish oil contains 23 kinds of fatty acids, including oleic acid, linoleic acid, palmitic acid, etc. The content of unsaturated fatty acid is 75.97%. There are four classes (phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine) and 69 kinds of phospholipid molecules were detected in the phospholipid extract. Phospholipids with at least one eicosapentaenoic acyl/docosahexaenoic acyl chain were frequently found, such as 16:0/20:5, 16:0/22:6, 18:1/22:6, 18:0/22:6, 20:0/22:6, etc. In conclusion, this method can efficiently extract phospholipids and fish oil simultaneously. It is simple, fast, and friendly to the environment.

    • Comparison of the digestibility of abalone (Haliotis discus hannai) produced by four different processing treatments

      2017, 41(6):928-936. DOI: 10.11964/jfc.20161010574

      Abstract (1697) HTML (534) PDF 11.53 M (1424) Comment (0) Favorites

      Abstract:In order to know the effect of different processing methods on protein digestion of abalone (Haliotis discus hannai), the effects of four processing methods including raw, boiling, canning, and drying on the digestibility of abalone muscular proteins were investigated. Simulated gastric fluid (SGF) as well as simulated intestinal fluid (SIF) was used to study the effects of in vitro digestion. The products were evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Scanning electronic microscopy (SEM) was used to observe the differences in the fiber of the four products. The results showed that the digestibility of proteins in canned abalone was the highest among the four processing methods. Proteins from dried abalone were most resistant to digestion both in SGF and SIF. The four processing methods revealed different fiber structures under SEM. Furthermore, the angiotensin-I converting enzyme (ACE) inhibitory activity of the digested products exhibited the following order: canned (464.2 μg/mL) < dried (665.4 μg/mL) < boiled (775.7 μg/mL) < raw (803.9 μg/mL). In conclusion, our present study suggested that different processing methods of abalone significantly affect the digestibility of proteins and the ACE inhibitory activity of the final products, which may provide a reference for abalone processing and consumption.

    • Isolation and characterization of paramyosin from abalone (Haliotis discus hannai)

      2017, 41(6):836-844. DOI: 10.11964/jfc.20160810521

      Abstract (1919) HTML (498) PDF 3.00 M (1464) Comment (0) Favorites

      Abstract:In order to investigate the characterization of paramyosin (PM), PM was purified from the muscle of abalone (Haliotis discus hannai) by ammonium sulfate fractionation and hydroxyapatite chromatography. The molecular mass of PM was about 97.0 ku as estimated by SDS-PAGE. Peptide mass fingerprinting of PM obtained 36 peptide fragments with a total of 403 amino acid residues, which were 99.7% and 72.0% identical with PMs from H. discus discus and Crassostres gigas, respectively. The isoelectric point of PM detected by two-dimensional electrophoresis was approximately 5.4, suggesting it is an acidic protein. Circular dichroism spectrum of PM solution demonstrated a rotatory maximum at 192 nm and two negative peaks at 208 nm and 223 nm, indicating the typical spectral characteristic of α-helix structure. Meanwhile, the denaturation temperature (Td) of PM was 58.1 ℃ as determined by circular dichroism spectrum analysis. FTIR spectra further confirmed that PM has intact α-helical structure. The isolation and physicochemical property investigation of PM from the muscle of abalone would provide theoretical foundation for studying proteins related to its texture and for deep-processing of abalone products.

    • Effects of mycosporine-like amino acids from Porphyra haitanensis on skin photoaging

      2017, 41(6):937-943. DOI: 10.11964/jfc.20161110609

      Abstract (1830) HTML (794) PDF 9.44 M (1514) Comment (0) Favorites

      Abstract:To investigate mechanism of mycosporine-like amino acid from Prophyra against ultraviolet irradiation-induced photoaging of skin and provide an experimental basis for clinical application of sunscreen cosmetics, MAAs derived from Prophyra haitanensis was extracted using hot water and the components of MAAs were separated and identified. The protective effects of MAAs on photoaging were observed by the degree injury of tissue appearance and pathological section. The protective mechanism of mycosporine-like amino acid from Prophyra against ultraviolet irradiation-induced photoaging of skin was measured by the activities of total superoxide dismutase(T-SOD), glutathione peroxidase(GSH-Px) and the levels of malondialdehyde (MDA)and hydroxyproline (Hyp). The results indicated that two major mycosporine-like amino acid components from Prophyra were separated: Porphyra-334 and shinorine. MAAs could prevent skin photoaging induced by ultraviolet irradiation. Compared with the control group, MAAs treatment group external inunctum exhibited significantly enhanced activity of T-SOD and GSH-Px, increased levels of Hyp, and reduced levels of MDA. But the groups of MAAs treatment external inunctum on antioxidant showed that it couldn’t have significant action compared with MAAs group gastric lavage . The mycosporine-like amino acid from Prophyra could protect skin from ultraviolet irradiation-induced skin photoaging.

    • Protective effects of Spanish mackerel (Scomberomorous niphonius) skin peptides against D-Gal-induced liver damage in rats

      2017, 41(6):944-951. DOI: 10.11964/jfc.20170210721

      Abstract (2036) HTML (524) PDF 9.38 M (1492) Comment (0) Favorites

      Abstract:Epidemiological studies consistently show that excessive amounts of reactive oxygen species (ROS) is an important underlying cause of the initiation of oxidative stress in various tissue injuries as well as cell death and several chronic diseases. Several compounds, such as D-Galactose (D-Gal), bromobenzene, carbon tetrachloride (CCl4), acetaminophen, and ethanol have been implicated in the etiology of liver diseases. D-Gal is commonly used as a toxin to induce reactive oxygen species and hepatic disorders, which has been extensively used in oxidative damage animal models to evaluate the therapeutic potential of drugs and dietary antioxidants. Due to the risks of synthetic antioxidants, there is a growing interest in the use of natural antioxidants to prevent ROS related liver pathologies. Therefore, during the past several decades, human nutrition and biochemistry research focused on antioxidants derived from foods that could prevent or diminish ROS-induced damage. More recently, there is growing interest in natural hydrolysed protein antioxidants from many plant and animal sources. So, we hypothesized that the administration of antioxidant peptides might be useful for preventing various types of oxidative stress in vivo. In our previous experimental studies, Fraction I (MW <1 ku), Fraction II (MW 1–4 ku) and Fraction III (MW >4 ku) were isolated from the hydrolysates of Scomberomorous niphonius skin through ultrafiltration membrane with the cutoff of 1 and 4 ku, respectively. Among them, the FractionⅡ (1–4 ku) exhibited the highest radical scavenging activity, inhibiting both lipid and protein oxidation of cooked patties during refrigerated storage, and protecting Caco-2 cells against the toxicity caused by H2O2. Therefore, the aim of this study was to evaluate the antioxidant effects of Fraction II on D-Gal-induced liver damage in rats. Wistar rats were randomly divided into 6 groups, which were normal control, negative control, D-Gal+Low-dose of Fraction II, D-Gal+Middle-dose of Fraction II, D-Gal+High-dose of Fraction II, and D-Gal +VE as positive control for seven weeks. The activities of serum asparate aminotransferase (AST), alanine aminotransferase (ALT), monoamine oxidase (MAO) and antioxidant enzyme activities including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), total antioxidant capacity (T-AOC), nitric oxide (NO) and malondialdehyde (MDA) contents in liver were determined. The result showed that all doses of Fraction II could significantly reduce the ALT and AST level in serum of the rat, while M-dose and H-dose of Fraction could sharply decrease the MAO level. Compared with negative control group, SOD, GSH-Px, CAT activity and T-AOC of liver of the rats were increased significantly. the MDA and NO contents in liver of the rats were reduced when treated with all doses of FractionⅡ. Treatment with high dose FractionⅡ (200 mg/kg) could increase the SOD, GSH-Px activity to 236.27 and 182.23 U/mg protein, which could reach the level of normal and positive control, decrease the contents of AST, ALT and MDA to 302.47 U/L, 220.43 U/L and 138.83 nmol/mg protein, which was close to the level of normal control. Moreover, Fraction II could significantly reduce the injury score of prominent nucleus, visible central veins and necrosis in rats. These data indicate that Fraction II can protect the liver against D-Gal induced oxidative damage.

    • Purification and enzymatic properties of TMAOase from muscles of Sepia esculenta

      2017, 41(6):845-853. DOI: 10.11964/jfc.20161210642

      Abstract (2028) HTML (659) PDF 1.16 M (1644) Comment (0) Favorites

      Abstract:In order to extract and purify TMAOase, acetate buffer made of NaCl (0.1 mol/L) and Tris-CH3COOH (pH 7.0, 20 mmol/L) was used to extract from the muscles of cuttlefish.After the process of acid, alkali, dialysis and concentrated treatment, the extract was further purified by DEAE-52 Sephacel and Sephacryl S-300 chromatography. The enzymatic properties of TMAOase were also studied. The results revealed that the enzyme purified by Sephacryl S-300 was 209.54 times purer than the crude enzyme. The optimum temperature of the curde and purified enzyme was 55 and 50 ℃, respectively. Moreover, their thermal stability decreased significantly over this temperature. As the temperature reached 80 ℃, crude enzyme still retaimed 21.9% of its activity. Whereas purified enzyme lost its activity totally. The optimum pH of the purified enzyme was 7.0, which stayed well at this pH, but decreased in acidic and alkaline conditions. As the pH increased to 9.0,especially, the activity of crude and pure enzyme reduced to 60.7% and 20.5%, respectively. The Km of TMAOase measured by Lineweaver-Burk double reciprocal mapping method was 22.8 mmol/L. The purity of the obtained TMAOase was proved by SDS-PAGE, with a molecular weight of 21.3 ku. Chemicals of citric acid and CaCl2 remarkably promoted the activity of the enzyme, while H2O2 and Na2S significantly inhibited TMAOase activity.

    • Study on antioxidant enzymes and exopolysaccharides of lactic acid bacteria separated from salt-dried fish products

      2017, 41(6):952-961. DOI: 10.11964/jfc.20170310746

      Abstract (1884) HTML (799) PDF 883.67 K (2077) Comment (0) Favorites

      Abstract:In order to study the main active material with anti-oxidative effects of lactic acid bacteria (LAB) from salt-dried fish, the intracellular antioxidant enzymes and extracellular exopolysaccharides (EPS) were investigated. Vitality of superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) of nine strains were determined and the highest activity were 44.67, 15.26, and 1.23 U/mg prot respectively, which was corresponding to L21, L4 and L21. The crude EPS of LAB was prepared, and the production of nine LABs were between (5.71±0.18)–(50.33±1.89) mg/L, the highest purity of (56.16%±1.08%) was showed in a Lactobacillus casei (L21). The antioxidant capacity of EPS was then investigated by 1,1-diphenyl-2-picryhydrazyl (DPPH) radical scavenging and reducing power. The compositive antioxidant capacity was the highest in L21. Finally the structure of its EPS was analysed using ultra performance liquid chromatography (UPLC). The EPS of L21 contained four kinds of monosaccharides, namely, mannose (Man), rhamnose (Rha), glucose (Glu) and galactose (Gal). Thus, the nine LABs with high antioxidative capacity isolated from salt-dried fish showed higher antioxidant enzyme activity, and the production and purity of EPS were also high, and could show a certain antioxidant capacity in EPS. Therefore, the strongest comprehensive antioxidant strain was L21, and it could be further used as a biological antioxidant.

    • Extraction of agar from Gracilaria lemaneiformis based on microwave method and its physico-chemical properties

      2017, 41(6):854-860. DOI: 10.11964/jfc.20170310771

      Abstract (1976) HTML (528) PDF 940.11 K (1597) Comment (0) Favorites

      Abstract:In order to find the optimal conditions of microwave extraction method in the extraction process of agar from Gracilaria lemaneiformis and investigate microwave's effects on the physico-chemical properties of agar, we extracted agar from G. lemaneiformis (cultivated in Weihai, Shandong) under laboratory conditions by microwave extraction procedure. The effects of the different microwave power (160, 480, 800 W) and microwave time (2, 4, 6, 8, 10 min) on agar yield, gel strength, sulfate content, 3,6-AG content, gelling temperature, melting temperature and other physico-chemical properties were investigated. The results showed that the optimal conditions of the extraction method were as follows: solid-liquid ratio was 1∶60 (W/V), microwave power was 480 W, microwave time was 6 min. The agar yield was 16.20% and the gel strength was 1003.6 g/cm2 under these conditions. The effects of microwave power and microwave time on physico-chemical properties of agar were significant, with the increase of the power and the time, the growth of agar yield and gel strength displayed inverted U type changes, and maximum value appeared in the best extraction conditions. 3,6-AG content increased at first and then decreased, while the sulfate content had been declining, and there was a negative correlation between sulphate content and 3,6-AG content in a certain range. Both gelling temperature and melting temperature demonstrated a trend of increasing at first and then decreasing, and the respective maximum values of 30.0 and 97.4 ℃ appeared in the conditions of 480 W and 6 min. The test results showed that the microwave power and time were important factors in microwave extraction of agar from G. lemaneiformis and they both had significant effects on the physico-chemical properties of agar. In conclusion, this research provided a theoretical evidence for the microwave extraction of agar from G. lemaneiformis.

    • Spoilage phenotypic characterization and identification of Aeromonas isolated from spoiled Larimichthys crocea

      2017, 41(6):861-869. DOI: 10.11964/jfc.20160510398

      Abstract (2103) HTML (510) PDF 2.97 M (1669) Comment (0) Favorites

      Abstract:To identify the spoilage potential of two Aeromonas strains isolated from the spoiled Larimichthys crocea, we identified the isolates that did not produce H2S by biochemical characterization and 16S rRNA. All of the isolates were able to grow aerobically from 4 ℃ to 37 ℃, survived below 60 salinity, and could reduce trimethylamine N-Oxide to trimethylamine (TMA). Biochemical characterization and phylogenetic tree analysis of 16S rRNA gene showed that AE03 and AE04 belonged to A. salmonicida and A. molluscorum, repectively. The isolate AE03 showed the faster growth rate than AE04 on the growth curves at 4 ℃ and 25 ℃, and exhibited the higher production of biogenic amine, TMA, and extracellular enzyme activity in vitro. In sterile fish juice, the total volatile basic nitrogen (TVB-N) value of AE03 was also significantly higher than that of AE04. Furthermore, two isolates could produce AHLs by C. violaceum CV026 and A. tumefaciens A136 biosensor detecting system, and AHLs activity in AE03 was higher than that in AE04.Thus, it was found that AE03 (A. salmonicida) was a strong spoiler in deterioration of L. crocea at refrigerated storage, and produced higher AHLs activtiy. The present study provided a good foundation to clarify the mechanism of spoilage of Aeromonas from the point of quorum sensing.

    • Methodology of the preparation of enzymatic hydrolysates with antioxidant activity of skipjack tuna (Katsuwonus pelamis) swim bladder protein

      2017, 41(6):962-970. DOI: 10.11964/jfc.20170110687

      Abstract (2104) HTML (495) PDF 6.40 M (1463) Comment (0) Favorites

      Abstract:In order to obtain higher added-value of skipjack tuna (Katsuwonus pelamis) swim bladder, compound proteinase was selected for enzymatic hydrolysis of skipjack swim bladder from seven enzymes including bromelaine, compound proteinase, alkaline proteinase, papain, pepsin, trypsin and dispase. With the DPPH radical scavenging rate of hydrolysates as evaluating index, single-factor experiment was employed to investigate the effects of enzyme dosage, initial pH, reaction temperature and time on the antioxidant activity of hydrolysates separately. On the basis of the above observations of single-factor experiment, the optimum conditions for preparing antioxidant hydrolysates of skipjack tuna swim bladder were explored through response surface methodology (RSM). The results showed that, the optimal hydrolysis conditions were as follows: 8.53 U/ mg of enzyme dosage, 5.54 of initial solution pH, 50.03 ℃ of reaction temperature and 5.07 h of reaction time. Furthermore, the hydrolysates were primarily sorted into three fractions with different molecular weight above 10 000 u, 3000 to 10 000 u and 0 to 3000 u by using ultrafiltration. The inhibitory concentration 50% (IC50) values to DPPH radical of three fractions were 0.64, 0.52 and 0.37 mg/mL, respectively. It is demonstrated that DPPH radical scavenging rate of the hydrolysates could be up to 72.00% under these optimal conditions, which was in good agreement with the predicted value of 71.60%, and that fraction below 3000 u of the hydrolysates possesses the strongest effect. Preliminary results indicate that the hydrolysates of skipjack swim bladder could be an effective ingredient for antioxidant products such as health food or cosmetics.

    • Study on the immunoreactivity of mannose-parvalbumin conjugate

      2017, 41(6):870-876. DOI: 10.11964/jfc.20160710498

      Abstract (1884) HTML (491) PDF 2.36 M (1447) Comment (0) Favorites

      Abstract:In order to determine the influence of Maillard reaction on the structural and immunological properties of parvalbumin, the major allergen of silver carp (Hypophthalmichthys molitrix), recombinant silver carp PV (rPV) was used and incubated with mannose at 100 ℃ for 100 min, and glycated PV (M-rPV) was then obtained after dialysis. Tricine-SDS-PAGE and Dot-blotting was performed to elucidate the change of mobility and immunoreactivity of rPV after glycation. Simulated gastrointestinal digestion experiment was carried out to compare the digestibility of rPV and M-rPV. Circular dichroism spectroscopy (CD) and scanning electron microscopy (SEM) were used to determine the change of the secondary structure and the microstructure of rPV after Maillard reaction. The results showed that M-rPV had significantly high amounts of protein-bound mannose of approximately 150 μg per microgram M-rPV as measured by the anthrone sulfuric acid method. Dimers and polymers formed in the glycated sample, which might be attributed to the covalent bonds formed during Maillard reaction as analyzed by reducing Tricine-SDS-PAGE. Formation of compact aggregates after Maillard reaction was further confirmed by SEM, which might block the access of immunoglobulins to the epitopes, and therefore decrease the immunoreactivity of M-rPV, as demonstrated by dot-blotting using mouse anti-silver carp parvalbumin monoclonal antibody. M-rPV exhibited less resistance against gastrointestinal digestion in vitro as revealed by Tricine-SDS-PAGE and dot-blotting. Maillard reaction also showed a minor effect on the secondary structures of rPV with a decrease of α-helix and an increase of β-strand content. The aggregation formation and change in the secondary structure of M-rPV might explain the decrease of rPV immunoreactivity and digestibility after Maillard reaction. Our work might be useful for understanding the effects of Maillard reaction on the decrease of immunoreactivity of food allergens in general.

    • Effects of cooking and storage on the volatile compounds of Litopenaeus vannamei

      2017, 41(6):971-983. DOI: 10.11964/jfc.20170310751

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      Abstract:To investigate the effects of cooking and storage on the volatile compounds of white shrimp (Litopenaeus vannamei), the electronic nose (E-nose) and headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) were used to analyze the volatile compounds in shrimp meat. The relative odor activity value (ROAV) and sensory evaluation methods were used to evaluate flavor change of shrimp meat. The results of E-nose showed that the effects of cooked and stored treatments were highly remarkable on the volatile compounds of white shrimp. According to GC-MS analysis, 50, 68, 63, 49 and 41 volatile compounds were detected in shrimp meat with raw shrimp, cooked shrimp, cooked shrimp cooled, cooked shrimp after placing at 4 ℃ overnight, and twice-cooked shrimp, respectively. After twice-cooking, the key flavor substances were slightly weakened and fresh aroma also decreased slightly in the shrimp meat. However, the first cooked had little effect on shrimp flavor. The raw shrimp meat were detected nonanal and decanal, which had a significant impact on flavor. Cooked shrimp were detected nonanal, decanal, tetradecanal and others. The twice-cooked shrimp meat were detected octadecanal, and butylated hydroxytoluene, which had a greater impact on flavor. The detected types and contents of volatile compounds were reduced in the cooked shrimp after storing, but the total difference was not significant. The results showed that the types and contents of volatile compounds of the twice-cooked shrimp could be significantly increased, and the key flavor kinds and contents of L. vannamei were also significantly lower than those first cooked shrimp. The flavor difference of cooked shrimp was not significant at 4 ℃ for 12 h storage.

    • Effects of high hydrostatic pressure on protein and microstructure of Litopenaeus vannamei

      2017, 41(6):877-887. DOI: 10.11964/jfc.20170110674

      Abstract (2025) HTML (512) PDF 16.96 M (1356) Comment (0) Favorites

      Abstract:High hydrostatic pressure (HHP) is a promising non-thermal food processing technology, which not only can inactivate microorganism and enzyme to ensure food safety, but also can maximize the retention of nutrients and color, aroma, taste and improve food texture and functional properties. HHP can maintain the balance of food safety and quality better. At present, HHP has been widely studied and applied in meat processing, seafood processing, fruit and vegetable processing, dairy processing, and so on. In recent years, HHP has been reported in the shrimp preservation and processing. For example, HHP can inactivate microorganism and polyphenol oxidase from Litopenaeus vannamei, but HHP has a little effect on qualities. HHP can also be used to shuck, eliminate allergens, and extract astaxanthin from by-products in the shrimp processing. These provide a new method for shrimp processing and utilization. In order to enrich the basis theory of HHP in shrimp preservation and processing and to realize industrial production, regarding untreated peeled shrimps as a control, the peeled shrimp were treated by HHP at 100, 300, 500 MPa for 5, 10, 20 and 30 min, respectively. The content, composition and thermostability of protein were analyzed. The microstructure of shrimp muscle tissues was observed by optical microscope and transmission electron microscope. The results showed that the content of sarcoplasmic protein slightly increased at 100 MPa, and decreased significantly at 300 and 500 MPa, and the content of myofibrillar protein significantly decreased. HHP treatment resulted in denaturation of peeled shrimp protein and decreased the thermostability of myosin and actin. With the increase of pressure and treatment time, HHP makes the arrangement of peeled shrimp myofibril tight and compact, and even the structure of myofibril collapse, sarcomere severe contraction, the gap among muscle fibers fuzzy and showing a flocculent structure. Therefore, high hydrostatic pressure can cause shrimp protein denaturation and gelation, which is conducive to digestion and absorption of the human body. The results show that high hydrostatic pressure can be used for processing instant shrimp products.

    • >ROUNDUPS
    • Research progress of characteristic volatile compounds of fish sauce

      2017, 41(6):984-992. DOI: 10.11964/jfc.20170310765

      Abstract (2320) HTML (563) PDF 523.97 K (1670) Comment (0) Favorites

      Abstract:In order to study the unique flavor of fish sauce, solve the flavor and quality problems of modern rapid fermentation process, fish sauce characteristics of volatile compounds in recent 20 years were reviewed in this paper. The research shows that research on the formation of fish sauce characteristic volatile compounds is feasible. Odor fingerprint technology and gas chromatography - mass spectrometry olfactometry artificial instrument (GC-O-MS) was used in combination on the formation of flavor characteristics of fish sauce; the smell of fish sauce is a blend of cheese flavor, taste, flavor, sour pickled ammonia, fishy smell and flavor of the meat complex excitant odour, and sulfur and nitrogen compounds are the characteristics of volatile compounds; the species of fish, halophilic microorganisms and enzymatic pathway have great influence on the formation of volatile compounds. The volatile flavor of fish sauce is a very complex system, and the effect is not a simple factor or individual compound transformation which leads to the formation of volatile compounds. Study on volatile compounds of fish sauce can solve the problems in improving the flavor quality of fish sauce.

    • >PAPERS
    • Effects of post-harvest handling on rigor of the Patinopecten yessoensis adductors

      2017, 41(6):888-895. DOI: 10.11964/jfc.20170110683

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      Abstract:The post-harvest handling of Patinopecten yessoensis has a significant effect on the rigor mortis which is an important factor affecting the quality of the adductor muscle. The effect of preservation on the storage of the adductor muscle was studied to delay rigor mortis. Three treatments of live storage were designed, including control with non-p preserved, preserved 3 days and preserved 7 days with circulating seawater-preserved at 10 ℃. Then the scallops were shucked and the adductor muscles were stored in ice for 7 d respectively. Rigor mortis, biochemical metabolites including ATP related compounds, K value, glycogen, the content and composition of soluble protein and pH of muscle tissues were examined during ice storage. The results showed that regardless of whether the preservation support, K value was less than 5% in 3-day ice storage, and it can meet the requirements of sashimi. With preservation, the content of ATP increased slightly (7 d group > 3 d group > control group). The content of ATP maintained stability in 2-day-ice storage, which can inhibit muscle contraction to reduce the loss of fluid. The content of glycogen and soluble protein in preserved group was lower than control group. In addition, the 30 ku protein from the preserved treatment group disappeared 1–2 days earlier than from the control group.

    • Volatile flavor compounds fingerprints during fish fermentation at different salt concentrations

      2017, 41(6):896-906. DOI: 10.11964/jfc.20161210666

      Abstract (1904) HTML (597) PDF 1.35 M (1722) Comment (0) Favorites

      Abstract:The main volatile flavor compounds of fish sauce were determined in order to investigate their changes and establish the fingerprints of volatile flavor compounds during pre-fermentation of fish sauce and clarify the main flavor compounds at 180 and 230 salinity. The volatile flavor compounds in samples were analyzed by gas chromatography-mass spectrometry (GC-MS) in the fermentation process. The results showed that the similarity of eight samples of fish sauce was good and reached 90% compared to the control. The volatile flavor compounds of the fish sauce were changed significantly at 180 salt concentration for 150 days. The fish sauce fermented in 180 salinity (YD1) group gained 51 common peaks and 58 as the fish sauce fermented in 230 salinity (YD2) group. All of those common peaks were calibrated to their respective reference fingerprint. Ethanol, acetone, isovaleraldehyde, 1-penten-3-ol and 2-methylbutyric acid were identified as the main volatile compounds in the pre-fermentation of fish sauce by the identification of the common peaks of the fingerprints. The results showed that fermentation changes of the YD1 group samples (180 salinity) occurred earlier and it is beneficial to the formation of delicious taste. But its changes of fermentation process happened slowly for the samples of 230 salinity. It is beneficial to the formation of cheese and meat flavor in fish sauce. The results of this study can provide effective references for revealing the regularity of main volatile flavor compounds and the quality control of fish sauce.

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