Abstract:Tropomyosin(TM) is a common pan-allergen in crustaceans, and its allergenicity is also confirmed in certain kinds of fish. Tropomyosin has a conservative structure, high homology, strong allergenicity and extensive immune cross-reactivity. The studies of tropomyosin allergenicity and its reduction method, immune cross-reaction are all related to the epitope on tropomyosin. Accordingly, epitope is the key target of tropomyosin research. This article briefly reviews the recent progress in aquatic tropomyosin study, including the properties, epitopes, immune cross-reactivity, allergenicity and its reduction.

Abstract:Eriocheir sinensis, commonly known as river crab and hairy crab, is a unique and precious aquatic product in China. Due to the great difference of geographical environment and breeding mode in various habitats, the well-known brand of E. sinensis is of higher value. However, the phenomenon of counterfeiting crabs of fake origin has become more and more serious in recent years. At present, it is urgent to establish an objective and effective method to identify the origin of E. sinensis. Therefore, more and more scholars have carried out identifications and studies on E. sinensis from different habitats. The identification methods include morphological index identification, biochemical index identification, element fingerprint, stable isotope, electronic nose, electronic tongue, molecular biology and so on. This paper summarized the advantages and disadvantages of various identification methods, and briefly introduced the research progress of identification of E. sinensis using the above methods. And the development trend of identification of E. sinensis was also discussed. It could provide a theoretical reference for exploring and establishing an objective, effective and rapid detection method to identify the origin of E. sinensis.

Abstract:Antioxidant peptides from sheep bone were prepared by enzymatic method, and the amino acids compositions of peptides were analyzed. On the basis of single factor test, the extraction conditions of antioxidant peptides from sheep bone were optimized using response surface methodology. At the same time, peptides with different retention molecular weights were isolated by ultrafiltration, and their antioxidant activity and amino acids compositions were detected. Salicylic acid method, 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and deoxidization Fe³⁺ method were applied to investigate the antioxidant activity of peptides with gradient molecular weights and their amino acid compositions were also analyzed. The results showed that the optimum enzyme for enzymatic hydrolysis of sheep bone was alkaline protease, and the optimum process for polypeptide preparation was as follows: pH was 8.9, the amount of enzyme added was 6 400 U/g, hydrolysis duration was 3.25 h, substance mass fraction was 8.8% and the hydrolysis temperature was 50 ℃. The ·OH scavenging activity, DPPH· scavenging activity and the reducing power of the optimal hydrolysis products were (91.31±0.48)%, (32.00±0.12)% and (0.085±0.003), respectively. Components ⅠM_r≤3 000), Ⅱ(3 000<M_r≤10 000) and Ⅲ(M_r>10 000) obtained through ultrafiltration had antioxidant capacity. In addition, component Ⅰ(M_r≤3 000) had the highest antioxidant activity, in which the essential and hydrophobic amino acids accounted for 30.41% and 43.13% of the total amino acids, respectively. The antioxidant peptides from sheep bone can be explored as a potential natural antioxidant.

Abstract:To efficiently remove αs1-casein,the primary allergen in dairy products, a strain of Bacillus subtilis S7 with decent desensitization ability was screened from 3 000 strains of wild bacteria. High performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry(LC-MS/MS) were adopted to analyze the flavor of desensitization dairy products made by the key enzyme in Bacillus subtilis S7 and the bioactive peptides produced. By comparison with another candidate Bacillus subtilis S21, it was found that S7 had a higher activity to α_s1-casein hydrolysis. To analyze this difference, all secreted enzymes were identified through peptide fingerprint. It was found that S7 could secrete and express more vegetative catalase. After the enzyme was recombinantly expressed and supplemented into the supernatant of Bacillus subtilis S21 fermentation broth, the activity of S21 to α_s1-casein hydrolysis was increased by about 1.5 times to a level similar to that of S7. The enzyme activity to allergen was improved by vegetative catalase, which helped proteases to hydrolyze. The results show that desensitized milk products prepared by vegetative catalase and subtilisin E in Bacillus subtilis S7 may have promising application in the food industry.

Abstract:The differences of volatile components and flavors of purple phenotype Toona sinensis from different provenances were investigated. Headspace solid-phase microextraction(HS-SPME) was used to optimize the volatile components extraction. Gas chromatography-olfactometry-mass spectrometry(GC-O-MS) and principal component analysis were used to detect the volatile components and analyze the flavor differences. The results showed that the optimal HS-SPME extraction condition was using 65 ?滋m PDMS/DVB fiber at 50 ℃ for 40 min. By GC-MS qualitative and quantitative analysis, 54 volatile compounds were identified in ten species of purple phenotype Toona sinensis, including 30 kinds of terpenes compounds, 14 sulfur compounds, 6 alcohols compounds, 3 aldehydes compounds and 1 acid compound. And the volatile components detected in Ximou, Linqu, Zibo, Qingzhou, Jiaozuo, heiyouchun, bashanhong, Yuncheng, Changshan and Hebei were 36, 32, 27, 38, 39, 34, 27, 34, 34 and 36 species, respectively. Based on the GC-O-MS analysis, 14 volatile components were identified in ten purple phenotypes Toona sinensis, including 6 sulfur compounds, 6 terpenes compounds and 2 aldehydes compounds. The relative contents of terpenes and sulfur compounds in four kinds of Toona sinensis from Shandong Province (i.e., Ximou, Linqu, Zibo, Qingzhou) were higher than those in other areas, where the unique volatile components (+)-β-apine was detected. According to the principal component analysis, the purple phenotype Toona sinensis in Ximou had the highest comprehensive score of flavor substance content and the best flavor, where the characteristic(+)-β-apine played the greatest impact on flavor. The Toona sinensis in Changshan got the lowest comprehensive score. After comprehensive evaluation, Ximou Toona sinensis was selected as the best flavory Toona sinensis, providing a basis for Toona sinensis application in food processing.

Abstract:To investigate the effect of wheat flour characteristics on the quality of oat noodles, the farinograph characteristics,extensograph characteristics,dry weight of glutenin macropolymer(GMP), gluten composition and its subunits of seven wheat flours were determined. Oat noodles were prepared to study the effects of wheat flour characteristics on the quality of oat noodles through correlation analysis.The results showed that the water absorption of wheat flour had a positive correlation with the hardness, palatability, toughness and sensory total score of oat noodles. The extension energy, extensibility and maximum resistance to extension exhibited a positive correlation with the tensile distance of oat noodles. The dry weight of GMP had a positive correlation with the hardness, adhesiveness, tensile force and palatability of oat noodles.High molecular weight glutenin subunits(HMW-GS) had a positive correlation with the hardness, chewiness, tensile force and palatability of oat noodles. The ratio of glutenin/gluten had a positive correlation with the hardness, tensile force and palatability of oat noodles. Therefore, the wheat flour with high water absorption, high dry weight of GMP,high HMW-GS content, high ratio of glutenin/gluten and good extensograph properties was suitable for oat noodles processing.

Abstract:Soybean meal, the main by-product of soybean oil processing, contains almost all the proteins in soybeans and has broad application prospects. In this study, soybean meal antioxidant peptides were prepared from ultrasonic-assisted enzymatic hydrolysis. Through single factor and response surface tests, the optimum technological parameters were determined as follows: substrate concentration of 9% (mass fraction), enzyme amount of 6 665.39 U/g, enzyme hydrolysis at pH 8.0 under 50 ℃ for 4.0 h and ultrasound for 9 min under 300 W. The components with molecular weight less than 1 000 were obtained through ultrafiltration membrane and identified by LC-MS/MS. An antioxidant pentapeptide from soybean meal was obtained. Its amino acid sequence was Ile-Trp-Asn-Leu-Asn (IWNLN), and the IC50 value of ABTS radical scavenging ability was （0.06±0.003） mg/mL. At a concentration of 0.01 mg/mL, the ORAC value was （7.614±0.138） mg TE/mg, and the IC₅₀ value of hydroxyl radical scavenging ability was （0.008±0.001） mg/mL. This study provides an experimental basis for the optimization of production process and the confirmation of functional factor sequence of soybean meal antioxidant peptide, and provides a new idea for the development of soybean meal protein peptide functional products.

Abstract:In order to comprehensively utilize the colored tomatoes, the carotenoid compositions of tomatoes in different colors were compared. The thermal stability of carotenoids was assessed, and the rules of isomerization and degradation were discussed. High-performance liquid chromatography- diode array detector(HPLC-PDA) with YMC Carotenoid C30 column was employed to separate carotenoids from tomatoes, and individual isomers were identified by the spectral characteristics.In addition, the effects of thermal treatment on the isomerization and degradation of carotenoids were investigated. The results showed that orange tomato-1 (OT-1) was rich in cis-lycopene (mainly 7,9,7’,9’-tetra-cis(7Z,9Z,7’Z,9’Z)), while orange tomato-2 (OT-2) was abundant in all-trans- (all-E-) β-carotene. The red tomato was rich in all-E-lycopene. The cis-lycopene content of OT-1 was 28.79 times and 12.57 times of that in OT-2 and red tomato, respectively. The total amount of phytofluene and phytoene was 7.52 times and 3.20 times of that in OT-2 and red tomato, respectively. In OT-1, the lycopene concentration decreased with the increment of heat time (0 ~ 5 h) and temperature (60~100 ℃). The value decreased to 1/3 of the initial content after treated at 100 ℃ for 3 h. Meanwhile, the 7Z,9Z,7’Z,9’Z isomer reduced significantly, which was not detected when treated at 100 ℃. However, the all-trans (all-E), 5-cis(5Z) and other cis-lycopenes increased to 28.51%, 28.73% and 42.76%, respectively. Heat treatment had no significant effect on the degradation and isomerization of lycopene and β-carotene in OT-2 and red tomato -P>>0.05). Besides, the retention rates of phytofluene and phytoene in OT-1 after treatment at 100 ℃ for 3 h still reached 84.32% and 88.76%. The results indicated that OT-1 was good source with high contents of cis-lycopene, phytofluene and phytoene.7Z,9Z,7’Z,9’Z-lycopene was less thermally stable than all-E lycopene and all-E-β-carotene, while phytofluene and phytoene showed better thermal stability. The above information is of great significance for the comprehensive utilization of tomato sources in different colors and the development of tomato products with high bioactivity.

Abstract:This study was to explore the effects of heat shock protein A1A(HSPA1A) on the proliferation of HeLa, HT29 and PC3 tumor cells and their underlying mechanisms. HSPA1A recombinant vector was constructed to transfect tumor cells. The cell morphology, MTT and cell cycle after transfection were observed to explore the effect of HSPA1A on tumor cell proliferation. The cells that HSPA1A played a role in cancer cell proliferation were determined by immunofluorescence positioning. After overexpression of HSPA1A, cell proliferation of tumor cells was significantly enhanced. Cellular immunofluorescence confirmed that HSPA1A was mainly localized in the cytoplasm. Cell cycle assay showed that transfection of HSPA1A mainly accelerated the G1 phase of cell growth cycle, which was determined by Western Blot. Overexpression of HSPA1A up-regulated G1-related cyclin D1, CDK4, CDK6, cyclin E1, and CDK2. It was speculated that HSPA1A might serve as a chaperone protein to maintain the stability of cyclin D1-CDK4/CDK6 and cyclin E1-CDK2-related proteins and accelerate the G1 phase of cell cycle. HSPA1A can promote tumor cell proliferation and play a role in the cytoplasm proliferation. This study provides a theoretical basis for the development of anti-tumor drugs based on HSPA1A.

Abstract:The preparation of pancreatic lipase-inhibiting peptide from ovalbumin(PLIPA) was studied by response surface method, and the stability of PLIPA was studied by simulated gastrointestinal digestion. C57BL/6J mice obesity model was successfully established after feeding high fat diet for 40 days. After 28 d of intragastric administration of PLIPA, the mice were killed and the related indexes were detected to study the control effect of PLIPA on body weight and body shape of nutritional obese mice. The results showed that when the concentration of ovalbumin and alkaline protease were 80 g/L and 2 240 U/g, respectively, the highest inhibitory rate of PLIPA was (56.06±2.64)% after hydrolyzed at 55 ℃, pH 9.0 for 4 h. After digestion of simulated gastric solution and simulated gastric and intestinal solution, the inhibitory rate of PLIPA per milligram of pancreatic lipase were 0.53% and 0.46%, respectively. The overall inhibition rate was still high and the stability was good. The body weight and Lee's index of PLIPA complex group were significantly lower than those of model group (P<0.05). The indexes of abdominal fat coefficient, triglycerides(TG), total cholesterol (TC), and low-density lipoprotein cholesterol(LDL-C) and high-density lipoprotein cholesterol(HDL-C) in the treatment groups were lower than those in model group, indicating that PLIPA could reduce body weight and fat in obese mice, and PLIPA complex group showed the best effect on controlling body weight and body shape.

Abstract:Rapid and non-destructive identification of fresh and long-term frozen pork was studied by visible-near infrared spectroscopy and electronic nose principal component analysis. The pork frozen at -18 ℃ for 0 and 3 months represented fresh samples, while those stored for 6 or 9 months represented long-term frozen meat samples. The spectrograms of all samples collected by near-infrared analysis were analyzed directly by discriminant analysis. Different pretreatment methods were used to optimize the discriminant model of long-term frozen pork and fresh pork, and then principal component analysis was carried out respectively. The model could effectively distinguish fresh meat from long-term frozen one. Electronic nose analysis showed that it could distinguish the long-term frozen pork from the fresh. This study provides a theoretical basis for the rapid and non-destructive identification of long-term frozen meat products.

Abstract:In order to study the sterilization technology of retort pouch food derived from channel catfish, firstly, the safe F value of sterilization was determined by the measurement of heat transfer curve at different sterilization temperature (110, 115, 118, 121, 129 ℃) and the heat preservation experiment. Under the same sterilization intensity (F＝4.5 min), the texture, color, sensory score and TBARS were used as indicators to investigate the effect of sterilization temperature on channel catfish quality. The results showed that with the increase of sterilization temperature, the a* value and b* value decreased significantly (P＜0.05), while the L* value, the hardness, springiness, chewiness and sensory score increased significantly(P<0.05). However, TBARS value decreased with sterilization temperature decreased. Therefore, higher sterilization temperature is beneficial to the product texture, color and sensory score, but too high temperature will also aggravate the oxidation degree of the product.

Abstract:The effect of Fu brick tea on hepatic lipid synthesis and oxidative stressin jury in APOE^-/- mice with non-alcoholic fatty liver was investigated in this study. Fifty-five male APOE^-/-mice aged 2 months were continuously fed with high fat diet for 13 week. Five of them were randomly selected for HE staining to estimate the successful development of animal model.The remaining fifty APOE-/- mice were randomly divided into model group,atorvastatin group,and high-, medium- and low-dose groups of Fu brick tea after successful modeling. All of APOE^-/- mice were respectively intervened with high fat diet through gavage for 8 weeks. At the same time, 2-month-old C57 mice 2 were selected as the control group and fed with normal diet for 13 weeks and then given saline for 8 weeks. At the end of the experiment, the liver tissues of mice were taken for liver function, oxidative stress, HE staining and RT-qPCR. Pathological morphology showed that the degree of liver steatosis in Fu brick tea of high- and medium-dose groups were lighter than that in the model group. Compared with the control group, the activity of GSH-PX and SOD in the liver of model group decreased, while the content of MDA, the activity of ALT and AST, NAS score, the gene expression of SCD-1、PPAR-γ and HMGCR increased (P<0.05). Compared with the model group, the content of MDA, the activity of ALT and AST, NAS score, the gene expression of SCD-1, PPAR-γ and HMGCR were decreased in different Fu brick tea dose groups, while the GSH-PX and SOD activity increased. Fu brick tea can reverse the early NAFLD by inhibiting hepatic lipid synthesis and reducing hepatic oxidative stress damage.