2022, 40(4):1-4. DOI: 10.12301/spxb202200758
Abstract:Food industry is the largest industry in China's national economy. The diversified development goals oriented with food safety, flavor, nutrition and health have been the important trends of innovating development of food industry. The basic situation of the development of China's food industry was introduced, and the major problems existing in food industry of China were analyzed. The dual wheel driven approach with scientific implementation of “less oil, less salt, less sugar” and “N plus” connotation of health was put forward to be the firm direction of our future food industry. And the dual wheel drive was emphasized as the key point for realizing the health transformation of Chinese food industry. The novel connotation of food safety and health in China was prospected, indicating that food safety was the basic guarantee of health and “double-orientation of flavor and health” was the development trend of food industry. It was suggested that the implementation of projects of “storing grain in food” and “storing grain among the people” should be actively promoted. Depending on the advantage of interdisciplinary integration, scientific and technological innovation should be used to further elevate the scientific connotation of food.
2022, 40(4):5-15. DOI: 10.12301/spxb202200549
Abstract:Sesame is one of the new “big eight” priority allergic foods. Sesame allergic reaction has attracted more and more attention all over the world because of its potential severity and increasing prevalence. Therefore, the study of sesame allergenicity mitigation technology is of great importance in ensuring food safety. The structures and immunological properties of the main sesame allergen (Ses i 1-Ses i 7), and the principles and research progress of the allergenicity mitigation technologies were summarized. The reported seven sesame allergens belonged to 2S albumin, 7S vicilin-type globulin, oleosin, and 11S globulin, among which 11S globulins and 2S albumins are the major allergen protein. Thermal processing techniques were used to mitigate the allergenicity of sesame, mainly through boiling, microwave, baking and so on to cause the depolymerization and denaturation of allergens, and then destroy the allergenic epitopes. Non-thermal processing techniques such as high pressure, irradiation, fermentation, enzymolysis and so on, could influence protein structure through the changes of chemical bonds such as hydrogen bonds and hydrophobic bonds, and the breakage of polypeptide chains, so as to cover or degrade directly the allergenic epitopes. At the same time, referring to other food allergen, the potential mitigation technologies of sesame allergens were further proposed, including pulsed electric field, cold plasma, ultrasonic wave, pulsed light, glycosylation modification and compound processing technology. In the future, it is necessary to study the epitopes of different sesame allergens, the effects of different processing technologies on the allergens structure and allergenicity, and carry out the allergenicity evaluation through serology, cell and animal models, and etc., so as to clarify the main mechanism of sesame allergenicity mitigation, and offer a theoretical basis and scientific guidance for the production of hypoallergenic or desensitized sesame products.
2022, 40(4):16-24, 34. DOI: 10.12301/spxb202200671
Abstract:Fruits are rich in vitamins, polyphenols and other antioxidants, which can delay aging and promote human health. However, fruit allergy induced food safety issues are increasing recently. The common fruit allergens and cross-reactivity allergy, as well as the principles and research progress of mitigation technology in fruit allergy were summarized. There were mainly seven types of common fruit allergens including thaumatin like protein (TLP), Bet v 1 homologous protein, lipid transfer protein, profilin, chitinase, cysteine protease and β-1,3-glucanase. Cross-reactivity allergy was one of the main factors causing fruit allergies, when multiple allergens contained similar structural sequences or determinants. Among them, Bet v 1 in pollen was most likely to trigger cross-reactivity allergy with common fruits. Physical processing technologies including high temperature, high pressure, pulsed electric field, ultrasound, and irradiation could directly destroy the structure of fruit allergens by breaking and rearranging the disulfide bonds, strengthening or weakening the hydrogen bonds, as well as breaking or cross-linking peptide chains. Chemical mitigation techniques such as lye or enzyme treatment could degrade epitopes in fruit allergens by disrupting their protein structures. At present, very limited studies were performed on the mitigation technologies of fruit allergens, and their effects of reducing the fruit allergenicity hardly reached ideal level. In the future, the combination of multiple technologies such as molecular dynamics simulation and novel food processing technologies could be used to precisely target and control fruit allergenicity. Innovative technologies including biological breeding and genome editing can cultivate new varieties of desensitized fruits, which fundamentally solve the challenges caused by fruit allergy, providing a scientific basis for the development and industrial application of hypoallergenic or desensitized fruit products.
2022, 40(4):25-34. DOI: 10.12301/spxb202200468
Abstract:Crab is an important economic aquatic product in China and one of the main ingredients to induce allergic reaction. Therefore, it is extremely urgent to understand the species and epitopes of crab aquatic product allergens and explore effective techniques to mitigate crab allergenicity. The identification of crab aquatic product allergens and their antigenic epitopes is an important prerequisite to mitigate their allergenicity. Firstly, the isolation and identification of crab aquatic product allergens including tropomyosin, arginine kinase, sarcoplasmic calcium binding protein, triosephosphate isomerase, and filamin c and so on at home and abroad were summarized. The linear epitopes and conformational epitopes of crab aquatic product allergens analyzed by bioinformatics, phage display technology, and one bead and one compound technology were introduced. Secondly, modern processing methods, such as irradiation, ultrasound, Maillard reaction, enzymatic crosslinking, and microbial fermentation technologies, used to modify the allergen epitopes or destroy the structure of allergen protein to reduce the allergenicity of crab aquatic products were compared. Finally, the future research trend of crab aquatic product allergens was emphatically analyzed, and the relationship between the structure-activity of crab aquatic product allergens and allergenicity was proposed as the research difficulty in this field. The advantages and disadvantages of physical methods, chemical methods, and biological methods in mitigating the allergenicity of crab aquatic products were compared, and it was suggested that the combined processing methods should be developed in the future, so as to reduce the allergenicity to a greater extent and provide technical basis for the development of hypoallergenic crab food or biological products.
2022, 40(4):35-44. DOI: 10.12301/spxb202100771
Abstract:Using citrus peels as raw materials, citrus nanofibers were prepared successfully by the method of the combination of 2,2, 6,6-tetramethylpiperidine-1-oxygen radical (TEMPO) oxidation and high pressure homogenization. Meanwhile, the effect of various molality of NaClO (5mmol/g, 25mmol/g, 50mmol/g) on the aspect ratio, morphology, physicochemical properties of citrus nanofibers were investigated. The results showed that with the increase of NaClO molality, the diameter and length of citrus nanofibers were gradually decreased. When the molality of NaClO was 50mmol/g, the diameter and length reached to the shortest, which were (150.57±24.99)nm and (2.74±0.29)nm, respectively. Results of scanning electron microscopy and FTIR spectra revealed that the lignin and hemicellulose in citrus fibers were hydrolyzed in the reaction of TEMPO oxidation with the increase content of NaClO, resulting in a rougher surface. The spectra of X-ray diffraction and thermogravimetry exhibited that TEMPO oxidation and high pressure homogenization treatment could improve the crystallinity and heat resistance of citrus nanofiber, and the formed cellulose I crystals was not destroyed. The analysis of physical and chemical properties of citrus nanofibers showed that the water holding capacity, oil holding capacity, cholesterol adsorption capacity and glucose adsorption capacity could be effectively improved after the TEMPO oxidation and high pressure homogenization treatment. And the strongest adsorption capacity was achieved when NaClO molality was 50mmol/g. The results showed that nano-sized citrus fiber possessed excellent functional properties, and this paper hoped to provide a scientific basis for the reuse of citrus peel.
2022, 40(4):45-54. DOI: 10.12301/spxb202100605
Abstract:The intestinal adhesion of probiotics is the key factor for long-term intestinal colonization. In order to increase the intestinal adhesion of exogenous probiotics, the sulfhydryl Codonopsis pilosula polysaccharide (sC-CPP-2) was prepared by two-step chemical modification of carboxymethylation and thiolation of the Codonopsis pilosula polysaccharide (CPP-2) isolated previously. Adhesion effect of intestinal mucus on Lactobacillus rhamnosus GG (LGG) with the addition of sC-CPP-2 was analyzed by in vitro adhesion test and laser confocal microscopy. The adhesion of sC-CPP-2 to LGG was indirectly verified by the composite film formed by Codonopsis pilosula polysaccharide and its modified components and sodium alginate. The interaction between sC-CPP-2 and intestinal mucus was detected by rheometer and classical tensile test. The results showed that the substitution degree of carboxymethyl Codonopsis pilosula polysaccharide (C-CPP-2) was 0.588±0.026, and the sulfhydryl content in sC-CPP-2 was (279.50±5.97) μmol/g. After thiolation modification, C-CPP-2 was in the coexistence of sulfhydryl and carboxyl groups. The thiol group on the surface of sC-CPP-2 could form disulfide bonds with the cysteine on the surface protein of LGG, which increased the intestinal adhesion of LGG. The maximum separation force between sC-CPP-2 and intestinal mucus was (101.82±5.78) mN, and the total adhesion work was (120.07±6.81) μJ. Interaction between sC-CPP-2 and intestinal mucus was enhanced, the apparent viscosity was increased, and the adhesion was significantly enhanced. It was confirmed that sC-CPP-2 could play a mediating role in connecting LGG and intestinal mucus, and enhance the intestinal adhesion of LGG, hoping to provide reference for improving the adhesion and colonization of probiotics in intestine.
2022, 40(4):55-63. DOI: 10.12301/spxb202100543
Abstract:Foods are vulnerable to contamination by pathogenic bacteria during production, transportation and storage, and this can cause foodborne illness. Linalool has antibacterial effects, but the mechanism of action remains unclear. In order to provide a theoretical basis for the development of linalool as a natural food preservative, the antibacterial activity and mechanism of linalool against Pseudomonas fragi were studied. The antibacterial activity of linalool was evaluated by measuring the minimum inhibitory concentration and plotting the bacterial growth curve. The antibacterial mechanism was investigated by scanning electron microscope observation, crystalline violet staining experiments, fluorescein diacetate staining experiments, and measuring the changes in electrical conductivity, nucleic acid leakage, respiratory metabolic activity and respiratory chain dehydrogenase activity. The results showed that linalool had a strong inhibitory effect against Pseudomonas fragi, and the minimum inhibitory concentration was 1.5mL/L. Linalool could damage the structure morphology and cell membrane of Pseudomonas fragi, and improve the permeability of the cell membrane, thus leading to the leakage of intracellular materials and the increase of electrical conductivity outside the cell membrane. It could inhibit the activity of respiratory metabolic and respiratory chain dehydrogenase, and damage the respiratory chain, thus leading to the disorder of intracellular metabolism. The research confirmed that linalool exerted a antibacterial effect by damaging the cell structure of Pseudomonas fragi and inhibiting its respiratory metabolism, and linalool could be studied and developed as a natural preservative.
2022, 40(4):64-73. DOI: 10.12301/spxb202100309
Abstract:Bacteriocins from different lactic acid bacteria have been successively isolated currently, however, these bacteriocins often suffer from the problem of a narrow antibacterial spectrum. Exploring new bacteriocins with broad-spectrum antibacterial properties has important theoretical value and application prospects. Commercially available pickled vegetables (sauerkraut) of 8 different brands with a long shelf life were selected as materials and bacteriostasis tests were done using Penicillium as indicator bacteria, the strain L3 which could produce bacteriostatic substances was screened out. The strain was identified as Lactobacillus plantarum and named Lactobacillus plantarum L3 after physiological and biochemical identification and 16S rDNA sequencing analysis, and the NCBI serial number was assigned MT781360. The bacteriocin L3 showed the strongest bacteriostatic activity when the strain L3 was cultured in MRS medium at 37℃ for 18-24h. The cell-free supernatant was extracted with ethyl acetate and purified by Sephadex G-50 gel filtration on a dextran gel column, and then subjected to Trinice-SDS- PAGE electrophoresis. The results showed that the molecular weight of the bacteriocin L3 was around 4-5kDa. The bacteriocin L3 was sensitive to proteases, but its activity was not affected by catalase, indicating that the bacteriocin L3 was proteinaceous substance. The bacteriocin L3 still kept high antibacterial activity after subjected to 60-100℃ treatment for 20min or 121℃ treatment for 15min and was stable over the range of pH 2-10. In addition, the bacteriocin L3 had good antibacterial activity against Gram-positive bacteria, Gram-negative bacteria and some fungi. In summary, the bacteriocin L3 produced by Lactobacillus plantarum L3 not only had good stability comparable to existing bacteriocins and the ability to kill Gram-positive bacteria, but also exerted an antibacterial effect on Gram-negative bacteria and some fungi. It is of great significance for the preservation of fruits, vegetables and dairy products, all of which are easily contaminated by fungi and spoilage. Therefore, this study was expected to provide new strain for the production of natural preservatives with broad-spectrum antibacterial properties.
2022, 40(4):74-84. DOI: 10.12301/spxb202100631
Abstract:To explore changes of the ripening properties of goat milk cheese made with Bacillus amyloliquefaciens GSBa-1 rennet (cheese B), commercial rennet and cheese prepared with the same batch of goat milk (cheese A) were used as the control group. Changes in main components, texture properties, microbial indicators and flavor substances were analyzed during the 60-day ripening of cheeses. The results showed that there was no significant difference in the cheese yield between the two groups. The moisture, protein and fat contents of cheese increased first and then decreased, and contents of cheese B were always higher than those of cheese A. The total contents of free amino acids increased first and then decreased, and the contents of phenylalanine, aspartic acid, isoleucine, methionine and serine in cheese B were higher than those of cheese A. The texture characteristics of cheese B in the early stage of ripening were better than cheese A. The number of Lactococcus lactis of cheese A increased by (5.22±0.02)% after ripening, and cheese B did not change significantly(P>0.05). During cheese ripening, the types and contents of volatile flavor substances in the two groups of cheese increased, but the nonanoic acid, octanol, 2-heptanone, 2-nonanone and dimethyl sulfone formed by cheese B gave goat milk cheese unique and rich flavor. Therefore, GSBa-1 rennet had the potential to replace commercial rennet in the production of goat milk cheese, and could promote the formation of cheese flavor and the improvement of quality.
2022, 40(4):85-95, 137. DOI: 10.12301/spxb202200017
Abstract:In order to enrich the strain resource, the bacterial diversity of milk and the biochemical characteristics of strains, lactic acid bacteria(LAB) of four naturally fermented camel milk samples from Laayoune, Morocco, were isolated and identified using the traditional pure culture method and metagenomic 16S rRNA gene sequencing technology. Meanwhile, the diversity of the bacterial metagenomic sequencing and the biochemical characteristics of strains were researched. The results showed that all the samples contained 82 LAB strains belonging to 3 genera and 8 species, of which 58.54% was Lactococcus lactis. According to the metagenomic sequencing results, the bacteria isolated from the four naturally fermented camel milk samples belonged to 7 phyla, 78 genera, and 147 species. Proteobacteria(54.64%) and Firmicutes(41.77%) were the dominant phyla in the samples, with Lactococcus(31.87%) and Lactococcus lactis (22.95%) accounting for the higher percentages, being the dominant species and genus in the samples. By comparing the growth situation and acid production rate of different LAB, the LAB with high growth rate and high acid production rate were screened out from the 48 strains of Lactococcus lactis, which were IMAU98054 and IMAU98084. The results showed that the optimal growth temperature of the 2 strains was 37℃, and the pH was 5.5-7.5. Moreover, the 2 strains had certain salt tolerance, and their growth wasn’t significantly inhibited when the NaCl concentration was less than 6%. When the strains were fermented at 37℃ for 18 h, the OD600 could reach 2.5218 and 2.5172, respectively. Natural fermented camel milk collected in Laayoune, Morocco, contained a variety of bacteria, of which Lactococcus lactis was the dominant strain, and 2 strains (IMAU98054 and IMAU98084), which had rapid growth rate and high acid production rate, had been screened out.
2022, 40(4):96-106. DOI: 10.12301/spxb202100229
Abstract:The oxidation of lard was obtained by heating and passing air in control, and three odor representative samples (peroxide values were 45.5,158.0,271.5mmol/kg fat respectively) were taken at the oxidation time of 1h, 3h and 4h. Due to the generally strong lipophicity, aroma compounds in fat are not suitable for solvent extraction. In this study, aroma compounds from the oxidized lard were directly extracted at 50℃ by high vacuum distillation and liquid nitrogen condensation using solvent assistant flavor evaporation (SAFE) apparatus, which has advantages with simpleness and mildness and without use of organic solvents. The aroma compound composition of extracts were analyzed by GC-MS and AEDA/GC-O. The results indicated that GC-MS identified 91 compounds among which aldehydes ranked the highest amount followed by acids. In comparision, the sample in a moderate oxidation degree (peroxide value was 158.0mmol/kg) with characteristic fatty odors had the most number and amount of compounds identified by GC-MS, whereas that in a lower oxidation degree(45.5mmol/kg)with green odors or higher oxidation degree (271.5mmol/kg) with pungent odors had fewer number and amount of compounds identified. And in all the three samples, hexanal, (E)-2-heptaneal, (E)-2-octenal, 1-octen-3-ol and hexanoic acid belonged to the top 5 compounds with higher content. AEDA/GC-O detected 39 aroma compounds, most of which were aldehydes. Sample in a moderate oxidation degree also had the highest number of odorants. In common, 1-octen-3-ol, hexanal, (E)-2-octenal, (E)-2-nonenal, (E,E)-2,4-decadienal, and pentanal exhibited higher dilution factors in all the three samples, and they were considered to contribute highly to overall aroma of the oxidized lard with different oxidation degrees. The results might help understand the mechanism of fat oxidization in control and provide guidance for optimal preparation of thermal reaction meat flavors using “fat oxidization in control-thermal reaction” process.
2022, 40(4):107-115. DOI: 10.12301/spxb202100314
Abstract:In order to explore the effects of thermal pretreatment temperature before enzymolysis on the taste components of chicken breast meat and chicken bone paste, sensory evaluation of chicken breast meat and chicken bone paste samples after different temperature treatments was carried out. The contents of free amino acids and nucleotides were determined and the equivalent umami concentration (EUC) value of each sample was calculated. Chicken breast meat and chicken bone paste samples with thermal pretreatment at 60℃ for 30min, followed by enzymolysis and milling exhibited the better sensory evaluation results and taste characteristics. Compared with the control groups without thermal pretreatment, thermal pretreatment can improve the overall taste of chicken breast meat and chicken bone paste samples. With the increase of thermal pretreatment temperature, the contents of free amino acids in the chicken breast meat and chicken bone paste samples decreased, among which the total amount of bitter amino acids declined the most (leucine content decreased the most), followed by sweet amino acids and umami amino acids. With thermal pretreatment at 60℃ and then enzymolysis, the content of 5′-CMP, 5′-GMP and 5′-IMP in chicken breast meat sample were higher than that in the control group without thermal pretreatment, and the chicken bone paste sample had a higher contents of 5′-IMP and 5′-AMP. In addition, the umami amino acid content and the EUC value of chicken bone paste sample (0.96g MSG/100g) were higher than that of chicken breast meat sample (0.52g MSG/100g). In conclusion, this study laid a data foundation for the effect of thermal pretreatment before enzymolysis on the taste components of chicken breast meat and chicken bone paste, which might be helpful to provide a theoretical basis for the optimization of enzymatic hydrolysis process in the industrial production of chicken flavored condiments.
2022, 40(4):116-126. DOI: 10.12301/spxb202100532
Abstract:To evaluate the in vitro antioxidant activities and carbohydrate digesting enzymes inhibitory activities of polyphenols among four varieties of Cinnamomum cassia Presl (C.cassia) cultivars (China Taiwan soil C.cassia and Qinghua C.cassia, Yunye C.cassia and Xijiang C.cassia), free and conjugated polyphenol contents, free and conjugated flavonoid contents of the four C.cassia cultivars were analyzed. The antioxidant activities and carbohydrate digesting enzymes inhibitory activities in vitro of crude extracts of free and conjugated polyphenols from the four C.cassia cultivars were also determined. Furthermore, correlation analysis of polyphenols and flavonoids with carbohydrate digesting enzymes inhibitory activity were performed. Qualitative and quantitative analysis of polyphenol compounds in the crude extracts of free polyphenols from the four C.cassia cultivars was carried out by UHPLC-MS/MS. The results showed that the contents of total polyphenols and total flavonoids in the four C.cassia cultivars ranged from 58.99-71.62mg/g and 46.49-58.05mg/g, respectively. And the contents of free polyphenols and flavonoids of the four C.cassia cultivars were higher than those of conjugated polyphenols and flavonoids. In addition, significant differences were detected with the antioxidant activity and carbohydrate digesting enzymes inhibitory activity among different cultivars. The antioxidant activity and carbohydrate digesting enzymes inhibitory activity of the China Taiwan soil C.cassia were significantly higher than those of other cultivars (P<0.05). Meanwhile, the results showed that free and conjugated polyphenol contents, free and conjugated flavonoid contents had a negative correlation with IC50 values of α-glucosidase, α-amylase and sucrase (P<0.05). The results obtained by UHPLC-MS/MS suggested that proanthocyanins, quercetin-3-O-glucoside and rutin might be the inhibitors of carbohydrate digesting enzymes in the extracts. The differences of the biological activity of C.cassia among the four cultivars provided a theoretical reference for the variety screening, precise processing and efficient application of C.cassia.
2022, 40(4):127-137. DOI: 10.12301/spxb202100729
Abstract:White peach slices were chosen as the test material, to explore the changes in physicochemical properties of sugar solution and white peach slices during cycle treatment under osmotic dehydration. Single-stage osmotic dehydration treatment (SODT) with constant sugar solution concentration and multi-stage osmotic dehydration treatment (MODT) with gradually increasing sugar solution concentration were studied. The sugar solution was recycled for five cycles without any adjustment. With the increase of the recycles, sugar solution showed low viscosity, indicating the dilution of the solution, which was found especially in SODT. Because of the low osmotic pressure differences between solution and samples, lower water loss and solid gain were observed in samples treated by SODT, which induced the significant increase in electrical conductivity, turbidity and ΔE. Based on the combined utilization of sugar solution with gradually increased concentration, the osmotic pressure differences could be good preserved in the MODT, contributing to the more water loss and solid gain of samples and the lower changes in electrical conductivity and turbidity of sugar solution. However, the significant browning reaction and the decrease in titratable acid content were illustrated in samples treated by MODT, which could be explained by the more oxygen induced by MODT. Therefore, the MODT could provide a novel idea and a good application prospect for the selection of osmotic dehydration mode of peach slices based on the efficiency of peach osmotic dehydration and properties retention of sugar solution.
2022, 40(4):138-147. DOI: 10.12301/spxb202100448
Abstract:To improve the drying efficiency of native potato flour, the effect of pectinase enzymolysis pretreatment with different time (60-80min) on hot air drying characteristics of raw mashed potato and physicochemical and processing properties of prepared pectinase-treated native potato flour (PNPF) were investigated. The results showed that the pectin content and initial water content of raw mashed potato were reduced after pectinase hydrolysis treatment , consequently improved the drying rate and caused greatly reduction of the drying time by up to 6.32%-7.81%. The contents of pectin, ash and protein in PNPF significantly decreased after pectinase treatment. Furthermore, amylose, amylopectin and total starch contents in PNPF increased significantly, and the relative crystallinity of starch and iodine blue value of PNPF decreased. At the same time, PNPF had higher solubility and swelling degree, and oil holding capacity was reduced significantly compared with non-treated flour. The water holding capacity was increased by 40.49%-49.58%. Moreover, the freeze-thaw water syneresis rate of PNPF decreased by 26.23%-62.11%, and the PNPF prepared by 180 min pectinase enzymolysis treatment exhibited the best freeze-thaw stability. The gelatinization characteristic analysis showed that peak temperature of PNPF decreased, the peak time shortened, the breakdown value increased, and the final viscosity and retrogradation decreased. In conclusion,pectinase enzymolysis pretreatment could improve hot air drying characteristics of raw mashed potato, shorten the drying time, and significantly improve the basic physicochemical and processing properties of the native potato flour.
2022, 40(4):148-158. DOI: 10.12301/spxb202100937
Abstract:In the process of chilled meat packaged in trays and storaged at 4℃, the exudate at the bottom will accelerates the growth of microorganisms, affect the color of meat, speed up the spoilage of chilled meat and shorten its shelf life. In this study, deacetylated crab shell powder (dCSP) were used as natural crosslinking agents to obtain bi-crosslinked sodium alginate antibacterial hydrogel water absorbent pads with high strength and high water absorption, which contained different volume fraction (0.3%, 0.6%, 0.9%, 1.2%) of cinnamyl aldehyde. Those water absorbent pads can be used to absorb exudation from the chilled meat during storage. The results indicated that the dCSP in the system could realize both Ca2+ crosslinking and polyelectrolytes interactions with sodium alginate. The addition of cinnamyl aldehyde could significantly enhance the performance of water absorbent pads. The hydrogel water absorbent pads showed denser structure, better swelling property, mechanical strength and antibacterial activity, when the cinnamyl aldehyde volume fraction was 0.6% or 0.9%. The pH value, total volatile basic nitrogen value, total viable count and volatile odor indicators of chilled meat with antibacterial hydrogel water absorbent pads were lower than the group without water absorbent pad and the group with wood fiber absorbent paper (P<0.05). The juice loss rate of chilled meat with antibacterial hydrogel water absorbent pads was low and the juice storage rate was 100%. The bi-crosslinked network formed between sodium alginate and crab shell powders which could enhance the mechanical properties and gel strength of water absorbent pads. In addition, the use of crab shell powders also could improve the comprehensive utilization rate of waste. The swelling ratio of hydrogel water absorbent pads were higher than that of commercial absorbent pads. The hydrogel water absorbent pads could not only effectively absorb the meat exudate, but also could trap those liquids inside the three-dimensional network. The hydrogel water absorbent pads have certain advantages of inhibiting the growth of microorganisms and extending the shelf life of chilled meat.
2022, 40(4):159-168. DOI: 10.12301/spxb202100381
Abstract:A real-time electrochemical sensor for detecting cholesterol was constructed due to the mimic enzyme characteristics of the metal organic framework (MOF). A new-type composite metal-organic framework (Fe3O4@Au/MOF) nanoparticle was prepared by self-assembly method, which had the advantages of recyclability of Fe3O4 magnetic particles and accelerating electron transfer of Au nanoparticles. The structure and morphology of the successfully prepared Fe3O4@Au/MOF were characterized by infrared spectroscopy, transmission scanning electron microscopy and X-ray photoelectron spectroscopy. With the dual catalytic performance of Fe3O4@Au/MOF peroxidase-like enzymes, cholesterol was oxidized to cholestyrtrione and H2O2. The oxidatively active hydroxyl radical produced by H2O2 can promote oxidation-reduction reaction of 3,3′,5,5′-tetramethylbenzidine (TMB), which increased the movement of charges in the system. According to the response of the electrical signal, the rapid qualitative and efficient quantitative detection of cholesterol can be realized. The research results showed that the optimal detection system determined by cyclic voltammetry was that the reaction temperature of 50℃, the addition amount of Fe3O4@Au/MOF of 0.0125g, scanning rate of 0.10V/s and buffer solution pH of 4. The working curve equation was y=20.6401x+4.7722, R2 was 0.9956, and the minimum detection limit was 2.7μmol/L, when the cholesterol concentration located in the range of 0.001~1.500mmol/L. The detection system had a good recovery rate and anti-interference with a good application prospects in food analysis and biochemical analysis.
2022, 40(4):169-176. DOI: 10.12301/spxb202200623
Abstract:In recent years, the self-heated food industry has been developing rapidly, but its quality and safety issues have been of great concern to society. This paper outlined the current situation of the development of the self-heated food industry, and systematically analyzed the possible quality and safety risk issues of the components in self-heated food from the perspective of industrial practice, explained the self-heated food regulatory policies and current standards introduced by the relevant departments in China, and at the same time discussed the trends of self-heating food standards and put forward corresponding countermeasures and suggestions, intending to provide a reference for industry enterprises to carry out safe production, regulatory departments to strengthen supervision, and to protect the food safety of consumers.