2023, 41(1):1-9, 21. DOI: 10.12301/spxb202200918
Abstract:Antimicrobial resistance (AMR) is involved in veterinary medicine, food, environment, medicine, and other fields. It endangers food safety, international trade, economic development, and life health. It has become a major public health problem facing the world. China was the world's largest producer and consumer of antimicrobials, about 60% of which were used in breeding industry. Due to its wide spread use and abuse in the breeding industry, many antimicrobial resistant bacteria appeared and spreaded rapidly. Following the “One Health” strategy, the United Nations encouraged countries to establish cross-sectoral AMR coordination mechanisms. This research compared the development, framework, and some monitoring results of foodborne bacterial antimicrobial resistance surveillance systems in China, the United States, and Europe. National surveillance systems basically covered population and food animal and food-related foodborne bacterial antimicrobial resistance, while also monitoring the use of antimicrobials in human medicine and food animals. American and European countries and regions started earlier and had relatively perfect systems. Through the development of nearly 30 years, they have mastered the baseline level of drug resistance and drug use of foodborne bacteria. Furthermore, scientific evaluation of surveillance data can play a risk management role, like optimizing surveillance programs (such as increasing surveillance of antimicrobial resistance in pets and environmental monitoring) and proposing interventions to limit the spread of resistant bacteria. The surveillance system of foodborne bacterial antimicrobial resistance started late in China. The surveillance of foodborne bacterial antimicrobial resistance in humans, food animals and related foods developed rapidly for 20 years, while the monitoring of antibiotic drug use in food animals began in 2018, and further improvement was needed for all aspects. At the same time, the EU monitoring system implemented the mechanism of breaking down departments to achieve data sharing. At present, different departments responsible for foodborne bacteria antimicrobial resistance monitoring systems have been established in our country. However, the data sharing mechanism has not been realized, and data “chimney” and information isolated island existed, which made it impossible to maximize the utility of existing data resources. By discussing the experiences of the United States and Europe, this research has the following inspirations for the antimicrobial resistance surveillance system in China. It is necessary to gradually improve the antimicrobial resistance surveillance system, establish a multi-sectoral collaborative governance mechanism, and accelerate the application of new technologies in data mining, to comprehensively improve the ability to curb bacterial resistance and protect people's health.
2023, 41(1):10-21. DOI: 10.12301/spxb202300015
Abstract:Short chain fatty acids (SCFAs), as important metabllites of gut microorganisms, organically link the complex interactions between host nutrition and gut microbiota. In recent years, accumulating scientific evidences have well indicated the strong relationship between SCFAs and host health. SCFAs have been found to be both the preferred energy source for intestinal epithelial cells and the natural ligands for free fatty acids receptors. Therefore, SCFAs play a multiple health role. SCFAs are essential in the regulation of lipid metabolism, immunity, inflammatory response, and appetite. The food sources of gut-derived SCFAs precursors, gut microbes involved in SCFAs metabolism and their metabolic pathways were summarized. Dietary approaches on gut-derived SCFAs regulation was further discussed. SCFAs are defined as volatile fatty acids, of which the number of carbon atoms is less than 7. The gut-derived SCFAs, in particular, acetic acid, propionic acid, and butyric acid, are fermented and transformed from SCFAs precursors by gut microbiota. The source of gut-derived SCFAs precursors are various, and non-digestible carbohydrates such as resistant starch, non-starch polysaccharides and oligosaccharide are considered as the main SCFAs precursors in food. SCFAs are produced through different metabolic pathways from SCFAs precursors by various gut microorganisms independently or synergistically. Supplementation with foods rich in SCFAs precursors not only affects the content of gut-derived SCFAs, but also maintains and enhances the steady state of gut microecology by selectively promoting the growth of beneficial bacteria in the gut, thereby regulating physiological function and contribute to host health. This review could provide new ideas for the prevention and treatment of related metabolic and immune diseases.
2023, 41(1):22-29. DOI: 10.12301/spxb202200301
Abstract:Substances such as choline, L-carnitine, and betaine contained in food can be converted into trimethylamine (TMA) under the action of gut microbiota. TMA can be easily absorbed by intestinal epithelial cells, transported to the liver through the portal circulation and then oxidized to trimethylamine-N-oxide (TMAO). The level of TMAO in plasma is closely related to the occurrence and development of cardiovascular diseases in humans. Therefore, gut-derived TMA is considered as a risk marker for cardiovascular disease. TMA is a metabolite of gut microbiota that get diet, gut microbiota, and cardiovascular disease closely linked, it provides a new target for the prevention and treatment of cardiovascular disease through diet and gut microbiota. Cardiovascular disease is considered to be a serious threat to human health, and analysis of the generation mechanism and influencing factors of gut-derived TMA could provide a reference for controlling gut-derived TMA and reducing cardiovascular disease incidence. The food sources of gut-derived TMA precursors and the gut microbes involved in the generation of TMA were described, and the metabolic pathways of TMA in body were systematically explained. For the control of gut-derived TMA, the aspects of reducing the intake of TMA precursors in food, reducing the proportion of gut microbiota that produce TMA, inhibiting TMA-producing enzymes, and intervening in the synthesis of gut-derived TMA were summarized. According to the probiotics and archaea intervention strategies with good application prospects, the current research results on the effects of probiotics and archaea on TMA were summarized, which provided possible directions for the prevention of cardiovascular diseases.
2023, 41(1):30-42. DOI: 10.12301/spxb202200616
Abstract:Headspace solid phase microextraction-gas chromatography-mass spectrometry technology was used to separate and identify the volatile flavor compounds in the fruiting bodies of Stropharia rugosoannulata at different drying periods, and the changes of volatile flavor compounds in the drying process under the condition of hot air drying at 55℃ constant temperature was explored. A total of 245 volatile flavor compounds were identified in the whole drying process, including 34 aldehydes, 29 esters, 40 alcohols, 37 ketones, 7 acids, 24 alkanes, 26 olefins and 48 other compounds. Aldehydes, ketones and alcohols accounted for a relatively large proportion, and the sum of the three contents accounted for 65.49%-89.30% of the total content, which were the main volatile substances in Stropharia rugosoannulata. A total of 45 key odor compounds were screened out through the thermal analysis of odor activity value combined with partial least squares discriminant analysis. Among them, 1-octene-3-ketone was always the compound with the largest contribution to the odor during the drying process, and there were 20 different compounds before and after the drying process. The comprehensive analysis showed that the aroma change law of Stropharia rugosoannulata during the drying process was as follows:with the drying process, the odors of soil and grass gradually weakened, and the flavors of coke and malt presented in the late drying process, but the mushroom flavor and soil odor were still the key flavor characteristics of Stropharia rugosoannulata during the whole process.Determination of key enzyme activities in the main metabolic pathways of aldehydes, ketones and alcohols, indicated that the enzyme would be activated by heat, and the enzyme activity showed a significant downward trend as a whole during the drying process. There was almost no activity at the end of the drying process. The correlation analysis between the metabolic enzyme activity and the corresponding compound content showed that lipoxygenase had a strong positive correlation with aldehydes and ketones, alcohol dehydrogenase had a strong negative correlation with alcohols. It was consistent with the dynamic change trend of aldehydes, ketones and alcohols during the drying process.
2023, 41(1):43-55. DOI: 10.12301/spxb202200519
Abstract:In order to study the changes of nutrition and flavor characteristics of fresh Tremella fuciformis before and after hot air drying, the basic nutrients, bioactive components, amino acids and mineral elements in fresh and dried T. fuciformis were comparatively measured. The flavor characteristics of fresh and dried T. fuciformis samples were analyzed by gas chromatography-ion mobility spectroscopy (GC-IMS) and gas chromatography-mass spectrometer (GC-MS). The results showed that the contents of crude protein, crude fat, total amino acids, crude polysaccharides, total polyphenols and total triterpenes in fresh T. fuciformis were significantly reduced after hot air drying (P<0.05). The amino acid content and composition of T. fuciformis changed after air drying, and the amino acid nutritional value of fresh T. fuciformis was closer to the WHO/FAO recommended model of protein. In addition, the contents of some mineral elements such as calcium, iron, copper and zinc in T. fuciformis were reduced after drying. A total of 30 volatile flavor compounds both in fresh and dried T. fuciformis were identified by GC-IMS, and 41 volatile flavor compounds were identified by GC-MS. The composition and content of volatile compounds in fresh and dried T. fuciformis were significantly different. Compared with dried T. fuciformis, fresh T. fuciformis was not only rich in 1-octen-3-ol with typical mushroom flavor, but also rich in α-pinene, ethyl propionate methyl butyrate and other esters with fruity flavor. It could be concluded that T. fuciformis was rich in nutrition and unique in flavor. The research results could provide a certain preliminary theoretical basis for the sales and deep processing of fresh T. fuciformis.
2023, 41(1):56-66. DOI: 10.12301/spxb202200875
Abstract:The protective effect of Lyophyllum ulmarium fibrinolytic enzyme (LUFE) on vascular endothelium injury in hyperlipidemic rats was investigated. The SD rats were randomly divided into normal control group, model group, positive control group, and LUFE group. The normal control group was fed with normal diet, while the rest groups were given high-fat diet, in which the LUFE group was simultaneously gavaged with LUFE (400mg·kg-1·d-1). Positive control group started gavage of atorvastatin calcium tablets (5mg·kg-1·d-1) at the 5 week of feeding. After 4 weeks and 8 weeks of rearing, the corresponding indexes were tested respectively. Hematoxylin-eosin staining was used to observe the pathological changes of aorta. Oil red O staining was used to observe the distribution of lipid plaques in aortic intima. The levels of plasma total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), catalase (CAT),malondialdehyde (MDA), superoxide dismutase 2 (SOD2), endothelin-1 (ET-1) and 6-keta-PGF1α were measured and the atherogenic index was calculated. Nuclear factor erythroid 2-related factor (Nrf2), silent information regulator 3(Sirt3), acetyl-superoxide dismutase 2(Ac-SOD2), and heme oxygenase 1(HO-1)of aorta were detected by Western blot. LUFE attenuated the pathological injury of aorta in hyperlipidemic rats, reduced the relative area of lipid plaque distribution in aortic intima, decreased the levels of TC, TG, LDL-C, ET-1 and MDA in plasma, and increased the levels of 6-keta-PGF1α, CAT and SOD2. The expression of Nrf2, HO-1 and Sirt3 protein in aortic tissue was up-regulated, and relative protein expression of Ac-SOD2 in aortic tissues was reduced. LUFE attenuated vascular endothelium injury induced by hyperlipidemia in rats, and the mechanism may be related to the reduction of blood lipid and oxidative stress injury.
2023, 41(1):67-76. DOI: 10.12301/spxb202200971
Abstract:The effects of Ganoderma lucidum spore oil (GSO) on liver fibrosis in rats induced by carbon tetrachloride (CCl4) combined with high-fat diet was investigated, and its potential mechanism was explored. Male SPF SD rats were divided into blank control group, model control group, positive drug group, and GSO low, medium and high dose groups. The liver fibrosis model was induced by CCl4 combined with high-fat diet for 6 weeks, and GSO was administered for 8 weeks at the same time. The protective effect of GSO on liver fibrosis was evaluated by detecting the serum physiological and biochemical indexes, morphology of rat liver slices , oxidative stress, and fibrosis related proteins of rat liver tissue. The results showed that GSO could significantly improve the survival rate of rats with liver fibrosis, making the survival rate recover to the level of the blank control group. The results of pathological staining showed that the liver tissue structure was improved in different degrees in each group, and the proportion of collagen area and areal density in the GSO middle and high dose groups was significantly decreased. The high dose group could significantly reduce the levels of plasma liver function-related indexes, the contents of liver fibrosis indexes. Meconwhile, GSO high dose group significantly decreased the content of MDA, increase the content of GSH, the activity of SOD survival status, liver fibrosis, and the expression of MMP-9. The results showed that middle and high dose of GSO (15 and 30 fold recommended dosage of human body) could improve the survival rate and antioxidant capacity of liver fibrosis model rats and had the protective effect on rat survival rate and liver fibrosis.
2023, 41(1):77-87. DOI: 10.12301/spxb202200432
Abstract:To study the inhibitory mechanism of microorganisms and their secondary metabolite against fungus such as Aspergillus flavus 2219, the active substance pamamycin produced by metabolism of Streptomyces alboflavus TD-1 screened from soil was isolated using thin layer chromatography, silica gel column chromatography, high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry. The inhibitory effect and mechanism of pamamycin against Aspergillus flavus 2219 and other fungus were determined by scanning electron microscope (SEM), fluorescence microscope and HPLC. Results showed that the molecular formula of active substances in the supernatant and mycelium of streptomyces alboflavus TD-1 was predicted to be C35H61NO7, pamamycin and its homologue, and the relative molecular weight were 593,607, 621,635, 649. According to SEM observation, the morphology of fungus cells treated with pamamycin was distorted in different extent. The minimum inhibitory concentration (MIC) of pamamycin for Penicillium citrus was 0.125mg/mL, for Botrytis cinerea was 0.500mg/mL, and for Aspergillus flavus 2219, Aspergillus niger, Trichoderma harzianum and Aspergillus oryzae was 1.000mg/mL. The action target of pamamycin was ergosterol on fungal cell membrane. The inhibition mechanism was to destroy the integrity of cell wall, change the permeability of cell membrane, affect the energy metabolism of mitochondria, inhibit the ergosterol biosynthesis in mycelial membrane. Pamamycin could reduce the synthesis rate of aflatoxin B1 by 98.3%. Therefore, Streptomyces alboflavus TD-1 and pamamycin could be used for biological control of toxigenic fungi in raw food materials.
2023, 41(1):88-98. DOI: 10.12301/spxb202100610
Abstract:In order to evaluate the inhibitory effect of eugenol on the biofilm of Bacillus amyloliquefaciens DY1a and the effect of eugenol on the adhesion and aggregation ability of the interface in the early stage of biofilm formation, the effects of eugenol at different mass concentrations on the formation of biofilms, the surface microstructure of biofilms, the number of viable bacteria in biofilms and the content of polysaccharide and protein in biofilm matrix were analyzed, and the scavenging ability of mature biofilms was evaluated. The effect of eugenol on the adhesion and aggregation ability of biofilms in the early stage of biofilm formation was comprehensively analyzed by bacterial motility experiment, cell surface hydrophobicity, cell surface Zeta potential and cell self-aggregation ability. The results showed that the minimum biofilm inhibitory concentration (MBIC) of eugenol against B. amyloliquefaciens was 1.500mg/mL, and the eradication rate of eugenol against mature biofilm was 28.85%. The biofilm formed at the air-liquid interface of eugenol medium supplemented with 1/2 MBIC and 1/4 MBIC was thinner and smoother, and the number of viable bacteria in the biofilm was significantly reduced. Moreover, eugenol was capable of suppressing bacterial swimming (22.16% to 100.00%), swarming motility (43.86% to 97.50%). And cell surface hydrophobicity, negative cell surface Zeta charge, and auto-aggregation were also decreased. In addition, eugenol significantly inhibited exopolysaccharides and protein synthesis of bacteria. Therefore, the antibiofilm mechanism of eugenol against B. amyloliquefaciens DY1a was associated with inhibitory of bacterial motility, changes of cell surface hydrophobicity and auto-aggregation, thus interfering with the adhesion ability of early bacteria at the film forming interface, and inhibiting the synthesis and secretion of extracellular polymeric substance components to delay the growth and maturation of biofilm. In conclusion, eugenol could be used as a potential antibiofilm agent for control biofilm formation of B. amyloliquefaciens at the air-liquid interface.
2023, 41(1):99-105. DOI: 10.12301/spxb202200231
Abstract:To study the formation conditions of protein and polysaccharide composite particles, especially the effect of processing conditions on the construction of their core-shell structure, whey protein isolate (WPI) and chitosan (CS), the only naturally positively charged polysaccharide, were used to form composite particles with protein as core and polysaccharide as shell. The conditions of particle formation and the influencing factors were investigated, and the particle size, potential and microstructure of the formed particles were characterized. The pH value and salt ionic strength were important factors for composite reactions of the two substance. The results showed that when the salt ionic strength was 0 and the pH value reached 5.47, the turbidity of the system reached maxium, which was 98.34% and complexation of the two substance reached the highest degree. Therefore, composite particles prepared at these conditions were used to study the effect of mixing mode, treatment temperature and shear treatment on the composition and particle size of composite particles. The results showed that there was no significant difference in the composition of the composite particles formed by heat-mixing (heat treatment of protein followed by mixing with chitosan) and heat-mixing (mixing of protein and chitosan followed by heat treatment), but the particle size of the particles formed by heat-mixing was smaller and the absolute value of ξ potential was larger, indicating that the particles were more stable. There was no significant difference in the proportion of protein and polysaccharide in the composite particles under heat treatment conditions of 75,85, 95℃, but the higher temperature, the larger particle size and the smaller absolute value of the potential. The particle size could be effectively reduced by shear treatment. The confocal laser scanning microscopy showed that the composite particles formed at 75℃ exhibited a clear co-localization of protein and polysaccharide fluorescence. The results showed that complete core-shell structured composite particles with particle size approximately 744.5nm could be prepared by heat treatment at 75℃, heat-mixing, and assisted with high-speed shearing.
2023, 41(1):106-114. DOI: 10.12301/spxb202200144
Abstract:Angiotensin-I-converting enzyme (ACE) inhibitory peptides play an important role in the prevention and treatment of hypertension to improve human health, because of their characteristics of safety, no side effects, and easy absorption. The objective was to prepare ACE inhibitory peptides from cottonseed protein using an appropriate protease (e.g., alcalase, protamex, flavourzyme, papain, and bromelain) under optimum conditions. The single-factor experiment was used to optimize hydrolysis conditions. The hydrolysate was then purified to identify sequences of bioactive peptides, and in vitro digestion and absorption stabilities of the hydrolysate was evaluated. It was found that the cottonseed protein hydrolyzed by protamex (1500U/g) at pH 8.0 and 55℃ for 5h resulted in the protein recovery rate of 39.8% and the highest ACE inhibitory activity (93.7%). The cotton protein hydrolysate was then separated into five fractions, in which fraction 4 with the highest inhibitory activity (IC50=220.1μg/mL). Three novel ACE inhibitory peptides were identified from fraction 4:VFNNNPQE, LLSQTPRY and VFPGCPET. LLSQTPRY exhibited the highest ACE inhibitory activity (IC50=105.2μmol/L). After in vitro gastrointestinal digestion and absorption by Caco-2 cell monolayer, the cotton protein hydrolysate retained ACE inhibitory activities of 53.8% and 20.5%, respectively. Therefore, the cottonseed protein hydrolysate prepared by protamex could be potentially used as a functional ingredient to develop antihypertensive food products.
2023, 41(1):115-125. DOI: 10.12301/spxb202200218
Abstract:In order to systematically explore the molecular mechanism of ferulic acid suppressing the activity of xanthine oxidase (XO), the effects of ferulic acid on the inhibitory reversibility, inhibition kinetics, binding properties, and structure were determined by enzymatic and spectroscopic methods. Molecular simulation technology was used to predict the binding conformation of ferulic acid with XO. The results indicated that ferulic acid could reversibly inhibit XO activity in a mixed-type competitive manner with an inhibiting constant of 4.5μmol/L. Ferulic acid had the strongest inhibitory activity on XO with the IC50 of 116.2μmol/L compared to caffeic acid, p-coumaric acid, chlorogenic acid, and gallic acid. Fluorescence titration experiments showed that ferulic acid could quench the fluorescence of XO through static and dynamic quenching procedures, among which static quenching was dominant. XO had a binding site for ferulic acid with a binding constant of 3.38×104L/mol at 298K. The binding process was spontaneously driven by hydrogen bonds and hydrophobic interactions due to ΔG<0, ΔH<0, and ΔS>0. Molecular docking revealed that ferulic acid entered the flavin adenine dinucleotides active center of XO and then affected the normal catalytic process of XO. The analysis of synchronous fluorescence and circular dichroism demonstrated that ferulic acid could alter the secondary and tertiary structure of XO. The polarity around tryptophan and tyrosine residues in XO was enhanced and their hydrophobicity was reduced. The α-helix content was increased and the β-fold content was decreased in XO, making its secondary structure tend to be tight. That was another factor impacting the XO activity. This study could provide a certain theoretical basis for the improvement of hyperuricemia through ferulic acid as an XO inhibitor.
2023, 41(1):126-134. DOI: 10.12301/spxb202200175
Abstract:To evaluate the improvement effect of piceatannol on cognitive impairment in Alzheimer's disease (AD) mice, seventy-two male Kunming mice were randomly divided into 6 groups with 12 mice in each group, including control group, model control group, positive control group, piceatannol intervention groups (low-dose, medium-dose and high-dose). AD mice were induced by AlCl3 and D-galactose intervention for 70 d. After 5 weeks of continuous intervention with piceatannol on the 35th day of modeling, Morris water maze experiment was used to test the spatial learning and memory ability of mice. Meanwhile, the protein expression levels of Aβ1-42 and TNF-α in the hippocampus of mice were determined by ELISA method, and the activity of superoxide dismutase (SOD) and content of glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) in mice serum were detected. Combined with relative viscera index, the improvement effect of piceatannol on AD mice was analyzed. The results showed that the latency of escape in model control group was significantly higher than that in control group and the memory ability was significantly decreased, while piceatannol effectively improved the cognitive behavior and memory ability of AD model mice (P<0.01). Compared with control group, the levels of Aβ1-42, TNF-α and activated microglia were significantly increased in model control group, while piceatannol significantly decreased the levels of Aβ1-42, TNF-α and activated microglia (P<0.01). Moreover, piceatannol effectively increased the activities of SOD and the content of GSH-Px and reduced MDA content in mice serum, and alleviated oxidative injury. In conclusion, piceatannol can improve the cognitive function of AD mice by reducing oxidative stress, neuroinflammation and Aβ production in the hippocampus.
2023, 41(1):135-142. DOI: 10.12301/spxb202200318
Abstract:The aroma substances change pattern of Hutai-8 rose wine during storage and the aroma protection effects of some additives were studied, which was useful to optimize the wine aging technology. Hutai-8 rose wine was added with glucan, gallic acid, mannoprotein, and glutathione respectively after alcohol fermentation. Wine samples were collected regularly, and aroma of samples was detected by instrumental and sensory analysis. The aroma substances were qualitatively and quantitatively analyzed by SPME-GC-MS and aroma characteristics were evaluated by a well-trained tasting panel. The result showed that a total of 33 aroma substances were detected in Hutai-8 rose wine, among which the odor activity value (OAV) of 9 aroma components was greater than 1, and the OAV of 11 aroma components was between 0.1 and 1.0. During the storage, the concentration of acetates and medium chain fatty acid ethyl esters decreased sharply at the beginning of the storage period and then leveled off. Higher alcohols gradually increased and then reached a plateau. Fatty acid, terpenes and phenethyl compounds gradually increased and then decreased at the end of the storage period. After one year storage, the contents of fruity esters, phenethyl compounds and hexene alcohols compounds in glucan treatment were obviously higher than those in other treatments whose differences were not significant. Sensory analysis also showed that glucan treatment had better aroma characteristics of temperate fruits, sweet, flowers and small berries than that of other wines. It was concluded that the treatment of 300mg/L glucan showed good potential to protect the aroma of Hutai-8 wines during storage.
2023, 41(1):143-153. DOI: 10.12301/spxb202100820
Abstract:Mono Trap has the characteristics of large extraction amount and simple operation. It has the advantages in the extraction of odor compounds in watermelon juice. Mono Trap and thermal desorption combined with gas chromatography-olfactory-mass spectrometry were used to extract and analyze the odor compounds of watermelon juice before and after thermal treatment. The three adsorbent materials, RGC18, RSC18 and RGPS, were used and identified 50 and 71 odor compounds from fresh and heated watermelon juice, respectively. The comparison results of the extraction effects of these three adsorbent materials showed that RGC18 had the best extraction effect on the odor compounds of watermelon juice. 41 and 53 odor compounds were extracted by RGC18 from fresh and heated watermelon juice, respectively. After the thermal treatment, the odor compounds of watermelon juice have changed greatly. The odor activity value of compounds exhibited bitter almond, soapy, and sharp acidic flavors, such as 2-methylbutanal, furfural, octanal, decanal, (E)-2-heptenal, acetic acid and formic acid increased, while hexanal, β-cyclic citral and (E,E)-2,4-nonadienal with green and lemon odor cannot be smelled. The changes of these compounds were the important reasons for the off-flavor of watermelon juice after thermal treatment.
2023, 41(1):154-162. DOI: 10.12301/spxb202200614
Abstract:To investigate the effects of different ozone concentrations (0,1,3,5mg/L) in ozone-ice slurry (O-IS) treatment on the flavor of Pseudosciaena crocea during the storage life of excellent grade, the change pattern of volatile flavor substances was analyzed and discussed using solid-phase microextraction-gas chromatography mass spectrometry (SPME-GC-MS) combined with electronic nose technique, and the fresh fish cubes and fish cubes preserved with traditional flake ice method were used as controls. The results showed that a total of 35 volatile components, mainly aldehydes, hydrocarbons and alcohols, were detected in the Pseudosciaena crocea samples by SPME-GC-MS. Among them, the quantitative analysis of hexanal, heptanal, 1-octen-3-ol and etc., which were the volatile substances that made the fish fishy, proved that 1mg/L O-IS treatment could degrade the content of fishy smell substances in Pseudosciaena crocea while reducing the oxidation effect of ozone on the fish flesh. Electronic nose analysis found that the response to fishy odor substances in the O-IS treatment groups were significantly lower than that in the control group. Moreover, after 1mg/L O-IS treatment, the fishy substances were not detected by the electronic nose. This study showed that within the shelf life of excellent grade of Pseudosciaena crocea, the 1.00mg/L O-IS treatment could significantly reduce the fishy substance content of Pseudosciaena crocea.
2023, 41(1):163-174. DOI: 10.12301/spxb202200604
Abstract:To study the effects of different modified atmosphere packaging on the postharvest quality and chlorophyll degradation in Chinese kale during storage, Chinese kale samples were packed with commercial micro-porous low-density polyethylene (LDPE) bags and two kind of modified LDPE bags. The gas content and quality changes of Chinese kale in the packaged bags were detected periodically. The results showed that during the storage at 15℃,the content of O2 decreased and CO2 increased significantly in the modified atmosphere packed bags, while no obvious changes for volume fraction of either O2 or CO2 in control group. Both of the modified atmosphere packaging groups exhibited similar effects on retarding the yellowing process and weight loss rate, and maintaining higher content of chlorophyll, vitamin C and soluble proteins ratio in leaves during storage. The commodity rate of two modified atmosphere packaging groups maintained at 100% on the third day of storage, and leaf chlorophyll mass ratio decreased slightly with 14.67% and 4.74%, respectively. Comparably, the commodity rate of the control group declined rapidly to 51.25%, and the leaf chlorophyll mass ratio decreased by 26.47%. The content of chlorophyll during leaf yellowing of Chinese kale regulated by the gene expression of CLH1, PPH, PAO, RCCR and NYC, and CLH1 took effect for the chlorophyll-degrading enzyme mainly at the early period of leaf yellowing. The modified atmosphere packaging treatments could slow down the physiological changes, inhibit the expression of gene involved in chlorophyll degrading enzyme, thus, delay the leaf yellowing in Chinese kale during storage. The result could provide a theoretical basis for controlling the postharvest quality deterioration and storage of Chinese kale.