SHAN Yang , DING Shenghua , SU Donglin , LIU Wei , ZHANG Juhua
2021, 39(4):1-13. DOI: 10.12301/j.issn.2095-6002.2021.04.001
Abstract:Citrus is the most productive fruit in the world and China. China is a big country in the production and processing of citrus. With the rapid development of citrus planting and processing industry, the by-product resources such as fruit dropping and residual fruit in the citrus planting process, waste and waste water during the processing process have also increased. Problems such as waste of resources and environmental pollution caused by low utilization of by-product resources are more prominent. At present, in addition to the direct utilization of citrus by-product resources, they were also used to prepare functional ingredients such as pectin, flavonoids, carotenoids, limonoids, essential oils, and synephrine by extraction, or prepare ethanol, citric acid, feed and organic fertilizer by fermentation and conversion of biomass. However, the problems of low comprehensive utilization rate, lack of key technologies and core equipment, and slightly fewer high-value-added functional products were also the current difficulties need to be resolved. Green, low-carbon, high-efficiency, high-value, comprehensive recycling will be the development trend of citrus by-product resource utilization. In response to the existing problems, suggestions on strengthening scientific and technological research, formulating special plans, and strengthening fiscal revenue might effectively improve the utilization of the by-product resources of citrus, hoping to provide a reference for the high-quality development of the comprehensive utilization of citrus by-product resources.
FENG Yunzi , ZHOU Ting , WU Weiyu , CAI Yu , ZHAO Mouming
2021, 39(4):14-28. DOI: 10.12301/j.issn.2095-6002.2021.04.002
Abstract:As a traditional Chinese condiment, flavor of soy sauce is an important quality indicator, and its functional activity has also attracted people's attention. However, the flavor and functional components of soy sauce are complex, and how to comprehensively analyze the volatile and non-volatile components that possess flavor and functional activities and effectively regulate them have always been the hot spots for condiment industry. According to research reports, there were 202 kinds of aroma-active compounds in soy sauce, which can be divided into sour, alcoholic, malty, floral, fruity, caramel-like, smoky, vegetable-like aromas, etc. according to the type of odor. The combination of different aroma compounds in a certain proportion forms the rich sauce (in Chinese “Jiang”) aroma of soy sauce. There were 230 kinds of non-volatile compounds in soy sauce, which brought comprehensive sense of sourness, sweetness, bitterness, saltiness, umami and kokumi taste to soy sauce. Among them, salty and umami taste were more prominent. The reported physiological functional substances in soy sauce were about 30 kinds, which possessed certain antioxidant, anticancer, antihypertensive, anti-hyperuricemic activities, etc. Overall, the changes, advantages and disadvantages of soy sauce flavor detection technology, its key active substance basis according to aroma characteristics, taste characteristics and functional activity classification were detailedly introduced, and the development direction of technology and theory was reviewed. This study aimed to provide a reference for the high-quality development of soy sauce and traditional fermentation industries.
WANG Min , SHEN Guangyue , SONG Jia , ZHENG Yu
2021, 39(4):29-36. DOI: 10.12301/j.issn.2095-6002.2021.04.003
Abstract:Vinegar is an indispensable condiment in people's life, the most widely used acid condiment in the world. China, Japan, Korea and other Asian countries mostly use sorghum, rice, glutinous rice and other grains as raw materials to ferment and produce cereal vinegar, while it is mainly brewed using fruit in Europe, America, Africa and other countries and regions. Flavor is the basic attribute of vinegar, which directly affects its quality and popularity. Vinegar flavor analysis methods mainly include concentration and extraction of flavor substances, the qualitative and quantitative of flavor substances, the determination of characteristic flavor compounds and their contribution, sensory evaluation, etc. Compared with Japanese, Korean and other countries's cereal vinegar, Chinese cereal vinegar has an enriched flavor and nutrient composition due to its diverse brewing raw materials and complex technology. The main flavor substances in Chinese cereal vinegar are organic acids, amino acids, sugars, polyphenols and flavonoids, alcohols, esters, aldehydes, ketones and other compounds. This paper focused on the research progress of Chinese cereal vinegar flavor analysis from the aspects of vinegar flavor chemistry and sensory evaluation.
HAO Yiming , YANG Zihui , LIU Jie , WANG Ziyuan , WANG Jing
2021, 39(4):37-45. DOI: 10.12301/j.issn.2095-6002.2021.04.004
Abstract:Obesity is associated with a state of low-grade chronic inflammation that leads to impairment of insulin signaling pathway. Wheat alkylresorcinols (ARs) are biomarkers and active ingrendients of whole wheat food. In this study, inflammatory factors were used to establish the insulin resistant model in 3T3-L1 adipocytes in vitro, and the protective effect of wheat ARs on insulin resistance of adipocytes in inflammatory state was investigated by measuring the level of lipolysis and glucose uptake of adipocytes. The results showed that wheat ARs had no toxic effect on adipocytes at the concentration of 5~20μmol/L and could improve insulin resistance in 3T3-L1 adipocytes induced by inflammatory factors in a dose-dependent manner, and the glucose uptake increased by 4.3%, 10.2% and 24.0%, respectively. Meanwhile, wheat ARs could significantly alleviate the lipolysis of adipocytes induced by inflammatory factors. In addition, the phosphorylation of Akt (p-Akt) and the expression of its downstream GLUT4 protein in adipocyte glycometa-bolism were significantly reduced by inflammatory factors, leading to glucose uptake disorder. ARs treatment significantly increased Akt phosphorylation and GLUT4 protein expression. After pre-treated with PI3K inhibitor (LY294002), the protective effect of ARs was reversed on 3T3-L1 adipocytes. The phosphorylation of Akt and the expression of its downstream protein GLUT4 were significantly inhibited. Additionally, the lipid accumulation and glucose uptake of adipocytes was inhibited by LY294002, which indicated that ARs could improve insulin resistance and lipolysis of adipocytes via activating p-Akt/GLUT4 signaling pathway. Furthermore, the protective effects of five major homologues of wheat ARs on insulin resistance of adipocytes were compared. These results indicated that heptadecylresorcinol (AR-C17) was the main active substance of wheat ARs.
LI Konghui , LIAO Sentai , LI Qian , ZOU Yuxiao , MU Lixia , LONG Xiaoshan
2021, 39(4):46-54. DOI: 10.12301/j.issn.2095-6002.2021.04.005
Abstract:The mouse model of ulcerative colitis was established with 5% sodium dextran sulfate to study the efficacy of Chinese yam peel polyphenols in preventing intestinal mucosal damage. Histopathological analysis, Western blotting and TUNEL staining were used to observe the disease activity index and the pathological changes of colon tissue in each group, and the relative expression of key proteins and the apoptosis rate of colonic epithelial cells were determined. The results showed that the disease activity index and the pathomorphology of colon tissue were significantly improved in mice treated with Chinese yam peel polyphenols. Chinese yam peel polyphenols also increased the expression of tight junction protein Occludin, prevented intestinal mucosal from the damage of mechanical barrier, reduced the expression of Caspase-8 and the apoptosis of colonic epithelial cells, and inhibited the expression of cyclooxygenase-2. Among them, the effect of oral administration of Chinese yam peel polyphenols with mass concentration of 240mg/(kg·d) was the best. Therefore, Chinese yam peel polyphenols could prevent intestinal mucosal injury in mice, and its molecular mechanism might be related to the inhibition of cyclooxygenase-2 expression.
CHEN Beibei , PENG Zhilan , ZHANG Chaohua , LIN Haisheng , GAO Jialong , ZHENG Huina , CAO Wenhong , QIN Xiaoming
2021, 39(4):55-63. DOI: 10.12301/j.issn.2095-6002.2021.04.006
Abstract:To explore the antidepressant effects of oyster hydrolysates, a zebrafish model of chronic unpredictable mild stress was applied in this study. Different doses of oyster hydrolysates were used to treat the zebrafish model, which were the low concentration, medium concentration, and high concentration. The zebrafish fish behavior and body mass index were measured, and then the zebrafish peripheral cortisol contents and brain cytokine expression levels were measured by enzyme-linked immunoassay. The results showed that after 5 weeks treatment of chronic unpredictable mild stress, zebrafish showed obvious depression-like behavior, and oyster hydrolysates effectively improved zebrafish depression-like behavior, and effectively improved zebrafish weight loss after stress. At the same time,oyster hydrolysates reduced the level of cortisol in zebrafish and reduced the expression of TNF-α in the brain. The results of this study also showed that oyster hydrolysates improved chronic unpredictable mild stress-induced depression-like behavior by regulating the level of stress hormones and inhibiting the expression of inflammatory cytokines induced by chronic unpredictable mild stress. This study aims to explore the neuroprotective effects of oyster hydrolysates deeply, and provide a theoretical basis for the further development of its active ingredients.
HAO Yiming , YANG Yuhong , LIU Xiaofang , WU Hao , WANG Baozhen , DU Lei
2021, 39(4):64-71, 86. DOI: 10.12301/j.issn.2095-6002.2021.04.007
Abstract:In order to investigate the preventive effect and mechanism of krill oil (KO) on lipopolysaccharide (LPS)-induced intestinal barrier injury, thirty-two male mice were randomly divided into four groups:normal control group (control group), model group (LPS group), KO group and fish oil (FO) group. The mice in control and LPS groups were given olive oil by gavage, while KO and FO groups were fed with 400mg/kg (based on body weight) of KO and FO (diluted in olive oil) orally once a day. After 4 weeks of intervention, the mice were intraperitoneally injected with 10 mg/kg (based on body weight) of sterile normal saline or the same amount of LPS in control group and the other three groups and were sacrificed 6 hours later. The histopathological changes of small intestine among four groups were observed by hematoxylin-eosin staining. The diamine oxidase (DAO) activity in the serumand small intestine of mice were determined. The protein levels of tight junction proteins and inducible nitric oxide synthase (iNOS) were measured by Western blot. The myeloperoxidase (MPO) and nitric oxide (NO) content were also determined. The mRNA expression of inflammatory cytokines was evaluated by quantitative real-time PCR. The protein levels of key factors involved in TLR4/NF-κB signaling pathway were also analyzed. The present findings revealed that KO intervention significantly suppressed the decrease in the ratio of villus length to crypt depth after treated with LPS. KO pretreatment also decreased the serum DAO activity, but increased the intestinal DAO activity in LPS-treated mice. The protein levels of tight junction proteins such as Claudin-1, Occludin and ZO-1 in small intestine were up-regulated by KO pretreatment. In addition, KO also decreased the MPO activity, iNOS protein level, NO content, the mRNA expression of TNF-α, IL-1β and IL-6 as well as the protein levels of key factors involved in TLR4/NF-κB signaling pathway in comparison with those in LPS group. The present study indicates that KO prevents LPS-induced intestinal barrier injury via inhibiting TLR4/NF-κB signaling pathway, and its effect is superior to FO.
ZHAO Linfen , HONG Zishan , YANG Kai , GONG Jiashun , TAN Chao
2021, 39(4):72-78. DOI: 10.12301/j.issn.2095-6002.2021.04.008
Abstract:Chinese coffee is mainly produced in Yunnan, which is lacking in flower and fruit flavor and sweet flavor. Fermentation is one of the important factors affecting the quality of coffee flavor. The physicochemical analysis, aroma composition analysis, and sensory evaluation were used to analyze the coffee beans, which were fermented under low temperature and anaerobic conditions using Saccharomyces cerevisiae adding vanilla, cinnamon, tropical fruits, honey and other raw materials. And the effect of fermentation on coffee quality was explored. The results showed that the ash and fat content had no significant difference (P>0.05) and soluble protein content was significantly increased (P<0.05) in coffee after fermentation with vanilla, cinnamon, apple, sweet orange, banana and honey compared with that in the control group. The addition of the substrates had various effects on the polysaccharide, reducing sugar, total protein and polyphenol in the final coffee bean without obvious regularity. A total of 36 compounds including 9 esters, 6 ketones, 8 aldehydes, 6 alcohols, 5 olefins, 1 furan and 1 acid were preliminarily identified by gas chromatography-ion mobility spectrometry in fermented coffee green bean. The ketones, aldehydes, alcohols and esters accounted for more than 60% of the volatile components in coffee green beans. Combined with the results of sensory evaluation, vanilla, cinnamon, tropical fruit fermentation with coffee could increase fruit aroma of coffee and promote the flower and fruit aroma characteristics of coffee. Among them, the spice group and sweet orange group met the standard of specialty coffee, the banana group had a more prominent aroma. However, there was no obvious change of aroma in the honey group accompanied with high acidity and no enough sweetness. This study provided a theoretical basis and data support for further improving the sweet and fragrant characteristics of Yunnan coffee and improving the flavor of coffee.
REN Mingjing , TAO Dejiang , CHENG Lei , LIANG Shan , WANG Chengtao
2021, 39(4):79-86. DOI: 10.12301/j.issn.2095-6002.2021.04.009
Abstract:The two-component StyS-StyR regulatory system locates in the upstream of the styAB gene, which encodes a key enzyme for indigo biosynthesis in Pseudomonas putida B3. As a kinase, StyS is an important mediator of phosphorylation-dependent signal transduction. However, the effect of StyS trans-autophosphorylation on indigo biosynthesis has not been clearly studied. Therefore, the StyS kinase protein in Pseudomonas putida B3 was used as the research object, and two different phosphorylation binding sites were discovered. Then a phosphorylation site-mutant strain was constructed. Indigo production and enzyme activity in the wild-type P. putida B3, a strain lacking the styS gene (P. putida B3-ΔstyS), a styS gene-backup strain (P. putida B3-ΔstyS-8), and the phosphorylation site-mutant strain (P. putida B3-ΔstyS-1) were compared. The results showed that the indigo yields of P. putida B3 and P. putida B3-ΔstyS-8 were 10.14mg/L and 3.63mg/L, respectively. It suggested that the phosphorylation site-mutant strain had no kinase activity and lost ability to produce indigo. The results indicated that StyS autophosphorylation played an important role in indigo production, which might provide references for further research on indigo biosynthetic pathway.
WU Shengwen , JIA Chenggang , CUI Chun
2021, 39(4):87-94. DOI: 10.12301/j.issn.2095-6002.2021.04.010
Abstract:Using hemp seed meal and unhulled hemp seed meal as raw materials,the effects of hulling treatment on the protein recovery, color, solubility, water holding capacity, oil holding capacity, emulsifying capacity, emulsifying stability, foaming capacity, foaming stability and digestibility of hemp protein were studied. The results showed that the protein recovery (83.90%±0.69%), protein mass fraction (88.56%±0.65%) and color of hemp protein extracted from hulled hemp seed meal were much preceded(P<0.05) than the protein recovery (45.88%±0.51%), protein mass fraction (81.97%±0.81%) and color of hemp protein extracted from unhulled hemp seed meal. The solubility curve and amino acid composition of hemp protein were not changed by hulling treatment. However, the functional properties of hemp seed protein were better than that of unhulled hemp protein. After simulation digestion in vitro, the digestibility of hemp seed protein reached 92.66%±0.23%, which was significantly (P<0.05) higher than that of the unhulled hemp protein (78.93%±1.12%). This study indicated that the hulling treatment might be a necessary method for extracting high-quality hemp protein from hemp seed meal.
LIN Jiali , LIU Yangjie , HAN Fuliang
2021, 39(4):95-103. DOI: 10.12301/j.issn.2095-6002.2021.04.011
Abstract:Caco-2 cell model for the transport of glucoside compounds was established to provide the basis for studying intestinal absorption of glucose and glucoside compounds. A reliable cell model was established by selecting the best medium for Caco-2 cells, measuring the single layer density, detecting monolayer permeability and the activity ratio of alkaline phosphatase on both sides of the cell, observing the single layer sub microstructure, and analyzing the mRNA and protein expression levels of SGLT1 and GLUT2. The results showed that the optimal medium for Caco-2 cells was DMEM medium containing low glucose and supplying 15% serum. The trans epithelial electrical resistance of Caco-2 cells tended to be stable in 14-17 days, and the apparent permeability coefficient of phenol red reached 0.49×10-6-0.51×10-6cm·s-1. The microvilli differentiated and matured, and the ratio of alkaline phosphatase on both sides of cells reached more than 2.0. The mRNA expression of glucose transporter SGLT1 was significantly higher on 14d than those on 17d and 21d, while the protein expression of glucose transporter SGLT1 and GLUT2 had no significant difference on 14d, 17d and 21d (P<0.05). Caco-2 cells could be cultured for 14-17 days to establish a reliable intestinal absorption model, which might be used to study the absorption of glucose and glucoside compounds in vitro.
HOU Xinglin , WU Xiaoxia , LAN Ying , LIU Haomiao , CHE Jiaxing
2021, 39(4):104-115. DOI: 10.12301/j.issn.2095-6002.2021.04.012
Abstract:To study the anti-fatigue function and safety of Olea europaea extract compounded with L-carnitine tartrate, the mice were randomly divided into three dose groups (1.05,0.70,0.35g/kg) and one negative control group, and Olea europaea compounds were administrated by gavage. After 30 days, the weight loading swimming time, blood urea nitrogen, hepatic glycogen, and blood lactic acid were measured. The acute toxicity test, genotoxicity test and the 30 days feeding test in rats were used to evaluate the safety of Olea europaea compounds. The results showed that after gavage administration for 30 days, compared with the negative control group, the weight loading swimming time of mice significantly extended in high dose group (P<0.05). The blood urea nitrogen content in mice significantly decreased in high dose group (P<0.05) and extremely significantly decreased in middle dose group (P<0.01) after swimming 90min without weight loading. The accumulation of blood lactic acid in mice significantly decreased in high dose group (P<0.05) after swimming 10 minutes without weight loading. The content of hepatic glycogen in mice had no significant difference (P>0.05). The safety assessment results showed that the Olea europaea compounds had no acute toxicity or genotoxicity. Compared with the negative control group, the animal body weight, food intake, food utilization, hematology, blood biochemistry and histopathology in the three dose groups had no significant difference (P>0.05) during the 30 days feeding test. This indicated that the Olea europaea compounds had obvious anti-fatigue function and high safety.
PENG Bo , GUAN Huanan , XUE Yue , WU Qiaoyan , GONG Dezhuang , ZHANG Na , LIU Xiaofei
2021, 39(4):116-122. DOI: 10.12301/j.issn.2095-6002.2021.04.013
Abstract:Ficin has peroxidase mimetic activity and can catalyze H2O2 to produce ·OH, which subsequently oxidizes the substrate ABTS and produces a color reaction. Vitamin C with strong antioxidant property can scavenge free radicals, and induce the reduction of green ABTS+· to colorless ABTS. Based on these reactions, a colorimetric detection system with high selectivity, high sensitivity and rapid detection of vitamin C content in food was established, and the system was optimized and the performance of vitamin C detection was evaluated. The results showed that the optimum combination of detection system was as follows:the addition of H2O2 was 0.5mol/L, the concentration of ficin was 0.5μg/mL, the temperature was 50℃, and the incubating time was 30s. Under the optimized conditions, a good linear relationship of vitamin C in the range of 0.001-0.080mmol/L was shown, and the linear regression equation was y=7.381x+0.1091, the correlation coefficient R2 was 0.9923 and the lowest detection limit was 0.43μmol/L, which indicated that the detection method had good sensitivity. Meanwhile, the recovery rate of this colorimetric detection method was between 95% and 105% with high selectivity and good stability, which might have good application prospects in fields of food analysis, biochemical and pharmaceutical applications.
LUO Jiqing , ZHANG Yongjie , WU Aipin , XIA Min , ZHANG Wei
2021, 39(4):123-130. DOI: 10.12301/j.issn.2095-6002.2021.04.014
Abstract:During the storage period, Botrytis cinerea infection was usually occurred, which caused serious rot in fruits and vegetables. In this study, cherry tomatoes infected with Botrytis cinerea were used to simulate the rot that might occur during storage, and the inhibitory effect of exogenous methyl jasmonate (MeJA) and isoleucine (Ile) on the enzymes activity related to grey mold was studied. In the experiment, Ile group and MeJA+Ile group were first soaked in 10mmol/L Ile, and the MeJA group and MeJA+Ile group were subsequently fumigated with 10μmol/L MeJA at 30℃ for 48h, then them were infected with Botrytis cinerea spores, and stored at room temperature. And the lesion diameter and enzyme activity were measured. The results showed that cherry tomatoes treated with MeJA and/or Ile had higher enzyme activity in phenylalanin-eammonialyase, polyphenol oxidase, peroxidase, superoxide dismutase, ascorbate peroxidase and catalase after infection, which was significantly different with that of the control group (P<0.05). Compared with the other three groups, the enzyme activities measured in the MeJA+Ile group were all higher, while the lesion diameter was smaller, which indicated that cherry tomatoes with MeJA and Ile combined treatment could activate the disease resistance enzyme and enhance the resistance to the infection of Botrytis cinerea. This study provides a reference for the prevention of Botrytis cinerea induced rot in fruits and vegetables during postharvest storage.
LIU Yuhang , ZHU Yong , ZHANG Min , LIANG Shan , LI Xinping
2021, 39(4):131-138. DOI: 10.12301/j.issn.2095-6002.2021.04.015
Abstract:In order to discuss the processing suitability of fresh-wet noodles of different potato varieties, the effects of the whole-flour raw materials of 13 main potato cultivars on the quality of fresh-wet noodle products were analyzed from the aspects such as rheological property, cooking quality, and texture property, etc. The results showed that among 13 potato varieties, Burbank whole flour had higher swelling degree, shear resistance, heat stability, hardness, jelly strength, peak time and gelatinization temperature during the gelatinizing process. The dough also had the strongest strength, and the cooking quality, texture property of fresh-wet noodle products were better than other varieties. Therefore, it was indicated that Burbank was suitable for fresh-wet potato noodles processing among the 13 main cultivars. The correlation analysis showed that the peak viscosity of potato whole flour was significantly related to the quality of fresh-wet noodles. It could be used as an important index of screening potato varieties for processing fresh-wet noodles. This study could provide a theoretical basis for the quality evaluation of fresh-wet noodles and the selection of special potato varieties for processing fresh-wet noodles.
LIU Yanxiang , GUAN Lina , SUN Ying , TAN Bin , LIU Ming , TIAN Xiaohong
2021, 39(4):139-147, 162. DOI: 10.12301/j.issn.2095-6002.2021.04.016
Abstract:The characteristics such as long cooking time, hard to cook, poor palatability and digestion, and short storage period of wholegrain brown rice limit the consumption and promotion of brown rice grains. In order to improve the cooking properties of wholegrain brown rice and satisfy consumers' pursuit of the health properties of wholegrain brown rice, the use of advanced processing technologies to enhance its eating quality, nutritional functionality and storage stability has become research focus. This paper expounded the composition and structural characteristics of wholegrain brown rice, analyzed the main factors affecting the cooking properties of wholegrain brown rice, emphatically introduced the application of biological and physical processing technologies and new non-thermal processing technologies in whole grain brown rice processing at home and abroad, illuminated the operating principles and characteristics of technologies, and pointed out the advantages and disadvantages of various processing technologies. The research direction of wholegrain brown rice grains was also expected, aiming to provide a reference for creating high-quality, high-nutrition, high-bioavailability and easy-to-cook wholegrain brown rice products.
XU Ping , HUANG Min , LIAO Tao , XIONG Guangquan , ZHANG Jinmu , WANG Juguang , GENG Shengrong , BAI Chan
2021, 39(4):148-155. DOI: 10.12301/j.issn.2095-6002.2021.04.017
Abstract:In order to prolong the shelf life of weevers (Micropterus salmoides), the effects of allicin and allicin compound preservative which prepared with tea polyphenols and grape seed extract on quality of weevers during refrigerated storage (4℃) for 15d were examined. The indexes of total viable count, juice loss rate, thiobarbituric acid reactive substance value, pH value, total volatile basic nitrogen value, Ca2+-ATPase activity and sensory quality were analyzed to characterize the preservative effect of allicin and allicin compound preservative on fresh weevers. The results indicated that in comparison with control group or single allicin treatment, the compound preservative exhibited better preservation effect on maintaining the good quality of weevers and reducing lipid oxidation, mitigating the increment of total viable count, total volatile basic nitrogen value and juice loss rate, retaining pH value, sensory quality and Ca2+-ATPase activity. Compared with that in the control group, the total volatile basic nitrogen value in groups treated with allicin or allicin compound preservative were above 25.9mg/100g at 12d and 15d, which extended the shelf life by 3d and 6d, respectively. The compound preservative significantly inhibited the decrease of Ca2+-ATPase activity. Compared with the beginning of the storage, the Ca2+-ATPase activity in the control group decreased by 59.9%, which decreased by 47.6% and 38.0% in groups treated with allicin and allicin compound preservative, respectively after 15d storage. Therefore, allicin compound preservative might be economic, environmentally friendly and harmless to human, which could provide data support for the development and application of natural plant extracts as aquatic product preservatives.
CAO Xuehui , BAI Ge , WANG Zhenni , ZHU Danshi , Lü Changxin
2021, 39(4):156-162. DOI: 10.12301/j.issn.2095-6002.2021.04.018
Abstract:In order to understand the effect of cryopreservation agents dextran and polylysine on the quality of frozen crown pear, calcium chloride, calcium chloride-dextran, calcium chloride-polylysine, and calcium chloride-dextran-polylysine were used as cryopreservation solution to impregnate crown pear. The freezing time was measured by a paperless temperature recorder, and the temperature change with time during the freezing process was analyzed. The indexes such as juice loss, texture and water distribution were measured after freeze-thaw. The results showed that the time required for the calcium chloride, calcium chloride-dextran, calcium chloride-polylysine, and calcium chloride-dextran-polylysine immersion freezing samples to pass through the maximum ice crystal formation zone was 12.87,10.12,10.20 and 7.50min. Moreover, the juice loss of cryoprotectant impregnated samples significantly (P<0.05) decreased. The ascorbic acids contents and hardness of samples in the cryoprotectant impregnation group increased compared with that of the calcium chloride impregnated freezing control group. Meanwhile, the peak area S23 corresponding to the sample vacuole water (T23) also increased to a certain extent. Compared with the traditional calcium chloride immersion freezing, the addition of protective agent dextran and polylysine could effectively reduce the damage of freezing to pear cell structure, reduce the loss of nutrients, and help to maintain the product quality.
QIAN Chong , ZHANG Mei , GOU Xinlei , BAI Yun , LIU Weili , GAO Xia , HU Guanghui
2021, 39(4):163-170. DOI: 10.12301/j.issn.2095-6002.2021.04.019
Abstract:An analytical method for simultaneous determination of organotins in food contact materials with different uses by gas chromatography-mass spectrometry was established. The derivatization conditions and detection conditions were optimized and the detection types of organotins were also extended. On the basis of 4 kinds of organtins detection (dibutyltin dichloride, tributyltin chloride, dioctyltin dichloride and triphenyltin chloride) of the current standard of SN/T 3938—2014 “food contact materials-polymers-determination of the organotin compounds-gas chromatography-mass spectrometry”, the detection types of organotins increased to 9 kinds (added:monobutyltin trichloride, tributyltin oxide, mono-n-octyltin trichloride, tetrabutyltin and tricyclohexyltin chloride), and the methodology validation experiments were completed. The good linear relationships were obtained with correlation coefficients of 0.9993-0.9995 in the range of 10-2000μg/L. The limits of detection and quantitation were 5-20μg/kg and 15-71μg/kg, respectively. The injection precisions were 1.07%-1.82%. The intermediate precisions were good, and the relative standard deviation (RSD) of the results detected by different laboratory technicians in different times were 1.52%-2.65%. The RSD of the detection results of durability were 1.51%-2.22%. In this study, 4 kinds of food contact materials with different uses were bought from the market and detected. These samples were made of PVC or plastic containing PVC, such as plastic wrap, heat preservation bag lining, place mat, and refrigerator storage box for dumplings, etc. The results showed that no organotins were detected in these 4 kinds of food contact materials. The recoveries and repeatability were good, the recoveries were 85.93%-117.39%, and the corresponding RSD were 1.12%-1.97%. The established method was highly sensitive, simple, reliable, and versatile, which could be applicable for the simultaneous detection of 9 kinds of organotins in food contact materials.