Table of Content

01 November 2021, Volume 44 Issue 6

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Basic Research

Effect of Ca2+ on Freeze-Drying Resistance of Lactobacillus plantarum LIP-1 and Survival of Added Probiotics in Hot Drinks

MAN Duhu, XUE Shuyuan, LIU Jiayuan, XIU Yufeng, MA Sinan, LIU Zexi, WANG Junguo

2021, 44(6):  1-5.  DOI: 10.15922/j.cnki.jdst.2021.06.001

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The effect of different concentrations of CaCl2 in the culture medium on the freeze-drying resistance and heat resistance of Lactobacillus plantarum LIP-1, a probiotic strain with hypolipidemic properties, was studied. The viable counts in different hot drinks were compared among freeze-dried cells of strain LIP-1 with or without added Ca2+ and a commercial probiotic. The results showed that the addition of 0.5 mmol/L Ca2+ to the medium not only significantly improved the freezedrying survival rate (P < 0.05) but also increased the heat resistance of the strain compared with the control group. When added to hot drinks, the survival rate of freeze-dried cells of strain LIP-1 with added Ca2+ was significantly higher that of a commercial probiotic. The intrinsic mechanism was investigated, showing that the damage degree of cell membrane and wall in LIP-1 were significantly lower than that in the other groups (P < 0.05). This was accompanied by a significant increase in the unsaturated fatty acid content of the cell membrane. The above results indicated that the addition of Ca2+ to the medium could significantly improve the cold and heat resistance of Lactobacillus plantarum LIP-1.

Processing Technology

Optimization of Microwave Detoxification Process for Flaxseed Meal and Its Application in Yogurt

QIN Bozhi, SUN Wancheng

2021, 44(6):  6-10.  DOI: 10.15922/j.cnki.jdst.2021.06.002

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The effect of microwave power, irradiation time and temperature on the detoxification efficiency of linseed meal was addressed by one-factor-at-a-time and orthogonal array design methods. Further, the effect of fermentation time, starter culture concentration and fermentation temperature on the content of cyanide in yogurt with added detoxified linseed meal was investigated by one-factor-at-a-time and orthogonal array design methods. The results showed that the optimum detoxification conditions that provided the lowest cyanide content of linseed meal of 14.02 mg/kg were as follows: microwave irradiation time 60 s, microwave power 640 W, and temperature 70 ℃. The optimum fermentation conditions that provided the lowest cyanide content of yogurt with added detoxified linseed meal of 8.45 mg/kg were as follows: fermentation time 9 h, fermentation temperature 41 ℃, and starter culture concentration 1.50 g/100 mL. In conclusion, yogurt fermentation could further reduce the cyanide content in flaxseed meal.

Analysis & Detection

Determination of Three Fumonisins in Infant Formula by High Performance Liquid Chromatography with Precolumn Derivatization

CHEN Tongqiang, GUO Jincai, LI Can, WANG Liangliang, XIANG Jun, ZOU Zijue, XU Wenyang, LI Kailong

2021, 44(6):  11-14.  DOI: 10.15922/j.cnki.jdst.2021.06.003

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A high performance liquid chromatography (HPLC) method was established for the simultaneous determination of the contents of three fumonisins in infant formula. Under optimized experimental conditions, the fumonisins were quantified by an external standard method. The analytical figures of merit such as linear relationship, recovery, precision, limit of detection and limit of quantitation of the method were examined. The results showed that the linearity of the method was good in a certain concentration range (r > 0.999). The detection limits of fumonisin B1, B2 and B3 were 10, 5, and 5 μg/kg, respectively. The limits of quantitation were 30, 15 and 15 μg/kg, respectively. The average recoveries of the fumonisins were 91.6% –95.7%, 89.5%–94.4% and 88.6%–92.3% at three different spiked levels, respectively, and the relative standard deviations (RSDs) for precision were less than 10%.

Simultaneous Determination of α-Lactalbumin and β-Lactoglobulin in Pasteurized Milk by High Performance Liquid Chromatography

HU Min, ZHANG Caiyun, LI Zhijun, DUAN Guoxia

2021, 44(6):  15-19.  DOI: 10.15922/j.cnki.jdst.2021.06.004

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A method for the determination of α-lactalbumin and β-lactoglobulin in pasteurized milk by high performance liquid chromatography (HPLC) was developed. The sample pretreatment procedure involved sequential water dilution, pH value adjustment to 4.6 for precipitation of casein, and filtration. The subsequent analysis was performed on an Xbridge Protein BEH C4 column using gradient elution with a mobile phase made up of 0.1% (V/V) aqueous trifluoroacetic acid and 0.09% (V/V) aqueous trifluoroacetic acid-acetonitrile. The analytes were detected by an ultraviolet (UV) detector and quantified by an external standard method. The results showed that a good linearity was observed for α-lactalbumin in the concentration range of 10–500 mg/L, with a correlation coefficient of 0.999 87. The recovery of α-lactalbumin spiked at levels of 200 to 1 032 mg/L in milk ranged from 97.9% to 104.0%, and the relative standard deviation (RSD) for precision was 0.00%–1.09%. The linear range for β-lactoglobulin was 20–900 mg/L, with a correlation coefficient of 0.999 96. The recovery of β-lactoglobulin spiked at levels of 600–4 727 mg/L in milk was 96.1%–103.0%, and the precision RSD was 0.00%–2.23%. This method has good separation effect and repeatability and is useful for accurate quantitation of α-lactalbumin and β-lactoglobulin in pasteurized milk.

Preparation of Monoclonal Antibody against Fipronil and Its Application for Fipronil Detection in Milk

ZHANG Erjing, LI Yujing, LI Ziran, ZHAO Li, LIU Jingjing, ZHANG Jing, ZHAO Baohua, LI Chunsheng

2021, 44(6):  20-24.  DOI: 10.15922/j.cnki.jdst.2021.06.005

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In this study, the complete antigens of fipronil and its analogue were synthesized using glutaraldehyde (GA) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as a cross-linker, respectively, and were identified by ultraviolet absorption spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). BALB/c mice were immunized with fipronil-bovine serum albumen to obtain hybridoma cell 3F6. Monoclonal antibodies were prepared by inducing ascites in mice. An enzyme-linked immunosorbent assay (ELISA) was developed and evaluated to determine fipronil in milk. The results showed that the concentration of the prepared monoclonal antibody, belonging to the IgG1 subclass, was 8.5 mg/mL, and the titer was 2.0 × 106. The cross-reaction rates with fipronil-desulfinyl, fipronil sulfone and fipronil sulfoxide were 9.21%, 14.02% and 21.46%, respectively. The recoveries of fipronil in spiked milk were 87%–118%, and the coefficient of variation for precision was less than 15%. In conclusion, this method is highly accurate and precise.

Reviews

Progress in Research on the Role of Galactooligosaccharide in Alleviating Intestinal Inflammation

GAO Haina, YANG Zhennai

2021, 44(6):  25-30.  DOI: 10.15922/j.cnki.jdst.2021.06.006

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Intestinal inflammation has become a social health problem and challenge in China, and its incidence rate is increasing rapidly. The causes of intestinal inflammation are complex. Currently, there is a lack of effective drugs for intestinal inflammation. Therefore, it is of vital importance to strengthen the research and development of effective drugs for intestinal inflammation. Galactooligosaccharide (GOS) is a functional oligosaccharide derived from milk with good therapeutic properties, it can effectively promote proliferation of intestinal probiotics, change the structure of intestinal flora and stimulate immune response, consequently improving intestinal mucosal barrier function, ultimately relieving intestinal inflammation. This paper reviews the recent progress in research on intestinal inflammation and the role of intervention with GOS in relieving intestinal inflammation and discusses future prospects for its application. We anticipate that this review will provide a scientific basis for further research in this field.

Progress in the Application of Seaweed Polysaccharides in Dairy Industry

LIU Xiaojie, NI Hui

2021, 44(6):  31-38.  DOI: 10.15922/j.cnki.jdst.2021.06.007

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Marine algae like brown, red, blue and green algae are a rich source of polysaccharides. Accumulating evidence has demonstrated that seaweed polysaccharides are bioactive substances that have a variety of physiological functions and health benefits such as immune regulation, antioxidant, anti-tumor and anti-inflammatory effects, blood lipid reduction, liver protection, and protection against radiation. In addition, seaweed polysaccharides have been used for many functions in foods as a thickener, stabilizer and humectant. This paper reviews the preparation methods, physiological functions and health benefits of seaweed polysaccharides, with an especial focus on the recent progress in their application in the dairy industry. This review concludes with an outlook on future hotspots and trends in the research and application of seaweed polysaccharides, which may lay a theoretical foundation for wider application in the dairy industry.

Advances of Membrane Technology in Dairy Processing Industry

SONG Bo, ZHANG Yumeng, PANG Xiaoyang, ZHANG Shuwen, LÜ Jiaping

2021, 44(6):  39-44.  DOI: 10.15922/j.cnki.jdst.2021.06.008

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The separation of ingredients from raw milk is an essential step during the production of dairy products. Membrane separation technology has been applied in the dairy processing industry for decades and has increasingly become indispensable in solving some problems such as separation, concentration, sterilization and in developing new dairy products. In this paper, the main applications of membrane separation technology in the dairy industry, including milk standardization, protein separation, whey desalination and waste water utilization are reviewed, in order to provide reference for process selection and optimization.

Progress in Research on the Protective Mechanism of Trehalose on Lactic Acid Bacteria

YANG Youxin, WANG Ruixue, WANG Junguo

2021, 44(6):  45-50.  DOI: 10.15922/j.cnki.jdst.2021.06.009

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Trehalose is a non-reducing disaccharide widely present in organisms. It has unique biological characteristics and plays an important role in protecting cells and biomolecules in many fields such as medicine, agriculture and food. In recent years, as an important microorganism in the food fermentation industry, lactic acid bacteria (LAB) have gradually become a research hotspot. In order to drive further research on the protective mechanism of trehalose on LAB, this article reviews recent studies on the protective mechanism of trehalose on biomolecules and its application in protecting LAB from environmental stress. Four hypotheses explaining the protection mechanism of trehalose on biomolecules have been proposed: water substitution, glass state, priority exclusion and intermolecular synergism. Trehalose can protect LAB from harsh environments such as dehydration stress, high temperature stress, freezing stress and oxidative stress. This article will provide a theoretical basis for applying trehalose as a protective agent to improve the resistance of LAB to adverse environments.

Progress in Research on Milk-Derived Bioactive Peptides

ZHAO Xuanying, LIU Zhenmin, YONG Jingyi, WANG Guojiao, LI Nan

2021, 44(6):  51-57.  DOI: 10.15922/j.cnki.jdst.2021.06.010

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Protein is an important nutrient for human health, and milk protein is considered an important source of natural bioactive peptides. Milk-derived bioactive peptides, mainly derived from casein and whey proteins by enzymatic hydrolysis or microbial fermentation, contribute to the development of human nervous, gastrointestinal, cardiovascular and immune systems and play a vital role in preventing cancer, osteoporosis, high blood pressure and other health problems. In this paper, the application of milk-derived bioactive peptides in nutraceuticals and functional foods has received more and more attention. This article summarizes the production technologies and biological activities of milk-derived bioactive peptides, and provides an outlook on the future production and application of milk-derived bioactive peptides.

Progress in Research on Nutritional Composition of Milk from Minor Dairy Animals

JIE Liang, SU Miya

2021, 44(6):  58-62.  DOI: 10.15922/j.cnki.jdst.2021.06.011

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Milk is rich in all nutrients and is one of the most nutritionally complete foods. Milk has many nutritional and functional characteristics. It contains all the nutrients needed to keep newborns and infants alive and to improve the quality of the human diet. But the milks of non-bovine species are always ignored because of low yield and consequently low economic benefits. Therefore, with the aim of making people understand the importance of milks from minor dairy species and sparking interest in researching and applying non-bovine milks, this article introduces readers to the nutritional composition of the milks of cow, yak, horse, donkey, sheep and camel. Next, it presents a comparison of the general composition, fatty acid composition, bioactive substances and functional characteristics of milks from minor dairy animals and cows, leading to the conclusion that milks from minor dairy animals have both nutritional and health benefits and are promising for application.

Prominent Problems in and Paths to Precision Governance of Food Safety Rumors

CHEN Hui

2021, 44(6):  63-68.  DOI: 10.15922/j.cnki.jdst.2021.06.012

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The effective governance of food safety rumors requires the use of precision thinking to achieve precision governance. Food safety rumors are started and spread based on the Internet environment. They are characterized by labeling, visualization and socialization, and are mainly spread among middle-aged and elderly groups. At present, there are still some weak links in the construction of the food safety rumor governance system, food safety risks cannot be resolved in a short time, and there are still some prominent problems in the primary responsibility of food enterprises and the supervision of Internet enterprises on rumors. Coordinating efforts and taking targeted measures according to rumor sources, communication media, communication subject and so on for food safety rumor governance system construction will help to achieve the precision and effective governance of food safety rumors.