Table of Content

01 March 2016, Volume 39 Issue 2

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Basic Research

Comparison of Thickening Characteristics of Several Marine Polysaccharides in Stirred Yoghurt

XUE Yuling, YANG Rui, ZHU Hong, GUO Shuntang, WANG Shijie, WANG Hua

2016, 39(2):  1-3.  DOI: 10.15922/j.cnki.jdst.2016.02.001

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Because of its gelling, thickening and stabilizing properties, marine polysaccharide can be used as stabilizer for stirred yogurt. In this study, the effects of carrageenan, sodium alginate, instant and ordinary agar on properties of stirred yoghurt were studied. The indexes observed were viscosity, acidity, fermentation state and flavor. In comparison, instant agar could improve the viscosity of yogurt, increase shear resistance, improve mouthfeel and enhance flavor, and decrease whey syneresis. The product with instant agar demonstrated smooth mouthfeel, a suitable viscosity, and extended shelf life. The stirred yogurt had the best taste when instant agar was added at 0.15%.

Safety Evaluation of Three Lactic Acid Bacteria Derived from Milk Orally Administered to Mice

LI Jinmin, ZHANG Zhiyan, JING Weifang, LIU Yong, WU Huanrong, HAN Yin, XU Haiyan, GU Wei

2016, 39(2):  4-7.  DOI: 10.15922/j.cnki.jdst.2016.02.002

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Objective: To assess the safety of 3 enterococci strains (LQ-R-16-1, FC-3-7 and FC-3-2) originating from milk in mice through 7-day acute oral toxicity test and 30-day feeding test. Methods: Kunming mice of clean grade were subjected to intragastric administration of different doses of enterococci and during the test, the mice were observed for changes in physical signs and daily weight gain; afterwards, they were anatomized to observe organ changes and bacterial translocation and calculate organ indices. Results: Acute toxicity and feeding tests exhibited no significant difference in daily weight gain or organ indices compared with the control group (P > 0.05), and after the 30-day feeding test bacterial translocation was found not to occur. Conclusion: Enterococci LQ-R-16-1, FC-3-7, FC-3-2 are safe to consume, having no toxic side effects.

Effects of Ultrasonic Treatment on Gel Properties of Whey Protein Concentrate

XING Shaoping

2016, 39(2):  8-10.  DOI: 10.15922/j.cnki.jdst.2016.02.003

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In this study, the effect of whey protein concentrate (WPC) concentration, WPC dispersion pH, ultrasonic power and irradiation time on gel properties of WPC was explored. Results showed that gel properties of WPC gradually increased with increasing intensity of ultrasonic treatment in a certain range. The WPC dispersion at neutral pH had the best gel properties after ultrasonic treatment. Therefore this study concluded that the combination of ultrasonic treatment with pH adjustment of WHC dispersion could effectively improve the gel properties of WPC.

Processing Technology

Optimization of the Formulation of a Dairy Beverage Containing White Mutant Strain of Auricularia fuscosuccinea

JIN Fengshi, ZHAO Xin, WANG Dawei

2016, 39(2):  11-16.  DOI: 10.15922/j.cnki.jdst.2016.02.004

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The white mutant strain of Auricularia fuscosuccinea was processed through high-pressure steaming and used as an ingredient for the formuation of a dairy beverage. Optimization of the formulation for improved beverage stablity and sensory quality was carried out using single factor and orthogonal array design methods. The results indicated that after high-pressure cooking, the hardness, elasticity, cohesiveness and gumminess of the white Auricularia fuscosuccinea were decreased, and the chewiness was increased. The optimum formulation was found to consist of 40.0% white Auricularia fuscosuccinea juice, 0.1% citric acid, 4.0% soft sugar, 4.0% milk powder and 0.1% compound stabilizer. The formulated beveage had the best sensory quality and a pure flavor, and was verystable and highly nutritious.

Analysis & Detection

Simultaneous Determination of 2 Ultraviolet Absorbers and 2 Antioxidants in Milk by High Performance Liquid Chromatography

ZHANG Dayuan, LI Hui, ZHANG Lantian, AI Lianfeng

2016, 39(2):  17-20.  DOI: 10.15922/j.cnki.jdst.2016.02.005

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A method was developed for the simultaneous determination of 2 ultraviolet absorbers UV-326, UV-1577 and 2 antioxidants AO-1010 and AO-2246 in milk by high performance liquid chromatography. Samples were extracted with acetonitrile. The effective separation of the target analytes was accomplished on Agilent HC-C8 (150 mm × 4.6 mm, 5.0 μm) column with gradient elution procedure using a mixture of water and acetonitrile as the mobile phase. External calibration was used for quantitative determination at detection wavelength of 280 nm. The linearity of 4 analytes were satisfactory with a correlation coefficient of > 0.9995 at concentrations ranging from 0.05 to 50 μg/mL. The limits of detection of the method were 0.02?0.5 mg/kg, and the recoveries at different spiked levels and precision (RSD) were 69.08%?115.87% and 0.43%?9.94%, respectively. The method is simple, sensitive, reproducible and suitable for the simultaneous determination of 2 ultraviolet absorbers and 2 antioxidants in milk.

Bioengineering

Overexpression of Bile Salt Hydrolase Genes in Lactobacillus casei LC2W

HUANG Yanna, LIU Zhenmin, YOU Chunping

2016, 39(2):  21-24.  DOI: 10.15922/j.cnki.jdst.2016.02.006

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In this study, the recombinant Lactobacillus casei LC2W were constructed for overexpressing four bsh genes from L. plantarum ST-III and the Bile salt hydrolase (BSH) enzyme activities were determined. It was shown that the four recombinant strains all showed a lower enzyme activity than the host, indicating that the bsh gene overexpression could not achieve the goal of enhancing the hydrolysis of the bile salts.

Reviews

Advances in Research on Ewe Milk Proteome and Its Stability

ZHU Yuying, WANG Cunfang, LIANG Rui

2016, 39(2):  25-28.  DOI: 10.15922/j.cnki.jdst.2016.02.007

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Milk protein is an important source of functional components in milk. Ewe milk, an emerging alternative to human breast milk, has become an important source of protein. Ewe milk has attracted growing interest from researchers. The protein quality and stability of ewe milk are a direct determinant of its nutritional quality. Therefore, this paper summarizes milk proteome and the techniques used to investigate milk proteome as well as the effect of ewe milk proteome and stability on the quality of milk proteins in order to provide a guideline to further ascertain the biological activity of unknown proteins in ewe milk and reveal milk proteome variation and its influence on the thermal stability of milk. Prospects for future research on ewe milk and ewe milk based products are also discussed.

Changes in Surface Fat during Production and Storage of Milk Powder and Its Effect on Functional Properties: A Review

LI Xueqing, YU Jinghua

2016, 39(2):  29-33.  DOI: 10.15922/j.cnki.jdst.2016.02.008

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Spray drying is one of the most commonly used drying methods in the food industry, which was first used in the early 20th century in the manufacture of skimmed milk powder. Spray drying of milk concentration leads to milk powder, on the particles of which milk fat exists. It has been experimentally found that the content and distribution of fat on and inside milk powder particles are different from the total fat. This paper describes the properties of fat on the surface of milk powder particles and effects of spray drying conditions, processing and storage on surface fat composition. Comparison of properties of milk powder before and after the removal of surface fat is also made in this paper.

Establishing a Database Application Program for Target Analytes Included in International Standards for Milk and Milk Products

WANG Zifei, JIANG Zhaoyao, XIAO Jing

2016, 39(2):  34-39.  DOI: 10.15922/j.cnki.jdst.2016.02.009

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Given the increasing focus on the safety of milk and milk products, this study set up a database application program using the target analytes included in the Codex standards for milk and milk products as search path, which can provide technical support to achieve network informatization of work on food safety and a technical platform to achieve resource sharing, thereby ensuring people’s health and safety. In addition, the present study can also facilitate further research on food safety standards for both domestic monitoring and international trade.