Table of Content

01 November 2016, Volume 39 Issue 6

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Basic Research

Growth Promotion of Lactobacillus plantarum ST-Ⅲ by the Fermented Supernatant of Paenibacillus spp.BD3526

HONG Qing, HANG Feng, WU Zhengjun

2016, 39(6):  1-5.  DOI: 10.15922/j.cnki.jdst.2016.06.001

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The growth promoting effect of the supernatant of fermented skim milk with Paenibacillus spp. BD3526 on Lactobacillus plantarum ST-Ⅲ inoculated into skim milk was analyzed in this study. The results showed that the supernatant of BD3526 cultured in skim milk for 5–9 d significantly promoted the growth of ST-Ⅲ in skim milk and exhibited high milkclotting activity. After ST-Ⅲ was cultured in skim milk added with the supernatant of BD3526 for 24 h, the pH value decreased from 6.44 to 4.70–5.08, and milk clotting was observed at 16 h along with a viable cell count of 9.22–9.35(lg(CFU/mL)).

Preparation and Activity Evaluation of Antioxidant Peptides Derived from Human Milk Whey Proteins

YE Qing, HAN Yuanyuan, LIANG Xiaona, WU Lanjun, CAO Xueyan, YANG Mei, WU Junrui, WU Rina, LIU Biao, YUE Xiqing

2016, 39(6):  6-11.  DOI: 10.15922/j.cnki.jdst.2016.06.002

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Breast milk is the best source of food for infants and young children, and the whey proteins contained in the milk are the base of nutritional and bioactive substances including bioactive peptides, which play an important role in promoting human health. In this research, the antioxidant activities of peptides prepared by enzymatic hydrolysis of breast milk whey proteins with four different proteases, i.e., neutral protease, alkaline protease, papain and trypsin, were assessed and compared. The hydrolysis conditions were optimized using combination of one-factor-at-a-time method and response surface methodology. Neutral protease was found to be the most suitable enzyme for the production of antioxidant peptides from breast milk whey proteins. The optimal hydrolysis conditions were established as follows: pH 7.21, 50.03 ℃, an enzyme/ substrate ratio of 4 486.68 U/g and 5 h. The effect of hydrolysis parameters on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was in the decreasing order: enzyme/substrate (E/S) ratio > temperature > initial pH. Fraction I with the highest antioxidant activity was separated chromatographically with macroporous resin, Sephadex G-25 and Sephadex G-15, which could scavenge 60.31% of DPPH radical.

Package & Storage

Development of Application of A Method for Testing the Opening Force for Film Cover Sealed Yogurt Plastic Cups

ZHANG Yu, LIU Xianghong

2016, 39(6):  12-15.  DOI: 10.15922/j.cnki.jdst.2016.06.003

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A method to test the opening force for cover film sealed yogurt plastic cups was put forward by quantifying the opening force using special force testing equipment to completely simulate human-machine operations, which is mainly characterized by the initial opening force and the continuous opening force. Commercial yoghurt packagings consisting of different combinations of two plastic cups made from polypropylene (PP) and polystyrene (PS) with aluminum foil composite film, aluminizer composite film and embossing aluminum sheet were tested using the method in this study, and the ranges of opening force for them were obtained. The results showed that the initial opening force was significantly greater than the continuous opening force; the initial opening force for PS and PP cups was 10–25 N, and the continuous opening force was more than 10 N for the cups sealed with embossing aluminum sheet, whereas for the cups sealed with aluminumplastic composite film it was only 4–8 N. For cups sealed with the same films, the opening force for PS cups was higher than for PP cups. Moreover, the initial opening force for cups sealed with aluminizer composite film was greater than for those made from the same material and sealed with the two other films, and the continuous opening force was significantly increased for cups sealed with embossing aluminum sheet compared with those sealed with the other films. There was a significantly smaller difference between the initial and the continuous opening force for embossing aluminum sheet, and the sealing intensity from it was more stable.

Analysis & Detection

Determination of Liquid Milk by Headspace Solid-Phase Microextraction and Gas Chromatography Mass Spectrometry with Internal Standard

LIU Jing, SU Miya, XU Zhiyuan, YOU Chunping, LIU Zhenmin

2016, 39(6):  16-19.  DOI: 10.15922/j.cnki.jdst.2016.06.004

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The major free middle-chain fatty acids (hexanoic acid, octanoic acid, decanoic acid) in raw milk and dairy products are regarded as important compounds that affect liquid milk quality and safety due to their strong flavor characteristics. This article provides an analytical method using headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) with an internal standard for the quantitative determination of free middle-chain fatty acids in liquid milk. The method was verified as an approach with high accuracy, simple operation and high extraction efficiency.

Reviews

Progress in Research on Probiotics in the Prevention and Control of Diabetes

HAN Jin, WU Zhengjun, YAN Minghui, GAO Caixia, XU Xiaofen, FENG Huafeng

2016, 39(6):  20-24.  DOI: 10.15922/j.cnki.jdst.2016.06.005

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Researchers have been making significant efforts to reveal the relationships between the gut microbiota and diabetes mellitus. As a special bacterial population in the intestinal tract, probiotics have unique advantages in delaying and controlling the occurrence of diabetes. In this article, the mechanisms of action and superiorities of probiotics in the prevention and control of diabetes are reviewed and some future development trends are also predicted.

Progress in Understanding of the Interaction between Lactobacillus bulgaricus and Streptococcus thermophilus

HUANG Yanna, YOU Chunping, LIU Zhenmin

2016, 39(6):  25-28.  DOI: 10.15922/j.cnki.jdst.2016.06.006

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This article summarizes the current progress in understanding the characteristics of mixed culture fermentation and interaction mechanism of Lactobacillus bulgaricus and Streptococcus thermophilus as well as the influences of mixed culture fermentation on the synthesis of exopolysaccharides and flavor substances. The aim of this review is to provide useful information for researchers to apply them and screen starter cultures.

Progress in the Immobilization and Application of Lactase

LI Jing, WANG Cunfang

2016, 39(6):  29-32.  DOI: 10.15922/j.cnki.jdst.2016.06.007

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Lactase is widely used in the field of dairy processing, and has a very important value for research and application. This paper describes the characteristics and origin of lactase with emphasis on the recent progress in its application in the field of dairy processing. Some prospects for the future development of lactase are also discussed. We hope that this review can provide references for the researchers to immobilize lactase.

Progress in Understanding Microwave Effect on Milk Quality and Its Application in the Dairy Industry

XU Yu, LIU Zhenmin, YOU Chunping

2016, 39(6):  33-37.  DOI: 10.15922/j.cnki.jdst.2016.06.008

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Microwave is a technology that enables fast heating. In this review, the recent progress in the application of microwave in the dairy industry with respect to its effect on milk quality and its use in the detection of dairy products and the degradation of dairy wastes. It is showed that microwave has broad prospects for application in the dairy industry.

A Review of the Main Processing Conditions Affecting the Quality of Industrial Long Shelf-Life Yogurt

CHANG Yunhe, WANG Jian, MA Hairan, SUN Yong, LI Luofei, OU Kai

2016, 39(6):  38-41.  DOI: 10.15922/j.cnki.jdst.2016.06.009

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In the manufacturing process of long shelf-life yogurt, there are many factors that may affect its quality, including pasteurization temperature and time, the homogenization degree of stirred mixtures, and filling temperature. The shelf life of yogurt can be extended by choosing a proper pasteurization temperature and time taking the product quality into account, and its texture can be improved by selecting a suitable homogenization approach, which is also beneficial to more uniformly heating yoghurt during sterilization, avoiding the collapse of the system. The recovery of yogurt viscosity can be affected by filling temperature. A proper filling temperature should be selected to reach the requirements of quality design during the manufacturing of yogurt.