Table of Content

01 January 2021, Volume 44 Issue 1

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Basic Research

Proteomics Analysis of Functional Properties of Proteins from Goat Milk, Cow Milk, and Human Milk

REN Rong, YANG Borui, PENG Haishuai, WANG Bini, ZHANG Fuxin, HUI Yuanyuan, JIA Rong

2021, 44(1):  1-6.  DOI: 10.15922/j.cnki.jdst.2021.01.001

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In order to obtain more data on proteins in goat milk, cow milk and human milk, their basic components were determined, and bioinformatic analysis of their proteins was performed by proteomics. The results showed that the protein contents of goat milk and cow milk were higher than that of human milk, while the contents of fat and lactose were higher in human milk. A total of 3 370 proteins were identified in the three kinds of milk, and gene ontology (GO) analysis of these proteins indicated that they were mainly involved in biological processes such as cell process and metabolism process, and distributed in the cell, organelles and extracellular region. Their molecular functions included binding and catalytic activity. The KEGG pathway varied in the three kinds of milk and was enriched in protein processing in the endoplasmic reticulum. In the protein-protein interactions network, the 307 shared proteins participated in several pathways such as carbon metabolism, glycolysis/gluconeogenesis, and amino acid biosynthesis.

Comparative Study on Nutritional Components of Chinese and Imported Infant Formula for Special Medical Purposes

LAI Pengwei, LI Jing, WANG Jiaqi, ZENG Xiaolong, ZHANG Zhaomin, DENG Zeyuan

2021, 44(1):  7-12.  DOI: 10.15922/j.cnki.jdst.2021.01.002

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In this study, nutritional data on the four major kinds of infant products for special medical purposes produced in China and some other countries were collected and compared for differences in the three calorigenic nutrients, vitamins, minerals, and mandatory or optional nutrients. Moreover, principal component analysis (PCA) was carried out on these data. The results showed that the domestic brands of amino acid-based or hypoallergenic infant formula were significantly richer in fat, vitamin K, pantothenic acid, and taurine than the imported brands (P < 0.05), but had a significantly lower content of folic acid (P < 0.05). The contents of fat, manganese, taurine, and carnitine in the domestic brands of partially hydrolyzed milk infant formula were significantly higher than those in the imported brands (P < 0.05). The contents of iron, vitamin D, and vitamin B2 in the domestic brands of lactose-free or low-lactose infant formula were significantly higher than those in the imported brands (P < 0.05). Notwithstanding, no significant differences in any of the tested nutrients were observed between the domestic and imported brands of infant formula for low birth weight infants and preterm infants. The results of PCA showed that the contents of manganese, VB5 and VB3 made the greatest contribution to the nutritional difference between the domestic and imported brands of amino acid-based or hypoallergenic infant formula, the contents of VB6, VB2, VB5 and VB3 made the greatest contribution to the nutritional difference between the domestic and imported brands of partially hydrolyzed milk infant formula, while the contents of VB5 and VB3 made the greatest contribution to the nutritional difference between the domestic and imported brands of lactose-free or low-lactose infant formula and of infant formula for low birth weight infants and preterm infants.

Oligosaccharide Composition of Human Breast Milk and Its Effect on Promoting the Proliferation of Probiotics

JIE Liang, SU Miya, JIA Hongxin, CHEN Wenliang, QI Xiaoyan

2021, 44(1):  13-17.  DOI: 10.15922/j.cnki.jdst.2021.01.003

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The composition and contents of oligosaccharides in two mixed samples of human breast milk were determined and the effect of the human milk oligosaccharides (HMOs) 2’-fucosyllactose (2’-FL) on the proliferation of two probiotic strains, Bifidobacterium Bb-12 and Lactobacillus fermentum CECT5716 was evaluated in this study. The results showed that the HMOs contents of the two mixed samples were 10.613 and 5.093 g/L respectively. This significant difference indicated that HMOs contents in breast milk from different mothers are affected by many factors, generally ranging between 5 and 15 g/L. 2’-FL promoted the growth of both priobiotics, indicating that the probiotics could utilize HMOs for growth and proliferation.

Antagonistic Effect of Lactobacillus Strains against Bacterial Pathogens and Performance Evaluation of Bio-preservative Starter Cultures

XU Xianrui, LI Cuifeng, ZHANG Zongbo, XIA Wenyang, SUI Yongjun, LI Daohe, CHEN Zhengyan, ZHANG Lanwei

2021, 44(1):  18-22.  DOI: 10.15922/j.cnki.jdst.2021.01.004

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A total of 15 food-grade Lactobacillus strains were evaluated for their antagonism against gastrointestinal pathogens using Bifidobacterium animalis subsp. lactis BB-12 as a control. The results showed that nine of the strains possessed excellent antibacterial properties against five indicator bacteria tested, and two of the remaining six strains were antagonistic against four of the indicator bacteria, Staphylococcus aureus, Salmonella, E. coli and Bacillus cereus. According to their antagonistic effect, acid producing ability and milk curding ability, four strains were selected and each of them was combined with Streptococcus thermophilus ST-21 for use as bio-preservative starter cultures. Streptococcus thermophilus ST-21 + strain Z-38 at a ratio of 2:1 could produce acid rapidly, have potent post-acidification capacity and produce a strong milky aroma, being suitable for the production of flavored yogurt. Streptococcus thermophilus ST-21 + strain Z-40 at a ratio of 2:1 resulted in the best texture of yogurt, being suitable for the production of fermented dairy drink. Yogurt fermented by Streptococcus thermophilus ST-21 + strain Z-12 at a ratio of 1:1 showed the lowest consistency and cohesiveness.

Processing Technology

Effect of Cheese Type on Quality of Sliced Processed Cheese

HONG Qing

2021, 44(1):  23-27.  DOI: 10.15922/j.cnki.jdst.2021.01.005

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In this paper, the basic physicochemical indexes, color and texture properties of 10 kinds of commercial sliced processed cheese were tested, and the differences in texture properties and the underlying mechanism were analyzed. The results showed that there were significant differences in pH value, color and texture of sliced processed cheeses made from different sources. The pH values of all samples were in the range between 5.94 and 6.15. The color difference was determined by pigments, and L*, a* and b* values varied among all samples. The texture parameters of hardness, adhesiveness, cohesiveness and chewiness rather than springiness were significantly different across the samples. Different kinds of natural cheese, pigment and emulsifying salt and the difference in water content could result in changes in the texture and color of processed cheese.

Analysis & Detection

Determination of Furfural Compounds in Cheese and Condensed Milk by High Performance Liquid Chromatography

XING Qianqian

2021, 44(1):  28-32.  DOI: 10.15922/j.cnki.jdst.2021.01.006

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In this paper, the extraction of furfural compounds (hydroxymethyl furfural, furfural, furyl methyl ketone and methyl furfural) from cheese and condensed milk for analysis by high performance liquid chromatography (HPLC) was optimized. The optimal parameters were determined as follows: 30 min ultrasonic extraction using ultrapure water as the extraction solvent at a solid-to-solvent ratio of 0.05:12 (g/mL). After release of bound furfural compounds and deprotenization, the HPLC analysis was performed. Under the optimized conditions, recoveries for spiked samples were more than 95%. The content of furfural compounds in processed cheese was significantly higher than that in cheese, and the content of furfurals in sweetened condensed milk was significantly higher than that in evaporated milk. Moreover, the amount of furfural compounds relative to per gram of protein in cheese, condensed milk and liquid dairy products followed the decreasing order of sweetened condensed milk > processed cheese > browning yogurt > room temperature yogurt > condensed milk > low temperature yogurt > ultra-high temperature sterilized milk > cheese > pasteurized milk.

Packaging & Storage

Application of the Global Stability Index Method to Shelf Life Modelling of Milk Powder

XUE Weifeng, LIU Yueting, LIU Dongyan

2021, 44(1):  33-38.  DOI: 10.15922/j.cnki.jdst.2021.01.007

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A new method for predicting the shelf life of milk powder based on the global stability index (GSI) theory was established. Under the accelerated storage conditions at different constant temperatures (20, 30, 40 and 50 ℃), changes in sensory quality, vitamin C content, hydroxymethyl furfural (HMF) content and water activity were monitored for the purpose of establishing the shelf life prediction model. Results demonstrated that the calculated values of GSI were satisfactorily fitted to a zero-order kinetic model. The activation energy and the pre-exponential constant were 49.47 kJ/mol and 4 474 924, respectively. The absolute value of relative error between the predicted and observed GSI values was within 20%. The product shelf life at 20, 30, 40 and 50 ℃ was calculated to be 147.5, 75.5, 40.3 and 22.4 d, respectively. The established model could effectively predict the shelf life of milk powder at storage temperatures in the range of 20 to 50 ℃.

Reviews

A Review of Recent Studies on the Light-Induced Oxidation of Milk

TAN Dongfei, WANG Shaolei, ZHANG Qingyang, SU Meicheng, JIA Man, CHEN Gang

2021, 44(1):  39-43.  DOI: 10.15922/j.cnki.jdst.2021.01.008

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Fat is one of the most important nutrients in milk; however, unsaturated fatty acids in milk, especially polyunsaturated fatty acids, are prone to oxidation. As transparent packaging has been increasingly applied by milk producers, the light-induced oxidation of milk fat has become one of the most important causes of the quality deterioration and rancidity of milk, which is detrimental to the flavor of milk. Furthermore, the oxidation products pose a huge threat to human health. This article reviews the mechanism, the main influence factors and the evaluation methods of milk fat photooxidation, which will provide a theoretical basis for evaluating and inhibiting photooxidation in milk, ensuring the quality of milk, and guiding the production, packaging and marketing of milk.

Progress in the Study of Bovine Milk Casein Gene Polymorphism

ZHAO Xuanying, LIU Zhenmin, YONG Jingyi, MU Haibo, LI Nan

2021, 44(1):  44-50.  DOI: 10.15922/j.cnki.jdst.2021.01.009

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Bovine milk is known as the “white blood” and is one of the most ideal natural foods, rich in protein, milk fat, calcium, vitamins and the eight essential amino acids, also known as a near-perfect food. However, in China, cow’s milk is mostly used for liquid milk processing, and its nutritional value has not been fully utilized. Casein gene polymorphisms are thought to affect milk yield, physicochemical properties and nutritional composition, dairy product manufacturing performance and nutrition, and hence have received much attention from scholars. In this paper, we summarize the existing studies on casein gene polymorphism, the methods used for its detection, and its application, hoping to provide some reference for the targeted breeding of dairy cows, the improvement of milk quality, and the precise development of functional dairy products.

Recent Progress in Understanding the Effects of Different Processing Methods on Casein Micelles

ZHAO Xinqi, CHEN Pinghua, MI Xiaolei, CHENG Ming, WANG Cunfang

2021, 44(1):  51-56.  DOI: 10.15922/j.cnki.jdst.2021.01.010

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(1.College of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China; 2.Shandong Panda Dairy Co. Ltd., Jinan 251400, China; 3.Qingdao Animal Husbandry and Veterinary Institute, Qingdao 266000, China)