Table of Content

01 September 2016, Volume 39 Issue 5

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Basic Research

Analysis of Cleavage Sites in Bovine Milk Proteins by Metalloproteinase (M4) from Paenibacillus spp.BD3526

HANG Feng, HONG Qing, WANG Qinbo

2016, 39(5):  1-6.  DOI: 10.15922/j.cnki.jdst.2016.05.001

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In order to find the difference between the cleavage sites in bovine milk proteins by metalloproteinase from Paenibacillus spp. BD3526 and chymosin, the peptides generated from αs1-, αs2- and κ-casein and β-lactoglobulin (β-Lg) digested by the enzymes were analyzed by high performance liquid chromatography coupled with quadruple-timeof- flight mass spectrometer (HPLC-Q-TOF-MS-MS). The results indicated that the cleavage sites in bovine milk proteins by metalloproteinase and chymosin shared high similarity and both of these enzymes specifically cleaved the Lys-Thr, Lys-Phe, Arg- Phe and Arg-Tyr peptide bonds to generate peptides with ACE inhibitory, antimicrobial and immunomodulating activities.

Comparative Analysis of Composition and Functionality of Milk Fat Globule Membrane Proteins in Bovine Colostrum and Milk

WU Lanjun, YANG Mei, WANG Manxia, MI Shuhui, WU Yongfeng, WU Junrui, WU Rina, LIU Biao, YUE Xiqing

2016, 39(5):  7-12.  DOI: 10.15922/j.cnki.jdst.2016.05.002

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SDS-PAGE was used for separating the protein components of milk fat globule membranes (MFGMs) from bovine colostrum and milk, and it was found that the compositions of milk fat globule membrane proteins in colostrum and mature milk were different. A total of 628 MFGMs were identified in bovine colostrum and 487 MFGMs in mature milk. Gene ontology (GO) annotation showed that the main role milk fat globule membranes from bovine colostrum and milk played in biological processes was biological regulation. With respect to molecular function, bovine colostrum fat globule membrane proteins had greater binding capacity than mature milk fat globule membrane proteins, and the former was found to exist much more abundantly in extracellular areas than the latter. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated that both membrane proteins participated in different metabolic pathways, implicating that bovine colostrum can be further processed into high-quality products.

Comparative Study on Milk Fat Globule Membrane Protein Composition of Human and Bovine Milk

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

2016, 39(5):  13-18.  DOI: 10.15922/j.cnki.jdst.2016.05.003

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In this study, proteins from human and bovine milk fat globule membranes were separated using SDS-PAGE and identified by liquid chromatography-mass spectrometry (LC-MS). It was found that 1 076 proteins from human milk fat globule membrane were identified, and 682 proteins from bovine milk fat globule membrane. Among these proteins, 757 specifically expressed proteins were derived from human milk fat globule membrane, and 363 specifically expressed proteins from bovine fat globule membrane, with 319 of these being common to both. According to gene ontology (GO) annotations analysis, human milk fat globule membrane proteins played a more significant role in biological process than did bovine milk fat globule membrane proteins, especially in cellular component organization. The molecular function of human milk fat globule membrane proteins was exerted mainly through binding. In cellular composition, human milk fat globule membrane proteins were more dominant than bovine milk fat globule membrane proteins, and mostly participated in intracellular components. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that there were 15 human milk fat globule membrane proteins involved in the digestion and absorption related KEGG pathway—enzymatic glycolysis. The study of human milk fat globule membrane proteins can improve the accuracy of milk fat globule membrane protein utilization, and the experimental data obtained may provide theoretical reference for future development of functional foods for infants.

Processing Technology

Development and in vitro Digestibility of Infant and Follow-up Formula Milk Powder

WU Xuezhi, LIU Yang, ZHANG Zhaomin, ZENG Xiaolong, XIONG Wenying, WANG Cheng

2016, 39(5):  19-24.  DOI: 10.15922/j.cnki.jdst.2016.05.004

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According to the characteristics of macronutrients in breast milk, infant and follow-up formula milk powder was developed suitable for Chinese infants and babies by adjusting the contents of protein, fat and carbohydrate in milk powder and the rationality of this design was evaluated using in vitro digestibility tests. The results showed the content of each macronutrient in the formula milk powder was in accord with the requirements of Chinese and international standards and could meet macronutrient needs of infants and babies. The total in vitro digestibility of proteins approximately was 88% in the formula milk powder, which was higher than that of commercial infant formula and goat milk powder, and it was increased to 95% by increasing enzyme levels. Therefore, the formula milk powder had a reasonable nutritional profile and could be easily be digested and absorbed by infants.

Package & Storage

Storage Stability Studies of Milk Powder with Different Forms of Packaging

JIA Hongxin, SU Miya, JIANG Wenyao

2016, 39(5):  25-28.  DOI: 10.15922/j.cnki.jdst.2016.05.005

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Changes in moisture content, water activity (aw ), color and 2-thiobarbituric acid (TBA) value of milk powder packaged with different packaging materials i.e., aluminum foil bags (polyethylene terephthalate/ polyamide/aluminum foil/ polyethylene (PET/PA/AL/PE)), cup-shaped capsule 1 (polypropylene/ethylenevinyl alcohol copolymer/polypropylene (PP/ EVOH/PP) and cup-shaped capsule 2 (PP) were examined during 12 weeks of accelerated storage in under constant temperature (37 or 42 ℃) and humidity (75%) conditions. The results showed that moisture content and aw in milk powder packaged with aluminum foil bags remained relatively stable during accelerated storage under the same conditions and color difference (ΔE) and TBA value increased with storage time. For milk powder packaged with cup-shaped capsules, all parameters (moisture content, aw, L*, a*, b*, ΔE and TBA values) continuously increased, and cup-shaped capsule 1 resulted in smaller increased in these parameters than did cup-shaped capsule 2. In conclusion, aluminum foil packaging was the best method for preserving milk powder, followed by cup-shaped capsule 1, and cup-shaped capsule 2 was the least effective method.

Screening of Antifungal Lactobacillus Plantarum and Application in Yoghurt as Preservative Culture

ZHENG Yan, WANG Jicheng

2016, 39(5):  29-33.  DOI: 10.15922/j.cnki.jdst.2016.05.006

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Biological preservatives of lactic acid bacteria (LAB) have been gradually applied to food preservation because of their excellent properties such as naturality, antibacterial activity, safety and reliability. The screening of Lactobacillus plantarum with superior fermentation ability and antifungal activity is important for the production and preservation of fermented milk. In this research 33 strains of L. plantarum with potential antifungal properties were used as starters to ferment skim milk. Variations in mold and yeast counts and post-acidification during storage at room temperature under open conditions and mixed-culture fermentation properties were assessed to select L. plantarum with superior preservation properties. The results indicated that 9 selected strains of L. plantarum from initial screening had obvious antifungal activity. The variation of acidity of milk fermented by L. plantarum IMAU80091 and IMAU80106 was significantly lower than that of milk fermented by other strains and commercial preservative bacteria (P < 0.05). Moreover, milk fermented with mixed cultures (1:1) of L. plantarum IMAU80091 and IMAU80106 showed great inhibitory activity against yeasts than did commercial preservative bacteria significantly (P < 0.05). After storage for 21 d, the titratable acidity was (138.24 ± 1.19) °T, which was significantly lower (P < 0.05) than that of milk fermented by commercial preservative bacteria (146.41 ± 1.18) °T. In summary, mixed cultures of L. plantarum IMAU80091 and IMAU80106 possess superior antifungal properties as a promising biopreservative and could prevent fungal contamination effectively.

Application of Wolf Formula for Structural Design of Corrugated Carton for Dairy Products

ZHANG Yu, LIU Xianghong, ZHANG Weirong

2016, 39(5):  34-37.  DOI: 10.15922/j.cnki.jdst.2016.05.007

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This study aimed at the application of Wolf formula for structural design of corrugated box for dairy products. Five kinds of corrugated boxes for 350 mL of Momchilovtsi, a Bright Dairy yoghurt brand, were designed according to the capacity and arrangement of the inner packaging, and their theoretical compression strength was calculated using Wolf formula as well as their minimum compression strength when 10 boxes were stacked and stored in the same environment using compression formula. Comparative analysis of the results of both calculations was carried out based on structural design elements such as ratio of length to width and length of sides. Moreover, verification was achieved using compression tests. Finally, we established the optimal structural design of 350 mL corrugated boxes for Momchilovtsi. It was showed that corrugated carton No. 4 had the highest marketability under the conditions: the same material and height, 3 × 3 arrangement mode, length/width ratio of 1, and length of sides of 74 mm.

Reviews

Advances in Proteomics Studies of Human and Bovine Milk

YANG Mei, CAO Xueyan, YE Qing, LIANG Xiaona, WU Lanjun, LIU Biao, YUE Xiqing

2016, 39(5):  38-43.  DOI: 10.15922/j.cnki.jdst.2016.05.008

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Milk protein is the most important nutrient in the initial stage of life, and it is abundant in kind and quantity. The composition of milk proteins has been made more complex and tremendously increased through a large number of genetic variations and sufficient protein translation. Proteomics permits one to systematically and integrally study milk proteins to understand the ways milk proteins constitute and regulate some life activities and further obtain a comprehensive and in-depth understanding of the expression levels of milk proteins. This paper describes the main techniques used in proteomics studies, including two dimensional electrophoresis, high performance liquid chromatography (HPLC), isobaric tags for relative and absolute quantitation (iTRAQ), mass spectrometry and bioinformatics techniques. The applications of proteomics in studies on human and bovine milk in particular differential proteomics analysis are discussed. To conclude, proteomics allows a better understanding of human and bovine milk which can provide a theoretical basis for developing infant foods and dairy products.