Table of Content

30 December 2014, Volume 37 Issue 6

Previous Issue    Next Issue

Basic Research

Application of Whey Protein Concentrate to Improve the Stability of Fermented Skim Milk Drink

WANG Yin-juan, WANG Xiao-jun, TIAN Fen, SUN Yong, OU Kai, WU Wei-Du, GAO Xing-hua

2014, 37(6):  1-5.  DOI: 10.15922/j.cnki.jdst.2014.06.001

Asbtract ( )   HTML ( )   PDF (1575KB) ( )  

Related Articles | Metrics

The influence of whey protein concentrate (WPC80) added to fermented skim milk drink on its stability was studied. The stability of fermented skim milk drink with different concentrations of whey protein concentrate was evaluated by particle size distribution, centrifugal analysis and Turbiscan analysis. The results showed that fermented milk drink containing 30% WPC80 had the smallest particle size and smallest centrifugal sediment. The turbiscan analysis showed distinctly that the fortified drink produced less sediment than the fermented milk drink with no added WPC80.

Antibiotic Susceptibility of Lactobacillus isolates

GUO Hui-ling, CHEN Xia, SHAO Yu-yu, PAN Lin, MENG HE Bilige, ZHANG He-ping

2014, 37(6):  6-10.  DOI: 10.15922/j.cnki.jdst.2014.06.002

Asbtract ( )   HTML ( )   PDF (1302KB) ( )  

Related Articles | Metrics

Forty-four strains of Lactobacillus isolated from fermented milk in different regions were identified by using 16S rRNA gene sequencing. The results showed that the species of these Lactobacillus isolates were Lactobacillus casei, Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus helveticus and Lactobacillus bulgaricus. Meanwhile, our present study focused on the susceptibility of these strains to 11 antibiotics from 6 different categories. Our results showed that different Lactobacillus species displayed different resistance to the antibiotics.

Effects of Dietary Supplementation of a Composite Enzyme Preparation FE907 on Milk Production and Economic Benefits from Dairy Cows during Early Lactation

XU Xiao-ming, CHAI Xian-qi, ZHANG Min, LI Guo-quan, LI Xin-liang

2014, 37(6):  11-14.  DOI: 10.15922/j.cnki.jdst.2014.06.003

Asbtract ( )   HTML ( )   PDF (1333KB) ( )  

Related Articles | Metrics

This experiment was conducted to investigate the effects of composite enzyme preparation FE907 on milk production and disease resistance of lactating dairy cows. A total of 28 lactating Holstein dairy cows were randomly allocated into two groups with 14 ones per group, which were fed a total mixed ration (TMR) alone and supplemented with 20 g/d·cow of FE907, respectively. The feeding experiment lasted four weeks. The results showed that the daily milk production was increased by 1.6 kg/d (P > 0.05) in response to dietary supplementation of FE907. In addition, an increase of 0.08% in the fat content of milk and of 0.09 kg/d in the production of milk was observed over the control group with significant differences (P < 0.05). The protein content of milk and the production of milk protein were also increased by 0.06% and 0.07 kg/d, respectively. The benefit per day from one cow was 6.28 RMB more than the control group. It is concluded that supplementing 20 g/d·cow of the enzyme preparation to the diet has a positive effect on improving the milk yield, milk composition and economic benefit while reducing the risk of developing mastitis.

Analysis & Detection

Microbiological Method for the Detection of Biotin, Folic Acid and Vitamin B12 in Infant Formula Powder

XU Qiong, WANG Zhi-wei, CHEN Xin-qin, GU Wen-jia, QU Qin-feng

2014, 37(6):  15-17.  DOI: 10.15922/j.cnki.jdst.2014.06.004

Asbtract ( )   HTML ( )   PDF (1208KB) ( )  

Related Articles | Metrics

Objective: To present a microbiological method for the detection of biotin, folic acid and vitamin B12 in infant formula powder. Methods: For quantification of these vitamins, the growth of the lactic acid bacteria with specific sensitivity to them was measured after incubation in their presence. Thirteen samples of commercial infant formula powder were detected by the proposed method. Results: More stable and repeatable data were obtained from the determination of biotin and vitamin B12 by the microbiological method with a relative standard deviation (RSD) of 0.056%～4.158% and 0.112%～3.848%, respectively, while the results obtained for folic acid varied in a wide range with a RSD of 1.236%～8.332%. Conclusion: This method is suitable for the quantitative analysis of the vitamins biotin, folic acid and vitamin B12 in infant formula powder.

Simultaneous Determination of Pb, Cr and Hg in Milk by Microwave Digestion and Inductively Coupled Plasma Mass Spectrometry

ZHANG Yang, ZHOU Wei, DONG Can, LU Jian

2014, 37(6):  18-21.  DOI: 10.15922/j.cnki.jdst.2014.06.005

Asbtract ( )   HTML ( )   PDF (1262KB) ( )  

Related Articles | Metrics

A method for the simultaneous determination of Pb, Cr and Hg in milk was developed by microwave digestion combined with inductively coupled plasma mass spectrometry (ICP-MS). The sample preparation procedure, the ICP-MS parameters, the internal standard and the monitor isotope were optimized. The results showed that the digestion temperature was 180 ℃. A mixed solution of 10 μg/L 72Ge and 209Bi was selected as the internal standard to eliminate the matrix effect, and 200 μg/L Au was added to the solution to eliminate the memory effect of Hg. 208Pb, 52Cr and 202Hg were monitored with ICP-MS to determine Pb, Cr and Hg, respectively. Under the optimal conditions, detection limits of 5.0 (Pb), 1.0 (Cr) and 0.5 (Hg) μg/kg were obtained. The contents of Pb, Cr and Hg in 40 batches of commercial milk were low. The detection values were smaller than 0.011 mg/kg for Pb and smaller than 0.031 mg/kg for Cr. Only 1 sample was found to contain Hg, and the detection value was 0.008 mg/kg.

Determination of Thiocyanate in Dairy Products by Ion Chromatography

WANG Yun-xia, DU Xiao-hua, SUN Li-hua, LI Cui-zhi, LIU Li-jun, SHAO Jian-bo

2014, 37(6):  22-25.  DOI: 10.15922/j.cnki.jdst.2014.06.006

Asbtract ( )   HTML ( )   PDF (1222KB) ( )  

Related Articles | Metrics

This report describes an ion chromatography method for determining thiocyanate in dairy products. Milk samples were deproteinized by adding acetonitrile followed by centrifugation, microporous filtration and chromatography on LC-C18 SPE column. The analyte was monitored by ion chromatography. The optimized mobile phase consisted of 1.7 mmol/L sodium bicarbonate, 1.8 mmol/L sodium carbonate and 10% aqueous acetone solution. The suppressor was activated and regenerated with 0.2% sulfuric acid as an inhibitor. The detection limit for thiocyanate was 2.0 mg/kg, and the standard curve exhibited a correlation coefficient above 0.99 in the linear range of 0.1–20 mg/kg (mg/L). Recovery rates for spiked samples ranged from 93% to 97%, and repeatability expressed as relative standard deviation varied between 0.8% and 1.34% (n = 5). The detection accuracy for milk powder standard was 98%. The presented method was characteristic of easy operation, accurate and repeatable results and low detection limit, and was useful for the determination of thiocyanate in dairy products.

Reviews

Recent Applications of High Performance Liquid Chromatography-Mass Spectrometry for the Determination of Penicillins and Their Metabolites Residues in Milk and Dairy Products

ZHANG Li-jia, HU Xue, BAI Yan-mei, KANG Kai, DUAN Guo-xia, LIU Li-jun, LI Cui-zhi

2014, 37(6):  26-30.  DOI: 10.15922/j.cnki.jdst.2014.06.007

Asbtract ( )   HTML ( )   PDF (1074KB) ( )  

Related Articles | Metrics

In this paper we review recent applications of high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), ultra high performance liquid chromatography coupled with high-resolution time-of-flight mass spectrometry (HRTOF-MS), and matrix assisted laser desorption ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTMS) to determine penicillin residues in milk and dairy products and their major enzymatic metabolites in vivo. This review describes recent progress in the development of sample extraction, purification, chromatographic separation and mass spectrometry detection methods for the determination of penicillin residues in dairy products.

Recent Progress in the Study of miRNAs in Mammalian Breast Milk and Its Potential Applications

ZHAO Fang-qing1,2, LI Song-tao3, ZHEN Zhuo1,2, GAO Xu1,4, MA Ning1,4,*

2014, 37(6):  31-34.  DOI: 10.15922/j.cnki.jdst.2014.06.008

Asbtract ( )   HTML ( )   PDF (1130KB) ( )  

Related Articles | Metrics

Milk is an important source of nutrition for infant growth. Protein, fat, sugar and trace elements in breast milk have been proved to be the sources of energy and immune. Recently, a number of studies have confirmed the presence of a class of small molecule RNAs-miRNAs in milk. Regulations of this class of biological molecules are mainly involved in gene expression, playing a regulatory role in physiology and pathology. At present, researches focused on the detection of miRNAs levels in milk, but its functions have not been known clearly. This review discusses the homology and content of human, bovine and rat miRNAs in breast milk at different lactation periods. At the same time, recent research on milk miRNAs functions is reviewed. The study of miRNAs milk will help to define the components of milk further and understand their functions, so as to provide references for the improvement of formula milk powder.