Table of Content

01 July 2016, Volume 39 Issue 4

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Basic Research

Regulatory Effect of Low Molecular Weight Levan on the Human Gut Flora

XU Xiaofen

2016, 39(4):  1-6.  DOI: 10.15922/j.cnki.jdst.2016.04.001

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Low molecular weight (LMW) levan was prepared from high molecular weight (HMW) levan produced by Paenibacillus bovis sp. nov BD3526 by the trichloroacetic acid (TCA) method with simultaneous removal of protein in HMW levan. The LMW levan was purified by anion-exchange chromatography. The molecular weight of the purified sample was determined by gel permeation chromatography (GPC). Its chemical structure was confirmed by nuclear magnetic resonance (NMR) and fourier transform infrared spectrometry (FT-IR). An atomic force microscope (AFM) was used to characterize its conformation in aqueous solution. To determine its potential impact on gut microbiota composition, in vitro fermentations using adult faecal inoculum treated with purified LMW levan and FOS were performed in a fermentation screening platform established by TNO (the Netherland). The results demonstrated the purified LMW levan could improve the growth of Bifidobacterium, especially B. infantis and B. longum. Furthermore, the levan was better than FOS in promoting the proliferation of B. infantis and B. longum.

Comparative Analysis of Whey Protein Composition of Human and Bovine Colostrum

YE Qing, SHI Jiaxin, YANG Mei, KONG Yan, YE Xinyang, LIANG Xiaona, WU Lanjun, CAO Xueyan WU Junrui, WU Rina, LIU Biao, YUE Xiqing

2016, 39(4):  7-12.  DOI: 10.15922/j.cnki.jdst.2016.04.002

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In this study, the whey proteins in human and bovine colostrum were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and identified by liquid chromatography-mass spectrometry (LC-MS). A total of 477 whey proteins were identified in human colostrum and 325 in bovine colostrum. Totally, 343 proteins were specifically expressed in human colostrum and 191 in bovine colostum. Moreover, 134 specifically expressed proteins were common to both. Gene ontology (GO) annotation analysis revealed that human colostrum whey proteins played a more important role in bioprocesses especially stress responses than their bovine counterparts. Human colostrum whey proteins exerted functions by binding to other molecules. Human colostrum whey proteins were more important constituents of cellular structures as compared with their bovine counterparts, and they were the most significant constituents of extracellular structures. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database, 23 whey proteins in human colostrum were involved in the KEGG pathway related to digestion and absorption, enzymatic glycolysis.

Processing Technology

Optimized Application of a Novel Brine Gel to Prolong the Storage Period of Fresh Mozzarella Cheese

LIU Peiyi, LIU Zhenmin

2016, 39(4):  13-17.  DOI: 10.15922/j.cnki.jdst.2016.04.003

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The effect of a novel brine gel on quality preservation of fresh Mozzarella cheese was evaluated. After dipping in brine gel, fresh Mozzarella cheese was packaged and sealed under aseptic conditions. The shelf life of cheese was noticeably prolonged during subsequent cold storage owing to combination of water-retaining property of the gel and antimicrobial activity of enzymatic hydrolysate of lactoferrin. The optimal combination of ingredients for the brine gel were 6% whey, 0.266% NaCl, 0.72% lactoferrin hydrolysate, 0.7% stabilizer (chitosan) and 0.3% thickener (sodium alginate). Over the storage period of 21 days, the cheese maintained good sensory quality and a total number of colonies not exceeding 1×108 CFU/mL. Additionally, Pseudomonas fluorescens was undetectable and no significant change was noted in the hydrolysis degree of casein and free amino acid concentrations of the brine. The shelf life of fresh Mozzarella cheese in this study was prolonged by at least 10 days compared with the traditional storage method.

Influence of Key Processing Parameters of Shelf-Stable Yoghurt on Modified Starch

WANG Jian, OU Kai, CHANG Yunhe, LI Luofei, WANG Yinjuan, GAO Xinghua

2016, 39(4):  18-21.  DOI: 10.15922/j.cnki.jdst.2016.04.004

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This study researched the effect of homogenization and post-sterilization of shelf-stable yoghurt the morphology of modified starch granules as one of its ingredients. It was demonstrated that with increasing either homogenization temperature or pressure, more starch granules were broken down. The optimal homogenization temperature was between 60 and 63 ℃ and the optimal pressure was in the range of 15–20 MPa. The starch granules further swelled under line pressure during ultra high temperature (UHT) processing, and they gradually enlarged or even cracked with an increase in either line pressure (up to 7 bar) or reflux cycles. Increased temperature up to 80 ℃ during UHT processing resulted in breakdown of more starch granules.

Analysis & Detection

Detection of 7 Additives in Dairy Products by High Performance Liquid Chromatography

LI Suqin, ZHAO Zhen, LIU Lijun, YUE Hong, LI Cuizhi, SHAO Jianbo

2016, 39(4):  22-25.  DOI: 10.15922/j.cnki.jdst.2016.04.005

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A method for detecting acesulfame-K, saccharin sodium, benzoic acid, sorbic acid, dehydroacetic acid, methyl vanillin and ethyl vanillin in dairy products by using high performance liquid chromatography (HPLC) is described. The sample was deproteinated and filtered, then separated on a C18 column with a mobile phase made up of methanol and ammonium acetate solution, and detected for absorbance at 230 nm. The seven substances were completely separated within 35 min. Their calibration curves were linear in the range of 1–100 mg/kg with correlation coefficients (R2) all above 0.999 0 under the selected conditions, and the recovery of the proposed method was 80.0% –105.7%. The method proved to be rapid, simple, and reliable.

Determination of Casein Phosphopeptide in Infant Formula Milk Powder by High Performance Liquid Chromatography

LIU Yujuan

2016, 39(4):  26-28.  DOI: 10.15922/j.cnki.jdst.2016.04.006

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A method for the determination of casein phosphopeptide (CPP) in infant formula milk powder by high performance liquid chromatography (HPLC) was developed. Casein phosphopeptide was extracted with water by ultrasonic treatment. The analysis was performed on a ODS column using 0.1% acetic acid and acetonitrile as the mobile phase under gradient elution. The limit of detection of the method was 6.25 mg/kg, the calibration curve was linear between 5.0 and 100.0 μg/mL. Recoveries were between 71.4% and 94.2%. This method was simple and the results complied with the qualitative and quantitative requirements. It therefore can be used to detect casein phosphopeptide in infant milk powder.

Rapid Determination of Vitamin B2 in Infant Formula Milk Powder by High Performance Liquid Chromatography

WANG Shuaishuai, ZHENG Xiaoping, MENG Jin

2016, 39(4):  29-31.  DOI: 10.15922/j.cnki.jdst.2016.04.007

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A rapid method for the determination of vitamin B2 in infant formula milk powder by high performance liquid chromatography (HPLC) was developed. Vitamin B2 was extracted by ultrasonic treatment with water, and the protein in the extract was removed by precipitation with zinc acetate and potassium ferrocyanide. The analysis was performed on a C18 column using 0.05 mol/L sodium acetate:methanol (70∶30, V/V) as the mobile phase. The limit of detection of the proposed method was 0.2 mg/kg, and a linear calibration curve was obtained in the range of 0.01 to 1.0 μg/mL. Recoveries of spiked samples were between 80.4% and 87.2%. The results indicated that this method was quick and convenient and could be used to detect vitamin B2 in infant formula milk powder.

Package & Storage

Stability of Vitamins and Active Components during-80 ℃ Storage of Human Milk

FANG Fang, LI Ting, Mauyau SZETO, YE Wenhui, LIU Biao, YUN Zhanyou

2016, 39(4):  32-35.  DOI: 10.15922/j.cnki.jdst.2016.04.008

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This research evaluated the stability of vitamins and active components under ultra-low temperature conditions in order to provide a basis to formulate the quality standard for breast milk bank to ensure minimal nutrient loss during storage at ?80 ℃. The results showed that vitamin contents significantly reduced with storage time up to 12 months, yet no significant change was observed in nucleotide contents. After 3 months of storage, the contents of VB2 and VA decreased to 35% and 29% of the original level, respectively, while VC was at undetectable level. Moreover, nicotinic acid at the end of storage dropped to 69% of the fresh breast milk. Considering the existing quality indicators, the quality standard for breast milk bank should be based on breast milk components to be analyzed and fresh breast milk should be used as far as possible to analyze ingredients with poor stability such as vitamins.

Reviews

Interpretation of the Provisions for Formula Registration of Infant Formula Milk Powder

DING Ning, LUO Jie

2016, 39(4):  36-38.  DOI: 10.15922/j.cnki.jdst.2016.04.009

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Infant formula milk powder is a main food for infants. Its product quality and nutritive value have drawn much attention from the public. This paper interprets the Provisions for Formula Registration of Infant Formula Milk Powder issued by the China Food and Drug Administration (CFDA) in 2016, and illustrates its background, main contents, characteristics, existing problems, etc.