Table of Content

01 January 2016, Volume 39 Issue 1

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Basic Research

Antimicrobial Activities of Ethanol Extracts from Phellinus baumii.towards Harmful Microorganisms in Dairy Products

WANG Qinbo, YANG Yan, QI Xiaoyan

2016, 39(1):  1-4.  DOI: 10.15922/j.cnki.jdst.2016.01.001

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Phellinus baumii is a highly-valued medicinal mushroom. In the current study, inhibitory effects of different concentrations of the 95% ethanol extract from Phellinus baumii were examined on Gram-positive, Gram-negative, molds and yeasts. The results showed that the Phellinus baumii ethanol extract at concentrations in the range of 0.1 to 5 mg/mL was effective against the growth of harmful bacteria and fungi and could obviously control the total number of bacteria in milk without having any significant adverse impact on beneficial bacteria. Meanwhile, the extract had a broader antimicrobial spectrum than antimicrobials such as nisin, suggesting its potential application for inhibiting harmful microorganisms in milk and dairy products.

Bioengineering

Subspecies Identification of Leuconostoc mesenteroides BD1710 Using Specific Primers

GAO Caixia, YAN Minghui, WU Zhengjun

2016, 39(1):  5-7.  DOI: 10.15922/j.cnki.jdst.2016.01.002

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Leuconostoc mesenteroides consists of four subspecies, L. mesenteroides subsp. mesenteroides, L. mesenteroides subsp. dextranicum, L. mesenteroides subsp. suionicum and L. mesenteroides subsp. cremoris. Among these subspecies, only L. mesenteroides subsp. mesenteroide is currently listed for use as a food additive by China’ Ministry of Health and the FDA. The subspecies of L. mesenteroides subsp. mesenteroide cannot be identified simply by 16S rRNA gene sequencing. Therefore, the present study investigated subspecies identification of L. mesenteroides BD1710 using the established primers based on 16S–23S rRNA gene intergenic spacer region sequence similarity and three specific housekeeping genes. The results confirmed the strain to belong to L. mesenteroides subsp. mesenteroides.

Analysis & Detection

Determination of Aluminum in Baby Formula by Microwave Digestion-Inductively Coupled Plasma-Optical Emission Spectrometry

LU Zhidong, MO Nan, HU Xue, DUAN Guoxia, LIU Lijun, LI Cuizhi

2016, 39(1):  8-10.  DOI: 10.15922/j.cnki.jdst.2016.01.003

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An inductively coupled plasma-optical emission spectrometry (ICP-OES) method for the determination of aluminum in baby formula was developed. The sample was digested by microwave digestion and analyzed by ICP-OES. Quantitation was performed using an external standard method. The detection limit was 0.5 mg/kg for 0.5 g of the sample digested and diluted to 25 mL. Linear relationship between emission intensity and aluminum concentration in the range of 0.01 to 50.0 μg/mL was found with a correlation coefficient (r) of 0.999 5. Average recoveries of spiked samples were between 92.2% and 107.0% with relative standard deviations (RSDs) varying from 1.43% to 2.34%. The proposed method permits efficient and accurate determination of aluminum in baby formula with wide linear range, low detection limit, good precision and high recovery and good repeatability.

High Performance Liquid Chromatography Determination of Lactulose in Milk Powder

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

2016, 39(1):  11-13.  DOI: 10.15922/j.cnki.jdst.2016.01.004

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A method for the determination of lactulose in milk powder by high performance liquid chromatography (HPLC) was developed. Lactulose was extracted with water. The analysis was performed on a NH2 column using 80% acetonitrile in water as the mobile phase. The recovery of lactulose spiked into milk powder in the range of 0.3–2.0 g/100 g was 97.4%– 103.0%. The limit of detection was 0.3 g/100 g. The results indicated that this method is accurate, simple and suitable for the analysis of lactulose in milk powder.

Reviews

Progress in Physiological, Nutritional and Metabolic Characterization of Periparturient Dairy Cows

DU Bingyao, MA Chen, YANG Kailun, YU Xiong

2016, 39(1):  14-18.  DOI: 10.15922/j.cnki.jdst.2016.01.005

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The periparturient period of dairy cows, namely a transition period from three weeks before calving to three weeks after calving, is characterized by endocrine and metabolic changes to accommodate parturition and lactation. Dairy cows experience some degree of negative energy balance during this period, which may affect the susceptibility of cows to metabolic disorders and infectious diseases, as well as to milk production. This paper summarizes the physiological, nutritional and metabolic characteristics in periparturient dairy cows. The aim of this review is to offer a new idea for the raising and management of dairy cows and relevant research.

Current Status of Research on Lactic Acid Biosythesis in Lactic Acid Bacteria

HUANG Yanna, LIU Zhenmin, YOU Chunping

2016, 39(1):  19-23.  DOI: 10.15922/j.cnki.jdst.2016.01.006

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Lactic acid is a valuable organic acid widely used in the food, pharmaceutical, cosmetic, and chemical industries, which is also the major end product of carbohydrate fermentation by homofermentative lactic acid bacteria. This paper summarizes the current status of studies on the species distribution of the microbial genus, and the biosynthesis pathway and metabolic regulation of lactic acid. Future prospects in this area are also discussed.

Progress in Research on Extracellular Proteases Produced by Psychrotrophic Pseudomonas in Milk

XU Yu, YOU Chunping

2016, 39(1):  24-27.  DOI: 10.15922/j.cnki.jdst.2016.01.007

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Pseudomonas is highlighted as predominant psychrotrophic spoilage bacteria in milk and dairy products. Its extracellular proteases are heat-resistant, and have residual activity even after ultra high temperature sterilization (UHT) treatment leading to short life of UHT milk. The current article summarizes recent studies on extracellular proteases of psychrotrophic Pseudomonas in milk, with special emphasis on their catalytic mechanisms as well as the application of protease genes including apr X to identify Pseudomonas. At last, the further research directions in this area are discussed.

Advances in Biochip and Its Application in the Detection of Dairy Products

CHEN Wanyi, YOU Chunping, LIU Zhenmin

2016, 39(1):  28-32.  DOI: 10.15922/j.cnki.jdst.2016.01.008

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Biochip serves as a novel microanalysis and high-throughput detection technique, and it has been gradually introduced in biological research, food, medicinal and agricultural fields. This paper summarizes the basic principle, classification and manufacturing process of biochip with special emphasis on its application in the field of food safety. Problems encountered in the development of biochip technology and future trends are also briefly described.