Table of Content

30 December 2012, Volume 35 Issue 6

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Basic Research

Application of Potato Starch in Ice Cream

2012, 35(6):  1-5.  DOI: 10.15922/j.cnki.jdst.2012.06.001

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Potato starch was used as a partial substitute for gelatin and sodium carboxymethyl-cellulose (CMC-Na) to produce ice cream. Its effect on overrun, melting rate and sensory quality was investigated. Using one-factor-at-a-time and orthogonal array design methods, the optimal formulation of ice cream was determined as follows: 4% potato starch, 0.1% CMC-Na, 0.3% monoglyceride and no gelatin. The final product was homogeneous, tasted smooth and delicate and had desired overrun and melting resistance.

Antioxidant Activity of Fermented Whey and Application in Ice Cream

2012, 35(6):  6-8.  DOI: 10.15922/j.cnki.jdst.2012.06.002

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In this study, process conditions for the fermentation of whey with Streptococcus salivarius subsp. thermophilus CH9, Lactobacillus delbrueckil subsp. bulgaricus LB and Lactobacillus plantarum LPC-37 together were optimized to obtain maximum reducing power of fermented whey. The optimum fermentation conditions were determined as follows: 2:1 of CH9 plus LB-to-LPC-37 ratio, 3% of inoculum size, and 10 h of fermentation time. Addition of fermented whey obtained under these conditions provided maximum sensory evaluation score at a level of 20% and maximum overrun at a level of 25%.

Effect of Ultra High Pressure Treatment on Processing Properties of Casein

2012, 35(6):  9-13.  DOI: 10.15922/j.cnki.jdst.2012.06.003

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The effects of different conditions of pressure, time and temperature for ultra high pressure (UHP) treatment on processing properties of casein were studied. After UHP treatment, casein showed improvements in emulsibility, viscosity, water solubility and water-holding capacity. The optimal UHP treatment conditions for improving processing properties of casein were established as follows: 400 MPa, 25 min and 25 ℃ for emulsibility and viscosity, 400 MPa, 20 min and 30 ℃ for water solubility, and 450 MPa, 25 min and 20 ℃ for water-holding capacity.

Processing Technology

Preparation of Colostrum Whey

2012, 35(6):  14-16.  DOI: 10.15922/j.cnki.jdst.2012.06.004

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Colostrum whey was prepared from defatted bovine colostrum using acid precipitation of casein. Based on acid type and strength and changes in IgG activity, the optimal conditions for acid precipitation of casein were determined as follows: defatted milk was adjusted with 0.8 mol/L lactic acid to pH 4.3 and diluted with water to a dry matter concentration of 10% followed by heating in 45 ℃ water bath for 15 min and centrifugal separation at 4000 r/min for 5 min. Only 3.05% of the IgG activity was found for the prepared whey.

Preparation and Process Mechanism Analysis of Fermented Soymilk

2012, 35(6):  17-20.  DOI: 10.15922/j.cnki.jdst.2012.06.005

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Fermented soymilk was prepared from soybean slurry obtained by axial flow grinding, white sugar, lactose and glucose. These substrates were fermented by inoculation with lactic acid bacteria. The optimum fermentation conditions were found as follows: 100 mL of soybean slurry with the addition of 90 g of white sugar, 10 g of lactose, 2 g of glucose as fermentation substrate, inoculum size 0.2 g, and fermentation at 42 ℃ for 6 h. Under these conditions, the best quality of fermented soymilk was obtained. After 24 h of storage at 4 ℃, the average viable cell count was 3.0 × 107 CFU/g with a coliform population of 79 per mL, and the protein and fat contents, acidity and pH were 3.6%, 2.5%, 90.05 °T and 4.52, respectively. Moreover, urease-negative results were obtained and no pathogenic bacteria were detected. Consequently, our fermented soymilk was in accordance with the requirements of Chinese national standards. Furthermore, the developed preparation procedure had advantages such as simple operation and good suitability for commercial applications.

Analysis & Detection

Determination of Silica Dioxide as Anti-Caking Agent in Milk Power

2012, 35(6):  21-22.  DOI: 10.15922/j.cnki.jdst.2012.06.006

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A method was proposed to determine silica dioxide, an anti-caking agent, in milk powder. After high temperature ashing, samples were dissolved in acid to remove soluble salts and other substances. The precipitate (silica dioxide and insoluble solids) was burned at a high temperature to a constant weight and treated with hydrofluoric acid to remove silica dioxide. Finally, the remaining residue was collected and burned again to a constant weight. As a result, this weight loss was silica dioxide. The limit of detection and limit of quantification of this method were 0.4 g/kg and 2.0 g/kg, respectively. Average recovery rates of silica dioxide in spiked blank samples ranged from 91% to 112%. This method was simple, rapid effective, and applicable for the determination of silica dioxide in milk powder.

Rapid Determination of Residual Chloramphenicol in Infant Milk Powder by LC-MS-MS

2012, 35(6):  23-25.  DOI: 10.15922/j.cnki.jdst.2012.06.007

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A high performance liquid chromatography tandem mass spectrometric (HPLC-MS-MS) method was developed for rapid determination of chloramphenicol residue in infant milk powder. D5-Chloramphenicol was used as internal standard. Samples were alkalified, extracted with ethyl acetate and centrifuged at a low temperature. Afterwards, the supernatant was concentrated by nitrogen gas blowing and dissolved again in HPLC mobile phase before HPLC-MSMS analysis. An excellent linear relationship between peak area and chloramphenicol concentration was obtained over the concentration range of 0.1 to 5 μg/L. Average recoveries of chloramphenicol in a blank matrix across three spike levels ranged from 80% to 110%, and inter-batch and intra-batch precision (RSD) was less than 15%. The limit of quantification of this method was 0.1 μg/kg. This method was rapid, simple and suitable for rapid determination of chloramphenicol residue in infant milk powder.

Comparative Analysis of Chinese, U.S. and New Zealand Monitoring Programs for Residues of Veterinary Drugs in Milk

2012, 35(6):  26-29.  DOI: 10.15922/j.cnki.jdst.2012.06.008

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Objective: To find the differences and disadvantages of Chinese monitoring program for residues of veterinary drugs in milk compared to U.S. and New Zealand counterparts so as to provide references for perfecting Chinese monitoring program. Methods: Data from Chinese, U.S. and New Zealand monitoring programs for veterinary drug residues in milk from 2008 through 2011 were collected and compared in terms of drug types, the number of samples and monitoring results. Results: Similar drug types but smaller amounts of samples and incomplete coverage of all pastures were observed for Chinese monitoring program compared to U.S. and New Zealand counterparts. In 2010, results of monitoring of antibiotic residues in milk in China were statistically significantly higher than those in the U.S. and New Zealand (P＜0.05). Based on this analysis, we suggest that the range of Chinese monitoring program should be widened to more regions and pastures and the number of samples should be increased.

Reviews

Recent Progress in Research on Interaction between Starch and Milk Proteins

2012, 35(6):  30-33.  DOI: 10.15922/j.cnki.jdst.2012.06.009

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Starch and milk protein may coexist in many food systems. This paper systematically introduces the recent progress in research on starch-milk protein interaction in yoghurt and cheese systems. This interaction can affect the gel structure of foods and consequently alter their texture and flavor. This paper is intended to provide theoretical evidence for applications of modified starch in dairy drinks.

Research Advance in the Development of Blueberry Dairy Products

2012, 35(6):  34-36.  DOI: 10.15922/j.cnki.jdst.2012.06.010

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Blueberry dairy products are more popular with consumers, because blueberries have a variety of healthpromoting effects. This paper describes the nutrition value and health-promoting functions of blueberries, reviews the current status of development of blueberry dairy products and the recent advance in research on key production technologies, and explores future perspectives.

Current Status and Trends in the Development of Dairy Products in China

2012, 35(6):  37-41.  DOI: 10.15922/j.cnki.jdst.2012.06.011

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The present paper reviews the current status of development of China’s dairy industry, analyzes features of development and current problems, and summarizes features of products developed in the year 2010. The last part of this paper explores future trends in the dairy industry.