Table of Content

30 October 2015, Volume 38 Issue 5

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Basic Research

Gelatinization Properties and Application of Three Modified Starches in Long Shelf-Life Yogurt

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

2015, 38(5):  1-5.  DOI: 10.15922/j.cnki.jdst.2015.05.001

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This study investigated the gelatinization properties of three types of modified starch and their application in long shelf-life yogurt. The three types of modified starch were physically modified starch (PMS), acetylated distarch phosphate (ADSP), hydroxypropyl distarch phosphate (HDSP). The results showed that the granular structure of the three kinds of starch remained intact after gelatinization. They all had strong shear resistance, and ADSP and HDSP showed stronger shear resistance and higher gelatinization temperature than PMS. Adding 2% (m/m) modified starch in long shelf-life yogurt increased its apparent viscosity, water holding capacity, viscoelasticity, yield stress, and storage stability. ADSP was better to improve the quality of long shelf-life yogurt than HDSP and PMS.

Comparison of the Effects of Different Lactobacillus on the Control of Mold Contamination in Yogurt

SUN Ting, ZHANG Xingchang, SZETO Ignatius Manyau, CHEN Shixian

2015, 38(5):  6-9.  DOI: 10.15922/j.cnki.jdst.2015.05.002

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The objective of this study is to identify the effect of two commercial Lactobacillus cultures, Lactobacillus plantarum (A) and a mixture of Lactobacillus rhamnosus, Lactobacillus plantarum and Lactobacillus paracasei, on the control of mold contamination, nutrients, texture and sensory qualities of stirred yogurt. The results demonstrated that these two cultures exerted different degrees of inhibition on mold growth. Culture B led to higher degree of mold inhibition than culture A when added at the manufacturer recommended amount (A: 2.0 × 106 CFU/mL, B: 1.38 × 107 CFU/mL). In contrast, culture B at 2.0 × 106 CFU/mL had less inhibition capability than culture A. The flavor of yogurt was adversely affected by culture B, while culture A showed no effect during the shelf-life period. Compared with the control group, the nutrients and texture of yogurt with culture A or B were not changed greatly. In conclusion, Lactobacillus cultures can inhibit the growth of mold in yogurt, where its bacteriostatic ability is related to the species and concentration of strains added.

Processing Technology

Optimization of Processing Conditions for Fruit-Vegetable Edible Paper Containing Goat Milk by Response Surface Analysis

ZHU Yuying, WANG Cunfang

2015, 38(5):  10-15.  DOI: 10.15922/j.cnki.jdst.2015.05.003

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In this study, the formulation of a fruit-vegetable edible paper using goat milk, carrot and hawthorn as main ingredients was optimized using one-factor-at-a-time method and response surface analysis. The effects of hawthorn added in different forms on the texture of goat milk-based edible paper were compared by texture profile analysis using a texture analyzer combined with particle swarm optimization (PSO) algorithm. The sensory quality of goat milk-based edible paper was improved by adding hawthorn juice compared with hawthorn mash. The optimum formulation was composed of a 5:8:3 (V/m/V) mixture of goat milk, carrot and hawthorn added with 0.87% compound stabilizer, β-cyclodextrin, color fixative, white sugar and honey at concentration levels of 0.12%, 0.1%, 10% and 2.4% (m/m), respectively. The resulting product had a unique mixed flavor of goat milk and carrot, a mixed color of carrot and hawthorn and a paper-like appearance. It was tasty with a good balance between sour and sweet and its sensory score was 91.32, showing a relative error of approximately 1.68% compared to the model-predicted value.

Optimization of the Formulation for a Milk Beverage Supplemented with Lentinus edodes-Derived Peptide

YU Xiaoping, LI Na, WANG Dawei

2015, 38(5):  16-20.  DOI: 10.15922/j.cnki.jdst.2015.05.004

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In this study controllable hydrolysis of Lentinus edodes with alkaline protease was performed to obtain peptides for subsequent application as an active ingredient in milk beverage. The formulation for the novel beverage was optimized based on sensory evaluation and stability using combination of one-factor-at-a-time method and orthogonal array design. The optimum proportions by weight of ingredients in the beverage were 2.0% Lentinus edodes-derived peptide, 1% milk powder, 10% white sugar, and 0.20% citric acid. The optimized formulation had a fine and smooth taste, good flavor and high stability.

Analysis & Detection

Rapid Determination of Taurine in Milk Powder by High Performance Liquid Chromatography with On-line Automated Pre-column Derivatization

LIN Yuzhou, HUANG Yaoyao, CONG Xiao, ZHONG Xiaodong

2015, 38(5):  21-24.  DOI: 10.15922/j.cnki.jdst.2015.05.005

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A rapid quantitative method for the determination of taurine in milk powder by high performance liquid chromatography (HPLC) with ortho-phthaladehyde (OPA) as pre-column derivatization reagent has been developed. After automated derivatization in the autosampler, the standards and samples were directly into the HPLC system for analysis. An Ultimate AQ-C18 (2.1 mm × 100 mm, 3 μm) was used for the analysis at 40 ℃. The separation was carried out using a mobile phase consisting of acetonitrile and 10 mmol/L sodium acetate solution (pH 4.2) at a flow rate of 0.4 mL/min. The linear range of the method was from 5.0 to 100 μg/mL with a correlation coefficient (R2) of 0.999 7. The spiked recovery was in the range of 97.33%–105.74%. At the signal-to-noise ratio of 3 (RS/N = 3), the limit of detection (LOD) was 0.06 mg/100 g and the limit of quantification was 0.2 mg/100 g (RS/N = 10) for taurine. The proposed method proved to be simple and sensitive for routine analysis of taurine in milk powder with good reproducibility.

Reviews

Application of Metagenomic DNA Analysis Technique to Detect the Microbial Diversity of Traditional Fermented Dairy Products

ZHANG Donglei, LIU Wenjun, SUN Tiansong

2015, 38(5):  25-28.  DOI: 10.15922/j.cnki.jdst.2015.05.006

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In this paper, we review metagenomic DNA analysis techniques which are widely used to detect the microbial diversity in traditional fermented dairy products with particular focus on molecular marker technologies based on 16S rRNA gene sequences, such as denaturinggradientgel electrophoresis(DGGE), restriction fragment length polymorphism (RFLP), terminal restriction fragment length polymorphism (T-RFLP) and single-stran dconformation polymorphism(SSCP). The recent progresses in the application of these methods are summarized in detail.

Occurrence and Prevention of Hypocalcemia during the Peripartum Period of Dairy Cows

LI Jinmin, ZHANG Zhiyan, HAN Yin, LIU Yong, YANG Lina, WU Huanrong, GU Wei

2015, 38(5):  29-32.  DOI: 10.15922/j.cnki.jdst.2015.05.007

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Dairy cows show lower disease resistance with late pregnancy, calving, lactation and other physiological changes during the peripartum period. Subsequently, the cows are prone to many diseases such as hypocalcaemia (milk fever) after calving. In this paper, the pathogenesis, hazards, influencing factors and control principles of hypocalcemia in dairy cows during the peripartum period are summarized in order to provide theoretical references for the feeding and management of dairy cows.

Recent Advances in Chromatographic Determination of Lactulose in Milk-Based Products

WANG Fengxian, LIU Boya

2015, 38(5):  33-36.  DOI: 10.15922/j.cnki.jdst.2015.05.008

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Lactulose as a prebiotic is widely used in milk-based products, especially in infant formula as an important component. For regulation, the Chinese national standard Food Additive-Lactulose Liquid GB8816—1988 has been relatively backward. And there is no regulation regarding the analysis of lactulose in foods. How to discriminate lactulose from other carbohydrates, especially from lactose, is a problem we are faced with and an obstacle for application. The chromatographic techniques for the determination of lactulose in milk-based products, including thin-layer chromatography, gas chromatography and liquid chromatography, are summarized. This work could provide a reference for lactulose detection in milk-based product by researchers.