Table of Content

30 October 2012, Volume 35 Issue 5

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Processing Technology

Development of Fresh Soft Soy-Milk Cheese

2012, 35(5):  1-3.  DOI: 10.15922/j.cnki.jdst.2012.05.001

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Fresh soft soy-milk cheese was made with soy bean juice as partial substitution of cow’s milk. The effects of soy bean juice, CaCl2 and rennet on coagulation time and the sensory quality of cheese were investigated by one-factor-at-a-time method and the three ingredients were optimized by orthogonal array design. The best sensory quality of cheese was achieved by adding 20% soy bean juice, 0.04% CaCl2 and 0.02% rennet.

Nutrition & Hygiene

Vasorelaxant Effect of Traditional Fermented Cheese Whey on Isolated Rat Thoracic Aortic Rings

2012, 35(5):  4-6.  DOI: 10.15922/j.cnki.jdst.2012.05.002

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Through many years’ efforts, we have demonstrated that traditional fermented cheese whey (TFCW), a traditional Kazakh medicine, is effective against atherosclerosis. In the present study, the effect of TFCW on isolated rat thoracic aortic rings was observed using Langendorff perfusion technique to determine whether TFCW has vasorelaxant functions. TFCW had no notable effect on fundamental tension in thoracic aortic rings and did not affect extracellular calcium influx in vascular smooth muscle (VSM) cells but showed a remarkable vasorelaxant effect on pre-contraction induced by 10 μmol/L phenylephrine (PE) in thoracic arterial rings probably through a multi-target mechanism.

Laxative Effect of Lactobacillus paracasei subsp. paracasei LC-01 in Constipated Mice

2012, 35(5):  7-11.  DOI: 10.15922/j.cnki.jdst.2012.05.003

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Lactobacillus paracasei subsp. paracasei LC-01 is a probiotic strain which has strong antioxidant and immunoregulatory activities. This study was designed to evaluate the laxative effect of strain LC-01 in constipated mice. Male Balb/c mice were randomly divided into blank group, model control group, positive control group and three dose groups. Both the blank and model control groups were administered orally with 10% skim milk at a dose of 0.1 mL/(kg·d) once a day. Lactobacillus casei subsp. casei Shirota (1 × 108 CFU/mL) and Lactobacillus casei subsp. casei LC-14 (1 × 106, 1 × 108 CFU/mL and 1 × 1010 CFU/mL) were used as control strains (also at 0.1 mL/(kg·d)). Strain LC-01 suspensions at concentrations of 1 × 106, 1 × 108 CFU/mL and 1 × 1010 CFU/mL were given to mice at the same dose as 10% skim milk. Constipation was induced in mice by compound diphenoxylate. After 7 days of administration of strain LC-01, the first defecation time of mice was shortened, and the number, weight and water content of stools were increased markedly. After another 7 days, the ink propelling rate became much higher. These results indicate that strain LC-01 has an outstanding laxative effect in constipated mice.

Isolation of Lactobacillus Species from Yogurt and Their Biochemical Characterization in Relation to Preventing Infections of the Female Reproductive Tract

2012, 35(5):  12-14.  DOI: 10.15922/j.cnki.jdst.2012.05.004

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Probiotic Lactobacillus strains were isolated from yogurt, cultured on de Man, Rogosa and Sharpe (MRS) agar and identified according to their 16S rRNA sequences. The Lactobacilli strains were assessed for hydrogen peroxide (H2O2) production and adhesion to HeLa cells to determine their potential for preventing infections of the female reproductive tract. A total of 10 isolates were identified including 5 L. acidophilus strains, 1 L. paracasei strain, 1 L. helveticus strain, 1 L. rhamnosus strain, 1 L. delbrueckii strain and 1 L. plantarum strain. The L. helveticus strain was strongly adherent to HeLa cells and demonstrated high H2O2 production, whereas other 9 strains had a relatively low ability to produce H2O2. Although most of the probiotic Lactobacillus strains isolated from yogurt did not have biochemical characteristics in relation to preventing infections of the female reproductive tract, the L. helveticus strain might have a protective effect on female urogenital health.

Analysis & Detection

Determination of α-Lactalbumin in Infant Formula Milk Powder by High Performance Liquid Chromatography

2012, 35(5):  16-17.  DOI: 10.15922/j.cnki.jdst.2012.05.005

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high performance liquid chromatographic method was established to determine native and denatured α-lactalbumin in infant formula milk powder. Guanidine hydrochloride buffer was used as both sample extraction solution and HPLC mobile phase. Beta-mercaptoethanol was used as reductant for sample pretreatment. The chromatographic separation was performed on a TSK-GEL G3000SWXL column and the pooled eluate was detected at 280 nm. The quantification was carried out using breast milk as internal standard. Good separation and accurate determination of α-lactalbumin in infant formula milk powder was completed using the method in around 20 min. The method was fast, accurate, and suitable for the determination of α-lactalbumin in infant formula milk powder.

Evaluation of the Uncertainty in Spectrophotometric Determination of Phosphorus Content in Infant Formula Milk Powder

2012, 35(5):  18-20.  DOI: 10.15922/j.cnki.jdst.2012.05.006

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Based on the basic method and procedure for uncertainty evaluation, a mathematical model was established to estimate the uncertainty in determining phosphorus content in infant formula milk powder by spectrophotometry. Uncertainty components in the measurement process were analyzed individually and synthesized. The phosphorus content in a commercial sample of infant formula milk powder was 180.5 mg/100 g, and the expanded uncertainty was calculated as being 3.3 mg/100 g.

Uncertainty Evaluation for HPLC Determination of Natamycin in Dairy Products

2012, 35(5):  21-23.  DOI: 10.15922/j.cnki.jdst.2012.05.007

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According to the principle and procedure of JJF1059—1999 Evaluation and Expression of Uncertainty in Measurement, a mathematical mode was established for uncertainty evaluation for HPLC determination of natamycin in dairy products. Sources of uncertainty in the entire measurement process were analyzed and each component of uncertainty was evaluated and synthesized. The synthetic standard uncertainty was 0.014, and the expanded uncertainty was 0.28 mg/kg. The confidence interval for natamycin determination was (9.95 ± 0.28) mg/kg, k = 2.

Machinery and Equipment

Application of Pulse Inverse Blow Filter Bag Dust Collector in Spray Drying System

2012, 35(5):  24-26.  DOI: 10.15922/j.cnki.jdst.2012.05.008

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A pulse inverse blow filter bag dust collector is a dust removal device where compressed airflow is instantaneously switched through an electromagnetic pulse valve and then sprayed into a filter bag through an injection pipe, and finally the resulting counterblast causes the filter bag to swell up, thus achieving dust removal. The dust collector can allow continuous, complete dust removal. As a time saving and efficient tool, it has recently been applied in various areas of spray drying production such as dairy products, medical and healthcare products and further processed corn and soybean products. However, there are some problems in its applications. This paper describes the design and application of a pulse inverse blow filter bag dust collector in MGYP01-500 type vertical pressure spray drying system for milk powder production. Besides, some attention points for its application are included.

Reviews

Research Progress on Analytical Methods for Melamine Determination in Milk and Dairy Products

2012, 35(5):  27-30.  DOI: 10.15922/j.cnki.jdst.2012.05.009

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We present a review and comparison of the current methods for melamine determination in milk and dairy products. Moreover, sample pretreatment problems are discussed.

Current Situation of Whey Cheese Production

2012, 35(5):  31-34.  DOI: 10.15922/j.cnki.jdst.2012.05.010

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This paper provides a comprehensive review of whey cheese production. The origin, classification in various countries, nutritional value and production technologies of whey cheese and the effects of heat, acidic pH, whey concentration techniques, addition of fresh milk, skim milk, semi-skim milk or cheese, fermentation starter, and non-milk derived protein on its quality are introduced in this review.

An Overview of Pasteurized Milk and Its Suitability for Drinking

2012, 35(5):  35-38.  DOI: 10.15922/j.cnki.jdst.2012.05.011

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Milk and dairy products are important components of a healthy diet. Drinking non-sterilized milk is probably harmful to health due to pathogenic contamination. By contrast, ultrahigh-temperature (UHT) sterilized milk has excessive nutrient losses. In this review, pasteurization is described as an effective way to preserve nutrients in milk and improve microbial safety. Thus, pasteurized milk is more suitable for drinking.