Table of Content

01 September 2017, Volume 40 Issue 5

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Processing Technology

Optimization of Preparation of Antioxidant Peptide-Containing Dairy Beverage Fermented with Lactobacillus paracasei

CHEN Suwan, TANG Yingxiu, DAI Chunhua, HE Ronghai, MA Haile

2017, 40(5):  1-7.  DOI: 10.15922/j.cnki.jdst.2017.05.001

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The aim of this study was to prepare a new antioxidant peptide-containing dairy beverage by the fermentation of Lactobacillus paracasei. The fermentation conditions and medium ingredients were optimized based on final viable cell count, acidity, peptide concentration, peptide yield, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. A shaking speed of 180 r/min, a fermentation time of 24 h, an inoculum size of 5％, a skim milk powder concentration of 12％ and a glucose concentration of 6％ were found to be the optimal conditions to obtain the highest peptide concentration of 0.98 mg/mL, highest final viable cell number of 8.5 × 108 CFU/mL and highest DPPH radical scavenging activity of 62.38％.

Process Optimization for Preparation of Antioxidant Peptides by Enzymatic Hydrolysis of Whey Protein Concentration with Protamex

ZHANG Ping, CHEN He, LIAO Na

2017, 40(5):  8-11.  DOI: 10.15922/j.cnki.jdst.2017.05.002

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The enzymatic hydrolysis of whey protein concentration for preparing antioxidant peptides was optimized using one-factor-at-a-time and orthogonal array design methods. The independent variables selected were temperature, pH, substrate concentration, and enzyme-to-substrate ratio. The responses were degree of hydrolysis, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion radical scavenging capacity, and ion chelating capacity. The optimal hydrolysis conditions were found to be hydrolysis at 60 ℃ and pH 8.5 at a substrate concentration of 2.5 g/100 mL with an enzyme-to-substrate ratio of 3.5％. Furthermore, the optimized values of process parameter were experimentally validated.

Application of Propylene Glycol Alginate in Stirred Yoghurt

DAI Zengying, FAN Suqin, WANG Xiaomei, LIU Haiyan, GAO Kedong, CHENG Wensheng, LIU Ranran

2017, 40(5):  12-15.  DOI: 10.15922/j.cnki.jdst.2017.05.003

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This study addressed the effect of different amounts of added propylene glycol alginate (PGA) on the stability of stirred yoghurt as determined by measuring its acidity, pH value, water-holding capacity, whey syneresis and sensory evaluation. The aim was to determine the optimal addition amount of PGA. The results that addition of PGA remarkably inhibited the postacidification of yoghurt during storage, enhanced water-holding capacity, deceased whey syneresis, and resulted in an improved texture and taste. Added PGA was beneficial for the stability of yoghurt in a concentration-dependent manner. From a cost-effectiveness point of view, the optimal amount of PGA in stirred yoghurt is 0.3％.

Analysis & Detection

Comparison of Free Fatty Acids and Volatile Flavor Compounds of Six Brands of Imported Camembert Cheese in China

YU Huaning, WU Shenmao, HANG Feng, LIU Zhenmin

2017, 40(5):  16-22.  DOI: 10.15922/j.cnki.jdst.2017.05.004

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The free fatty acid and volatile flavor compositions of six brands of imported Camembert cheese in China were measured comparatively by gas chromatography-mass spectrometry (GC-MS) and headspace solid phase microextraction (HS-SPME) combined with GC-MS. The results showed that all analyzed samples had an identical free fatty acid composition, myrisitc, palmitic, linoleic, and stearic acid being the major ones and no significant difference among the total free fatty acid contents of the six samples was found. On the other hand, a significant difference was noted in the contents of volatile flavor compounds, the samples FRA1 and FRA2 containing the highest contents of carboxylic acids while the remaining samples having higher contents of ketone compounds, which may be related to the maturity of cheese. Sensory evaluation of FRA1 and FRA2 showed lower scores for sensory attributes and overall quality, while the other four samples showed no significant difference.

Detection of Changes in Volatile Organic Compounds of Infant Formula Milk Powder during Storage by Fast Gas Chromatography Electronic Nose

JIA Hongxin

2017, 40(5):  23-27.  DOI: 10.15922/j.cnki.jdst.2017.05.005

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The volatile organic compounds (VOCs) of infant formula milk powder stored for different periods of time at different temperatures were identified using Heracles Ⅱ fast gas chromatography electronic nose based on comparison of Kovat retention index with AroChemBase. Principal component analysis (PCA) was carried out on the characteristic peaks. Results indicated that the main VOCs of infant formula milk powder were aldehydes, ketones and alcohols. PCA could clearly distinguish different storage periods of infant formula milk powder, and less significant differences in VOCs were found with shorter storage intervals. Stronger off-flavor appeared with increasing storage time. Accordingly, Heracles Ⅱ fast gas chromatography electronic nose was useful for rapid detection of VOCs and odor compounds in infant formula milk powder.

Reviews

A Review of Probiotics in the Treatment of Irritable Bowel Syndrome

HONG Qing, LIU Zhenmin, WANG Guojiao, HANG Feng

2017, 40(5):  28-31.  DOI: 10.15922/j.cnki.jdst.2017.05.006

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Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that causes abdominal pain, diarrhea and constipation, reducing the quality of life in patients. Probiotics have been shown to regulate the intestinal flora balance, enhance intestinal barrier function and modulate the immune response, thereby providing new approaches to treat IBS. This article aims to review the literature concerning the treatment of IBS with probiotics with respect to the subtypes of IBS, changes in the intestinal flora of IBS patients, the therapeutical effect of probiotics on IBS and the underlying mechanism for the purpose of providing useful information for applying probiotics to treat IBS and broadening their scope of application.

Innovation Trend of Dairy Packaging

CHEN Jiyu, LIU Xianghong, CAI Yongji

2017, 40(5):  32-37.  DOI: 10.15922/j.cnki.jdst.2017.05.007

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With the rapid growth of dairy products and the increasing consumption of dairy products in China, the dairy industry has developed rapidly, which has put forward higher requirements for dairy packaging, and also led to the rapid development of dairy packaging industry. In this paper, the concept of dairy packaging is described briefly, and the main innovation trend of dairy packaging in China and abroad is analyzed. Finally, we conclude with some personal perspectives on how dairy terminal manufacturers promote and utilize packaging innovation.