Moisture sorption characteristics of mango–soy-fortified yogurt powder

Moisture adsorption isotherms of plain yogurt, mango–soy-fortified yogurt (MSFY) and MSFY containing 0.4% gelatin stabilizer (MSFYG) powder were determined at 20, 30, 40 and 50°C. A gravimetric static method was used under 0.11–0.81 water activity ranges for the determination of sorption isotherms that were found to be typical type II sigmoid. Experimental data were fitted to five mathematical models viz. modified Henderson, modified Chung–Pfost, Oswin, Smith and Guggenheim–Anderson–de Boer (GAB). It was found that both Oswin and GAB models were acceptable in describing equilibrium moisture content–equilibrium relative humidity (EMC–ERH) relationships for yogurt powder samples over the entire range of temperatures.     

益生素和益生元在营养和健康中的新观念

益生素在预防腹泻、增强乳糖耐受和调节免疫等方面具有很好的功效;益生素还具有预防癌症和降低血清胆固醇的潜力.双歧杆菌和乳酸菌作为2种主要有益菌在改善肠道微生物菌群中起重要作用.非消化性低聚糖即益生元可选择性促进结肠内有益菌生长和增强肠道健康.益生素和益生元在调节胃肠道功能中是最具前景的功能性食品，包括调控食物转运时间、肠道习性、粘膜蠕动性以及表皮细胞增殖;平衡结肠微生物区系，调节营养物质特别是离子的生物学利用率;调控消化道系统的免疫活性和内分泌活性，调节脂代谢.益生素和益生元的混合制品即合生元具有叠加和协作效应，在应用效果上较单独使用益生素或益生元更佳.本文主要综述了益生素、益生元和合生元的概念、生理功能及其应用，并简要讨论了这些功能性食品的安全性及其未来的发展趋势。     

Effect of probiotic Lactobacillus casei Zhang on fermentation characteristics of set yogurt

The effect of four inoculation levels of Lactobacillus casei Zhang (0.001, 0.01, 0.1 and 1.0 g/100 g) on the fermentation characteristics of set-style yogurt, and the changes in viable counts of lactic acid bacteria, pH value, syneresis, apparent viscosity, sugar and organic acid contents were determined during fermentation and storage over 21 days. The presence of 0.001 to 0.01 g/100 g L. casei Zhang did not affect the growth of the yogurt strains, and the yogurt inoculated with 0.00 1 g/100 g of L. casei Zhang had the highest apparent viscosity among the samples. However, a high inoculated level of L. casei Zhang (1.0 g/100 g) resulted in yogurts with inferior quality.     

Prevention and Control of Diseases by Use of Pro- and Prebiotics (Synbiotics)

Probiotics are microorganisms (bacteria or yeasts) that can reestablish and recolonize the human intestinal micro flora to give beneficial effect to a host. Prebiotics are the food ingredients that are nondigestible and affect the consumer by encouraging the number and activity of beneficial but selective colonic bacteria. The probiotics perform more efficiently in the presence of prebiotics, with the enhanced beneficial potential of live microorganisms having additional benefits of the prebiotic. Due to the concept, recently much research attention is focused on the combined use of probiotics and prebiotics, generally known as synbiotics, to get their synergistic health properties. This article provides an overview of possible synbiotic combinations, and their mode of action and health benefits upon consumption. In addition, research trends are also elaborated.     

Developing a prebiotic yogurt: Rheological,physico-chemical and microbiological aspects and adequacy of survival analysis methodology

The addition of prebiotics such as oligofructose to yogurt can result in a product with consumer benefits, since they stimulate growth of benefic bacteria present in the intestine and also provide a low calorie product, since one can add less sugar to the formulation due to their sweetening power. This work aimed to evaluate the effect of increasing concentrations of oligofructose addition on physicochemical, rheological and microbiological characteristics of non-flavored yogurt. Furthermore, it was investigated the reaction of consumers with the use of the survival analysis methodology. The addition of oligofructose showed no influence on the pH, proteolysis or the viability of Streptococcus thermophilus or Lactobacillus bulgaricus during 28 days of refrigerated storage (p > 0.05). According to rheological measurements the yogurt supplemented with oligofructose was characterized as a weak gel, showing thixotropic and pseudoplastic behavior. Survival analysis was used to investigate consumer responses with respect to different levels of supplementation of plain yogurt with oligofructose (0%, 2%, 4%, 6% and 8% wt. v⁻¹). Using the survival analysis and considering a rejection by 25% of the consumers, the level of oligofructose that can be added to the yogurt was shown to be 2.58% wt. v⁻¹.     

海洋生物新材料中益生元的开发与应用

海洋益生元主要包括一些功能性低聚糖、微藻及天然产物等,具有调节蛋白质、脂肪和矿物质代谢以及调节免疫功能的作用.本文介绍了海洋生物新材料中一些主要的新益生元物质例如螺旋藻、甲壳低聚糖等的研究现状,与陆源益生元物质作了比较,讨论了其特殊的免疫激活和风味改善等作用,并对海洋生物新材料中益生元物质的开发作了展望.可以预见,从海洋生物新材料中将不断开发出能满足人类健康需求的丰富多样的益生元物质。     

The potential effect of FOS and inulin upon probiotic bacterium performance in curdled milk matrices

Inulin and fructooligosaccharides were studied for their prebiotic effect upon growth/survival of probiotic bacteria and technological potential in probiotic food processing, via characterization of glycolysis, proteolysis and lipolysis in curdled milk matrices; the ultimate goal is the manufacture of synbiotic cheeses. Prebiotic compounds did not significantly affect growth/viability of all strains studied, except Lactobacillus acidophilus La-5. Proteolysis indices revealed considerable casein degradation in probiotic and synbiotic matrices inoculated with Bifidobacterium lactis B94 and Lactobacillus casei-01; lower values were achieved in those inoculated with L. acidophilus La-5, yet a synbiotic effect was apparent in NPN values. Lipolysis was not extensive over storage, irrespective of matrix type; however, interesting differences in terms of the qualitative free fatty acids profile were observed. CLA isomers, and α-linolenic and γ−linolenic acids were detected upon 15 d of ripening of all inoculated matrices. Principal component analysis was able to discriminate the various matrices according to degree of maturation, throughout the ripening period. Microbiological and biochemical parameters unfolded a very good technological potential, especially of B. lactis B94 and L. casei-01, to produce novel types of functional dairy matrices - although extrapolation to actual cheeses should still be done with care, because e.g. syneresis was not considered.     

The influence of additives on the rheological and sensory properties of nonfat yogurt

In this work, response surface methodology was applied to a study of the effects of the addition of skim milk powder and stabilizers on the apparent viscosity and sensory attributes of nonfat yogurt. The addition of stabilizers has been shown to produce a significant effect on sensory attributes, while high concentrations of xanthan and guar gum are seen to decrease the overall acceptability of the yogurt, with gelatin producing the higher apparent viscosity and consistency. The correlation among apparent viscosity, which is an instrumental measurement, and consistency, which is a sensory evaluation, was 0.72.     

Influence of calcium fortification on sensory, physical and rheological characteristics of fruit yogurt

There has been great demand of calcium fortified dairy products as they can serve as an ideal vehicle for carrying extra calcium to fulfill the nutritional needs but there is need to generate information on the effect of fortification of calcium on the physical properties of these products. In the present study, the calcium enriched mango yogurt was prepared after fortification of pasteurized yogurt mix with 50 mg Ca/100 ml of calcium lactate, this level selected from a preliminary study of sensory evaluation. Fortification of yogurt with calcium lactate at this level significantly (P<0.005) increased the water holding capacity (WHC) by 2.99% on 1st day of storage. WHC of calcium fortified fruit yogurt was higher than control fruit yogurt on 7th and 14th day of storage. Measurements performed on slowly stirred samples (flow curves and final apparent viscosity) showed that calcium-enriched fruit yogurt had stronger structures. Calcium fortified fruit yogurt showed less shear thinning behavior as compared to control. Also, apparent viscosity measurements at constant shear rate showed a significantly (P<0.05) less decrease in initial apparent viscosity in calcium fortified fruit yogurt. However, no statistically significant (P>0.05) difference was observed in tan δ values of control and calcium fortified fruit yogurt indicating similar nature of bonds involved in the gel structure formation of both the yogurt samples. The more firm structure of the calcium fortified fruit yogurt is thus attributed to the higher extent of colloidal calcium phosphate cross-linking between casein micelles due to increased calcium content by fortification. Also flavor, color, and body and texture scores of control and calcium fortified fruit yogurt did not show any significant difference (P>0.05).     

益生菌与益生元对人体肠道正常菌群的调节作用

为了解益生菌与益生元对人体肠道菌群的调节作用，选择符合试验要求的成年志愿者，分别食用益生菌和益生元，其中益生菌组150人，益生元组200人，男女各半。结果表明：益生菌与益生元均可增加人体肠道内的双歧杆菌和乳杆菌：均可使肠道内肠杆菌数量下降。但益生菌组双歧杆菌和乳杆菌增加的数量及肠杆菌和拟杆菌降低的数量均高于益生元组，说明在该试验条件下，益生菌组的效果要好于益生元组。     

酸奶中苯及苯同系物气相色谱-质谱检测 方法的建立

目的建立适合于检测酸奶中微量苯及其同系物的顶空固相微萃取-气质联用检测方法。方法采用顶空固相微萃取进行目标物分离富集,用萃取头进行固相微萃取后上机测定,顶空固相微萃取条件为样品装液量10 mL,NaCl添加量2.0 g,转子设定转速为5000 r/min,萃取时间20 min,萃取温度60℃。采用相对校正因子内标法对苯系物进行定量分析。结果以氯苯为内标物,苯、甲苯、对(间)二甲苯、邻二甲苯、苯乙酮的相对校正因子依次为:10.87、3.07、0.34、0.55、4.867,检出限依次为:2、0.05、0.01、0.01、0.05μg/L(信噪比S/N≥3),定量限依次为:5、0.12、0.05、0.06、0.15μg/L(信噪比S/N≥10)。苯系物的加标回收率为82%~104%,相对标准偏差(RSD)均小于4%。采用此方法对6种酸奶样品进行检测,苯系物的含量在4~24μg/L范围之间。结论该方法灵敏度高,准确性好,能够很好的检测酸奶中的苯系物含量。     

2017～2019年三亚市县冷冻饮品微生物检测结果分析

目的 分析近三年三亚市县冷冻饮品的检测结果,微生物污染是制约冷冻饮品质量安全的主要因素。方法 根据国家食品安全监督抽检和风险监测工作实施要求,从4个市县10家生产企业抽取50批冷冻饮品,按国标GB 2759-2015食品安全国家标准 冷冻饮品和制作料检测。结果 3批菌落总数超标;5批大肠菌群超标;菌落总数和大肠菌群不合格率分别是6.0%和10%,说明冷饮饮品指示菌超标问题较严重。结论 微生物污染是影响产品质量合格的主要因素,建议企业加强卫生管理,对制作过程卫生及储运条件把控,确保冷冻食品安全,建议监管部门对不合格产品继续加强监管力度,以确保食品安全。     

Survival of Escherichia coli O157:H7 in yogurt drink, plain yogurt and salted (tuzlu) yogurt: Effects of storage time, temperature, background flora and product characteristics

The survival of Escherichia coli O157:H7 at 4 and 22°C in yogurt drink, plain yogurt and salted yogurt (yogurt native to Hatay, Turkey) was studied. Total aerobic plate count (TPC), total mould and yeast count, pH and titratable acidity during the storage period were measured. pH and TPC count of the samples at 22°C were significantly higher than those of samples at 4°C ( P <  0.01). E. coli O157:H7 survived in the products at both 4 and 22°C, whereas survival of E. coli O157:H7 was significantly lower at 4°C than at 22°C ( P <  0.05). Multiple linear regression models were used to determine factors affecting the survival of E. coli O157:H7.     

气相色谱法检测茶饮料中4种残留农药

目的 建立利用固相萃取-气相色谱法同时测定茶饮料中乐果、腐霉利、哒螨灵、高效氯氰菊酯4种农药的分析方法.方法 考察了提取剂、固相萃取柱对检测的影响.样品采用乙腈提取,经弗罗里硅土柱净化,色谱柱采用Rtx-5(30 m×0.25 mm×0.25 μm).结果 4种农药的线性良好,相关系数为0.999 4～0.999 9,加标回收率为88.76％ ～ 102.4％,相对标准偏差小于5％,检测限在0.001～0.01mg/kg之间.结论 该操作简单,节约了时间与有机溶剂,为饮料中多残留分析提供参考.