喀什帕米尔高原牦牛乳传统发酵生奶酪中微生物多样性及分子鉴定

目的:研究喀什帕米尔高原塔县地区传统牦牛乳发酵生奶酪中微生物的多样性和菌群结构。方法:从帕米尔高原区不同牧民家庭中采集6份生奶酪样品,采用高通量测序技术分析其微生物多样性。通过纯培养方法分离传统牦牛乳发酵生奶酪样品中的菌种,采用传统分类与16S rDNA序列测定和26S rDNA D1/D2间隔区序列测定方法对分离的细菌和酵母菌进行种属鉴定。结果:通过细菌的16S rDNA基因V3-V4区测序,共获优化序列945432。通过真菌的ITS区域测序,共获优化序列1302962。在属水平上,优势细菌属为乳杆菌属和链球菌属,优势真菌属为克鲁维酵母属、有孢圆酵母属、伊萨酵母属和未分类的真菌类群。根据主坐标轴分析,6份样品的群落结构间既有相似性又有差异性。在MRS和MC培养基中共分离52株细菌,在YGC培养基上共分离46株酵母菌,通过细菌16S rDNA序列和真菌26S rDNA D1/D2隔间区序列分析,将52株细菌归为7个属11个种,分别是耐久肠球菌、粪肠球菌、热带芽孢杆菌、蜡样芽孢杆菌、类副粘杆菌、希腊假单胞菌、副干酪乳杆菌、鸡乳杆菌、霍氏肠杆菌、细黄链霉菌、表皮葡萄球菌。将46株酵母菌归为8个属9个种,分别是解脂耶氏酵母、诞沫假丝酵母、发酵毕赤酵母、库德毕赤酵母、普兰久浩酵母、异常威克汉逊酵母、马克思克鲁维酵母、东方伊萨酵母、酿酒酵母。本研究首次对帕米尔高原地区传统发酵乳制品中微生物资源进行分析,其结果可为该地区发酵乳制品的研究提供参考。需要进一步更系统的的深入研究挖掘。

北疆传统发酵生奶酪中乳酸菌的耐受性及益生特性测定

【背景】北疆乳制品中生奶酪作为发酵乳制品,其中有多种微生物的参与,是优质食品级微生物的宝贵来源,然而其中蕴含的丰富的微生物资源也面临着流失。【目的】研究已筛选出的41株乳酸菌的生长曲线变化规律,并对其在低pH环境的耐酸特性及益生特性进行分析。【方法】通过人工模拟胃肠液和含0.3%、0.5%、1.0%浓度牛胆盐溶液培养,对从生奶酪中分离鉴定的41株乳酸菌菌株进行人工胃肠液、牛胆盐耐受性试验。【结果】41株乳酸菌中有6株乳酸菌(编号为QM-5、QM-27、UM-12、UM-18、NM-11和NM-14)均能在pH值分别为2.0、2.5、3.0、3.5、4.0时生长较好,在pH 2.0的环境下也保持一定程度的生长。菌株存活率大于50%,乳酸菌含量为108 CFU/mL以上。从生奶酪分离的乳酸菌有极强的耐酸、耐胆盐特性,可以预测在胃肠道环境生存。41株菌对大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)和枯草芽孢杆菌(Bacillus subtilis)均有抑制作用。【结论】通过比较耐酸性、胃肠道模拟、胆盐耐受性和抑菌特性等实验结果,初步选出了3株综合耐受性良好的优势菌株。

Obtaining Cheese with Milk Mixture and Inca Peanut （Plukenetia Volubilis）

The Inca peanut, a plant native to the Peruvian Amazon, has an important nutritional contribution to 53% oil and 33% protein [ 1, 2], high content of Omega 3 and 6, Vitamin E. Recent research suggests the nutritional and therapeutic significance of consumption for the control of free radicals [3], being an alternative food to reduce nutritional deficiencies of macro and micronutrients in the diet. The results show that the cheese made from a mixture of milk and Inca peanut （70：20 v/v） 0.15 M of Ca sulphate is of firm consistency, with a clotting time of 9 min and yields 14.56% at 80 ℃, is similar to fresh milk cheese sensory characteristics determined by the test of acceptability. Respect to nutrition cheeses present values of protein and fat （16.3% and, 25.05%, respectively）. Sensory evaluation process cheese 70：30 v/v showed an acceptance of 67% relative to a commercial cheese. The texture profile of the finished product, applying a deformation of 30%, have hardness values for 1.88 N, elasticity 0.08, cohesiveness 0.86, adhesiveness 0.36, gumminess 1.62 and chewiness 0.13.

Production of High Quality Functional Labneh Cheese Using Exopolysaccharides Producing Encapsulated Lactobacillus Bulgaricus

Production of polysaccharides by lactic acid bacteria is vital and its technology is very important, too in dairy study. The selection ofexpolysaccharides producing encapsulated Lactobacillus bulgaricus in alginate gel and the factors affecting the production of polysaccharides such as time, temperature, pH and the growth with Streptococcus thermophilus were studied, pH 5.5 and temperature 35℃/18hr were found to be optimal for exopolysaccharides production by encapsulated L. bulgaricus and free culture yielding 600 mg/L and 380 mg/L respectively. Co-culturing L. bulgaricus with S. thermophilus increased exopolysaccharides production at 35 ℃/18hr to 660 mg/L by encapsulated cells and 400 mg/L by free culture. Results of this study were applied in the manufacture of Labneh cheese vitally containing probiotic species ofL. acidophilus, L. gasseri, L. johnsonii and protection of these bacteria by polysaeeharide produced encapsulated L. bulgaricus. The use of exopolysaccharides producing encapsulated L. bulgaricus and probiotic bacteria can provide acceptable quality to functional Labneh. This product can be used as therapeutic and diabetic milk product with highly acceptable qualities. It is noted that all of the results are the means of triplicate experiments.

Characterization of Fresh Cheese with Addition of Probiotics and Prebiotics

Sensorial and microbiological characteristics of a Brazilian fresh cheese samples with Bifidobacterium animalis subps. lactis as well as samples with this probiotic and polydextrose, a prebiotic ingredient, were evaluated. The addition of this microorganism was studied as： （1） lyophilized probiotic added to cheese curd and （2） by using milk previously fermented by this probiotic to produce the cheese. Cheese samples were microbiologically characterized after 0, 7, 14, 21 and 28 days of storage at a temperature of 4 ℃. The microbiological analyses conducted were quantification of total lactic acid bacteria, mesophilic microorganisms, Bif. animalis subps, lactis, coliforms at 30 ℃ and 45 ℃. Affective sensory test was conducted for two different cheese samples （with probiotic and with probiotic and prebiotic） as well as for control one week after manufacturing date. Cheese samples provided acceptable results for coliform counts at 30 ℃ and 45 ℃ in compliance with legislation. The cheese samples produced using milk fermented by probiotic showed counts of 107-108 CFU/g after 28 days of storage, which assures functional property for this product to be claimed.

Microbiological Quality of Traditional Romanian Cheeses from the Rucar-Bran Pass and its Surrounding Regions

The traditional products＇ quality is often recognized based on organoleptic characteristics without considering the microbiological features, which bring a special note to these products＇ composition and aroma. It is especially the case of cheeses, whose taste varies from one geographical region to another depending on specific flora and technological processes used in traditional systems. The paper tries to bring new elements on the methodology used in order to elucidate some aspects related to traditional products＇ quality, products obtained by private producers in the Bra^ov district （Rucar-Bran pass）. Covasna district and Bistrita Nasaud district were analyzed organoleptically, physico-chemically and microbiologically samples of fresh cow cheese, soft cow cheese, smoked curd cheese, gaiter cheese and cottage cheese taken within the strategic and self-control program from individuals in the rural areas of Fundata, Poiana Sibiului, Sirnea, Pfirliu, Cristian, Cincaor, Sohodol, Ranov, Brarov, Bod, Roadea, Harnan, Prejmer, Soars, Rupea, Lunca Calnicului, Balanii, Mari, Bran, Buzaiel, Bacut, H~.lchiu, Fagraa, Moeciu de Sus, Purcaareni, Bran-Simon, Venelia de Jos, Vama Buzatului, lntorsura Buzaului, Vatrghia and Sita Buzaului.

ahospholipase Applications in Cheese Production

Phospholipase is an enzyme that hydrolyzes phospholipids releasing a variety of products, like for example lyso-phospholipids, free fatty acids, di-acylglycerols, choline phosphate and phosphatidates, depending on the site of hydrolysis. In cheese production, lysophospholipids act as surface-active agents in the cheese curd, helping emulsification of water and fat during processing and reducing syneresis. Phospholipases are more specific and have little or no activity toward di- or triglycerides. As a result of phospholipid hydrolysis, flavor defects do not occur due to the main formation of palmitic, oleic, and stearic acids, which are non-volatile short chains fatty acids. According to the scientific studies the use of phospholipase is able to increase the yield of cheese and reduce the environmental impacts of cheese production. Protein and fat largely determine cheese yield. Depending on the milk composition, 75% to 78% of milk protein and 85% to 95% of milk fat are entrapped in the cheese curd. The remaining protein and fat are lost in the whey and, to a lesser extent, in the brine. Crucially in the production of pasta filata cheese fat losses occur in the hot stretching step, where the fresh curd is molded and stretched in hot water. The lysophospholipid-casein complexes should be studied to understand the mechanism leading to cheese yield improvements.

Some Properties of Traditional Whey Cheese （Mud Cheese） Produced in Turkey

In this study, the basic composition and microbiological properties of traditional Mud （Gamur） cheese produced in Tire region of Turkey was evaluated. The total solids, fat, protein, water soluble nitrogen （WSN）, acid value of cheese, fat, salt, titratable acidity, pH levels in Mud cheeses were variable according to whey characteristics used in their production. Wide variations were found in the total bacteria, Coliform bacteria, Staphylococcus aureus, yeast-mould, Lactobacillus spp. and Streptococcus spp. counts of cheese samples. The presence of coliforms, Staph. aureus and yeast-moulds indicate poor hygienic conditions of cheese production.

Effect of Fortifying Camel Milk with Sheep Milk on the Processing Properties, Chemical Composition and Acceptability of Cheeses

This study investigates the properties of cheeses made from camel milk, sheep milk and their mixtures. Cheeses were made using Camifloc enzyme as a coagulant after addition of calcium chloride. Camel＇s milk was mixed with sheep＇s milk at the levels of 25%, 50% and 75%. Then, the cheeses were stored for 21 days in the whey at room temperature （37-40 ~C）. The study revealed that fortifying camel＇s milk with sheep＇s milk improved the processing properties of camel milk for cheese making. The addition of 50% sheep＇s milk to camel＇s milk reduced the coagulation time to about 46.15%. The addition of 25%, 50% and 75% sheep＇s milk to camel＇s milk revealed yield of 13.76%, 21.33% and 26.2%, respectively. However, the cheese made from pure camel＇s milk and sheep＇s milk revealed yield of 10.66% and 23.53%, respectively. There were significant （P 〈 0.001） differences in total solids, protein, fat, ash, acidity and overall acceptability among the cheeses made from different types of milk. The cheeses made from camel＇s milk after addition of 75% and 50% sheep＇s milk were the most acceptable compared to other cheeses. Hence sheep＇s milk could be added to camel＇s milk for improvement of cheese properties.

Interaction between Dairy Yeasts and Lactobacillus rhamnosus GG in Milk

The presence of Geotrichum candidum in fresh cheese is considered to be a contaminant and may lead to the product spoilage. The oxidative yeast Candida maltosa firstly isolated from the spoiled fruit yoghurt surface in Slovakia belongs to the yeast contaminants of fermented dairy products. The effect of the cultivation temperature and the presence of Lactobacillus rhamnosus GG on the growth of dairy spoilage yeasts in ultrapasteurized milk was studied. Addition of Lb. rhamnosus GG in milk caused partial inhibition of the yeast growth dynamics in milk. The water activity transformation of Gibson model after the temperature modification （Tw） was applied to model growth dynamics of G. candidum in pure and mixed culture, respectively： In μ_Gc=-5.0376＋2.7281 Tw-0.4217Tw^2, lnμ_CC_LGG=-6.0033＋3.2996Tw-0.5553Tw^2. The effect of different Lb. rhamnosus GG addition and the incubation temperature on the C. maltosa growth dynamics was analyzed by linear regression methodology and described by using following equations： lnGr1=-5.3674＋0.2341T＋0.2599N0-0.0032T^2-0.0492N0^2-0.0068TN0 and lnGr11=-9.5457-0.249T＋2.3823N0 ＋0.0099T^2-0.2324N0^2＋0.0098TN0 Based on the principles of predictive microbiology, the mutual microbial interactions and potential application of the lactobacillus strains in food protection are discussed.

The Survey of Microbiological Contamination of Pitcher Cheese in West Azarbayjan Province, Iran

Milk acts as a suitable peripheral culture for growth and propagation of different kinds of micro organisms. During the process of producing cheese, some micro organisms such as Escherichia coli, Coliform, Staphylococcus, Mold and Yeast may cause its contamination. In respect to the fact that pitcher cheese is produced in traditional way in different regions in West Azarbayjan, the aim of this research is examining the rate of contamination of pitcher cheese in West Azarbayjan. About 42 samples of pitcher cheese were gathered under strill condition from different parts of West Azarbayjan. In order to study microbes contamination, the samples were examined by standard microbiologic ways in laboratory from the 42 samples of pitcher cheese, four samples were contaminated by Staphylococcus aureus coagulase positive, 16 samples were contaminated by E. Coli, 21 samples by Coliform, 17 samples by mold and yeast. The producing and delivering should be controlled because of the rate of contamination in pitcher cheese and this kind of cheese should be produced in half industrial way by controlling and making special facilities for pitcher cheese producers.

Esterase Activities and Biochemical Properties of Lactic Acid Bacteria Isolated from Goat＇s Milk Cheese in Argentina

Twenty-two lactic acid bacteria （LAB） strains isolated from Argentinean goat dairy products were evaluated for its biochemical properties and esterase activities relevant to flavor development. Streptococcus thermophilus （UNSE314）, Lactobacillus （L.） delbrueckii subsp, bulgaricus （UNSE309）, L. rhamnosus （UNSE308）, L. plantarum （UNSE287, UNSE316, UNSE317） and Pediococcus pentosaceus （UNSE315） strains presented high acidifying activity. All strains tested metabolized citrate and produced diacetyl-acetoin in goat milk. Based on these results, 10 strains with the best performance in diverse technological properties were selected to determine esterolytic activity. In all evaluated strains, esterase specific activity （ESA） was detected on ct-naphthyl （ct-NA） acetate and 13-naphthyl （[3-NA） acetate, propionate, eaprylate and ct-NA butyrate. No activity was detected on [3-NA laurate. The highest values were detected when using a-NA instead of fI-NA derivatives as substrate. In Pediocoecus strains, wide variability in ESA were observed, which were species- and strain-specific. These results allow us to select strains with biochemical properties and esterase activities to design starter and adjunct cultures that contribute to flavor development during cheese ripening, thus preserving the typical organoleptic characteristics of Argentinean goat cheeses.

Probiotic properties of lactic acid bacteria isolated from traditionally fermented Xinjiang cheese

Six lactic acid bacterial （LAB） strains were isolated from traditionally fermented Xinjiang cheese and evaluated for functional and probiotic properties and potentials as starter cultures. The isolated six LAB strains com- prised Lactobacillus rhamnosus （one strain）, Lactobacillus helveticus （one strain）, and Enterococcus hirae （four strains）. All of the six strains were tolerant to acidic and bile salt conditions. Among which, the L. rhamnosus R4 strain showed more desirable antimicrobial, auto-aggregation, and hydrophobic activity. In addition, the strain L. rhamnosus R4 exhibited the highest level of free radical scavenging activity （53.78% of 1,1-dipheny1-2-picrylhydrazyl （DPPH） free radicals and 45.79% of hydroxyl radicals）. L. rhamnosus R4 also demonstrated cholesterol and triglyceride degrada- tion by 50.97% and 28.92%, respectively. To further examine the health-promoting effects of these LAB strains on host lifespan, Caenorhabditis elegans was used as an in vivo model. Worms fed LAB as a food source had significant differences in lifespan compared to those fed Escherichia coil OP50 （as a negative control）. Feeding of L. rhamnosus R4 extended the mean lifespan of C. elegans by up to 36.1% compared to that of the control. The results suggest that the strains isolated from Xinjiang fermented dairy products have high potential as starter cultures in the cheese industry.