功能性开菲尔牛奶酒最佳发酵条件的研究

本文利用开菲尔粒中分离的酵母菌和乳球菌采用两步发酵法研制开菲尔牛奶酒。针对影响牛奶酒制品最终品质的三个因素,采用三因素三水平L9(34)正交试验确定了功能性开菲尔牛奶酒的最佳发酵条件。成品开菲尔牛奶酒口感细腻、酸度适中,风味柔和,有浓郁的醇香和酯香味。     

功能性开菲尔牛乳酸马奶酒的最佳发酵条件

本文针对影响开菲尔酸马奶酒制品最终品质的三个因素,采用三因素三水平[L9(34)]正交实验 设计,确定了从开菲尔粒中分离的酵母菌和乳球菌为生产发酵剂的功能性开菲尔酸马奶酒的最佳发酵 条件。     

开菲尔粒增殖的最佳工艺条件的研究

本文从影响开菲尔粒增殖的三个因素入手，利用三因素三水平的正交实验设计，探索出影响开菲尔粒增殖的最佳工艺条件；同时，确定了开菲尔粒在每一代的增殖速度及清洗对开菲尔粒增殖的影响，具有一定的理论和较强的现实意义。     

开菲尔牛奶啤酒最佳发酵条件的研究

开菲尔奶啤酒是以牛奶和麦汁为原料,采用开菲尔粒复合菌体进行发酵而制成的啤酒。本实验研究了开菲尔牛奶啤酒的发酵工艺,用四因素三水平正交实验L9(34),确定了最佳发酵条件为:发酵时间7d,发酵温度28℃,牛奶∶麦汁为2∶8。     

Box-Behnken中心组合设计研发新型开菲尔乳酒

为改善传统开菲尔乳酒的感官特性,试验以开菲尔菌粒、酿酒酵母为发酵剂,牛奶、白砂糖为原料进行新型开菲尔乳酒的酿制。在单因素试验的基础上,选取白砂糖添加量、开菲尔菌粒接种量、酿酒酵母接种量及发酵时间4个因素,以开菲尔乳酒的感官评分与乙酸乙酯的含量为响应值,进行响应面试验。结果表明:新型开菲尔乳酒最优的发酵工艺条件为:白砂糖添加量12.9%、开菲尔菌粒接种量1.2%、酿酒酵母接种量0.4%、发酵时间115 h;在此条件下可获得感官评分为88.1分、乙酸乙酯含量为0.95 g/L的新型开菲尔乳酒。     

功能性开菲尔酸奶复合发酵剂的研制

本文利用开菲尔粒中分离的乳球菌和乳杆菌采用混合发酵法研制开菲尔酸奶复合发酵剂。针对影响发酵剂品质的三个因素，采用三因素三水平L9（3^4）正交试验确定了功能性开菲尔酸奶复合发酵剂的最佳发酵条件：球菌和杆菌的接种比例为2：1，接种量为3％，发酵温度为43℃。用此发酵剂制作成品酸奶，凝乳时间短，凝固结实，口感细腻，甜酸度适中，有浓郁的酯香风味。     

开菲尔菌粒与酿酒酵母混合发酵优化开菲尔乳酒生产工艺

为寻求开菲尔乳酒的最佳酿造工艺,试验以开菲尔菌粒、酿酒酵母为发酵剂,牛奶、白砂糖为原料进行开菲尔乳酒的酿制。在单因素试验基础上,选取白砂糖添加量、开菲尔菌粒接种量、酿酒酵母接种量及发酵时间4个因素,以开菲尔乳酒的感官评分为响应值,采用Box-Behnken中心组合试验设计建立数学模型,进行响应面试验。结果表明,开菲尔乳酒最优的发酵工艺条件为:白砂糖添加量12.6%、开菲尔菌粒接种量1.2%、酿酒酵母接种量0.4%、发酵时间4.9 d;在此条件下可获得色泽微黄透明、奶香与酒香和谐、酒体丰满圆润的开菲尔乳酒,感官评分为84.6分。     

开菲尔紫苏粕发酵乳工艺及稳定性研究

为研究和探讨开菲尔紫苏粕发酵酸乳的最优发酵条件,试验以开菲尔为发酵剂对添加紫苏粕酶解液的牛乳进行发酵,采用单因素和正交试验优化发酵工艺参数。结果表明,开菲尔紫苏粕发酵乳最佳发酵工艺为:蔗糖添加量10%、开菲尔接种量10%、紫苏粕酶解液添加量25%、培养时间12 h。在此发酵条件下进一步研究和探讨CMC-Na、蔗糖酯和卡拉胶这三种稳定剂添加量对开菲尔紫苏粕发酵乳稳定性的影响。试验结果表明:开菲尔紫苏粕发酵乳最佳稳定条件为:CMC-Na添加量0.5%、蔗糖脂肪酸酯添加量0.5%、卡拉胶添加量0.07%。     

利用开菲尔粒制作发酵乳饮料工艺技术研究

采用响应面法对开菲尔发酵乳饮料工艺进行优化。在单因素试验基础上,选择开菲尔粒接种量、发酵时间和发酵温度为自变量,以发酵乳饮料酸度及感官评价值确定的复合指标为响应值,利用Box-Benhnken中心组合方法进行三因素三水平的试验设计,并做响应面分析,建立数学回归模型。结果表明,曲面回归方程拟合性好,利用开菲尔粒制作发酵乳饮料的最优工艺条件为:开菲尔的接种量2.8%,发酵时间22 h,发酵温度22℃。在优化条件下经3次重复试验验证,预测值与验证试验平均值接近。说明该工艺稳定、可行。     

中华开菲尔发酵乳制品的研制

采用食品微生物培养与发酵技术研制中华开菲尔(Kefir)发酵乳制品.研究了中华开菲尔发酵剂的制备方法,探讨了影响母发酵荆培养的有关因素,包括接种比例,培养温度和时间,开菲尔粒大小等;分别采用滤除开菲尔粒后的培养物为发酵剂和直接使用冻干的开菲尔母发酵刺两种方法研制中华开菲尔发酵乳制品.经研究和产品试制,已初步确定了中华开菲尔发酵剂的制备工艺条件,也初步确立了中华开菲尔发酵乳制品的发酵生产工艺过程.试制产品的感官与理化指标符合预期要求,毒理试验结果为无毒.     

Microbiological study of lactic acid bacteria in kefir grains by culture-dependent and culture-independent methods

Lactic acid bacteria (LAB) in different original kefir grains were first assessed using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) by a culture-dependent way, and were further confirmed by DNA sequencing techniques. Results indicated that a combined method of cultivation with PCR-DGGE and subsequent DNA sequencing could successfully identify four LAB strains from three kefir grains from Taiwan (named Hsinchu, Mongolia and Ilan). Lactobacillus kefiri accounted, in the three kefir grains, for at least half of the isolated colonies while Lb. kefiranofaciens was the second most frequently isolated species. Leuconostoc mesenteroides was less frequently found but still in the three kefir grains conversely to Lactococcus lactis which based on culture-dependent isolation was only found in two of the kefir grains. It was interesting to find that all three kefir grains contain similar LAB species. Furthermore, the DGGE as a culture-independent method was also applied to detect the LAB strains. Results indicated that Lb. kefiranofaciens was found in all three kefir grains, whereas Lb. kefiri was only observed in Hsinchu kefir grain and Lc. lactis was found in both Mongolia and Ilan samples. Two additional strains, Pseudomonas spp. and E. coli, were also detected in kefir grains.     

Diversity and functional characteristics of lactic acid bacteria from traditional kefir grains

Traditional kefir grains were collected from distinct parts of Turkey, and their microbial profile was determined. A wide bacterial biota was observed formed by distinct lactic acid bacteria (LAB) in which Lactococcus lactis strains appeared to be dominant. Yeast species were also identified in kefir grains. Significant levels of antifungal and antibacterial activities were monitored in kefir isolates. All tested LAB produced an exopolysaccharide (EPS) containing glucose and galactose, and some strains formed a fructan‐type EPS. Importantly, low levels of antibiotic resistance were observed among the kefir isolates.     

Determination of lactic microflora of kefir grains and kefir beverage by using culture-dependent and culture-independent methods

Abstract: In this study, we investigated the bacterial compositions of kefir grains and kefir beverages collected from different regions of Turkey by using culture‐independent and culture‐dependent methods. In the culture‐independent detection, 10 different species of bacteria were detected in total by using the polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) analysis of the 16S rRNA gene V3 region. Among these species, Lactobacillus kefiranofaciens was the most dominant one in the kefir grains, while Lactococcus lactis was found to be significantly prevalent in the kefir beverages. In the culture‐dependent detection, the primary differentiation and grouping of the isolates from kefir beverages and kefir grains were performed using repetitive sequence‐based PCR (rep‐PCR) fingerprinting, and the results were validated by 16S rDNA full‐length sequencing. According to the results of culture‐dependent methods, the most frequently isolated species were L. lactis, Leuconostoc mesenteroides, and Lactobacillus kefiri, respectively. Only 3 species, which are L. lactis, Lactobacillus acidophilus, and Streptococcus thermophilus, were detected with both culture‐dependent and culture‐independent methods. This study showed that the combination of both methods is necessary for a detailed and reliable investigation of microbial communities in kefir grains and kefir beverages. Practical Application: Due to their artisan‐ and region‐dependent microflora, kefir products can be a source of interesting lactic acid bacteria, either new taxa or strains with specific functional properties, which might be used for the development of new starter cultures and innovative food products. Therefore, an increasing demand exists for new strains that show desirable effects on the product characteristics Artisan dairy products are a candidate source of such microorganisms. For this reason, in this study, the bacterial compositions of kefir grains and kefir beverages obtained from different regions of Turkey were studied using culture‐dependent and culture‐independent molecular methods.     

Review: functional properties of kefir

Kefir is a unique cultured dairy product due to combined lactic acid and alcoholic fermentation of lactose in milk. Kefir is produced by microbial activity of "kefir grains" which have a relatively stable and specific balance of lactic acid bacteria and yeast. Due to the claimed health benefits of kefir which include reduction of lactose intolerance symptoms, stimulation of the immune system, lowering cholesterol, and antimutagenic and anticarcinogenic properties, kefir has become an important functional dairy food and consequently, research on kefir has increased in the past decade. In the following review, recent studies on the functional properties of kefir are reviewed.     

Short communication: Physicochemical features and microbial community of milk kefir using a potential probiotic Saccharomyces cerevisiae KU200284

The aim of this study was to analyze the β-glucan contents, physicochemical features, and microbial communities in milk kefir prepared using Saccharomyces cerevisiae KU200284 isolated from cucumber jangajji, a fermented vegetable commonly eaten in Korean. Three types of milk kefir were manufactured, with (1) activated kefir grain, (2) activated kefir grain with commercial S. cerevisiae BOF, and (3) activated kefir grain with S. cerevisiae KU200284. β-Glucan contents of milk kefir using kefir grain and kefir grain with S. cerevisiae strains BOF and KU200284 were 8.29, 8.59, and 8.57%, respectively. The pH, titratable acidity, viscosity, Brix level, and alcohol contents of milk kefir using kefir grain with S. cerevisiae strains were acceptable compared with milk kefir using only kefir grain. In milk kefir produced using kefir grains and S. cerevisiae strains, 16S rRNA reads showed representative strains of Lactobacillus kefiranofaciens (>72% relative abundance) and Acetobacter fabarum (>16% relative abundance). In particular, milk kefir using kefir grain with S. cerevisiae KU200284 had the highest relative abundance of L. kefiranofaciens. In addition, the internal transcribed sequence (ITS) rRNA reads in tested milk kefir showed representative strains of Kluyveromyces marxianus (>52% relative abundance) and Saccharomyces cerevisiae (>16% relative abundance). In contrast, milk kefir using S. cerevisiae strains had higher relative abundance of S. cerevisiae (>37%). The β-glucan production, physicochemical properties, and microbial community profiling indicate that S. cerevisiae KU200284 could be used in functional dairy products as a starter culture.     

藏灵菇酸奶发酵工艺优化及抑菌特性研究

以藏灵菇为唯一发酵剂,通过正交试验探讨藏灵菇酸奶发酵的最佳生产工艺和藏灵菇菌块、发酵液的抑菌特性.结果表明,藏灵菇发酵酸奶的最佳生产工艺为发酵温度37℃,接种量5％,发酵时间16h,牛奶装液量40mL;藏灵菇菌块和发酵液对金黄色葡萄球菌有明显的抑菌作用.此外,藏灵菇菌块对大肠杆菌有较明显的抑菌作用.     

Effect of different growth conditions on biomass increase in kefir grains

Kefir is a functional dairy product and the effects of kefir consumption on health have been well documented. Kefir grains have naturally high numbers of lactic acid bacteria and yeasts and are used in manufacturing kefir. The biomass of kefir grains slowly increases after successive fermentations. The effects of adding whey protein isolate, modified whey protein (MWP, fat replacer; Carbery Inc., Cork, Ireland), or inulin to milk and different atmospheric conditions (ambient or 6% CO₂) during fermentation on the increase in biomass of kefir grains were investigated. Reconstituted milks (10% milk powder) enriched with whey protein isolate (2%), MWP (2%), and inulin (2%) were inoculated with kefir grains and fermented in ambient and 6% CO₂ incubators at 25°C until a final pH of 4.6 was reached. Biomass increments of kefir grains were determined weekly over 30 d. Lactic acid bacteria and yeast contents of kefir grains were also determined. The highest biomass increase (392%) was found in kefir grains grown in milk supplemented with whey protein isolate under ambient atmospheric conditions. Application of CO₂ did not provide a significant supporting effect on the biomass of kefir grains. Addition of MWP significantly accelerated the formation of kefir grain biomass (223%). The use of whey protein isolate, MWP, or inulin in milk did not cause any adverse effects on the microbial flora of kefir grains.     

西藏开菲尔发酵乳中挥发性风味物质分析

采用顶空固相微萃取结合气相色谱-质谱联用技术对两种不同地理来源西藏开菲尔粒的发酵乳中挥发性化合物进行检测,并结合化合物的阈值计算香气活力值(odor activity value,OAV)。结果表明,两种发酵乳中共鉴定出挥发性化合物30种,酸类和醇类在两种发酵乳中均占优势。两种西藏开菲尔粒的产挥发性风味物质能力存在差异,发酵乳B中挥发性化合物的种类和总含量均高于A。酯类是两种发酵乳中最重要的香气贡献化合物,辛酸乙酯在两种发酵乳中香气贡献最高。不同类别化合物对两种发酵乳的总香气贡献存在差异,醇类对发酵乳A的总香气贡献高于B,酯类、酸类和酮类对发酵乳B的总香气贡献高于A。     

Characterization of Polysaccharide and Volatile Compounds Produced by Kefir Grains Grown in Soymilk

ABSTRACT: The characteristics of polysaccharides isolated from milk and soymilk kefir grains, and the composition of flavor and volatile compounds from soymilk kefir were investigated. Soymilk kefir grains revealed lower polysaccharide content than milk kefir grains, with a polysaccharide profile consisting primarily of glucose and galactose, with the former predominating. The apparent molecular weight of the polysaccharide was estimated at 1.7 × 10⁶ Da. In comparison to nonfermented soymilk, the concentrations of the key volatile compounds for soymilk kefir (such as acetaldehyde, acetone, diacetyl, and ethanol) increased, while n-hexanal concentration decreased. The acetaldehyde level for soymilk kefir was slightly higher, but levels for the other volatile compounds were lower than for milk kefir.     

Protective action of Lactobacillus kefir carrying S-layer protein against Salmonella enterica serovar Enteritidis

Eight Lactobacillus kefir strains isolated from different kefir grains were tested for their ability to antagonize Salmonella enterica serovar Enteritidis (Salmonella enteritidis) interaction with epithelial cells. L. kefir surface properties such as autoaggregation and coaggregation with Salmonella and adhesion to Caco-2/TC-7 cells were evaluated. L. kefir strains showed significantly different adhesion capacities, six strains were able to autoaggregate and four strains coaggregated with Salmonella. Coincubation of Salmonella with coaggregating L. kefir strains significantly decreased its capacity to adhere to and to invade Caco-2/TC-7 cells. This was not observed with non coaggregating L. kefir strains. Spent culture supernatants of L. kefir contain significant amounts of S-layer proteins. Salmonella pretreated with spent culture supernatants (pH 4.5-4.7) from all tested L. kefir strains showed a significant decrease in association and invasion to Caco-2/TC-7 cells. Artificially acidified MRS containing lactic acid to a final concentration and pH equivalent to lactobacilli spent culture supernatants did not show any protective action. Pretreatment of this pathogen with spent culture supernatants reduced microvilli disorganization produced by Salmonella. In addition, Salmonella pretreated with S-layer proteins extracted from coaggregating and non coaggregating L. kefir strains were unable to invade Caco-2/TC-7 cells. After treatment, L. kefir S-layer protein was detected associated with Salmonella, suggesting a protective role of this protein on association and invasion.