直接使用型酸奶发酵剂的研制

我们将保加利亚乳杆菌和嗜热链球菌培养在以１．０％碳酸钙作为缓冲剂的１２％脱脂乳中，使菌体浓度最高可达５．６９×１０９个／ｍｌ，在超速冷冻高心机中，从７０００ｒｐｍ，３５ｍｉｎ，４℃使菌体得到浓缩。浓缩的菌体以添加适当保护剂的１０％脱脂乳制成菌悬浮液，经真空冷冻干燥机干燥后得到每克含活菌数为４．２×１０１０个的高活力酸乳发酵剂。本发酵剂可直接用于制备酸奶，还制备生产发酵制。     

酸奶发酵剂的研究进展

酸奶发酵剂一般由两种乳酸菌组成：嗜热链球菌和保加利亚乳杆菌。论述了酸奶发酵剂的发展现状、种类及制备方法,并对其前景进行展望。     

酸奶发酵剂的研究进展

酸奶发酵剂一般由两种乳酸菌组成：嗜热链球菌和保加利亚乳杆菌。论述了酸奶发酵剂的发展现状、种类及制备方法,并对其前景进行展望。     

冻干保护剂对复合低温乳酸菌发酵剂的影响

以青藏高原牧区分离筛选出的低温乳酸菌为研究对象,以活菌数为指标,比较了4种冻干保护剂对复合低温乳酸菌发酵剂的影响,并通过正交实验优化了其中3种较优冻干保护剂的复配配方。结果表明,复合低温乳酸菌冻干保护剂的最优组合为:甘油为8m L/L,蔗糖为10%(w/v),脱脂乳为15%(w/v),以此为保护剂冻干存活率达到了90.55%。与商业发酵剂相比,低温发酵剂发酵酸乳组织状态良好,滴定酸度为92°T,感官评分为95分,活菌含量(10.3lg CFU/m L)极显著高于商业发酵酸乳(p0.01)。实验结果为制备高活力直投式低温乳酸菌发酵剂的冻干菌粉提供理论支撑,对开发低温乳酸菌发酵剂具有重要意义。     

冻干保护剂对复合低温乳酸菌发酵剂的影响

以青藏高原牧区分离筛选出的低温乳酸菌为研究对象,以活菌数为指标,比较了4种冻干保护剂对复合低温乳酸菌发酵剂的影响,并通过正交实验优化了其中3种较优冻干保护剂的复配配方。结果表明,复合低温乳酸菌冻干保护剂的最优组合为:甘油为8m L/L,蔗糖为10%(w/v),脱脂乳为15%(w/v),以此为保护剂冻干存活率达到了90.55%。与商业发酵剂相比,低温发酵剂发酵酸乳组织状态良好,滴定酸度为92°T,感官评分为95分,活菌含量(10.3lg CFU/m L)极显著高于商业发酵酸乳(p<0.01)。实验结果为制备高活力直投式低温乳酸菌发酵剂的冻干菌粉提供理论支撑,对开发低温乳酸菌发酵剂具有重要意义。      

受芽孢杆菌污染的乳酸菌冻干发酵剂分纯方法

发酵奶是奶在特定微生物的作用下,通过乳糖发酵而制得的,最早起源于近东,后来在欧洲得以发展.由于这类产品具有独特风味及医疗保健作用,因此近几十年来发酵奶制品在世界各国得以普及并实现工业化生产、我国近年来酸奶生产呈现激增局面,据统计京、津、沪、武汉、南京、     

酸奶混合菌种连续继代培养对母发酵剂稳定性的影响

母发酵剂的活性以及产酸性能是酸奶生产菌种保存与扩培的根本条件。本实验利用嗜热链球菌与保加利亚乳杆菌混合菌种进行连续继代培养。在各种影响因素限定的条件下，可使其继代稳定性长期不变。     

直投式酸奶发酵剂的商品化生产研究

通过对不同保加利亚乳杆菌与嗜热链球菌菌株的酸化活力、黏度、蛋白水解能力和共生能力等生理学指标的测定,筛选出4对适于发酵生产用的菌株组合,并以菌株Y6+ST1作为进一步研究对象,获得其最佳增殖培养基为番茄汁为2.5%,乳糖为1.0%,酵母膏为0.5%,蛋白胨为1.5%,42℃培养6h后其活菌数达到1.4×109mL-1;Y6+ST1组合的最佳保护剂组成为脱脂奶粉为18.0%,甘油为2.0%,谷氨酸钠为1.0%和吐温-80为0.5%,经冷冻干燥后其活菌数达到3.62×1011g-1。该组合工业化生产的最佳工艺参数是培养温度42.3℃,pH值为6.4,搅拌转速86.8r/min和3%的接种量,1.0%补料(脱脂乳),发酵时间6h;-40℃,15h后,最终冷冻干燥产品活菌数为1011g-1。     

酸奶发酵剂及酸奶工艺的优化研究

合适的酸奶发酵剂及酸奶工艺的选择对酸奶产品的风味、口感、品质以及货架期有着重要的意义。介绍酸奶发酵剂的发展历史、发酵剂的分类以及发酵剂的性能,通过介绍酸奶工艺的优化,明确影响酸奶品质的因素,最后对酸奶发酵剂及酸奶工艺的优化进行总结与展望。     

植物基杏仁酸奶的研制及不同发酵剂对酸奶品质的影响

该研究以杏仁为原料,经乳酸菌发酵制成植物基杏仁酸奶,通过单因素试验结合响应面法优化发酵工艺,并探究不同乳酸菌发酵剂对杏仁酸奶品质的影响。结果表明,最优的发酵工艺为料液比1 ∶10（g/mL）、发酵剂添加量0.6%、发酵温度40 ℃、发酵时间10 h,在该条件下,杏仁酸奶质地均匀、口感醇厚、色泽均一,感官评分为89.00,而不同类型发酵剂单发酵杏仁乳均能直接影响植物基杏仁酸奶品质,市售的酸奶发酵剂保加利亚乳杆菌及嗜热链球菌,能稳定有效发酵产酸,发酵制成的植物基杏仁酸奶各项品质指标均优于其他乳酸菌单发酵酸奶。     

弱后酸化酸奶发酵剂的筛选

酸奶在贮存、运输、销售、食用前这一过程中发生后酸化现象,酸奶后酸化现象导致的结果是酸奶无法长期贮存,酸奶贮存期短的缺陷困扰着酸奶的消费。控制酸奶后酸化的措施有很多种,最好的控制措施是选育在高温条件下产酸较强、在低温条件下产酸甚微的菌株作为发酵剂。在以前研究的基础上,对几种有潜力的酸奶发酵剂进行了初步研究,发现汉森公司的YF-L812发酵的酸奶后酸化程度很小,在6℃条件下贮存30d时酸度仅上升了14.5°T。     

酸奶冻干发酵剂制备中保加利亚乳杆菌不同菌株特性的研究

研究了不同来源的7株保加利亚乳杆菌在乳中的生长与发酵特性、后酸化活性以及抗冷冻干燥特性。结果表明,7菌株在乳中42℃发酵,L.b-S1和L.b-DR凝乳时间最短,为3 h,凝乳后的活菌数、pH值、滴定酸度均无显著差别,活菌数均达1×108 mL-1以上,pH值均达4.5～5.0,滴定酸度均达90～100°T;7菌株在发酵后的酸乳中冷藏期间,L.b-S1和L.b-DR的后酸化活性最低,4℃冷藏21 d,酸度上浮不足10°T,pH值下降0.2～0.4,活菌数下降1个log数量级左右;7菌株在以脱脂乳为保护剂的冷冻干燥试验中,L.b-S1抗冻干性最强,其次为L.b-DR,其冻干存活率分别达31.46%和20.39%。     

高黏度低后酸酸奶发酵剂的筛选

对分离到的12株优良乳酸菌,进行了单发酵试验和复配发酵实验。在单发酵实验中分析嗜热链球菌的产粘特性和保加利亚乳杆菌的产酸特性,在复配发酵实验中测定在贮藏期内(21 d)酸度、pH值、黏度、脱水收缩性及对其进行感官鉴评。结果表明,组合PZST4-PZLB5在储存期间保持了良好的风味和流变学特性,并且后酸化程度较小、产黏高,因而适合作为优良的酸奶发酵剂。     

嗜酸乳杆菌粉末发酵剂的研制

研究了来自动物、植物及微生物的天然复合有机营养物对嗜酸乳杆菌在高温下的保护作用。结果表明,植物寡聚糖和动物多肽,植物寡聚糖和藻类浸提物,植物寡聚糖和动物多肽和真菌多糖,植物寡聚糖和真菌多糖和藻类浸提物,植物寡聚糖和动物多肽和藻类浸提物分别与脱脂乳混合使用,其抗热效果显著,菌存活率分别为32.8％、25.6％、41.8％、29.9％和72.2％,而对照组只有1.21％。以植物寡聚糖和动物多肽和藻类浸提物和质量分数为15％牛乳的混合物为培养基,培养菌体,经喷雾干燥,制得的嗜酸乳杆菌发酵剂,经检测,质量指标均符合发酵剂要求,其中嗜酸乳杆菌活菌数达8.7×108g-1。     

嗜酸乳杆菌高密度培养及发酵剂的研究

研究了嗜酸乳杆菌的高密度培养条件,并使用喷雾干燥法对嗜酸乳杆菌粉末发酵剂进行了制备。实验表明,嗜酸乳杆菌6012的最佳增菌培养基为：乳清培养基＋0．6％（w／v）低聚异麦芽糖＋0．6％（w／v）黄豆粉＋10％（v／v）胡萝卜汁＋0．5％（w／v）CaCO3,在培养过程中伤脑筋20％柠檬酸钠调节培养基pH值为6．2,37℃静置培养18h,活菌数可达1．0&#215;10^9 cfu/mL。以0．5％甘油＋0．5％葡萄精＋3％大豆分离蛋白＋2％海藻酸钠作为抗热保护剂,菌体经过喷雾干燥,其发酵剂活菌数为8．0&#215;10^9 cfu／g。     

An economic evaluation of freeze-dried kefir starter culture production using whey

An economic study is presented in which industrial-scale production of freeze-dried kefir starter culture is discussed based on results on a laboratory scale. Industrial scale-up was based on a 3-step process using 3 bioreactors of 100, 3,000, and 30,000 L for 300 kg of freeze-dried culture/d of plant capacity. The major cost component of the total investment was the freeze-drying machinery, which consisted of 57% of the total investment. Production cost was reduced from €15.4/kg ($18.5/kg) to ∉2.9/kg ($3.5/kg) when the production capacity was increased from 30 to 900 kg/d. An economic analysis revealed a 3.5-fold increase in production cost compared with the corresponding production cost of the wet product, with an added value of up to ∉10.8 × 10⁹ ($13.0 × 10⁹) within the European Union.     

Effects of yogurt starter cultures on the survival of Lactobacillus acidophilus

Recognized to confer health benefits to consumers, probiotics such as Lactobacillus acidophilus are commonly incorporated into fermented dairy products worldwide; among which yogurt is a popular delivery vehicle. To materialize most of the putative health benefits associated with probiotics, an adequate amount of viable cells must be delivered at the time of consumption. However, the loss in their viabilities during refrigerated storage has been demonstrated previously. This study focused on the effects of yogurt starter cultures on the survival of five strains of L. acidophilus, with emphases on low pH and acid production. Differential survival behavior between L. acidophilus strains was further analyzed. To this end, viable cell counts of L. acidophilus were determined weekly during 4 °C storage in various types of yogurts made with Streptococcus thermophilus alone, L. delbrueckii ssp. bulgaricus alone, both species of the starter cultures, or glucono-delta-lactone (GDL). All yogurt types, except for pasteurized yogurts, were co-fermented with L. acidophilus. Yogurt filtrate was analyzed for the presence of any inhibitory substance and for the amount of hydrogen peroxide. Multiplication of L. acidophilus was not affected by the starter cultures as all strains reached high level on day 0 of the storage period. Throughout the 28-day storage period, cell counts of L. acidophilus PIM703 and SBT2062 remained steady (~ 6 × 10⁷ CFU/g) in yogurts made with both starter cultures, whereas those of ATCC 700396 and NCFM were reduced by a maximum of 3 and 4.6 logs, respectively. When starter cultures were replaced by GDL, all strains survived well, suggesting that a low pH was not a critical factor dictating their survival. In addition, the filtrate collected from yogurts made with starter cultures appeared to have higher inhibitory activities against L. acidophilus than that made with GDL. The presence of viable starter cultures was necessary to adversely affect the survival of some strains, as pasteurized yogurts had no effect on their survival. In particular, the inhibitory effect exerted by L. delbrueckii ssp. bulgaricus on L. acidophilus NCFM was highly pronounced than by S. thermophilus, nevertheless, the same effect was not observed on SBT2062. The inhibition against stationary-phase NCFM cells might be caused by the elevated level of hydrogen peroxide produced by L. delbrueckii ssp. bulgaricus. Delineating factors driving the differences in survival trait among probiotic strains will lead to a more efficacious delivery of health benefits in fermented dairy products through targeted technological interventions.     

Preparation of a Lactobacillus plantarum starter culture for cucumber fermentations that can meet kosher guidelines

A method is described for growth of a Lactobacillus plantarum starter culture in jars of commercially available pasteurized fresh-pack kosher dill cucumbers so that jars can be used to inoculate commercial scale cucumber fermentation tanks. A procedure is also described to transfer lactic acid bacteria from frozen storage in MRS broth into cucumber juice and commercial jars of kosher dill cucumbers so that a selected strain of lactic acid bacteria can be kosher certified for commercial fermentations in processing plants that operate under kosher certification. The strain of L. plantarum used in these experiments grew to maximum cell numbers in 4 d at 20 to 25 °C and then maintained viable cell numbers for 2 wk at >10(8) CFU/mL so the culture was suitable for inoculation of fermentation tanks. Refrigeration of jars of culture after they grow to maximum numbers minimizes die-off of cells sufficiently so that a pure culture can be maintained by aseptically transferring brine containing viable bacteria to a new pH-adjusted jar only once every 4 mo. PRACTICAL APPLICATION: This report describes a method to prepare a lactic acid bacteria starter culture suitable for kosher vegetable fermentations.     

The bacteriocin producer Lactobacillus amylovorus DCE 471 is a competitive starter culture for type II sourdough fermentations

Type II sourdoughs were prepared using Lactobacillus amylovorus DCE 471, a producer of the bacteriocin amylovorin L. The strain was used as a starter culture for rye and wheat sourdoughs on laboratory scale (10 L), and in rye sourdough on pilot scale (100 L). The sourdoughs were acidified to a pH of around 3.5 within 15 h (laboratory dough) to 25 h (pilot‐scale dough). Final amylovorin L titres of 0.3–0.4 (laboratory scale) and 0.2 (pilot scale) MAU kg^?1 of sourdough were detected. After baking of wheat dough that was supplemented with the pilot‐scale sourdough, no amylovorin L activity was recovered from the breadcrumbs. On laboratory scale, aeration or the addition of complex carbohydrates hardly affected growth or amylovorin L production. Rye and wheat sourdough fermentation were rather similar despite differences in sugar concentrations. The persistence of L. amylovorus DCE 471 during rye sourdough fermentation, both on laboratory and pilot scale, was confirmed by repetitive sequence‐based polymerase chain reaction (rep‐PCR) and by testing isolates towards an amylovorin L‐sensitive organism. Further, rep‐PCR indicated that the background microbiota of the flour—probably responsible for the production of low amounts of acetic acid—grew poorly and were overgrown by L. amylovorus DCE 471 during the pilot‐scale fermentation. Copyright © 2007 Society of Chemical Industry     

Influence of salt-to-moisture ratio on starter culture and calcium lactate crystal formation

The occurrence of l(+)-lactate crystals in hard cheeses continues to be an expense to the cheese industry. Salt tolerance of the starter culture and the salt-to-moisture ratio (S:M) in cheese dictate the final pH of cheese, which influences calcium lactate crystal (CLC) formation. This research investigates these interactions on the occurrence of CLC. A commercial starter was selected based on its sensitivity to salt, less than and greater than 4.0% S:M. Cheddar cheese was made by using either whole milk (3.25% protein, 3.85% fat) or whole milk supplemented with cream and ultrafiltered milk (4.50% protein, 5.30% fat). Calculated amounts of salt were added at milling (pH 5.40 ± 0.02) to obtain cheeses with less than 3.6% and greater than 4.5% S:M. Total and soluble calcium, total lactic acid, and pH were measured and the development of CLC was monitored in cheeses. All cheeses were vacuum packaged and gas flushed with nitrogen gas and aged at 7.2°C for 15 wk. Concentration of total lactic acid in high S:M cheeses ranged from 0.73 to 0.80 g/100 g of cheese, whereas that in low S:M cheeses ranged from 1.86 to 1.97 g/100 g of cheese at the end of 15 wk of aging because of the salt sensitivity of the starter culture. Concentrated milk cheeses with low and high S:M exhibited a 30 to 28% increase in total calcium (1,242 and 1,239 mg/100 g of cheese, respectively) compared with whole milk cheeses with low and high S:M (954 and 967 mg/100 g of cheese, respectively) throughout aging. Soluble calcium was 41 to 35% greater in low S:M cheeses (low-salt whole milk cheese and low-salt concentrated milk cheese; 496 and 524 mg/100 g of cheese, respectively) compared with high S:M cheeses (high-salt whole milk cheese and high-salt concentrated milk cheese; 351 and 387 mg/100 g of cheese, respectively). Because of the lower pH of the low S:M cheeses, CLC were observed in low S:M cheeses. However, the greatest intensity of CLC was observed in gas-flushed cheeses made with milk containing increased protein concentration because of the increased content of calcium available for CLC formation. These results show that the occurrence of CLC is dependent on cheese milk concentration and pH of the cheese, which can be influenced by S:M and cheese microflora.