Sour beer production: impact of pitching sequence of yeast and lactic acid bacteria

Lactic acid bacteria have long been used in brewing to acidify mash or wort and in the production of traditional sour beer styles (Lambic, Gueuze) using spontaneous fermentation. This approach is time consuming (some sour beers are matured for three years to obtain the appropriate flavour), so many brewers choose a faster approach using mixed cultures (yeast and bacteria). In this study, the influence of the pitching sequence of bacteria and yeast on the fermentation process was evaluated (by rate of fermentation and acidification, attenuation degree and ethanol concentration). The trials were performed using three procedures: (i) the addition of bacteria followed by the yeast; (ii) the addition of the yeast followed by the bacteria and (iii) the simultaneous addition of yeast and bacteria. In each trial the following time intervals were applied: 24, 48 and 72 h. Weight loss of samples and drop in pH were measured daily, and ethanol content, real extract and lactic acid concentration measured at the end of the process. It was shown that the order of addition of yeast and bacteria determines the success of the lactic acid fermentation. The appropriate yield of lactic acid (ca. 6 g/L) and the drop in pH (<3.6) can be achieved by inoculating the bacteria prior to the inoculation of yeast. When yeast was pitched before the bacteria, the lactic acid content was ca. 2 g/L and pH was 3.9–4.2. © 2019 The Institute of Brewing & Distilling     

奶啤生产中乳酸菌对酵母菌发酵作用的研究

利用乳酸菌和酵母菌的共生作用,对牛乳进行了混合菌种的发酵研究。分析了共生作用对产品pH值、滴定酸度、乙醇含量和α-氨基酸态氮的影响。研究结果表明,乳酸菌的加入不仅可以提高酵母菌的生长速度,而且可以提高产品的风味,奶啤的酒精含量相对啤酒较低,是酒精度较低的健康型饮料。     

自然与乳酸菌强化发酵过程中红酸汤品质变化

利用红酸汤为原料,以总酸、亚硝酸盐、pH、还原糖、可溶性固形物、水分、抗坏血酸为检测指标,分析不同发酵时间自然与乳酸菌强化发酵的红酸汤品质变化规律。结果表明,在整个发酵过程中,自然与乳酸菌强化发酵的红酸汤中还原糖、抗坏血酸、可溶性固形物均呈逐渐下降的趋势;总酸含量和pH均在第6天达到峰值,分别为10.11 g/kg和3.04与10.26 g/kg和2.84;水分含量在第6天达到最低,分别为84.83%与84.18%;亚硝酸盐含量最高分别为0.052 2 mg/kg与0.030 4 mg/kg,未超标。因此,与自然发酵相比,乳酸菌强化发酵明显减少亚硝酸盐含量,缩短了红酸汤发酵周期,但自然发酵红酸汤品质更好。     

酸笋中高产乳酸乳酸菌的筛选、鉴定及发酵条件优化

为获得酸笋中高产乳酸乳酸菌,以柳州传统发酵酸笋为原料,利用MRS培养基对乳酸菌进行分离纯化,然后通过溶钙圈法和高效液相色谱（HPLC）法对高产乳酸乳酸菌进行筛选,并采用形态观察及分子生物学技术对其进行菌种鉴定,最后优化该菌种产乳酸的发酵条件。结果表明,分离并筛选得到一株高产乳酸的乳酸菌菌株LB-1-23,并鉴定其为植物乳杆菌（Lactobacillus plantarum）,该菌株发酵产乳酸的最适条件为接种量2.6%,pH值5.5,发酵温度32 ℃,发酵时间30 h,葡萄糖为碳源,细菌学蛋白胨为氮源。在此优化条件下,乳酸产量为12.74 g/L。该研究为酸笋来源乳酸菌发酵产生乳酸的应用奠定了理论基础。     

湘西传统酸豆角优势乳酸菌分离及鉴定

从湘西传统发酵酸豆角中分离出A、B、C、D、E等5株乳酸菌,经过培养特性、生理生化试验、发酵能力测定,筛选出B、D两株产酸快、发酵风味好的菌株作为优势菌株。经初步鉴定,确定B菌株为肠膜明串株菌（Leuconostoc mesenteroides）,D菌株为短乳杆菌（Lactobacillus bevies）。     

发酵肉制品中乳酸菌的主要发酵特性

从发酵肉制品中分离、纯化乳酸菌132株,对它们的主要发酵特性如耐盐性、耐硝性、产黏液、产气等进行了测定,并比较了它们在不同培养基中的产酸情况。     

乳酸菌发酵柿汁的制备工艺

介绍了以柿子汁为原料制备乳酸菌发酵饮料的工艺流程,并对原材料和发酵产品的一些营养指标进行了测量。实验表明,乳酸菌发酵的最佳条件是发酵温度30℃、接种量6%、菌种AS1.1482∶6038=2∶1。产品既保留了部分柿子汁的原有风味,又具有乳酸发酵形成的特殊风味,营养价值较高,有一定的保健作用。     

Biological acidification and beer quality: addition of lactic acid bacteria isolated from malt

Two lactic acid bacteria, Pediococcus acidilactici HW01 and Leuconostoc citreum isolated from Pilsner malt, were added during mashing and the impact on fermentation examined. The pH of lactic acid bacteria supplemented (bioacidified) wort and finished beer were lower than that of the control. Bioacidified worts resulted in higher levels of free amino nitrogen, reducing sugars and alcohol in the corresponding beers. Foam stability of beers from P. acidilactici and L. citreum worts were increased by 19% and 26%, respectively. The filtration time was reduced in P. acidilactici treated beers but increased with L. citreum. The use of P. acidilactici and L. citreum as bioacidification agents resulted in beers with higher sensory quality. © 2020 The Institute of Brewing & Distilling     

乳酸菌发酵混合蔬菜的初步研究

采用单因素试验和正交试验,研究并优化混合蔬菜乳酸菌发酵工艺,确定适宜的工艺参数,并对发酵液的感官、酶活、理化指标进行检测。结果表明,优化的乳酸菌发酵混合蔬菜的发酵条件为加糖量40%,嗜热链球菌∶保加利亚乳杆菌=1.5∶1.0,接种量3.00%,发酵时间20 d,发酵产品中淀粉酶活28.74 U/mL,超氧化物歧化酶活45.63 U/mL,蛋白酶活51.66 U/mL,总多酚4.52 mg/mL,总黄酮63.40 mg/mL,总糖344.38 g/L,还原糖291.25 g/L,总酸8.48 g/L,亚硝酸盐含量为0.16 mg/kg,感官评分为88分。该发酵产品具有一定的营养价值和保健功效。     

Selection of lactic acid bacteria for acidification of brown juice (grass juice), with the aim of making a durable substrate for L‐lysine fermentation

BACKGROUND: Brown juice is a waste product from the green crop‐drying industry. Heating and pressing of green crops prior to drying produces a juice rich in nutrients, which can be converted to a stable universal fermentation medium by lowering its pH to 4.0–4.5 via lactic acid fermentation. The aim of this study was to select a strain of lactic acid bacteria for industrial acidification of brown juice. RESULTS: Several strains were tested in fermentation experiments and Lactobacillus salivarius ssp. salivarius DSM 20555 was found to be the best choice. It showed high growth rates at temperatures ranging from 40 to 48 °C, with an optimum temperature of 46 °C (µ_max = 2.2 h^?1), and maintained a high productivity at pH 4.0 in continuous fermentation. The highest productivity of 7.23 g L^?1 h^?1 was found at a dilution rate of 1.0 h^?1. CONCLUSION: With today's increased focus on utilisation of residues from food and agro‐industry, coupled with restrictions on their use as fertiliser for farmlands, lactic acid fermentation could play a significant role in conservation of these nutrient‐rich liquids. This study shows that Lb. salivarius ssp. salivarius DSM 20555 is a very promising micro‐organism for use in such a process. Copyright © 2008 Society of Chemical Industry     

乳酸菌发酵香蕉酸奶的研究

本研究是将香蕉制汁后和牛奶混合,将嗜热链球菌及保加利亚乳杆菌以１∶１混合作为发酵剂进行乳酸发酵,用Ｌ９（３~４）正交试验得出最佳配料组合,研制出了具有浓郁香蕉风味的乳酸菌发酵酸奶。     

乳酸菌发酵在谷物产品中的应用及研究进展

谷物食品是人类能量摄入的主要来源之一，随着人们生活水平的提高，谷物食品的营养价值和食用品质受到了广泛关注。发酵是改善食品性质、功能及营养缺陷的重要方法，也是谷物加工的重要手段。乳酸菌能够利用碳水化合物进行生长代谢，在食品工业中被广泛应用于各种发酵制品，其发酵产生的代谢产物有许多重要的生理功能，包括调节肠道菌群平衡、提高免疫力、抗菌和抗肿瘤等。因此，乳酸菌发酵在谷物食品中的研究与应用，对提升食品品质具有重要意义。本文综述了乳酸菌发酵对谷物营养成分、生物功能和结构、理化性质的影响，总结了乳酸菌发酵谷物产品的优势以及乳酸菌发酵在多种谷物产品中的应用，分析了乳酸菌发酵谷物食品目前研究的不足及可能的发展方向, 拟为乳酸菌发酵在谷物中的研究与开发提供参考。     

An improved plate culture procedure for the rapid detection of beer‐spoilage lactic acid bacteria

Lactic acid bacteria (LAB) are the most frequently encountered beer‐spoilage bacteria, and they can render beer undrinkable owing to the production of lactic acid, diacetyl and turbidity. Three beer‐spoilage strains, 2011–6, 2011–8 and 2011–11, were isolated from finished beers. Based on the 16S rRNA sequence analysis, these three isolates were identified as Lactobacillus acetotolerans. Only the horA homologue was detected in these strains, while the horC homologue was not detected. In addition, an improved plate culture method for the rapid detection of beer‐spoilage LAB by the addition of catalase was evaluated. Supplementation with catalase enhanced the growth and colony sizes of the spoilage LAB investigated. These beer‐spoilage bacteria, including some slowly growing strains, were detected within five days of incubation using the modified method. Taken together, the modified procedure could be a rapid countermeasure against beer‐spoilage LAB, and it compared favourably with the conventional plate culture method. Copyright © 2014 The Institute of Brewing & Distilling     

利用纯种乳酸菌制作泡萝卜的技术研究

研究了不同纯种乳酸菌即肠膜明串珠菌、发酵乳杆菌、嗜热链球菌、嗜酸乳杆菌、保加利亚乳杆菌的组合发酵制作泡菜的变化和风味。结果表明,与传统发酵制作工艺相比,嗜酸乳杆菌+肠膜明串珠菌+发酵乳杆菌组合发酵(添加量为发酵液的5%),发酵速度快、产品风味好、亚硝酸盐含量为0.385×10-6mg/kg低于传统工艺生产的产品(1.55×10-6mg/kg),产品质量稳定。     

Conversion of isoflavone glucosides to aglycones in soymilk by fermentation with lactic acid bacteria

ABSTRACT:  Four lactic acid bacteria (LAB), Lactobacillus paraplantarum KM, Enterococcus durans KH, Streptococcus salivarius HM and Weissella confusa JY, were isolated from humans and tested for their capabilities of converting isoflavone glucosides to aglycones in soymilk. Changes in growth, pH, and titratable acidity (TA) were investigated during fermentation at 37 °C for 12 h. After 6 to 9 h of fermentation, each population of 4 LAB reached 10⁸ to 10⁹ CFU/mL. The initial pH of 6.3 ± 0.1 decreased while the TA of 0.13%± 0.01% increased as fermentation proceeded, resulting in the final range between 4.1 ± 0.2 and 4.6 ± 0.1 for pH and between 0.51%± 0.02% and 0.67%± 0.06% for TA after the 12 h of fermentation. The glucoside concentrations were significantly decreased in soymilks fermented with either L. paraplantarum KM, S. salivarius HM, or W. confusa JY with fermentation time ( P < 0.05). L. paraplantarum KM was the best in percent conversion of glucosides to corresponding aglycones, resulting in 100%, 90%, and 61% hydrolysis of genistin, daidzin, and glycitin, respectively, in 6 h. Consequently, the aglycone concentrations in soymilk fermented with L. paraplantarum KM were 6 and 7-fold higher than the initial levels of daidzein and genistein, respectively, after 6 h of fermentation. Changes in the daidzin and genistin levels were not significant in soymilk fermented with E. durans KH. The rates of hydrolysis of glucosides varied depending on the species of LAB. Especially, L. paraplantarum KM seems to be a promising starter for bioactive-fermented soymilk based on its growth, acid production, and isoflavone conversion within a short time.     

柳州酸笋中降亚硝酸盐乳酸菌的筛选及鉴定

为了获得适用于柳州酸笋发酵的降亚硝酸盐乳酸菌,利用MRS培养基对柳州酸笋中的乳酸菌进行分离、纯化及鉴定,并探讨影响菌株降解亚硝酸盐能力的因素。结果表明,共分离获得22株乳酸菌,用盐酸萘乙二胺法对这22株乳酸菌进行降亚硝酸盐能力测试,得到一株降解能力较强的乳酸菌LC-3-3,经分子生物学鉴定为植物乳杆菌（Lactobacillus plantarum）;该菌株在以葡萄糖为碳源（20 g/L）、蛋白胨为氮源（10 g/L）、接种量为6%、pH值为6.0、温度为37 ℃的条件下,亚硝酸盐的降解率为76.58%,降解效果较好。     

乳酸菌发酵法生产高活性大豆低聚糖的研究

通过对八株乳酸茵进行初筛和复筛,得到一株选择性利用蔗糖的乳酸菌株。经单因素实验证明,其发酵大豆乳清的最优条件为：接种量10％,发酵液初始pH7．0,大豆低聚糖浓度10mg/mL,添加1％的蛋白胨和0．5％的无水乙酸钠,37℃下培养48h。发酵液中蔗糖、棉子糖和水苏糖的保留率分别为：0．72％、96．9％和96．5％。      

蔬菜乳酸菌腌渍发酵过程亚硝酸盐变化研究

研究了蔬菜腌渍发酵过程中添加乳酸菌纯培养液对亚硝酸盐含量变化的影响。实验结果表明,接种乳酸菌能降低蔬菜腌渍发酵过程中亚硝酸盐含量。4组乳酸菌腌渍发酵实验中,接种混合菌种(干酪乳杆菌∶鼠李糖乳杆菌∶植物乳杆菌=1∶1∶1)对蔬菜湿腌发酵时菜料和菜汤的亚硝酸盐含量降低效果最佳,接种植物乳杆菌对蔬菜干腌发酵时菜料亚硝酸盐含量降低作用最显著。     

乳酸菌固态发酵豆粕产酸性能分析

该研究以实验室保藏的优良乳酸菌为研究对象,探究6株乳酸菌液体和固态发酵豆粕产有机酸的变化。结果显示,6株乳酸菌MRS培养基液体发酵和固态发酵豆粕产酸效果均存在较大差异。菌株MRS培养基发酵结果表明,植物乳杆菌（Lactobacillus plantarum）BLCC2-0410、BLCC2-0069总酸含量分别为18.90 g/L、18.25 g/L,显著高于其余4株菌（P＜0.05）。固态发酵豆粕结果表明,使用植物乳杆菌BLCC2-0410发酵后豆粕pH值可下降到4.33,总酸含量最高为33.73 g/kg,乳酸含量为18.91 g/kg,酒石酸含量为10.43 g/kg,柠檬酸含量为3.79 g/kg,明显高于其他菌株,因此,确定发酵豆粕产酸的最适菌株为植物乳杆菌BLCC2-0410。     

柳松菇抽提物对乳酸菌发酵性状的影响

将柳松菇抽提物添加到脱脂乳中，以嗜热链球菌和嗜酸乳杆菌为发酵剂制成发酵乳，考察柳松菇抽提物对发酵乳的凝乳时间、凝乳效果、在发酵及贮存过程中乳酸菌的生长、滴定酸度、pH值、黏度及感官性状等的影响。结果表明，5％的添加量能明显促进乳酸菌在乳中的生长，提高产酸速率，缩短凝乳时间，增强凝乳效果，改善发酵乳品质。