玉米青贮过程中乳酸菌动态变化

为了揭示青贮玉米在发酵过程中乳酸菌数量及种群的动态变化,以及微生物添加剂对乳酸菌种群变化的影响,采用了培养方法计数发酵过程中乳酸菌数目的变化,利用16S rRNA基因序列比对方法分析青贮玉米中乳酸菌的多样性及种群变化趋势。经过对15d时间内青贮玉米中乳酸菌变化趋势的分析显示:一周后对照组乳酸菌数最高达到2.1×106CFU/g,两处理组中处理组Ⅱ乳酸菌数达到最高5.5×107CFU/g;利用MRS平板分离、培养出典型乳酸菌菌落152株,经16S rRNA基因序列比对分析为乳杆菌属和片球菌属,其中86%的菌株属于乳杆菌属。此研究表明微生物添加剂有利于青贮玉米发酵过程中乳酸菌的快速增殖,乳杆菌属和片球菌属都是青贮玉米发酵的启动菌之一,在发酵前期一直存在,但发酵后期乳杆菌属是玉米青贮过程中乳酸菌的主要菌群。     

玉米原料无蒸煮酒精发酵工艺的研究

在玉米原料无蒸煮酒精发酵过程中,添加少量的纤维素酶,酸性蛋白酶可提高糖化酶对生淀粉的糖化作用,减少糖化酶用量。在料水比１：２．５,糖化酶加量２００ｕ／ｇ,纤维素酶加量５ｕ／ｇ,酸性蛋白酶加量０．０１％,３０℃,ｐＨ３．５条件下,Ｎｏ．２１４菌株经９６ｈ发酵,醪液酒精度达１２．８％,淀粉利用率达９２．１％。     

用固定化乳酸菌发酵乳浆生产乳酸

乳浆是奶酪生产过程中从乳中分离的产品,其成分包括水、乳糖(4—5％)、蛋白质、维生素和矿物质。常被作为发酵工业价格低廉的糖源。乳酸通常通过乳酸菌发酵粮食、糖蜜和乳浆而得,用于制药、化学和食品工业中,最初作为酸味剂和保护剂。     

玉米发酵面团工艺优化研究

通过单因素试验和正交试验确定了玉米发酵面团最佳制作工艺,并采用感官评价和质构特性对玉米发酵面团品质进行分析,得出酵母添加量0.8%、发酵时间为1.5h、醒发时间为40min条件下制得的玉米发酵面团硬度5 967.618、弹性809、黏聚性772、咀嚼性3 728.860、回复性354,品质良好。研究结果可为玉米主食化加工奠定良好的基础,间接推动玉米产业发展。     

酵母发酵玉米秸秆水解液产麦角甾醇应用研究

生物质是一种可再生资源,生物质发酵可产生高端化工产品.本文主要探讨蒸汽爆破处理玉米秸秆及水解可发酵单糖,考察酵母发酵玉米秸秆糖化液产麦角甾醇的应用研究.实验结果表明:当固液比10%,盐酸浓度1.5%,90℃水解反应3 h,还原糖含量达到53.3%,纤维素转化率79%.发酵工艺参数为玉米秸秆糖化液6.0°Bx,玉米浆4%,pH 7.5,接种量10%,28℃摇床振荡培养32 h,细胞生物量达8.5 g/L,麦角甾醇含量可达2.35%.同时对玉米秸秆发酵产麦角甾醇晶体进行结构表征.     

黑曲霉固态发酵及酶解玉米皮

以玉米提取淀粉后的玉米皮渣为主要原料,采用黑曲霉固态发酵法产酶再酶解的二步法降解玉米皮中纤维素类物质。经Plackett-Burman法及响应面设计优化发酵条件得:温度30℃,接种量10%,初始水分体积分数60%,物料厚度2.47 cm,初始pH 5.79,发酵时间6 d;滤纸比酶活可达11.01 U/g,较原始酶活提高了40.61%;产酶结束后加入pH 4.8醋酸-醋酸钠缓冲液,置于50℃下酶解144 h,中性洗涤纤维与酸性洗涤纤维降解率分别为46.09%、48.82%,还原糖质量分数达到9.02%。     

酸白菜发酵中乳酸菌群的分析

酸泡菜是世界性大众化蔬菜发酵制品,其主要发酵菌群是乳酸菌。对西式泡菜、朝鲜泡菜、四川泡菜发酵过程中微生物区系已有较多研究,进而探索出接种微生物纯培养物促进蔬菜发酵的新方法,用于工业生产。但对酸白菜这一中国特有发酵制品的微生物学研究及接种后发酵过程中乳酸菌种类的变化,国内尚未见报道。 我们根据接种发酵和自然发酵对比试验结果,分析不同发酵过程中乳酸菌种类及其变化,说明接种乳酸杆菌促进酸白菜发酵的作用机理。 1     

花生乳的乳酸菌发酵研究Ⅱ．乳酸菌的筛选和发酵产物初测

利用溶钙圈等方法从不同生境中分离乳酸菌,从中筛选出能利用花生乳生长发酵的三株菌ＴＬ－Ｐ３、ＴＬ－Ｂ１３和ＴＬ－Ｓｔ。此三株菌在３８℃发酵１０ｈ后,花生乳ｐＨ值可从６．５降至５．０。定性测出发酵产物中有乳酸和双乙酰。发酵后的花生乳具有特殊香味,有凝乳现象产生。     

酸奶发酵剂和乳酸菌生物技术育种

由新鲜牛奶制成的酸奶由于其丰富的营养、特殊的风味、爽滑的质构和良好的生理功能 ,倍受人们青睐。对酸奶乳酸菌的微生物种类、功能及其组成的酸奶发酵剂进行了综述 ,并简要介绍了乳酸菌生物工程育种方面的研究进展及酸奶乳酸菌研究领域一些令人感兴趣的课题。     

Biotechnological production of lactic acid integrated with fishmeal wastewater treatment by <Emphasis Type="Italic">Rhizopus oryzae</Emphasis>

Fishmeal wastewater, a seafood processing waste, was utilized for production of lactic acid and fungal biomass by Rhizopus oryzae AS 3.254 with the addition of sugars. The 30 g/l exogenous glucose in fishmeal wastewater was superior to starch in view of productivities of lactic acid and fungal biomass, and COD reduction. Fishmeal wastewater can be a replacement for peptone which was the most suitable nitrogen source for lactic acid production among the tested organic or inorganic nitrogen sources. Exogenous NaCl (12 g/l) completely inhibited the production of lactic acid and fungal growth. In the medium of COD 5,000 mg/l fishmeal wastewater with the addition of 30 g/l glucose, the maximum productivity of lactic acid was 0.723 g/l h corresponding to productivity of fungal biomass 0.0925 g/l h, COD reduction 84.9% and total nitrogen removal 50.3% at a fermentation time of 30 h.     

Microbiology of the malolactic fermentation: Molecular aspects

Abstract Malolactic fermentation conducted by lactic acid bacteria follows alcoholic fermentation during winemaking, and several positive effects make it indispensable for most wines. Research has focused on the growth and physiology of lactic acid bacteria in wine; resulting in the design of malolactic starter cultures. Future work on these starters will concentrate on aromatic changes as additional criteria for strain selection. Although the main features of the malolactic enzyme and its gene are known, the detailed mechanism of the malolactic reaction remains unclear. Cloning and expression of this activity in enological strains of Saccharomyces cereuisiae might be one of the next most important advances in the control of malic acid degradation in wine.     

Probiotic Strains Influence on Infant Microbiota in the In Vitro Colonic Fermentation Model GIS1

The main goal of our study was to evaluate the effect of the individual administration of five lyophilized lactic acid bacteria strains (Lactobacillus fermentum 428ST, Lactobacillus rhamnosus E4.2, Lactobacillus plantarum FCA3, Lactobacillus sp. 34.1, Weissella paramesenteroides FT1a) against the in vitro simulated microbiota of the human colon using the GIS1 system. The influence on the metabolic activity was also assessed by quantitative determination of proteins and polysaccharides at each segment of human colon. The obtained results indicated that the lactic acid bacteria L. rhamnosus E4.2 and W. paramesenteroides FTa1 had better efficiency in synthesising exopolysaccharides and also a better probiotic potential and therefore could be recommended for use in probiotics products or food industry.     

A microbiological study of Sobia: a fermented beverage in the Western province of Saudi Arabia

Sobia is a traditional fermented beverage prepared from wheat and malt flours in the Western province of Saudi Arabia. Fourteen samples of sobia were collected from Makkah Al-Mukarrmah (Western province) and from Riyadh (Central province). Samples were examined microbiologically for total bacterial counts, lactic acid bacteria, yeasts and moulds as well as coliforms. Titratable acidity and pH were also analysed. The results revealed that sobia samples had high total bacterial and lactic acid bacteria counts that ranged from 4.17 to 8.09 log c.f.u./ml and from 4.01 to 8.19 log c.f.u./ml respectively. Yeasts and moulds counts ranged from 3.96 to 5.87 log c.f.u./ml. The coliform count was from 0.67 to 3.84 log c.f.u./ml. Acidity expressed as percent lactic acid ranged from 0.04 to 0.30%, while the pH of the samples ranged from 3.37 to 5.53. Identification of microorganisms in sobia revealed the presence of lactic acid bacteria, coliforms, yeasts and moulds. Lactic acid bacteria consisted of Lactobacillus cellobiosus (26.8%), L. buchneri (17.9%), L. plantarum (8.9%), L. brevis (23.2%), L. delbrueckii. delbrueckii (8.9%), Leuconostoc lactis (8.9%), and Pediococcus pentosaceus (5.4%). Coliforms consisted of Klebsiella pneumoniae (25.8%), Enterobacter aerogenes (6.1%), E. sakazakii (33.3%), E. cloacae (19.7%), and Serratia liquefaciens (3%). Yeasts comprised Saccharomyces cerevisiae (27.6%), Candida tropicalis (26.3%), C. ciferrii (13.1%), C. guilliermondii (13.1%), C. lipolytica (6.58%), Kloeckera japonica (13.1%), and Rhodotorula rubra (1.3%). All moulds were Penicillium spp.