提高嗜酸乳杆菌在豆乳中发酵性能的研究

测定了嗜酸乳杆菌、保加利亚乳杆菌和嗜热链球菌发酵豆乳的单菌产酸曲线与混菌产酸曲线,并采用正交实验分析了它们对发酵豆乳的品质影响及与单菌发酵豆乳贮存期质量变化的比较。结果表明,嗜酸乳杆菌、保加利亚乳杆菌是影响酸豆乳质量的主要因素,嗜热链球菌次之。按体积分数为2.2%嗜酸乳杆菌、体积分数为3.0%保加利亚乳杆菌、体积分数为1.8%嗜热链球菌配比共同发酵,可得到组织状态、口感风味较好的酸豆乳,克服了单一嗜酸乳杆菌发酵豆乳产酸慢、凝乳时间长、活菌数不高且贮存期活菌数下降快的缺陷。     

瑞士乳杆菌与干酪乳杆菌在不同原料中的发酵特性研究

研究了瑞士乳杆菌和干酪乳杆菌单独与组合,以及与嗜热链球菌和保加利亚乳杆菌组合在纯牛乳、纯豆乳和混合乳中发酵12h后pH值和酸度值变化,以此来说明它们在3种原料中的生长情况.结果表明,瑞士乳杆菌在纯牛乳和混合乳中产酸能力很强,在纯豆乳中产酸能力不够强,生长不够好;干酪乳杆菌在纯豆乳中生长产酸能力比瑞士乳杆菌强;研究还得出瑞士乳杆菌和干酪乳杆菌组合,以及他们分别与嗜热链球菌和保加利亚乳杆菌组合在纯豆乳生长产酸能力相当.     

提高嗜酸乳杆菌酸乳菌活力的研究

以嗜酸乳杆菌为主发酵剂,嗜热链球菌和保加利亚乳杆菌为辅助发酵剂制作嗜酸乳杆菌酸乳,采用正交实验,并分析发酵过程中pH、乳酸菌数以及感官品质的变化,确定混合菌种的最佳比例。结果表明,嗜酸乳杆菌1.8%、嗜热链球菌1.4%、保加利亚乳杆菌0.6%混合发酵,可以提高乳中嗜酸乳杆菌的菌活力并改善其风味。经验证,混合菌种发酵制作的酸奶在风味和保健功能等方面明显优于单一菌种发酵制作的酸乳。     

瑞士乳杆菌和嗜热链球菌产酸特性的研究

研究了瑞士乳杆菌和嗜热链球菌单一及混合菌种在发酵过程中产酸特性。结果表明:瑞士乳杆菌产酸能力较嗜热链球菌强;不同比例的混合菌种产酸均比单一嗜热链球菌产酸快;瑞士乳杆菌与嗜热链球菌(1:1)混合培养后酸化弱。     

不同乳酸菌对凝固型荔枝酸奶的发酵特性和质构的影响

以纯牛奶和荔枝汁为主要原料,以干酪乳杆菌、保加利亚乳杆菌和嗜热链球菌为发酵菌种,探讨三种乳酸菌的不同组合发酵对凝固型荔枝酸奶的发酵特性和质构的影响。结果表明:干酪乳杆菌产胞外多糖能力较强,单独发酵时胞外多糖含量达到22.50g/L,而嗜热链球菌和保加利亚乳杆菌单独发酵时胞外多糖的含量分别为5.73 g/L和0.29 g/L;各种不同乳酸菌组合发酵后酸奶的表观粘度和持水力与胞外多糖的含量呈正相关(R2=0.98);干酪乳杆菌产酸能力弱,单独发酵后p H高于其它添加有嗜热链球菌和保加利亚乳杆菌的组合,导致酸奶的硬度偏低,但干酪乳杆菌联合嗜热链球菌或保加利亚乳杆菌发酵时,发酵酸奶的硬度和乳酸菌活菌数均明显优于单独发酵组。因此,当干酪乳杆菌与嗜热链球菌及保加利亚乳杆菌联合发酵时,能充分发挥三个菌种的各自优势,菌落总数、胞外多糖含量和质构均能达到较好的品质水平。     

直投式酸豆乳液态发酵剂的研究

以保加利亚乳杆菌和嗜热链球菌作为酸豆乳的发酵菌种,对发酵型酸豆乳菌种的驯化、增殖条件,以及对酸豆乳直投式液态发酵剂的浓缩条件进行了研究,制得了发酵性能良好的直投式液态发酵剂。     

发酵型酸豆乳工艺条件的研究

以大豆为主要原料,研究了嗜热链球菌、保加利亚乳杆菌和嗜酸乳杆菌为混合发酵剂进行乳酸菌发酵酸豆乳的制备工艺.通过单因素和正交实验确定了最佳制备工艺:接种嗜热链球菌、保加利亚乳杆菌、嗜酸乳杆菌的比例为1∶1∶2,接种量为4％,发酵温度为43℃,蔗糖的添加量为6％,发酵时间4h.在此条件下发酵的酸豆乳活菌数可达2.8×108 mL-1,具有淳厚的豆香味和清香的乳酸味,质地均匀,且酸甜可口.     

嗜热链球菌噬菌体对酸奶质量的影响

研究嗜热链球菌噬菌体对酸奶直投式发酵剂(direct vat set,DVS)发酵产酸、嗜热链球菌与保加利亚乳杆菌比例、酸奶黏度、口感、后酸化、乳清析出等方面的影响。结果表明：嗜热链球菌噬菌体可影响酸奶发酵剂发酵产酸、明显改变酸奶嗜热链球菌与保加利亚乳杆菌比例,导致产品黏度降低、口感变差、乳清析出及后酸化严重,嗜热链球菌噬菌体对DVS 生产酸奶有着严重的危害。     

利用豆粕生产发酵酸豆乳的工艺研究

介绍了一种以脱脂豆粕为原料生产发酵酸豆乳的生产工艺。通过80℃碱液(0.15%NaOH溶液)浸提、胶体磨与高压均质机的处理,采用保加利亚乳杆菌和嗜热链球菌为发酵菌种的发酵环节可生产质优价廉的发酵酸豆乳产品。     

乳酸菌在豆乳中的生长特性

本论文将保加利亚乳杆菌、嗜热乳链球菌和双歧杆菌按一定配比制作成混合发酵剂,按5%接种量接种到豆乳中,39t发酵,定时检测发酵过程中的pH、总酸及乳酸茵数等。试验结果表明:发酵剂中加入双歧杆菌,可提高豆乳发酵的产酸速度,但双歧杆菌使用量过大时,对发酵不利;在发酵过程中,总酸一直呈稳定增长的趋势,最终酸度为50-60”T。     

CARBOHYDRATE UTILIZATION and GROWTH KINETICS IN the PRODUCTION of YOGURT FROM SOYMILK PART I: EXPERIMENTAL METHODS

ABSTRACT. Growth and sugar utilization of Lactobacillus bulgaricus and Streptococcus thermophilus were measured in soymilk. Total cell counts in the inoculum were made using the Breed smear. Correlations were developed between direct microscopic count and biomass dry weight for Lactobacillus bulgaricus and for Streptococcus thermophilus. A 1 g to 1 g ratio of the pure cultures was found to be superior to a 1:1 cell number ratio for the mixed culture inoculum. Carbohydrate substrate concentrations (sucrose and stachyose) were followed by high performance liquid chromatography. the methodologies for making these measurements on set cup style soymilk yogurts were developed and checked for precision in this study.     

Interactions between EPS-producing Streptococcus thermophilus strains in mixed yoghurt cultures

Mixed cultures of different EPS-producing Streptococcus thermophilus strains in combination with a Lactobacillus delbrueckii subsp. bulgaricus strain with negligible EPS-production were used for yoghurt production. The yoghurt texture was characterised with respect to sensory, rheological and microstructural properties and the EPS-concentrations were determined. The cultures resulted in yoghurts with highly different texture properties, and positive interactions between certain Streptococcus thermophilus strains were observed. The underlying properties of yoghurt texture are multidimensional, but a number of microstructural characteristics were apparent in the yoghurts with the highest mouth thickness, creaminess and viscosity. A strong protein network, not too dense and with medium size pores containing EPS, seems associated with these properties. The presence of capsular polysaccharides (CPS) also appeared to be beneficial as did a combination of EPS types, which were distributed differently in the protein network (in serum pores, respectively in association with protein). Obviously, a certain concentration of EPS must be present to provide for these effects on yoghurt texture, but other factors than concentration per se seem more important.     

不同乳酸菌发酵杜仲叶水提液的香气成分分析

利用电子鼻辅助同时蒸馏萃取-气相色谱-质谱（Simultaneous distillation-extraction-gas chromatography-mass, SDE-GC-MS）联用技术研究不同乳酸菌（植物乳杆菌、德氏乳杆菌、嗜酸乳杆菌和嗜热链球菌）发酵杜仲叶水提液的主要香气成分差异性。SDE-GC-MS分析结果表明,未发酵液的挥发性成分共鉴定出31种,以醛类相对含量最高（14.3591%）;植物乳杆菌、德式乳杆菌、嗜酸乳杆菌和嗜热链球菌发酵后鉴定出的挥发性成分依次为45、38、51和43种,分别以酮类（18.8255%）、杂环类（25.7828%）、醇类（18.3376%）和醇类（14.1481%）相对含量最高。通过电子鼻分析,PCA和LoA主成分贡献率均大于95%,说明传感器识别效应和样品间的风味区分度较好。同时,ROAV分析结果显示,乳酸菌发酵增加了杜仲叶提取液关键香气成分含量,降低原本杜仲叶的青叶味。经乳酸菌发酵后的杜仲叶提取液,不仅挥发性成分数量较多,且关键香气成分含量增加显著,更有利于杜仲叶提取液香气提升。研究结果为杜仲叶产品后期研发提供了参考依据。     

固定化乳酸菌发酵胡萝卜酸奶工艺研究

通过固定化乳酸菌发酵胡萝卜酸奶,建立新的胡萝卜酸奶发酵工艺。经过单因素试验和正交试验,确定固定化乳酸菌发酵胡萝卜酸奶的配方和发酵工艺。胡萝卜酸奶的配方：奶粉9g、胡萝卜13g、白砂糖8g、蒸馏水100mL。胡萝卜酸奶发酵工艺：固定化德氏乳杆菌保加利亚亚种与固定化唾液链球菌嗜热亚种的比为2:1 接种发酵液(菌种的总添加量为6g/100mL)、在37℃发酵培养7h、然后4℃冷藏12h。结果表明,采用固定化乳酸菌新技术可以发酵生产营养丰富、口感良好的胡萝卜酸奶。     

Functional and textural properties of vegetable‐fibre enriched yoghurt

In this study, different vegetable‐fibre enriched yoghurts namely control (C), pumpkin (PY), carrot (CY), green pea (GY) and zucchini (ZY), were produced. It was observed that Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus counts were higher in yoghurts supplemented with vegetable purees, in accordance with the enhanced growth of lactic acid bacteria due to the fibres, phenolic compounds and organic acids present in the vegetables. Furthermore, vegetable puree supplementation affected the pH, titratable acidity, syneresis, colour (L*, a*, b*, ΔE values), texture (firmness, cohesiveness, consistency and viscosity index) and sensorial properties of the yoghurts. Firmness, consistency and viscosity indices were higher in the yoghurt produced with carrot puree, whereas the highest antioxidant capacity was detected in the pumpkin yoghurt, which corresponded to the highest total phenolic, ascorbic acid and total carotenoid contents. The results of the present study could lead to an innovative approach in the functional dairy product market for the development of dairy products enriched with vegetables that have nutritional and potential therapeutic characteristics.     

褐色饮用型酸奶的工艺优化

以脱脂奶粉、葡萄糖为主要原料,保加利亚乳杆菌（Lactobacillus bulgaricus）和嗜热链球菌（Streptococcus thermophiles）（1∶1）为发酵剂,以感官评价作为主要评价标准,在单因素试验的基础上采用正交试验优化褐色饮用型酸奶的制备工艺。结果表明,褐色饮用型酸奶的最佳工艺为褐变条件98 ℃,150 min,复配稳定剂（羧甲基纤维素钠∶果胶∶黄原胶=3∶4∶1）添加量0.20%,菌种添加量3%,葡萄糖添加量8%,发酵温度42 ℃,发酵时间8 h。在此最佳条件下,褐色饮用型酸奶颜色适中,特有焦糖风味明显,质地均匀,酸甜适宜,口感爽滑细腻,感官评分为91.2分。     

中温发酵酸乳的挥发性风味成分与感官特性的研究

通过正交实验研究了球杆茵比例、全脂乳浓度、发酵终点以及蔗糖添加量对中温发酵酸乳的感官和挥发性风味成分的影响.以九个不同工艺配方为研究对象,采用描述分析感官评价法和固相微萃取结合动态顶空方法对酸乳的感官评价值和风味成分进行测定,并运用主成分分析法和偏最小二乘分析法得到感官结果和仪器测定结果的相关性.结果表明:球杆菌比例和全脂乳浓度是影响酸乳风味和挥发性风味成分的重要因素.偏最小二乘回归分析得到3种气味、3种滋味和2种余味与挥发性成分、乳酸和柠檬酸量的相关性.     

益生菌混合菌种在发酵豆乳中的优化

采用益生菌混合物AST和TLB分别在42℃进行豆乳的发酵,在发酵豆乳的发酵和贮存过程中(4℃下28d),观察pH值和活菌数的变化情况。在AST益生菌混合物(嗜酸性乳杆菌,双歧杆菌和嗜热链球菌)的培育下,42℃下发酵时间减少到8h。但嗜酸性乳杆菌在冷藏的过程中生存状态较差,其活菌数在冷藏后一周后未达到标准。将豆乳在42℃下用TLB益生菌(嗜热链球菌,保加利亚乳杆菌和动物双歧杆菌乳酸亚种Bb12)进行发酵,结果发酵时间缩短到4h,双歧杆菌活菌数目的对数增加了约一半,而且经过28d的冷藏,细菌数仍然维持在107 CFU/mL以上。     

红薯酸奶的研制

以红薯和鲜牛乳为主要原料,配以蔗糖和稳定剂,使用保加利亚乳杆菌和嗜热链球菌混合菌种发酵,制成风味独特、营养全面的保健饮品。通过正交试验法优选出最佳发酵工艺条件为：接入3%的保加利亚乳杆菌和嗜热链球菌（1）,在42℃下发酵5h,后发酵时间为22h。