嗜热链球菌对瑞士乳杆菌发酵乳后酸化的影响
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摘要
瑞士乳杆菌是潜在的功能发酵乳发酵剂,为改善瑞士乳杆菌的发酵特性,使用嗜热链球菌配合瑞士乳杆菌用于发酵乳制备。结果表明:嗜热链球菌与瑞士乳杆菌混合发酵将凝乳时间缩短了3.5 h,黏度提高了1.8倍,改善了乳清析出和质构;嗜热链球菌的使用有效减弱了发酵乳的后酸化,贮藏20 d发酵乳的pH值仍大于4.2。为研究这一现象的原因,测定发酵乳中的活菌数、乳糖消耗量、谷氨酸脱羧酶和β-半乳糖苷酶活性,结果表明,混合发酵乳贮藏期间具有较低的谷氨酸脱羧酶和β-半乳糖苷酶活性,乳糖利用量较低,这是后酸化减弱的主要原因。与嗜热链球菌混合发酵是提高瑞士乳杆菌发酵特性的有效手段。
To improve the fermentation performance of Lactobacillus helveticus, Streptococcus thermophilus as a potential starter culture for functional fermented milk was utilized together with L. helveticus to produce fermented milk. As results, the mixed culture fermentation shortened the curding time by 3.5 h, increased yogurt viscosity by 1.8 times and improved whey syneresis and texture properties as compared to L. helveticus alone. Interestingly, S. thermophilus weakened the postacidification of fermented milk containing L. helveticus, maintaining a pH value greater than 4.2 for 20 d of storage. To account for this finding, the number of living bacterial cells, lactose consumption and the activity of glutamate decarboxylase and β-galactosidase were measured. It was found that the activity of glutamate decarboxylase and β-galactosidase of the fermented milk containing the two strains was lower, resulting in a lower lactose consumption and consequently weakening yogurt postacidification. This study concluded that co-fermentation with S. thermophilus was an effective means to improve the fermentation performance of Lactobacillus helveticus.
To improve the fermentation performance of Lactobacillus helveticus, Streptococcus thermophilus as a potential starter culture for functional fermented milk was utilized together with L. helveticus to produce fermented milk. As results, the mixed culture fermentation shortened the curding time by 3.5 h, increased yogurt viscosity by 1.8 times and improved whey syneresis and texture properties as compared to L. helveticus alone. Interestingly, S. thermophilus weakened the postacidification of fermented milk containing L. helveticus, maintaining a pH value greater than 4.2 for 20 d of storage. To account for this finding, the number of living bacterial cells, lactose consumption and the activity of glutamate decarboxylase and β-galactosidase were measured. It was found that the activity of glutamate decarboxylase and β-galactosidase of the fermented milk containing the two strains was lower, resulting in a lower lactose consumption and consequently weakening yogurt postacidification. This study concluded that co-fermentation with S. thermophilus was an effective means to improve the fermentation performance of Lactobacillus helveticus.
引文
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[3]GRIFFITHS M W,TELLEZ A.Lactobacillus helveticus:the proteolytic system[J].Frontiers in Microbiology,2013,4:30.DOI:10.3389/fmicb.2013.00030.
[4]OHSAWA K,NAKAMURA F,UCHIDA N,et al.Lactobacillus helveticus-fermented milk containing lactononadecapeptide(NIPPLTQTPVVVPPFLQPE)improves cognitive function in healthy middle-aged adults:a randomised,double-blind,placebo-controlled trial[J].International Journal of Food Sciences and Nutrition,2018.69(3):369-376.DOI:10.1080/09637486.2017.1365824.
[5]ELFAHRI K R,VASILJEVIC T,YEAGER T,et al.Anti-colon cancer and antioxidant activities of bovine skim milk fermented by selected Lactobacillus helveticus strains[J].Journal of Dairy Science,2016,99(1):31-40.DOI:10.3168/jds.2015-10160.
[6]王菲.复合乳酸菌的抑菌作用及其在鲜肉保鲜中的应用[D].上海:上海海洋大学,2014:11-16.
[7]隋雯丽,张日俊.木耳提取物与乳酸菌混合发酵的营养价值及应用前景[J].饲料工业,2014(增刊1):41-43.DOI:10.13302/j.cnki.fi.2014.z1.012.
[8]刘志强,肖翔,周立平.红曲霉与乳酸菌混合发酵产γ-氨基丁酸工艺研究[J].中国食品添加剂,2011(3):112-117.DOI:10.3969/j.issn.1006-2513.2011.03.018.
[9]王柳,吕嘉枥,王笋.柱前衍生-H P L C法分析酸奶中的还原糖[J].中国乳品工业,2014,42(1):55-58.DOI:10.3969/j.issn.1001-2230.2014.01.016.
[10]黄桂东.Lactobacillus brevis NCL912的耐酸特性及其酸胁迫下差异表达蛋白的研究[D].南昌:南昌大学,2011:33-34.
[11]郭清泉,张兰威,林淑英.普通酸奶制品在贮存过程中发酵剂菌的β-半乳糖苷酶活性测定及变化规律研究[J].食品工业科技,2002(3):34-36.DOI:10.13386/j.issn1002-0306.2002.03.013.
[12]任晓辉,姜淑娟,钱方,等.嗜热链球菌胞外多糖的分离纯化及理化性质研究[J].食品与机械,2012,28(1):159-161.DOI:10.3969/j.issn.1003-5788.2012.01.042.
[13]《乳业科学与技术》丛书编委会.发酵乳[M].北京:化学工业出版社,2016:135-139.
[14]YOAST S,ADAMS R M,MAINZER S E,et al.Generation and characterization of environmentally sensitive variants of the beta-galactosidase from Lactobacillus delbrueckii subsp.bulgaricus[J].Applied and Environmental Microbiology,1994,60(4):1221-1226.
[15]NYANGA-KOUMOU A P,OUOBA L I,KOBAWILA S C,et al.Response mechanisms of lactic acid bacteria to alkaline environments:a review[J].Critical Reviews in Microbiology,2012,38(3):185-190.DOI:10.3109/1040841X.2011.640978.