Williams A G, Withers S E, Brechany E Y, Banks J M
Hannah Research Institute, Ayr, UK.
J Appl Microbiol. 2006 Nov;101(5):1062-75. doi: 10.1111/j.1365-2672.2006.03017.x.
The study was undertaken to investigate the occurrence of glutamate dehydrogenase activity in different species of lactobacilli, and to determine, in a series of cheese-making trials, the effects of glutamate dehydrogenase-producing adjunct cultures on sensory attribute development during the maturation of cheddar cheese.
The presence of dehydrogenase activity with glutamate as substrate was monitored in cell lysates of >100 strains from 30 different species of lactobacilli using a qualitative colorimetric plate screening assay. Activity was detectable in 25 of the 29 representative species obtained from culture collections and in 12 of the 13 non-starter species isolated from cheese. There were pronounced interspecies and strain differences in the occurrence, level and pyridine nucleotide specificity of the glutamate dehydrogenase activity detected. Among the non-starter lactobacilli the highest frequency of enzyme occurrence and activity was detected in the Lactobacillus plantarum isolates. The establishment of glutamate dehydrogenase-producing adjunct strains in the predominant population of lactobacilli in the cheese curd affected the formation of a number of volatile compounds in ripening cheddar cheese, while the presence of Lact. plantarum strains, in particular, was associated with an intensification and acceleration of aroma and flavour development during the maturation period.
Glutamate dehydrogenase formation by lactobacilli is a strain-dependent metabolic attribute, and adjunct cultures expressing the activity that are able to proliferate during cheese ripening have a positive impact on the rate of development and the intensity of cheddar cheese aroma and flavour development.
It has been demonstrated that some strains of glutamate dehydrogenase-producing lactobacilli have potential use as adjunct cultures to accelerate and intensify aroma and flavour formation during the manufacture of cheddar and, by analogy, other similar varieties of cheese. The importance of phenotypic discriminative monitoring of the dominant lactobacilli present during ripening to confirm adjunct establishment and population complexity was highlighted as was the requirement to establish the metabolic attributes of the non-starter population in uninoculated control cheeses in comparative trials.
本研究旨在调查不同种类乳酸菌中谷氨酸脱氢酶活性的发生情况，并在一系列奶酪制作试验中，确定产生谷氨酸脱氢酶的辅助培养物对切达干酪成熟过程中感官特性发展的影响。
使用定性比色板筛选法，在来自30种不同乳酸菌的100多个菌株的细胞裂解物中监测以谷氨酸为底物的脱氢酶活性。从培养物保藏中心获得的29个代表性物种中的25个以及从奶酪中分离出的13个非发酵剂物种中的12个可检测到活性。所检测到的谷氨酸脱氢酶活性在发生情况、水平和吡啶核苷酸特异性方面存在明显的种间和菌株差异。在非发酵剂乳酸菌中，植物乳杆菌分离株中酶的发生频率和活性最高。在奶酪凝乳中占主导地位的乳酸菌群体中建立产生谷氨酸脱氢酶的辅助菌株，会影响成熟切达干酪中多种挥发性化合物的形成，特别是植物乳杆菌菌株的存在与成熟期香气和风味发展的强化和加速有关。
乳酸菌形成谷氨酸脱氢酶是一种依赖菌株的代谢属性，在奶酪成熟过程中能够增殖并表达该活性的辅助培养物对切达干酪香气和风味发展的速率和强度有积极影响。
已经证明，一些产生谷氨酸脱氢酶的乳酸菌菌株有潜力用作辅助培养物，以加速和强化切达干酪以及类似的其他奶酪品种制造过程中的香气和风味形成。强调了在成熟过程中对存在的优势乳酸菌进行表型鉴别监测以确认辅助培养物的建立和菌群复杂性的重要性，以及在比较试验中确定未接种对照奶酪中非发酵剂菌群代谢属性的必要性。
