Department of Biological Science, Cork Institute of Technology, Bishopstown, Cork, Ireland.
School of Nutrition and Health, University College Cork, Cork, Ireland.
Int J Food Microbiol. 2020 May 16;321:108546. doi: 10.1016/j.ijfoodmicro.2020.108546. Epub 2020 Feb 1.
The demand for sugar reduction in products across the food and beverage industries has evoked the development of novel processes including the application of fermentation with lactic acid bacteria. Heterofermentative lactic acid bacteria (LAB) are diverse in their ability to utilise fermentable sugars and can also convert fructose into the sweet tasting polyol, mannitol. The sourdough microbiota has long been recognised as an ecological niche for a range of homofermentative and heterofermentative lactic acid bacteria. A leading determinant in the biodiversity of sourdough microbial populations is the type of flour used. Ten non-wheat flours were used and back-slopped for 7 days resulting in the isolation of 52 mannitol producing isolates which spanned six heterofermentative species of the genera Lactobacillus, Leuconostoc and Weissella. Assessment of mannitol productivity in fructose concentrations up to 100 g/L found Leuconostoc citreum TR116, to have the best mannitol producing characteristics, consuming 95% of available fructose and yielding 0.68 g of mannitol per gram of fructose consumed which equates to the maximal theoretical yield. Investigation of the effects of initial pH on mannitol production and other fermentation parameters in the isolates found pH 7 to be best for isolates Lactobacillus brevis TR052, Leuconostoc fallax TR111, Leuconostoc citreum TR116, Leuconostoc mesenteroides TR154 and Weissella paramesenteroides TR212, while pH 6 was optimal for Leuconostoc pseudomesenteroides TR080. The fermentation of apple juice with each isolate resulted in sugar reduction ranging from 30.3-74.0 g/L (34-72%). When apple juice fermentation with Leuconostoc citreum TR116 was scaled up to 1 L bioreactor a reduction in sugar of 98.6 g/L (83%) was achieved along with the production of 61.6 g/L mannitol. This demonstrates a fermentative process for sugar reduction in fruit juice with concomitant production of the sweet metabolite mannitol to create a fermentate that is suitable for further development as a low sugar fruit juice alternative.
产品在食品和饮料行业的减糖需求引发了新型工艺的发展，包括应用乳酸细菌发酵。异型发酵乳酸菌（LAB）在利用可发酵糖方面具有多样性，还可以将果糖转化为甜味多元醇甘露醇。酸面团微生物群长期以来一直被认为是一系列同型发酵和异型发酵乳酸菌的生态位。影响酸面团微生物种群多样性的主要因素是所用面粉的类型。使用了 10 种非小麦面粉，并进行了 7 天的回混，从而分离出 52 株产甘露醇的菌株，这些菌株跨越了乳杆菌属、肠膜明串珠菌属和魏斯氏菌属的 6 个异型发酵种。在高达 100g/L 的果糖浓度下评估甘露醇生产力，发现肠膜明串珠菌 TR116 具有最佳的产甘露醇特性，消耗 95%的可用果糖，每消耗 1 克果糖可产生 0.68 克甘露醇，相当于最大理论产率。研究初始 pH 值对菌株产甘露醇和其他发酵参数的影响，发现 pH7 最适合短乳杆菌 TR052、腐败肠膜明串珠菌 TR111、肠膜明串珠菌 TR116、乳脂肠膜明串珠菌 TR154 和魏斯氏菌 TR212，而 pH6 最适合中间肠膜明串珠菌 TR080。用每个菌株发酵苹果汁，糖的减少量从 30.3-74.0g/L（34-72%）不等。当将肠膜明串珠菌 TR116 用于苹果汁发酵扩大到 1L 生物反应器时，实现了 98.6g/L（83%）的糖减少，同时生产了 61.6g/L 的甘露醇。这展示了一种用于果汁减糖的发酵工艺，同时产生甜味代谢物甘露醇，从而创造出一种适合进一步开发为低糖果汁替代品的发酵液。
