Gänzle Michael, Ripari Valery
University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada.
University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada; Università Politecnica delle Marche, Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Ancona, Italy.
Int J Food Microbiol. 2016 Dec 19;239:19-25. doi: 10.1016/j.ijfoodmicro.2016.05.004. Epub 2016 May 7.
Sourdough has traditionally been used as leavening agent in artisanal baking. The production of baked and steamed cereal products increasingly employs sourdough as baking improver to achieve improved bread quality, or to obtain "clean label" products. Sourdoughs are maintained in bakeries by continuous propagation; composition and metabolic activity of sourdough microbiota and their impact on bread quality are therefore shaped by processing parameters and fermentation substrates. The diversity of fermentation processes leads to diverse compositions of sourdough microbiota. This communication explores whether concepts in community assembly support an improved understanding of the microbial ecology of sourdough. Community assembly is determined by diversification, drift, dispersal, and selection. Evidence for diversification in sourdoughs is inconclusive. Drift has been shown to shape sourdough microbiota only in specific cases. Increasing knowledge on the primary habitat of sourdough lactobacilli indicates that dispersal (limitation) is an important determinant in sourdoughs that are propagated only for short periods of time. In contrast, selection of adapted organisms mainly determines the microbiota of sourdoughs that are propagated for a long time. Bacterial metabolic traits that determine competitiveness in sourdough fermentation, i.e. effective use of maltose, exopolysaccharide formation from sucrose, the use of electron acceptors by heterofermentative lactic acid bacteria, and acid resistance mediated by arginine and glutamine conversion, also determine bread quality. The concepts in community assembly thus provide a valuable tool to understand the influence of the technology of sourdough fermentation on microbial ecology and on bread quality.
传统上，酸面团一直被用作手工烘焙中的膨松剂。烘焙和蒸煮谷物产品的生产越来越多地使用酸面团作为烘焙改良剂，以提高面包品质，或获得“清洁标签”产品。面包店通过连续传代来维持酸面团；因此，酸面团微生物群的组成、代谢活性及其对面包品质的影响受到加工参数和发酵底物的影响。发酵过程的多样性导致了酸面团微生物群的不同组成。本通讯探讨了群落组装的概念是否有助于更好地理解酸面团的微生物生态学。群落组装由多样化、漂变、扩散和选择决定。关于酸面团中多样化的证据尚无定论。仅在特定情况下，漂变才被证明会影响酸面团微生物群。对酸面团乳酸菌主要栖息地的了解越来越多，这表明扩散（限制）是仅短期传代的酸面团中的一个重要决定因素。相比之下，对适应性生物体的选择主要决定了长期传代的酸面团的微生物群。决定酸面团发酵竞争力的细菌代谢特征，即麦芽糖的有效利用、蔗糖形成胞外多糖、异型发酵乳酸菌对电子受体的利用以及精氨酸和谷氨酰胺转化介导的耐酸性，也决定了面包品质。因此，群落组装的概念为理解酸面团发酵技术对微生物生态学和面包品质的影响提供了一个有价值的工具。
