Modulation of in vitro predicted glycaemic index of white wheat bread by different strains of Saccharomyces cerevisiae originating from various beverage applications

A low glycaemic index (GI) in bakery products can be associated with a decrease of cardiovascular disease and a protective role against the development and management of non-insulin-dependent diabetes. In this study, the impact of different Saccharomyces cerevisiae strains applied to the bread-making process on the GI of bread was investigated. The GI was measured using an in vitro enzymatic model system in relation to the metabolic patterns of the different yeast strains and the compositional analysis of the breads. Although total and resistant starch contents of the breads were similar, a significant reduction in GI was obtained for breads fermented with S. cerevisiae s-23, wb-06 and Blanc. Differences in the amount of protein and fat were observed. However, their proportion when related to carbohydrate content was not high enough to effectively alter the GI of the breads. Considering the fermentation process, S. cerevisiae wb-06, Blanc and to some extent s-23 were characterised by slower fermentation rates. The resulting breads were reduced in GI with lower specific volumes as well as firmer crumb structures. Breads high in GI were either characterised by an increased glucose content (S. cerevisiae us-05) or high specific bread volumes and soft crumbs (S. cerevisiae Baker's yeast and T-58) indicating a relationship between complete starch gelatinisation during baking and starch digestibility. Conclusively, the GI of white wheat bread can be significantly decreased using different strains from the species S. cerevisiae.