Physicochemical changes of corn starch during lactic acid fermentation with Lactobacillus bulgaricus

Lactic acid fermentation (LAF) has been used since antiquity to conserve food including starchy food. The bioaccessibility of starch depends on the food microstructures. Therefore, the understanding of the physicochemical transformations of the starch suffered during LAF will allow to develop an adequate processing of the alimentary matrices. In this work, native corn starch (NCS) dispersions were inoculated with Lactobacillus bulgaricus (2x107 cells ml-1) and fermented for 24 h at 38 ºC. Physicochemical changes of starch granules during fermentation time were monitored by XRD, FTIR and DSC. The crystallinity content achieved a maximum value (39.72±1.02%) after 12 h of fermentation. In contrast, the absorbance ratio 1047/1022 from FTIR measurements increased as the fermentation advanced. Likewise, DSC analysis showed that the gelatinization enthalpy increased 60.0% after 12 h of fermentation, reflecting the production of ordered microstructures. Thus, it is suggested that LAF increased the resistant starch content in corn starch granules.

Keywords: corn starch, lactic acid fermentation, Lactobacillus bulgaricus, structural changes, cristallinity.