Bioaccessibility of Maillard Reaction Products from Biscuits Formulated from Buckwheat Flours Fermented by Selected Lactic Acid Bacteria

The in vitro bioaccessibility of the soluble protein and Maillard reaction products (MRPs) such as furosine (an early indicator of the MR), free FIC (fluorescent intermediate compounds), and FAST index (fluorescence of advanced MRPs and tryptophan), and the level of melanoidins defined by the browning index were analyzed in biscuits formulated from raw and roasted common buckwheat flours fermented by select lactic acid bacteria (LAB). The content of soluble proteins in fermented buckwheat flour and biscuits before and after digestion in vitro was significantly dependent on the LAB applied and the type of flour used and was the highest in the digested biscuits, indicating increased bioaccessibility. Generally, in all analyzed biscuits a lower furosine content was observed as compared to control samples, and its high bioaccessibility was noted after digestion. The free FIC in biscuits was strain-dependent, resulting in low bioaccessibility with the exception of biscuits obtained from both types of flours fermented by Streptococcus thermophilus MK-10. Compared to control biscuits obtained from raw buckwheat flour, the almost twice-increased FAST index was found for samples fermented by L. plantarum IB or Streptococcus thermophilus MK-10. After digestion, at least a fivefold higher value of the browning index was noted in control and tested biscuits, indicating the high bioaccessibility of melanoidins. This study indicates that fermentation of buckwheat flours by selected lactic acid bacteria seems to be a good way to obtain a product with high bioaccessibility of MRPs. However, further research on their functional properties is needed.

Automated summary

The in vitro bioaccessibility of soluble proteins and Maillard reaction products (MRPs) in biscuits made from fermented buckwheat flours was studied. The results showed that the bioaccessibility of soluble proteins increased after digestion, and the content of furosine, a MRP indicator, was lower in the fermented biscuits. The FAST index, indicating the fluorescence of advanced MRPs, was almost twice as high in the biscuits fermented by specific strains of lactic acid bacteria. The study suggests that fermentation by lactic acid bacteria can enhance the bioaccessibility of MRPs in buckwheat products.