Oligosaccharide and antinutrient content of whole red haricot bean fermented in salt–sugar and salt‐only solutions

Abstract

AbstractCommon beans (Phaseolus vulgaris L.) are nutritious and confer numerous health benefits. However, they are also high raffinose family oligosaccharides (RFOs) and antinutrients. Appreciable amounts of RFOs and antinutrients remain after soaking and cooking, causing flatulence and lowered mineral bioavailability to bean consumers. Fermentation has been shown to lower RFOs and antinutrients in bean flours and milk. However, beans are majorly consumed as whole grains. The purpose of this study was to develop a protocol for fermenting whole common beans. We fermented boiled whole red haricot beans and evaluated their effect on RFOs, tannins, and phytates. A factorial research design was used. Beans were sorted, soaked for 15 h, and boiled for 1 h. The beans were then fermented in 2% salt–sugar solution (SSF) and 2% salt‐only solution (SOF) for 120 h. Microbial growth and pH were monitored every 24 h during fermentation. After fermentation, the beans were dried, milled, and the flours subjected to biochemical analysis. Fermentation favored the growth of lactic acid bacteria (LAB), lowering the pH to 3.88 and 5.26 in SSF and SOF batches, respectively. Tannin content reduced significantly by 64.70% and 73.19% in the SSF and SOF batches, respectively. Phytates reduced by 58.88% and 68.85%, respectively. Raffinose reduced significantly by 96.40% and 95.01%, respectively, whereas stachyose reduced by 95.92% and 94.11%, respectively. The highest reduction of antinutrients and RFOs occurred between 24 and 72 h of fermentation. Higher antinutrient losses occurred in the SOF batch, whereas higher RFO losses occurred in the SSF batch.