The potential of different cooking media during hydrothermal treatment to steer the microstructure of black bean-based flour by influencing pectin solubilization kinetics

• Cooking media affect black bean cooking by impacting pectin solubilization kinetics • Pectin solubilization is an important factor for the microstructure of bean flour • Specific cooking media shorten cooking time for a desired bean flour microstructure The possibility to create a cellular pulse-based flour (i.e., flour with intact cotyledon cells) has gained a lot of interest, due to possible health benefits. Hydrothermal treatment prior to mechanical disintegration is a critical step in creating such a cellular ingredient. In this study, the impact of various cooking media on the cooking kinetics of black beans and the microstructure of black bean-based flour was investigated. It was shown that the use of 0.1 M Na 2 CO 3 and 0.1 M citric acid accelerated cooking, with the main mechanism linked to increased β-elimination of the pectin structure and the chelation of divalent cations, respectively. Contrarily, the use of 0.1 M CaCl 2 resulted in a reduced softening of the beans during cooking. Analysis of the microstructure and the amount of solubilized pectin in flours made at either an equivalent cooking time of 45 min or at a hardness reduction of 50% obtained by cooking, showed that the reduction in hardness of black beans during cooking, and consequently pectin solubilization kinetics, are critical factors determining the microstructure of black bean-based flours. The use of 0.1 M Na 2 CO 3 clearly increased pectin solubilization due to its alkaline pH (pH 10.2), while the use of 0.1 M CaCl 2 reduced pectin solubilization due to pectin cross-linking, leading to a low fraction of intact cells in the flour. These results showed the potential of reducing the cooking time to obtain a desired flour microstructure by the use of specific cooking media.