Physicochemical characteristics, pasting behaviors and production cost of pre-soaked soybean and corn flours from local and improved varieties for supporting local food utilization

Flour production from soybeans and corn is a promising strategy to increase their use as local ingredients in diverse food applications. In this study, local and improved varieties of soybean and corn seeds collected from Sumenep, Indonesia, were subjected to soaking pretreatments for 0, 24, 48, and 72 h prior to flour production. The resulting flours were characterized for their physicochemical and pasting properties and evaluated regarding their production cost. The results showed that variety and soaking time significantly affected the physicochemical properties of soybean and corn flours (p < 0.05). Longer soaking time reduced the bulk density and increased the whiteness of soybean and corn flours, except for the local corn variety, which was similar to the control (0 h). The yield increased for corn flour, while it decreased for soybean flour. Greater yield values were obtained for improved varieties relative to local varieties. The fat, protein, and amylose contents of both flours increased along with soaking time; however, ash and carbohydrate contents decreased. The pasting behaviors showed that soybean flours were hardly gelatinized, with no detectable peak viscosity at any soaking time. Conversely, corn flours gelatinized at a range of 72.35–75.65 ℃, with the highest values noted for 0-h soaking. Soaking for 24 h resulted in the highest peak viscosity, with values of 303.33 cP for the local Sumenep and 201.67 cP for HJ 21. A soaking pretreatment for 24 h was likely suitable for soybean seed, while corn required a longer (48 h) period. The economic analysis showed that home-scale production was feasible and profitable to be developed in the study area, with B/C ratios of 1.11–1.14 for soybean flour and 1.40–1.45 for corn flour.