Effect of short microwave heating time on physicochemical and functional properties of Bambara groundnut starch

Bambara groundnuts (Vigna subterranea) are a good source of starch that may be potentially used for various industrial applications. The effect of microwave heating time (0, 10, 30 and 60 s) on the physicochemical and functional properties of Bambara groundnut starch was investigated. Native and microwaved Bambara groundnut showed the A-type crystallinity pattern. However, there was a decrease in the relative crystallinity of the starch after microwaving. Microscopically, the native starch granules were smooth but had pinholes after microwaving. Microwaving resulted in significant (p ≤ 0.05) reduction in peak viscosity, hot paste viscosity, cold paste viscosity, pasting temperature and set back ratio. The swelling power of Bambara groundnut starch similarly decreased with increasing microwaving time. Microwave heating led to a shift in the gelatinization range to higher temperatures. However, the enthalpy of gelatinization decreased after microwaving. Short microwaving times (≤60 s) were sufficient to cause significant improvement in the pasting and thermal properties of Bambara groundnut starch. Microwaved Bambara groundnut starch with reduced swelling can be potentially used in food products that do not require high swelling such as noodles.