Effect of pre-treatment on physicochemical, microstructural and pasting properties of pearl millet and cowpea

The effects of soaking, germination and fermentation on physicochemical, microstructural and pasting properties of improved and drought-tolerant Mozambican varieties of pearl millet and cowpea were investigated. Total starch content in both germinated pearl millet (GPM, 67.2 % of DM) and germinated cowpea (GCP, 47.4 % of DM) was found to be affected by germination, which consequently affected the amylose content of GPM and GCP. Morphological and pasting properties of pearl millet starch granules were altered by germination, with numerous holes and broken starch granules developing, leading to a drastic reduction in final viscosity (4 mPa.s). Cowpea starch granule structure was not markedly affected by pre-treatment, but peak (310 mPa.s) and final viscosity (196 mPa.s) were decreased by germination. Cowpea flour had smaller particle size distribution than pearl millet, but no significant differences in the flour were observed after pre-treatment (soaking, germination, fermentation). Therefore, these simple, low-cost and culturally acceptable treatments can be used to alter technical functionality and improve the nutritional benefits of flour, e.g. different pre-treatments of pearl millet and cowpea could be used to develop food products with high energy density and acceptable sensory profile such as porridge for undernourished children in low and middle-income countries.