Effect of Malting and Fermentation on α-amylase inhibitors and subsequent digestibility in Pearl Millet

Abstract

In this study, a combination of malting and fermentation was used to reduce the alpha-amylase inhibitor levels in pearl millet and to increase starch digestibility. The samples were subjected to three different processing treatments (malting, fermentation, malting / fermentation), and compared to the raw unprocessed grain. Malted samples were prepared by steeping 500g of millet for 3h at 250C and germinating at 300C for 5d and dried at 500C in a hot air vacuum drier. Fermented samples were prepared by subjecting 500g of millet to natural fermentation for 24h in distilled water at 30oC, drained and dried at 500C in a hot air vacuum drier. The malted/fermented samples were prepared by first malting the grain, then subjecting the malted grain to natural fermentation as described above. Triplicate samples of raw, malted, fermented, malted/ fermented millet were assayed for alpha-amylase inhibitor and starch digestibility. A significant (P<0.05) difference was observed in the alpha-amylase inhibitor content values for the malted/fermented samples (44.9%), malted samples (47.7%), raw samples (54.3%) and fermented samples (55.6%). This reduction would seem to have contributed to the observed increase in the digestibility of the samples, with the fermented (38.0%), malted (40.2%) and Malted/fermented (48.5%) samples been significantly (P<0.05) higher than the raw (22.1%) samples.