Effect of different treatments on keeping quality of pearl millet flour

Abstract

The flour of pearl millet ( Pennisetum americanum) after different treatments, namely, addition of antioxidants (butylated hydroxyanisole, butylated hydroxytoluene and ascorbic acid), thermal treatment, defatting and salting was stored in earthen pots at prevailing room temperature (28 to 34°C) and relative humidity (60 to 80%) for 30 days. The flour was analysed periodically (10, 20 and 30 days) for keeping quality by chemical methods. The levels of peroxide and fat acidity increased and that of unsaturated fatty acids decreased during storage. The development of peroxides in antioxidant-treated flour samples was lower than other treated (thermal and salt) and untreated flour. Butylated hydroxyanisole and thermal treatments significantly retarded the increase in fat acidity values. The defatted flour had the lowest fat acidity and peroxide values, which did not vary during storage. The loss of unsaturated fatty acids was slightly less in flour treated with butylated hydroxyanisole and butylated hydroxytoluene. The proportion of unsaturated fatty acids remained almost constant in defatted flour. Microbiological examination of the flour samples revealed a considerable increase in fungal count while the bacterial count remained constant during storage. Butylated hydroxyanisole and ascorbic acid showed inhibitory effects against fungal growth.