Influence of g-irradiation on antioxidant, thermal and rheological properties of native and irradiated whole grain millet flours
Millets of different types like Barnyard (Echinochloa utilis), Finger (Eleusine coracana), Foxtail (Setaria italic), Kodo (Paspalum setaceum) Little (Panicum sumatrense), Pearl (Pennisetum glaucum) and Proso millets (Penicum miliaceum) are staple foods for Indian and African diets. The germination, fungal and microbial contamination leads to postharvest losses mainly due to poor warehouse storage in Asia and Africa. Six millet varieties conditioned at 12% and 14% moisture content and irradiated at a dosage of 2.5 and 5 kGy and then milled into flours. The flour was analysed for composition, antioxidant and the rheological and thermal properties. Pearl, Proso, Finger Kodo at 12% moisture contents showed significant (P < 0.05) increase in Phenolic contents at 2.5 kGy level of irradiation treatments compared with native and 5% irradiation treatment level. The DPPH activity showed an interesting results (42.77-72.65%) with wide variation and a mixed trend of high and low results with irradiation. Thermal transition temperatures showed that the irradiation decreased the transition temperatures primarily due to loss of the crystalline and amorphous starch structure due to radiation that lead to rapid water uptake and shorter time to reach peak viscosity. We are further studying the application of the irradiated flours in different food products to understand the influence of irradiation on nutritional, sensory and functional properties in cereal-based products.