Response surface optimization of gamma radiation-induced variation in functional quality of Nelumbo nucifera rhizome flour at various particle sizes

Abstract

The cumulative effect of particle size (PS), gamma radiation dose (GRD), and suspension period (SP) on the functional quality of N. nucifera rhizome flour was optimized. A tri-factorial central composite design was constructed at five levels of each of PS, GRD, and SP. The N. nucifera rhizome flour at the selected particle sizes (50, 100, 150, 200, and 250 μm) was subjected to gamma irradiation at the selected levels of GRD (5, 10, 15, 20, and 25 kGy) followed by the analysis of its functional properties at different levels of SP (6, 12, 18, 24, and 30 h). The response-surface analysis showed a statistically significant linear positive effect of PS on the water absorption capacity (WAC) and swelling capacity (SC) and a linear negative effect on protein solubility index (PSI) ( p=0.000-0.028). The GRD showed a significant linear positive effect on oil absorption capacity (OAC) and PSI while a linear negative effect on WAC and SC (p=0.000-0.008). The PS and GRD showed significant quadratic negative effects on WAC, OAC, and SC. However, the SP showed no significant linear effect on the studied functional properties of the flour