Quality evaluation of germinated rice and rice products

Abstract

The study entitled “Quality evaluation of germinated rice and rice products” was undertaken to evaluate the physical, cooking, biochemical, nutritional, organoleptic and keeping qualities of germinated rice. The study also aimed to evaluate the physical and keeping qualities of roasted rice flour and to assess the acceptability of the products prepared with rice flour. The rice variety Jyothi was selected for the study. After soaking for 12hours, it was germinated under laboratory conditions. The treatments were T0 – Ungerminated rice, T1- Rice- soaked for 12 hours, T2 – Rice- soaked and kept for germination for 3 days and T3 – Rice- soaked and kept for germination for 6 days. Milling recovery was found to be very low in germinated rice which in turn resulted in higher milling loss. Total milled rice and head rice recovery of germinated rice decreased significantly during storage when compared to control. Significant variation among treatments was observed with respect to thousand grain weight and thousand grain volume. To obtain optimum cooked rice, a cooking time of 22.33 to 29.33 minutes was noticed among different treatments. A positive correlation between water uptake, volume expansion and grain elongation was noticed in all the treatments. Germination decreased the amylose content thereby affecting the gel consistency. Intermediate gelatinisation temperature index was noticed in all the treatments. Moisture content of rice from four treatments varied from 10.51 to 12.67 per cent which increased significantly during storage. A significant increase in total and reducing sugar was observed as a result of starch degradation during germination. Variations were noticed in the protein, fat and fibre content among treatments. Progressive increase in the thiamine content was observed with advancement in days of germination. Compared to control, calcium, iron and phosphorus content of germinated rice were significantly low. During germination, in vitro starch digestibility of rice from different treatments increased by 5 to 17 per cent. Significant increase in in vitro mineral availability was also noticed. Bulk density of roasted rice flour from different treatments varied from 0.78 to 0.84 g per ml. Compared to control, lower water absorption index and higher water solubility index was noticed in roasted rice flour from germinated rice. The evaluation of retrogradation property in roasted rice flour from different treatments revealed that syneresis per cent increased with advancement in days of observation. Maximum syneresis was noticed in germinated rice. The products prepared using rice (cooked rice, unniappam and kozhukatta) and rice flour (iddiappam and puttu) from germinated paddy had mean scores above 6.0 for different quality attributes. Germinated rice was found to be more suitable for the preparation of unniappam and puttu. Mean scores for various quality attributes increased when the products were prepared from stored rice and rice flour. The rice and roasted rice flour were evaluated for the presence of bacteria, fungi and yeast initially and after three months of storage. Presence of bacteria was detected in both periods under study. Fungal growth was not noticed in any of the rice and rice flour samples initially but after three months of storage fungal growth was detected in roasted rice flour of T0 and T1. Yeast count was not detected in rice and rice flour initially and after three months of storage. Insect infestation was not noticed in rice and rice flour from different treatments throughout the storage period.