Quality evaluation of parboiled rice and rice products from germinated rice.

Abstract

The study entitled “Quality evaluation of parboiled rice and rice products from germinated rice” was undertaken to evaluate the physical, cooking, biochemical, nutritional, organoleptic and keeping qualities of parboiled rice from germinated paddy. 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. Paddy variety Jyothi was selected for the study. After soaking for 12 hours, the paddy was germinated at laboratory level. Paddy soaked for 12 hours (T1), germinated for 3 days (T2) and 6 days (T3) were selected as treatments. Ungerminated paddy (T0) was the control. Parboiling of the selected treatments was carried by hot soaking process. Milling recovery was found to be very low in germinated samples, compared to control, which in turn resulted in higher milling loss. Milling recovery of germinated samples decreased significantly during storage whereas, in control an increase was noticed. 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 37.66 to 44.67 minutes was noticed among different treatments and it increased significantly during storage. A positive correlation between water uptake, volume expansion and grain elongation was noticed in all the treatments. Germination decreased the amylose content by 4 to 14 per cent in different treatments there by affecting the gel consistency. Intermediate gelatinisation temperature was noticed in all the treatments. Moisture content of parboiled rice from four treatments varied from 11.02 to 12.10 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. Variation was noticed in the protein, fat and fibre content among treatments. Progressive increase in the thiamine content was noticed with advancement in the days of germination. Compared to control, significant decrease in the calcium, iron and phosphorus content of germinated samples was noticed. During germination, in vitro starch digestibility of parboiled rice increased by 3 to 14 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/ml. Lower water absorption and water solubility indices were noticed in rice flour from germinated samples compared to control. The evaluation of retrogradation property in roasted rice flour from treatments revealed that syneresis per cent increased with advancement in days of observation. Maximum syneresis was noticed in germinated samples. The products prepared using rice (cooked rice, iddli and Kozhukatta) and rice flour (idiyappam and puttu) from germinated paddy had better taste. But germination influenced the texture of the products except in 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 bacteria, fungi and yeast initially and after three months of storage. Presence of bacteria was detected in both and the count increased during storage. Fungal and yeast growth were 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.