EVALUATION OF EFFECTIVENESS OF PREGELATINIZATION, FORCE -GELATINIZATION AND POST-GELATINIZATION TECHNIQUES IN MANUFACTURING OF HIGH QUALITY RICE BREAD

Abstract

Study was focused to incorporate more than 60% of rice flour in manufacturing of rice bread using pre-gelatinization, force-geiatinization and post-gelatinization techniques concerning rice's availability and nutrient significant. Other specific objectives of this study were maintaining of high quality bread crumb structure and an attractive crust similar to wheat bread, maintaining of leavening index of rice bread to par with wheat bread and maintaining of orgonoleptic properties to meet same with wheat bread.The study was carried out by resorting 24 factorial design with 4 factors such as initial moisture content (12% & 15.4%), gelatinization method (no gelatinization & force gelatinization), method of soaking (cold soaking & hot soaking) and particle size (150 pm & 300 pm). 20 kg of white raw rice was taken and divided in to 2 equal portions and moisture content of one portion was adjusted to get 12%. The rest portion was taken as it is at 15.4% moisture content. There after the rice at 12% moisture content was divided in to 2 equal portions and one portion was subjected to force gelatinization process at 90-95 °C at 3 minute. The rest portion was kept untreated. These two portions were divided in to 2 equal portions again and one portion of each was subjected to cold soaking and hot soaking process for 24 hours and 3 hours respectively. 4 treatments obtained from above treatments were divided in to 2 equal portions and each of which was subjected for grinding process to get particle size 150 pm and 300 pm. Similar process was adopted to get 8 treatment combinations from raw rice at 15.4% moisture content too.Rice flour obtained from 16 treatment combinations were subjected for leavening index test by substituting 50:50, 60:40 and 70:30 rice flour, wheat flour respectively. As leavening index is related to increment volume divide by initial volume, leavening index of all treatments were measured and best treatments with respect to 60:40 and 70:30 rice flour,wheat flour combinations were selected in terms of high leavening index. The treatments that have shown high leavening index (15.4% of moisture, force gelatinization, cold soaking, 150 pm particle size) were subjected for bread manufacturing process and physical, chemical and orgonoleptic properties of these breads were compared as against same properties of wheat bread.As in the case of organoleptic properties, statistical test (kruskal-wallis) review that taste, texture, appearance and overall acceptability- of rice bread (60:40) are significantly better than wheat bread. However crusts of all breads are same in each other. As in the case of pbysiochemical properties, statistical test (one way ANOVA) review that pH, moisture and bolt density of rice breads (60:40 and 70:30) are closer to the values of wheat bread.