EVALUATING THE EFFECTS OF PARBOILNG PROCESSES ON THE, PHYSICO-CHEMICAL PROPERTIES OF RICE (Oryza sativa L)

Abstract

Parboiling of paddy rice is a post harvest management process practiced differently at separate parts of the world with cultural and geographical underlines. The manner and procedure at which the parboiling process is conducted determines the qualities of final product both nutritional, physical and marketability. Developing a reliable, practicable and sustainable parboiling procedure that optimizes the physical, nutritional and eaten qualities of the final product for our ecological zone has not yet been carried out. This research work began with a survey conducted in the three northern regions of Ghana to obtain an overview of how parboiling processes are been conducted. Appropriated soaking and steaming containers were designed and fabricated and used to simulate the processes of parboiling in the laboratory using two varieties of rice; Jasmine 85 and Nerica 14. Four (4) different soaking times (6, 20, 24 and 36 hrs) were combined with three different steaming times (40, 60 and 90 minutes) at 80°C. Samples from each soaking/steaming combination were taken and analysed for physical, nutritional, cooking and eaten qualities. The mean value ± SD of two replicate of each parameter were taken using the Z-score test. The data were then subjected to ANOVA test and factors that were statistically significant (P<0.05) identified. The best parboiling condition (soaking and steaming time combination) was soaking for 20 to 24 hrs followed with 60 to 90 minutes steaming. Soaking for 20 hrs, combined with 60 minutes of steaming was the recommended parboiling condition for paddy rice in the three Northern regions of Ghana. An example of parameters with high mean scores were, husking efficiency; 93.7 ±2.3 and 96.7±1.4, broken percentage; 12.0 ±1.4 and 9.5±2.1, v-' head rice yield (HRY); 88.5 ±3.5 and 89.5±2.1 etc for Jasmine 85 and Nerica 14 varieties respectively. A lot more parameters showed significant difference at 20 hrs soaking combined with 60 minutes of steaming.