ABSTRACT
Rice storage has significant effect on rice quality. During storage rice undergoes a process called rice ageing. Rice ageing is a complicated process which is classified as natural ageing and artificial ageing process, during this process changes in the physical, chemical and physicochemical properties of rice occurs. This research mainly focused on the certain physical changes which occur during natural ageing process in particular Head Rice Yield (HRY) which is considered as the standard quality parameter of rice. The research was conducted under different storage conditions for commonly grown rice cultivars in north western Ethiopia. The study used factorial design with three replications of 4 treatments which are metal silo, Perdue Improved Crop Storage (PICS) bag, polypropylene bag and local storage in two rice varieties (Shaga and Edget) for a six-month storage period. HRY, stored rice moisture content (MC), insect infestation, germination percentage, milled rice and broken rice percentage were monitored during the storage period. The results showed that rice ageing had significant effect on HRY, rice moisture content, germination percentage and insect infestation. Traditional storages (polypropylene bag and local storage) presented statistically significant higher mean infestation and broken rice percentage and a significant drop in the germination percentages, moisture content and HRY with storage period. When compared to traditional storages, modern storage systems (PICS bag and metal silo) had statistically significant higher germination percentage and HRY. The highest HRY (55.5%) was recorded for PICS bag and no statistically differences were observed in broken rice percentage during storage for metal silo and PICS bag conditions at p<0.05. The results indicated that PICS bag is the best option for natural ageing process. From the two rice cultivars under study, Shaga rice had significantly higher HRY while there was a significant drop on Edget rice cultivar. Though rice ageing is a complicated process and need further study on its effect on properties of rice, this research found that ageing had a positive significant effect on physical properties of rice such as HRY so a good emphasis should be given for this process to introduce it for rice processing industry and improve rice quality.
