EFFECTS OF VARIED PARBOILING CONDITIONS ON PROXIMATE AND MINERAL COMPOSITION OF JASMINE-85 AND NERICA-14 RICE VARIETIES IN GHANA

Abstract

Parboiling of paddy rice is an integral part of post-harvest rice processing. This practice of parboiling varies among individuals or groups. This study investigated the effect of different parboiling conditions on the nutrient content of two rice varieties, Jasmine-85 and Nerica-14. The paddy was soaked in a warm water of 40°C at four different periods of 6, 20, 24 and 36 h, and then steamed at 40, 60 and 90 min at a temperature of 100°C. Guidelines of Association of Official Analytical Chemists were used to obtain the proximate and mineral compositions of the parboiled rice. Concentration of minerals like iron, zinc, calcium and manganese was determined using Atomic Absorption Spectroscopy whiles Flame Emission Spectroscopy technique was used to determine the concentration of potassium and sodium. Results obtained from the varied levels of parboiling showed that averagely protein content decreased from 6.8 to5.1% (P<0.05), carbohydrate content decreased from 70.3 to 55.9% (P<0.05) and crude fibre content reduced from 2.9 to 2.1% (P<0.05) after parboiling. Also the concentration of the iron, zinc, calcium, manganese, potassium, and sodium decreased as a result of parboiling. For instance iron concentration decreased from 1.8 ppm in non-parboil rice to 1.0 ppm in parboiled rice (P<0.05) and Zinc also reduced by 0.33 ppm due to parboiling (P<0.05). A parboiling condition of 20 h soaking; 60 min steaming gave better results on all the parameters. In conclusion, parboiling of paddy rice affects the proximate and mineral contents of rice. It is recommended that practitioners should parboil for 21 h (20 h soaking followed by 1 h steaming) for optimum nutrients and minerals content.