Effect of Processing Conditions on Physical Properties of Parboiled Rice.

Abstract

A laboratory-scale parboiling setup was fabricated to produce parboiled rice at low steaming temperatures for determination of its physical properties, the quality indicators, and to compare those qualities with rice produced at higher temperatures. Parboiled rice was prepared under different steaming conditions using different sample sizes, both of which affected the rice temperature and quality. A sample size of 200 g, which maintained a 10 mm thick layer of rough rice, was found adequate for favorable quality. Better quality of parboiled rice was achieved at lower steaming temperatures (80–100°C) than that at higher temperatures (110 and 120°C). The temperature-time combinations of 80°C-40 min, 90°C-30 min and 100°C-20 min were recommended steaming conditions. Parboiled rice produced under these conditions has adequate lightness and color intensity, 4.0 to 7.5% more milling yield having 55 to 80 N hardness values compared with an untreated sample. It is believed the proposed parboiling method would be seen as important by both household and commercial parboiling plants in their production of a good quality product.