A review of rice parboiling systems, energy supply, and consumption

Parboiling is an energy and labour intensive pre-milling process aimed at improving the quality of paddy rice. Several parboiling processes along with different energy supply systems have been developed and reported to improve the overall grain quality, processing time and energy consumption. This paper reviews the parboiling process concept, systems, energy supply and consumption, as well as the impact of energy use on product quality. Rice husk is most widely used energy source for parboiling and has been used primarily in direct combustion systems, as briquettes or through gasification systems. Parboiling energy consumption varies widely depending on the process conditions, parboiling system, processing capacity and the energy source.