Rice and rice products supply two thirds of Chinese people with their staple food. This thesis reports studies of dry and wet rice processing methods on levels and in vitro solubility of minerals, and of phytic acid in rice and rice products with the aim to contribute to the improvement of the bioavailability of minerals in rice-based diets.
Iron levels in 56 rice varieties from China ranged 9-45 mg kg-1, zinc 13-39 mg kg-1, and phytic acid ranged between 7.2-11.9 g kg-1. Presence of phytic acid in brown rice will make bioavailability of minerals < 4%. Dry processing by abrasive milling showed that phytic acid and iron are gradually removed at similar rates, while zinc is retained better. Distribution of ingredients offers limited opportunities for optimization of abrasive milling for maximum phytate removal, at minimum losses of yield and minerals. Wet processing (soaking under various conditions, phytase application, fermentation, and germination) revealed that removal of phytic acid and improvement of bioavailability of minerals differed with methods. Study of rice products available in supermarkets in China indicated that neither primarily nor intensively processed products were good sources for minerals.
Discussion about the food chain showed that in the short term, dietary intervention by mineral supplementation and food dephytinization and fortification should be considered. On the longer term, selection and breeding of new rice varieties and nutrition education of the general public will be sustainable solutions for the future.