Alteration in the physico-chemical traits and nutritional quality of rice under anticipated rise in atmospheric CO2 concentration: A review

Changes in climatic conditions with increasing atmospheric CO2 concentration is bound to pose serious challenges for the continued production and supply of high-quality grain with superior nutritional quality. This review highlights that elevated atmospheric CO2 (eCO(2)) condition will have a negative impact on grain processing and nutritional quality. Studies on physical and biochemical traits have shown that changes in starch composition with reduced amylose content leads to lower gelatinization temperature and higher viscosity, presumably making the cooked rice softer and more palatable. However, it is interpreted that increased chalkiness under eCO2 with reduced processing recovery will yield broken rice. Broken rice grains with deteriorated nutritional quality, characterized by decreased protein content, micronutrient levels, vitamin profile and increased phytic acid (PA) content, may have significant repercussions on the nutritional security of resource poor countries in the changing atmospheric CO2 scenario. Further, it appears that the reduction in milled rice recovery may affect the marketability of rice, which in turn may influence the rice industry to develop value added products of rice, based on soft and broken rice. This review also addresses the research needs for ensuring the nutritional quality of rice grain as well as maximizing the grain quality under future warm and eCO2 conditions for global food and nutritional security.