Effects of a brief, intense infrared radiation treatment on the nutritional quality of maize, rice, sorghum, and beans

Abstract

Maize, sorghum, rice, and beans were subjected to a temperature of 22,000°C for 0.5 minute in an infrared radiator 3 m long. The uncharred grains exited the radiator at a temperature of 140° C and were cooled to room temperature. The moisture content dropped to 3% to 7%, thus affecting the proximate composition of the grain components. The digestibility of cereal starch remained high and unchanged (71%-84%), whereas protein digestibility was reduced by 7%, 21%, and 25% in rice, sorghum, and maize, respectively. The caloric values of the cereals remained unaltered. Anti-trypsin factor in beans and haemagglutinins in both beans and sorghum were inactivated. Tannin in sorghum was reduced extensively. The traces of aflatoxin in sorghum and maize were completely destroyed. It was concluded that since there is always some loss of protein quality in thermal food preservation processes, the slight decline in protein digestibility did not have practical significance in comparison with the benefit of radiation as a brief, high-temperature preservation technique that could be adopted as a pre-processing treatment to destroy anti-nutrients and dehydrate food to the very low water activity desirable for long shelf life