Effect of high temperature drying on amino acid decomposition in feed rice

Drying experiments with crushed feed rice (Oryza sativa, L., japonica, ‘Mizuhochikara’) were conducted to investigate the thermal decomposition effect on seventeen amino acids, including lysine which is the first limiting amino acid in pig nutrition, with drying air temperatures of 40, 50, 60, 70 and 80 °C and relative humidity of 10%. The lysine content in crushed rice decreased with increasing drying temperature; however, there was no significant thermal effect on the decomposition of amino acids during hot-air drying. It was suggested that the crushed rice samples contained lower amino acid levels than whole brown rice because the graded, crushed rice included a little germ and bran layer. It was also confirmed that the amino acid components of the provided brown rice sample showed a similar trend to previous studies. It is expected that high-temperature drying techniques for crushed rice will become a useful method for feed rice drying, because it can achieve rapid, energy-efficient processing without causing damage to the amino acid composition.