The use of amino acids as anti-browning agents in rice parboiling: Effects on quality attributes of three South American genotypes

Abstract

The parboiling process improves the physical and nutritional quality of rice, but promotes browning, mainly due to the occurrence of the Maillard reaction (MR). Five different amino acids (glycine, methionine, glutamine, sodium glutamate, and aspartate) were studied as limiting agents of the MR in the parboiling process of two pure lines (Guri Inta CL and Irga 424 RI) and a hybrid (Titan CL) genotype. Samples were hydrated under two concentrations of those amino acids (1.5% and 3.0%) during the first step of parboiling. Methionine, glutamine, and aspartate were less effective in preventing the browning of parboiled rice. Glycine (26.63–28.48 GBZ) and sodium glutamate (26.88–28.12 GBZ) were able to provide lighter color to parboiled rice in comparison to control treatment (23.68 GBZ). Parboiled rice treated with amino acids had a lower degree of gelatinization when compared to the control treatment. The extent of gelatinization in parboiled rice produced by using amino acids as anti-browning agents may vary as a function of the applied amino acid molecule and its concentration as well as a result of the characteristics of the selected rice genotype. The percentage of broken grains only increased for the Irga 424 RI genotype, which exhibited shorter cooking time due to the greater ability of the grains to soften during cooking.