Efeitos dos genótipos e das pressões de autoclavagem sobre parâmetros de qualidade de arroz parboilizado de cultivares da América do Sul.

Abstract

In the present study, six rice genotypes were subjected to the parboiling process with different steaming pressures and evaluated for chemical, physical and technological properties. The pure (Puita INTA CL, Guri INTA CL and Irga 424 RI) and hybrid genotypes (Titan CL, Lexus CL and Inov CL) were subjected to the parboiling process with steaming pressures of 0.25, 0.50 and 0.75 kgf.cm-2. The impacts of starch characteristics and steaming conditions were evaluated on the gelatinization degree, percentage of broken grains, cooking time, hardness, crystallinity and physicochemical properties of parboiled grains, as well as the susceptibility to darkening of the genotypes through color, soluble sugars, free lysine and HMF evaluations. Among the genotypes studied, Titan CL starch (the only material with medium amylose content) showed higher values of relative crystallinity, gelatinization temperatures and average of amylopectin chain length. Gelatinized rice under severe conditions (0.75 kgf.cm-2) showed a higher gelatinization degree, a lower percentage of broken grains and greater hardness, with a consequent reduction in paste viscosity and crystallinity of the flours. In addition, the gelatinized grains at 0.75 kgf.cm-2 were less porous, more translucent, with a lower degree of whiteness and higher levels of hydroxymethylfurfural. The content of soluble sugars and free lysine in the parboiled grains appeared to be more dependent of the genotype than parboiling conditions. The results obtained allow to identify and select the appropriate processing conditions, according to the plant material characteristics, besides to supporting the practice of industrial segregation for the parboiling of rice aiming the high quality of parboiled rice.