Microstructural and rheological properties of irradiated rice

Abstract

The culinary quality of rice directly results in its market value and consumer acceptance. Thus, the present study evaluated the effect of gamma irradiation on the properties of the polished white rice starch, as well as their characteristic pulp. Doses of 6.5 kGy and 7.5 kGy did not alter the microstructure of rice starch granules, but interfered with rheological properties when compared to the control treatment, resulting in a reduction of the maximum and final viscosity and retrogradation. Since the microstructural and rheological properties within the values associated with rice quality, it was inferred that gamma irradiation did not alter the decisive characteristics for the acceptability of this cereal.Index terms: Free radical, paste characteristics, food irradiation. RESUMOA qualidade culinária do arroz resulta diretamente em seu valor de mercado e aceitação do consumidor. Assim, no presente estudo, avaliou-se o efeito da irradiação gama sobre as propriedades do amido do arroz branco polido, bem como na sua característica de pasta. Doses de 6,5 kGy e 7,5 kGy não alteraram a microestrutura dos grânulos de amido de arroz, mas interferiram nas propriedades reológicas quando comparado ao tratamento controle, resultando na redução da viscosidade máxima e final; e retrogradação. Esse resultado pode estar correlacionado à presença de radicais livres no arroz branco polido recém-irradiado, os quais se estabilizaram ao passar quatro meses. Desde que as propriedades microestruturais e reológicas se encontrem dentro dos valores associados à qualidade do arroz, a irradiação gama não altera as características determinantes para a aceitação do cereal.Termos para Indexação: Radical livre, características de pasta, irradiação de alimentos.

Gamma radiation as a modifier of starch – Physicochemical perspective

“…A defined maltese cross structure in the hilum was observed in the native rice starch but no changes were seen in the microstructure of these starch granules alike corn starch. However, the diameter of the granule was observed to decrease in the irradiated sample in a dose-dependent manner ( Ben Bettaïeb et al, 2014 ; Guimarães et al, 2013 ; Gul et al, 2016 ). AFM and TEM studies were performed on gamma radiated maize starch for evaluation of structural changes.…”