Aplicação de microondas na parboilização de arroz

AUTOR(ES)

Carlos Roberto Rocha

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

20/02/1998

RESUMO

Parboiling of rice is essentially an hydrothennically based process that starts when the grains are made to hydrate to a moisture level near 30% by immersion in potable water at a temperature above 58°C. Later on the rice starch undergoes a partial or total gelatinization after the soaked grains are heat treated, then dried before one final milling operation. An expressive advantage results from the high yield of head rice after milling as well as a considerable increase of the nutritive value of rice. This work has studied the effects caused by microwave energy application to the parboiling of rice, during the stage of starch gelatinization, by replacing retort steaming operation of the conventional process. It has taken advantage of the intrinsic properties of microwaves like the very fast heating both at the surface as well inside the grains, thus reducing drastically the processing time, from 20 to 30 minutes in the conventional process down to 2 to 5 minutes by means of microwave treatment. Processing conditions were studied in a manner so as to provide the best head rice yield, mainly by actuating on the process variables: maximum process temperature and holding time under maximum temperature. The best results with respect to the head rice yield were achieved, for both varieties IAC 165 and IAC 102 that were studied, under the condition of maximum temperature 95°C and 1 minute holding time, after 3 minutes spent for heating up the kernels from ambient to maximum temperature. For these conditions the results were the yield increase from 60.9% for the "in natura" IAC 165 to 68.1 % after microwave parboiling and the yield increase from 23.1 % for the "in natura" IAC 102 to 59.9 % after microwave parboiling. The observed color of the kernels for both varieties after microwave parboiling was considerably clearer as compared to the color of the kernels submitted to the conventional method of parboiling.

ASSUNTO(S)

microondas tratamento arroz parboilizado aquecimento

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