Effect of gamma ray on colour and quality of 'RD 41' parboiled rice

N. Ranmeechai, P. Boonyaritthongchai, A. Uthairatanakij, S. Photchanachai
The objective of this research was to investigate the effect of gamma ray on colour and quality of ‘RD 41’ parboiled rice. There were two types of rice in this study: parboiled paddy (PP) and parboiled rice (PR). The 300 g of parboiled paddy and 200 g of parboiled rice were packed in paper bags and then irradiated at 6 and 9 kGy at the Thailand Institute of Nuclear Technology (Public organization). The non-irradiated PP and PR were used as control samples. After irradiation, the parboiled paddy was de-husked and polished to get parboiled rice (PP+Ir+PR) for quality measurements similar to the parboiled rice (PR+Ir) irradiated with the same doses of gamma ray. The results showed that irradiation did not affect head rice yield of PP+Ir+PR. Irradiation at 9 kGy had a significant effect in increasing yellowness (b* value), thiobarbituric acid (TBA) value and reducing sugar content of PP+Ir+PR and PR+Ir, compared to irradiation at 6 kGy and control samples. Irradiation at both 6 or 9 kGy significantly raised b* value and reducing sugar content of PP+Ir+PR more than PR+Ir, while the TBA value of PR+Ir was significantly higher than that of PP+Ir+PR. The moisture content (MC) was significantly decreased by irradiation. Irradiation at 9 kGy significantly decreased MC of PP+Ir+PR more than that at 6 kGy, but the MC of PR+Ir irradiated with 6 or 9 kGy was not significantly different. Therefore, the promising type of rice for irradiation at 9 kGy in improving yellowness with less rancidity is parboiled paddy.
Ranmeechai, N., Boonyaritthongchai, P., Uthairatanakij, A. and Photchanachai, S. (2018). Effect of gamma ray on colour and quality of 'RD 41' parboiled rice. Acta Hortic. 1213, 489-494
DOI: 10.17660/ActaHortic.2018.1213.72
gamma ray, parboiled rice, parboiled paddy, golden colour

Acta Horticulturae