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Red rice ( Oryza sativa L .) use in flour production: Convective drying and bioactive quality
Author(s) -
Santos Newton Carlos,
da Silva Wilton Pereira,
Barros Sâmela Leal,
Almeida Raphael Lucas Jacinto,
Brito Araújo Ana Júlia,
da Silva Nascimento Amanda Priscila
Publication year - 2020
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/jfpe.13490
Subject(s) - food science , chemistry , diffusion , moisture , water activity , titratable acid , red rice , water content , thermodynamics , physics , geotechnical engineering , organic chemistry , engineering
This study aimed to develop red rice flours in order to provide alternatives to replace conventional flours in the production of gluten‐free foods for people who suffers from celiac disease. To obtain the flour, red rice grains were dried at temperatures of 40, 50, 60, 70, and 80°C and air velocity of 1.5 m/s. Mathematical models (empirical and diffusive) were fitted to the experimental data obtained and, subsequently, the dehydrated grains were ground to obtain the flour, which was subjected to physicochemical and bioactive characterization to verify the impact of the applied temperatures on the final product quality. It was found that the Page model is more reliable to describe the drying kinetics of red rice, since it showed higher coefficients of determination ( R 2 ) and lower chi‐square ( χ 2 ). The diffusion model showed satisfactory fit, with coefficient of determination ( R 2 ) higher than 0.99 and chi‐square ( χ 2 ) lower than 0.0146659. Higher drying rate was found at the temperature of 80°C, but cracks were observed in the grains and there was greater degradation of anthocyanins. The pH, total titratable acidity, and flavonoids did not differ between the temperatures applied. Lower values of moisture content, water activity, total phenolic compounds, and antioxidant activity were obtained in the grains subjected to temperature of 80°C. Therefore, the temperature of 40°C was the one that ensured greatest conservation of all bioactive compounds analyzed and greater antioxidant activity for all three methods. Practical applications The diffusion model provides a realistic and physical interpretation of the drying operation, stimulating the correct time needed to reduce the moisture content of the material, of initial value at the equilibrium value. In this way, it is possible to save energy and reduce the degradation of bioactive compounds promoted by thermal damage, which material is submitted, in addition to aiming at the optimization of drying equipment projects.