Rice grain quality alteration through manipulation of parboiling procedures to affect the concentration of macro- and micro- nutrient elements, B-vitamins, inorganic toxicants, and bacterial contamination

Abstract

A Bangladesh village rice parboiling plant was used to investigate how to improve essential elements and B-vitamin content of rice, while reducing the toxicants arsenic and cadmium, and potential bacterial pathogens. A 2⁵ -factorial experiment was conducted where husked and de-husked rice was parboiled at different pre-parboiling soaking times, pre-parboiling soaking temperatures, parboiled through either boiling or steaming, and parboiled for 2 different times. Three rice cultivars were used. Using wholegrain, rather than rough rice, with 15 mins of parboiling, gave the optimal reduction in inorganic arsenic (25 %), as compared to widely used rough rice parboiling procedures. This combination of treatments also enhanced calcium (circa. 200 %) and iron (circa. 50 %), but lost circa. 50 % of potassium. The wholegrain parboiling procedures reduced vitamin B1 and B6 compared to rough rice parboiling, but made no difference for B2 and B3. Bacillus and Enterobacter related sequences showed highest levels of abundance, and were identified in 100 % and 77 % of non-parboiled rice samples, respectively. The overall implications of this study was that wholegrain, as compared to rough rice, parboiling should be adopted, but the B-vitamin and potassium intakes of the receiving populace need to be considered.