Mitigation of arsenic in rice grains by polishing and washing: Evidencing the benefit and the cost

Abstract

Arsenic (As) mitigation strategies are necessary to decrease As in rice grains. Polishing and washing are important methods to achieve the Codex Alimentarius limits for As. This investigation evaluated a procedure for As-mitigation by removing it from rice grains by polishing and washing for potential implementation in food-industries. It was evaluated the conditions of washing-time, rice:water ratio, temperature, and pH, in which the values were 8 h, 1:2, 35 °C, and 6, respectively. The benefits of the processes, polishing and polishing+washing, were the removal of 13.8/40.5%, 15.6/37.9%, and 41.3/54.6% of As in grains polished during 20s, 40s, and 60s, respectively. Approximately 38.8% of As was removed from the husked grains by simple washing. The As-speciation showed a maximum elimination of inorganic As for grains washed+polished 60s. Regarding Cd and Pb, by comparing non-washed husked grains and washed+polished 60s, the removals were 17% and 66%, respectively. The cost of this procedure was the removal of essential elements. Approximately 83%, 95%, 78%, 58%, 45%, and 33% of Mn, Fe, Co, Cu, Zn, and Se, respectively, were removed. Therefore, it is necessary a balance between benefit and cost when using polishing and washing for As-mitigation, especially for populations that have high rice consumption.