Removal of free cyanide in dry-milled cassava flour using atmospheric nonthermal plasma treatment

Abstract

The primary concern for the cassava industry is reducing hydrogen cyanide (HCN) in the final product to a level that meets the Codex standard. Wet milling and drying to produce cassava starch can reduce cyanide compounds to levels that are safe for human consumption and meet international regulations, but at a high cost in terms of water. The purpose of this study was to investigate the effect of atmospheric nonthermal (ANT) plasma treatment on the removal of free cyanide from dry-milled cassava flour, as well as other physical and chemical properties. To generate cold plasma, helium was used as the feed gas in a dielectric barrier discharge reactor. The results show that the first-order kinetic model can explain the fraction degradation of cyanide by ANT plasma. The rate of HCN fraction removal increased from 0.0116 min−1 to 0.0453 min−1 and 0.0119 min−1 to 0.0349 min−1 with increasing voltage level (10–20 kV) when the initial HCN were 143 ± 7 and 233 ± 5 mg kg−1 dw, respectively. The 20 kV-15 min ANT plasma treatment of cassava flour containing 143 ± 7 mg kg−1 dw reduced 35.7% of HCN without affecting starch crystallinity, protein, fiber, fat, or moisture content, but significantly changed the pasting properties (P < 0.05).