Low pressure radio frequency plasma effects on the mould control, physical quality, nutritional value, mineral content and trace element content of brown rice snack bars

This study investigated the application of low pressure radio frequency (RF) plasma from 30 W to 160 W at exposure times from 5 min to 30 min on an Aspergillus flavus infected brown rice snack bar. Changes in the microbial quality (total yeast and mould), physical quality (colour and hardness), nutritional value, mineral content and trace element content of a brown rice snack bar before and after treatment (130 W for 30 min) were also studied. Low pressure RF plasma at 130 W for 30 min inhibited A. flavus on a brown rice snack bar the best. Plasma treatment at these conditions provided a 4 log CFU.g(-1) reduction of yeast and mould and kept the snack bar at an acceptable quality. Low pressure RF plasma did not affect the brown rice snack bar colour (L* a* b*), hardness quality, crude protein, fibre or ash (p < 0.05). There were no significant changes in sodium, potassium, zinc, manganese and selenium (p > 0.05). However, the contents of crude fat, calcium, magnesium and copper were significantly higher than before treatment (p < 0.05). These results suggest that low pressure RF plasma can be effectively used as an alternative method for snack bar sterilization.