Effect of airborne ultrasonic technology on microbial inactivation and quality of dried food ingredients

Conventional methods for decontamination of dried foods have various limitations including undesired effects on both food quality and nutritional parameters. Airborne acoustic technology is a potential technology for microbial inactivation which has limited impacts on food quality. The objective of this study was to investigate the potential of airborne acoustic technology for the decontamination of black pepper grains (Piper nigrum L.) and tapioca starch (Manihot esculenta) inoculated with Bacillus subtilis vegetative cells and spores. Black pepper and tapioca starch samples were subjected to airborne acoustic waves at 170 W for treatment times of 0 (control) to 120 min at room temperature. Significant reductions of 2.19 log CFU/g and 2.01 log CFU/g were achieved after 30 min of treatment for black pepper and tapioca starch respectively (p < 0.05). No significant reductions were observed in spore contaminated samples (p > 0.05). Total phenolic content of black pepper and rheological properties of tapioca starch were not significantly influenced by airborne acoustic treatment at treatment times required to achieve 2 log reductions (p > 0.05). This study demonstrated that airborne acoustic technology can be employed for microbial inactivation of dried food ingredients with minimal impacts on food quality.