Efficacy of individual and combined UVC light and food antimicrobial treatments to inactivate Aspergillus flavus or A. niger spores in peach nectar

• UVC inactivation of Aspergillus niger and A. flavus spores in peach nectar
• Combination of UVC and antimicrobial agent effects on mold spores inactivation
• Potassium sorbate reduces UVC inactivation effect.

This study examined the efficacy of short wave ultraviolet (UVC) irradiation for the inactivation of Aspergillus flavus or Aspergillus niger inoculated in peach nectar. A commercial UVC-disinfection unit with a total dose of 203 kJ/m2 achieved 4 and 3 log reductions for A. flavus and A. niger, respectively. Variations observed in the characteristics of the nectar (acidity, color, pH, and soluble solids) before and after the treatment were minimal. The efficacy of combined treatments of UVC with commercially available food antimicrobial agents, potassium sorbate (KS, 250–2000 ppm) and sodium benzoate (NB, 250–1000 ppm) was tested. Inactivation effectiveness decreased with increasing KS concentration. The highest microbial inactivation (up to five logarithmic cycles) was achieved for A. flavus during the combined UVC–NB treatments, which also exhibited nectar microbial stability up to 15 days at 25 °C. Weibull model adequately described the UVC inactivation of A. flavus and A. niger, obtaining a shape parameter for both populations of n < 1.Industrial relevanceCombined treatments of food antimicrobials and UVC irradiation can be utilized effectively for the reduction of microbial contamination of peach nectar. Potassium sorbate absorbs UVC-light therefore, in a combined treatment it can only be added after the UVC treatment; but sodium benzoate and UVC proved to be more successful at reducing microbial populations of A. flavus and A. niger than their individual treatments.