The effect of using peracetic acid in the processing terminal to reduce microbial contamination of pistachio

Pistachio is a crusial agricultural product in Iran, but its contamination with various micro-organisms can cause problems in production, consumption, and export. Peracetic acid is an antimicrobial substance that can eliminate a wide range of micro-organisms quickly. This study aimed to evaluate the effectiveness of peracetic acid in reducing microbial contamination of pistachios in processing terminals.

Harvested pistachios were treated with concentrations of 0 (control), 1, and 2% peracetic acid at the washing basin of the terminal. Then microbial growth, bacterial and fungal population, lipid percentage, and peroxide number of pistachio kernels were evaluated at 0 and 6 months after treatment.

The results showed that both 1 and 2% peracetic acid inhibited bacterial and fungal growth by about 100% and reduced microbial flora growth by more than 90%. As there was no significant difference between 1 and 2% peracetic acid, the final recommendation is to use 1% concentration. After 6 months, the contamination level increased by about 5%, possibly due to storage conditions and contamination in subsequent stages. Different concentrations of peracetic acid did not have a significant effect on lipid percentage or peroxide number of pistachio kernels.

Research limitations: 

As the treatment time with peracetic acid in the washing basin is uncontrollable, this factor has been eliminated in this research.

Originality/Value: 

The study confirms the importance of using peracetic acid in the terminals to reduce and control pistachio contamination without producing harmful by-products. Economic evaluation also showed that using 1% peracetic acid for disinfecting pistachios in processing terminals is cost-effective.