The Effect of Peracetic Acid on the Microflora of Pistachio (Pistacia vera) Nuts

The economic importance along with high nutritional value of pistachio has necessitated further research on this agricultural product. One of the most important problems in the production, consumption and export of pistachio is its contamination with various microorganisms at different stages. Pistachio kernel is considered as a fatty seed and this makes it very susceptible to fungal and bacterial contamination and as a result, its shelf life would be reduced. Peracetic acid is a strong oxidizer which can rapidly remove a wide range of microorganisms and is also environmentally safe. In this research, pistachio seeds were treated with different concentrations (0, 5, 10, 12.5 and 15%) of peracetic acid for 0.5, 1, 1.5, 2 and 5 min. Then the growth of bacteria, fungi, and common microflora were evaluated. The results indicated that the treatment of pistachio with 10% peracetic acid for 0.5 min, reduced the contaminating microflora more than 99%. Therefore, disinfection of pistachio nuts with peracetic acid can be done in pistachio terminals (inside washing tank) to improve its quality before introducing to the market.