Effect of edible coatings on some physicochemical properties and fungi growth during different storage periods of pistachio nuts

Abstract EN

The aim of this study was to examine the effects of regular edible coating treatments on the local Pistacia vera Kaleghouchi to determine changes in composition, physicochemical parameters, and microbial analysis of the pistachio during different storage periods.

Pistachio nuts were coated with chitosan at different concentrations of 1% , 1.5% , and 2% , with 50% and 60% of whey protein isolate by immersion method.

Samples were stored at room temperature for 5 months.

The obtained results showed that there was a significant difference (p ≤ 0.05) between coated and uncoated samples.

The highest acid value, peroxide value, viscosity and density were observed in the control samples (1.05 mg KOH/g oil, 9.33 mEq active O2/kg oil, 142.77 cP and 0.922 g/mL) respectively, while the lowest peroxide value was found in the treated nuts with chitosan 1.5% and whey protein isolate (50% ), which both were 4 mEq of active oxygen kg-1.

lowest acid value (0.73 mg KOH/g oil) and viscosity (80.21 cP) was observed in the chitosan 1.5% coated samples.

As the lowest density was resulted in coated pistachios with both 1% and 2% chitosan and they both were 0.916 g/mL.

Chitosan significantly (p ≤ 0.05) reduced the mould count (Aspergillus), the highest mould count (75×101 CFU/g nuts) was noticed in control sample, while lowest (5×101 CFU/g nuts) was observed in the treated samples with 2% chitosan.