The Effect of Persian Gum Coating Containing Green Mint Extract and Ultraviolet Ray on the Duration of Fresh Pistachio (Pistacia Vera)

Pistachio is one of the most popular nuts of the world due to its taste and nutritional value. The storage conditions of pistachios play an essential role in preserving the quality and organoleptic characteristics of the product, while unsatisfactory storage conditions, create undesirable reactions and provide poor products quality.
This study was carried out to evaluate the effect of various ultraviolet rays (4, 8,12 Kj/m2), Persian gum (7% w/v), and mint extract(1.5% v/v) on oxidative reactions and microbial characteristics of pistachio kernels of Kaleghuchchi cultivar. After applying the treatments, pistachios were packed in polyethylene bags and kept at refrigerated temperature (4 ± 1 ℃) for two months. In the first, third, fifth and eighth weeks, phenolic compounds, acidity, peroxide value, thiobarbituric acid number and lossing weight were measured. On the first and last days of storage, the total microbial load and yeast mold were evaluated. Inorder to evaluate the effect of gum and extract of mint on the sensory properties on the last day, five-point gradient Hedonic test was carried out. Statistical analysis was performed using SPSS20 software in a completely randomized design with three replications in LSD test.
The result showed that by increasing the intensity of radiation, the microbial load decreased (p <0/05), because the radiation by the nucleoide acid causes the breakdown of the primidine nucleotides, but it increases the acidity, peroxide, and thiobarbituric acid because the radiation causes degradation due to its photocatalytic activity. Phenolic compounds andantioxidant activity is reduced. In the coating samples, especially gum and mint extract coating, the levels of microbial, acidity, peroxide, and tiobarbituric acid were reduced (p <0.05) due to the presence of antioxidant capacity. the sensory evaluation results indicated that there was no significant difference in terms of smell, tast and overall acceptancebetween thesamples.
Using Persian gum coating with mint extract, the increases antimicrobial power and also reduces the negative effect of UV on fat oxidation.