Pistachio hull, as the dominant component of pistachio processing wastes, is a source of phenolics with antioxidant properties. Extracting these compounds from pistachio wastes has recently attracted a lot of attention. The current study aimed to identify the optimal conditions for extracting phenolics from pistachio hulls. Firstly, some parameters such as different sample to solvent ratios (1:10, 1:20, and 1:40), extraction temperatures (25, 45, and 65°C), and duration times (1, 2, and 3 h) were evaluated under extracting solvent of water. The content of total phenolics and antioxidant activity were determined using spectrophotometric methods. The results indicated that the highest phenolics (~35 mg g-1) were extracted at 2 h extraction time, 65 °C, and the sample to solvent ratio of 1:10 (optimum condition by the solvent of water). Secondly, other organic solvents of ethanol, methanol, and acetone 50% were evaluated to identify the best solvent under optimal conditions. All of these organic solvents were more efficient than water in extracting total phenolics (with antioxidant property) from pistachio hulls. However, the highest amount of total phenolics (~47 mg g-1) was extracted by ethanol. Optimizing the extraction of phenolic compounds from pistachio hulls would be important in terms of reducing human and environmental risks caused by the waste accumulation, as well as producing naturally beneficial compounds and using them instead of synthetic antioxidants in the human diet. Manuscript profile

The economic importance along with the high nutritional value of pistachio has necessitated further research on this agricultural product. Its contamination with various microorganisms causes several problems for the production, consumption and export of pistachio every year. Pistachio as a fatty nut is very susceptible to fungal and bacterial contamination and thereby, 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 firstly treated with different concentrations (0, 1, 2 and 2.5%) of peracetic acid for 0.5, 1, 1.5, 2 and 5 min. Then the growth of fungi and bacteria were evaluated. The results indicated that 2% peracetic acid for 0.5 min led to 99% reduction in contaminating microflora . In the next step, the most common microflora contaminating pistachio seeds were detected and exposed to different concentrations of peracetic acid for 0.5, 1, 1.5, 2 and 5 min. The results showed that 1% peracetic acid for 0.5 min inhibited the growth of the dominant microflora more than 99%. Peracetic acid treatment in the tested range had no significant effect on lipid content but reduced peroxide value. Therefore, disinfection of pistachio product with a concentration of 1-2% peracetic acid in the washing basins of pistachio processing terminals may be an applicable approach to inhibit their microbial (bacteria and fungi) contamination up to 99% and improve their quality before introducing to the market. However, this idea requires further field research. Manuscript profile