Lipase and Lipoxygenase Activity of Pistacia vera L.

In this work lipase and lipoxygenase activity of Pistacia vera L. nuts of two different origins: Italy (var. Bianca) and Turkey (var. Siirt) was evaluated. Moisture content, peroxide number and acidity of Pistacia vera samples were also determined. In order to highlight the relationship between enzymes and lipids, the triacylglycerol composition and fatty acids distribution were investigated. Italian pistachio showed the highest enzymatic activity as well as moisture, acidity and peroxide number. The difference in enzyme activities among pistachio samples could be explained by the higher moisture and chlorophyll levels at ripeness, in Italian samples. Lipid oxidation and hydrolysis reaction are influenced by the water content, chlorophyll acts as a sensitizer to generate singlet oxygen in the photo-oxidation. Moreover, an effect of different picking time cannot be excluded. In fact, in order to compare samples with a similar green color, the studied samples were picked as follows: the Turkish pistachio at the end of August, the Italian one during the 2nd-3rd week of September. The main triacylglycerols were: OLO, OLL, OLP, LLP and LLL, that account for about 70% of the total TGs in both pistachio samples. TGs with polyunsaturated fatty acids, such LLLn, LLL, OLLn, LnLP, OLL and LLP, were lower in Italian pistachio. This is confirmed by fatty acids composition, so, Turkish samples have a greater polyunsaturated fatty acids content. As lipase and lipoxygenase can have negative effects on the quality of pistachio during storage, it would be useful to optimize the drying process as well as storage conditions.