The Effect of Plant Water Status on the Chemical Composition of Pistachio Nuts (Pistacia vera L. Cultivar Bianca)

Abstract

Pistachio nuts are worldwide appreciated for their chemical and organoleptic profiles. There are several studies on the influence of irrigation on pistachio productivity, whereas there are little available data on the influence on nut quality. In this study we characterized some qualitative traits of pistachio nuts cultivar Bianca in Mediterranean environment and how plant water status affected them. Water status had a positive and significant influence on the chlorophylls content, nuts from less stressed trees showed higher values of chlorophyll a (14.7 mg/100 g) and b (21.1 mg/100 g) compared than more stressed trees (9.3 and 11.5 mg/100 g for a and b, respectively). Solid phase microextraction technique in headspace followed by gas chromatography/mass spectrometry (HS-SPME GC/MS) identified seventeen different compounds with terpenes being the major class of volatiles; the most abundant were α-Pinene (range 26.2–35 μg/g), D-Limonene (2.8–3.3 μg/g), 2-Carene (1.8–3 μg/g) and β-Myrcene (0.6–1.4 μg/g). Overall, we found higher level of terpenes in less stressed trees and for α-Pinene and β-Myrcene differences were significant. The fatty acid composition analysis revealed oleic acid (70.1–71.1%), linoleic acid (13.5–14.4%) and palmitic acid (9.6–9.8%) as the most abundant compounds, but tree water status did not influence their concentration. Overall, the data reported proved that supplemental irrigation contributes to increase pistachio nut quality.