ROASTING EFFECTS ON AROMA VOLATILES AND ANTIOXIDANT ACTIVITY IN PISTACHIO KERNELS (CV. SIIRT)

Abstract

Roasting is a key processing step that strongly influences the sensory and chemical quality of pistachio kernels. This study investigated the effects of roasting (160 °C for 25 min) on Turkish pistachio (Pistacia vera L.cultivar “Siirt”) kernels by comparing raw and roasted samples. Color parameters (L*a*b*hue angle)total phenolic content (TPC)and antioxidant activity (DPPH assay) were evaluated. Sugars and organic acids were quantified by HPLCwhile volatile compounds were characterized using HS-SPME/GC–MS. Roasting did not significantly affect L*b*or hue angle valueswhile a* and chroma (C*) decreased significantlyindicating partial pigment degradation without pronounced lightness changes. Total phenolic content decreased significantly from 343.38 to 284.72 mg GAE/100 gwhereas DPPH radical scavenging activity increased markedly from 21.56% to 57.19%. Roasting significantly increased sucroseglucoseand fructose concentrations and enhanced levels of citricmalicand succinic acidswhile ascorbic acid decreased. Volatile analysis revealed an increase in identified compounds from 23 to 30with monoterpene hydrocarbons remaining dominant and limonene as the major compound. Aldehydes and Maillard-derived heterocyclic compounds such as pyrazines and pyrroles were detected mainly in roasted kernels. Overallroasting enhanced aroma complexity and antioxidant activity while reducing some heat- sensitive compoundsproviding valuable information for optimizing roasting conditions in “Siirt” pistachios.