Roasting-Like Thermal Reconfiguration of Bioactive and Pigment Profiles in Pistachios From Distinct Geographical...

Roasting profoundly influences the phytochemical composition of pistachio (Pistacia vera L.) kernels, yet the interaction between processing and geographical origin remains poorly understood. This study evaluated the impact of a dry roasting-like treatment at 140°C for 45 min on the bioactive profile, pigments, and antioxidant capacity of pistachios from Iran, Spain, the USA, and Turkey. Raw and roasted samples subjected to a dry roasting-like treatment were analyzed for total phenolic content (TPC), individual (poly)phenols by HPLC-DAD, antioxidant capacity using ABTS and DPPH assays, and pigments including chlorophylls and carotenoids. Results showed that geographical origin influenced all parameters. Among raw samples, Turkish pistachios exhibited the highest antioxidant capacity, with ABTS and DPPH values of 1.05 and 3.73 mg TE/g dw, respectively, whereas Iranian samples showed the highest TPC, at 2.5 mg GAE/g dw. The dry roasting-like treatment induced marked compositional shifts, particularly in Turkish samples, with increases of 105% in ABTS, 255% in DPPH, and 255% in TPC. HPLC-DAD identified p-hydroxybenzoic acid as the predominant phenolic compound. The treatment affected individual (poly)phenol concentrations differently depending on origin: total quantified levels increased in USA samples from 140 to 156 μg/g dw but decreased markedly in Turkish samples, from 665 to 241 μg/g dw. Specifically, gallic acid increased across all origins, likely due to the thermal hydrolysis of complex phenolic structures, whereas protocatechuic acid decreased. In terms of pigments, chlorophylls underwent extensive degradation, while carotenoids remained relatively thermally stable. Overall, the dry roasting-like treatment triggered a compositional reconfiguration in which the degradation of thermolabile compounds may have been counterbalanced by the formation of Maillard reaction products, resulting in a net enhancement of functional quality. These findings elucidate the dynamic interaction between geographical origin and thermal processing and provide a scientific basis for promoting pistachios subjected to a dry roasting-like treatment as a functional food contributing to the dietary intake of bioactive phytochemicals.