Chemical determinants of dried Thai basil (O. basilicum var. thyrsiflora) aroma quality

Herbs market is constantly growing worldwide, and is trying to find new species and varieties coming from specific geographical regions. While the increasing production demands novel solutions for product preservation, consumers demand guaranteed quality for these products. In case of herbs, the most common preservation method is thermo-based process - drying, which strongly affects products quality. Regarding the technological possibilities and efficiency, convective drying (CD), microwave drying, vacuum-microwave drying (VMD) and combined convective pre-drying followed by vacuum-microwave finish-drying (CPD-VMFD) methods are the most popular ones. In this study, the influence of the drying methods (CD, VMD and CPD-VMD) on Thai basil (O. basilicum var. thyrsiflora) quality was evaluated for the very first time. The chemical composition of their essential oils (EOs), dried samples (aroma profiles, APs) and sensory quality of the dried products were also studied. As a result of multiple chemical and sensory analyses and after cross-checking all these results, guidelines for chemical markers of Thai basil aroma quality were established. Odour-active compounds (OACs) contribution in Thai basil EOs did not show a clear pattern to link it with quality assessments; however, OACs contribution in APs did. The drying treatments leading to the dried products with the highest quality were: (i) 2 h CPD at 50 degrees C followed by VMFD with 360 W (2 h CPD50) and (ii) 1 h CPD at 70 degrees C followed by VMFD with 360 W (1 h CPD70).