Postharvest Microwave Drying of Basil (Ocimum basilicum L.): The Influence of Treatments on the Quality of Dried Products

Abstract

Edible herbs are widely used in the human diet due to their pleasant flavors and countless health benefits associated with their components having, mainly, antioxidant and anti-inflammatory therapeutic functions. Since herbs are highly perishable materials because of their high water content, to guarantee products are safe and stable over time, it is necessary that they undergo stabilization operations. The application of microwave-assisted drying, a promising technique in terms of process sustainability, for the stabilization of the aromatic herb, Ocimum basilicum L., was investigated. The activities were carried out by applying different operating conditions in order to evaluate the impact of the time/temperature combination on the final quality of dried basil. The latter was investigated via the chemical characterization of extracted essential oils and tissue damages. Conventional convective processes were also applied to perform comparisons between dried basil products both under production and the quality preservation points of view. Results showed that microwave heating is suitable as a drying method, as expected, due to the well-known interaction between vegetable tissue (rich in water) and the electromagnetic field; and that drying methods have a different influence on the chemical composition of the essential oils extracted from dried products, in terms of the number (ranging from 41 to 18 components in different dried samples) and percentage (until 67% in linalool and 21% in α-trans-bergamotene in different dried samples) of its’ constituents.

Application of the Cryo-Drying Technique in Maintaining Bioactive and Antioxidant Properties in Basil Leaves (Ocimum basilicum)

“…In the study by De Martino et al (2022) [38], who evaluated the influence of drying on the quality of the aerial parts of Ocimum basilicum, including the convective heating oven for 24 h at 50 • C, a post-drying U% of 10.52% was observed, this being greater than that obtained in the present study, which was 5.2%. This inequality of values may be related to the drying temperature, in which the one in the present study was 55 • C, proving to be more efficient in removing the free water present in the sample.…”