Evaluation of modified humidity and controlled-release thymol on the preservation of blueberries and blackberries

Abstract

Blueberries and blackberries are highly valued and increasing in demand over the last twenty years, despite facing challenges like water loss, shriveling, softening, and vulnerability to phytopathogens, impacting their storage and marketability. Thus, postharvest quality preservation is a crucial area of interest for the small fruit industry. In this study, blackberries and blueberries were packed in modified humidity clamshells (named as LV, for low-vented), with an opening ratio 6.43 times lower than that in commercially available clamshells (COM). Also, the antifungal effect of the thymol, an essential oil, microencapsulated in a pectin-alginate matrix as a controlled-release system was assayed. Results show that relative humidity within LV clamshells remained higher and less variable than in COM clamshells, which led to significantly lower weight loss in both crops. Blueberry firmness, shriveling and marketability were positively impacted by storage in LV clamshells, and the inclusion of a microencapsulated thymol sachet successfully reduced postharvest decay. Our results indicate that these two tools could be used to extend blueberry shelf life, with their combination yielding the most optimal results. However, the same strategies were ineffective for blackberry quality maintenance. After exposure to thymol, more decay was observed, whereas firmness, shrivel and marketability were not affected either by clamshell vent area or thymol treatment. This underscores the importance of tailoring storage conditions, packaging design, and handling methods to each specific fruit type.