Effectiveness of the fountain-microwave drying method in some selected pumpkin cultivars

- Five pumpkin cultivars were dried using the fountain-microwave method.
- Compression was dependent on the variety.
- The dried variety 'Butternut Waltham' had the highest polyphenols content.
- The dried variety 'Muscade de Provence' had the highest carotenoids content.

Nowadays, the least invasive methods of pumpkin drying are sought. They include the microwave drying technique that applies energy carried by short electromagnetic waves for heating and thus dehydrating the material. In the study, five pumpkin cultivars of the species Cucurbita moschata and C. ficifolia were dried using the new fountain-microwave method. As a result, dry material was obtained whose stress resistance was 10-30 times lower than that of raw pumpkin. It also had 2 times lower resistance to cutting compared to the raw material, especially for the cultivars 'Butternut Waltham', 'Muscade de Provence' and 'Cabello de Angel'. The content of bioactive compounds and antioxidative properties were found to depend on the microwave power applied. Pumpkins dried at 100 W were characterized by greater content of bioactive compounds, but had markedly higher water activity, which is not desirable in dry products. The highest antioxidant activity was found for 'Butternut Waltham' cv. and the lowest for 'Muscade de Provence' cv., although the latter had the highest carotenoid content. The antioxidant activity was decisively more affected by polyphenols than carotenoids.