Effect of Different Drying Methods and 24-Month Storage on Water Activity, Rehydration Capacity, and Antioxidants in Boletus edulis Mushrooms

This article evaluates the effect of air drying, freeze drying, and 24-month storage at 4 and 20 degrees C on unblanched and blanched Boletus edulis. Water content and activity were lower in freeze-dried mushrooms than in air-dried mushrooms, whereas rehydration capacity showed the opposite tendency. Drying resulted in substantial losses of the following antioxidants: total flavonoids (4-7%), vitamin C (2-36%), beta-carotene (26-32%), and total tocopherols (72-81%); total polyphenols increased during air drying (7-17%) and decreased during freeze drying (5-7%). Antioxidant activity increased 1-33% during drying. Storage led to further changes in the quality of dried mushrooms. After 24 months, no vitamin C or tocopherols were detected, and water content and activity were moderately high.