Evaluation of the Effect of Pretreatment Processes on the Bioactivity and Physicochemical Properties of Quince Slices Dried Using Vacuum-Combined Infrared Radiation

Abstract

This study investigated the effects of citric acid, ultrasound, ethanol solution, freeze-thawing, and blanching pretreatments and their combinations on quality parameters, phenolic profile, antioxidant activity, phenolic bioaccessibility, and α-glucosidase inhibitory activity of quince slices dried by vacuum-combined infrared radiation. Drying time was significantly shortened when pretreatments were applied, especially their combinations. The pretreatment combinations also resulted in a decreased rehydration ratio of the samples and high L* values. The pretreatments increased the contents of chlorogenic, neochlorogenic, and cryptochlorogenic acids, decreased rutin content, and resulted in variable amounts of procyanidins B1 and B2. 5-Hydro-xymethylfurfural was detected in dried quince slices pretreated with citric acid (61.3 mg/kg DM), ultrasounds (9.2 mg/kg DM), freezing-thawing (62.4 mg/kg DM), and blanching (4.3 mg/kg DM). The total phenolic, total flavonoid, and condensed tannin contents and antioxidant activity decreased after in vitro gastrointestinal digestion. Lower phenolic bioaccessibility was found especially in dried quince slices after pretreatment combinations. The α-glucosidase inhibitory activity of quince slices ranged from 17.94 to 24.84 mg/mL, which was higher than that of acarbose (26.79 mg/mL). The results showed that the pretreatments employed in quince drying can be used separately rather than in combination and that sample exposure to ultrasounds turned out to be be the most suitable pretreatment method