A New Rotary Dryer Assisted by Infrared Radiation for Drying of Acerola Residues

摘要

Acerola is a tropical fruit whose residues from its processing contain amounts vitamin C, phenolic and other bioactive compounds at the same level of the fruit pulp and juice. In this work we used a novel system for acerola waste drying, which is composed by a new rotary dryer (developed by our research group), named roto-aerated dryer, equipped with a new pre-drying system using infrared radiation. In addition, a pretreatment with ethanol was performed to improve the process performance. The ascorbic acid content, total phenolic content, total flavonoid contents, and antioxidant activity were quantified before and after drying. The main phenolic acids and flavonoids were identified by high performance liquid chromatography. Operating conditions that promoted high moisture removal (91.2%) and that yield to a product with high antioxidant activity (IC50 = 11.6 +/- 0.3 mu g/mL) and low water activity (0.374) were identified. The pretreatment with ethanol led to an increase of up to 72% of the moisture reduction. Therefore, the drying results revealed that this novel dryer system combined with the ethanol pre-treatment is a good alternative for dehydration, reducing the process time and maintaining a high antioxidant activity.[GRAPHICS].