Production and Characterization of Dehydrated Acerola Pulp: A Comparative Study of Freeze and Refractance Window Drying

Abstract

Acerola is a perishable fruit with high vitamin C levels and an attractive nutrition property. The goal of the present work was to produce dehydrated acerola pulp with preserved vitamin C, selecting freeze-drying and refractance window (considered a novel and promising drying method) as suitable technologies. The final properties of dehydrated pulps using the drying technologies freeze-drying and refractance window were compared: i) water activity, ii)moisture content, iii) hygroscopicity, iv) color parameters, v) microstructure, vi) antioxidant activity, and vii) ascorbic acid stability (30 °C, 75% RH). The dried acerola pulps exhibited low moisture, water activity, and hygroscopicity regardless of the drying technology. However, the pulp dehydrated by refractance window presented significantly higher antioxidant activity than the freeze-dried pulp, with higher ABTS^•+ (1,838.60 μM TE/g dehydrated pulp) and FRAP (1,290.00 μM TE/g dehydrated pulp) values. The ascorbic acid stability values were also higher for the pulp dried by the refractance window, which showed a final content of 98.03 mg/100 g dehydrated pulp after ten days of storage. The refractance window is a more appropriate technology to dehydrate acerola pulp with high vitamin C content, antioxidant activity, and ascorbic acid stability than freeze-drying.