LOW-CALORIES RAISINS OBTAINED BY COMBINED DEHYDRATION: PROCESS OPTIMIZATION AND EVALUATION OF THE ANTIOXIDANT EFFICIENCY

Abstract

A healthy dehydrated food of high nutritional-quality and added-value was developed: low-calories raisin obtained by an ultrasonic assisted combined-dehydration with two-stage osmotic treatment (D3S) complemented by drying. Pink Red Globe grape produced at Mendoza (Argentina), experienced a substitution of sugar by natural sweetener Stevia in two osmotic stages under different conditions (treatment with/without ultrasound; sweetener concentration 18, 20, 22% w/w; time 35, 75, 115 minutes), evaluating soluble solids (SS), moisture (M), total polyphenols (PF), antioxidant efficiency (AE) and sugar profile. The multiple optimization of the process by response surface methodology and desirability analysis, allowed to minimize M, maximize SS (Stevia incorporation), and preserve the maximum amount of PF. After the first stage, the optimal treatment reduced the majority sugars of the grape in 32% (sucrose, glucose), and the 57% at the end of the dehydration process.

Keywords

• raisins
• sugar substitution
• antioxidant polyphenols
• osmotic treatment