Ultrasound-assisted Dehydration Process Applied to Red Globe Grapes for Producing Low Calorie Raisins

MARIANA LABORDE; ANA PAGANO; GASTÓN BARRETO

American Journal of Food Science and Technology

Science Pubications (SciPubs)

Año: 2018 vol. 6 p. 209 - 214

2333-4835

 In this paper the application of ultrasound was investigated as a method for improving mass transferduring the first stage of a process of osmosis combined with dehydration drying to obtain grapes reduced in highcalorie sugars. Fresh grapes (Vitis vinífera L.) Red Globe variety were subjected to immersion in distilled water atroom temperature with assistance ultrasound (40 kHz) using a weight ratio fruit: solvent of 1: 4, during regularlyspaced intervals in the range 0-30 minutes; comparatively a control treatment without application of ultrasound (0kHz) was conducted. Subsequently, the grapes were stabilized by drying at 70°C. The analysis of variance showedsignificant influence of treatment on the soluble solids content and gain at all times. The greatest sugars reductionswere achieved when ultrasound was used. Process monitoring was conducted by assessing the change in the sugarcontent of grapes by refractometry (°Brix), and confirming the results by HPLC. The best treatment that significantlyreduced (p <0.05) the content of the major sugars in fresh fruit (30% fructose and 27% glucose) turned out to be 25minutes immersion assisted by ultrasound.