TITLE:
The Influence of Abrasive Pretreatment on Hot Air Drying of Grape
AUTHORS:
Giuseppina Adiletta, Wijitha Senadeera, Loredana Liguori, Alessio Crescitelli, Donatella Albanese, Paola Russo
KEYWORDS:
Grape, Drying, Raisin, Abrasive Pretreatment, Sugar Content, Shrinkage, Texture, Rehydration
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.6 No.3,
March
13,
2015
ABSTRACT: The
drying of grapes is a more complex process compared to the dehydration of other
agricultural materials due to the necessity of a pretreatment operation prior
to drying. Grape drying to produce
raisins is a very slow process, due to the peculiar structure of grape peel, that
is covered by a waxy layer. Its removal has been so far carried out by using
several chemical pre-treatments. However, they cause heterogeneity in the waxes
removal and create microscopic cracks. In this paper an abrasive pretreatment
for enhancing the drying rate and preserving the grape samples is proposed. Two
cultivars of grape were investigated: Regina white grape and Red Globe red grape.
The drying kinetics of untreated and treated samples were studied using a
convective oven at 50°C. Fruit quality parameters such as sugar and organic
acid contents, shrinkage, texture, peel damage (i.e. by SEM analysis) and rehydration capacity were studied to
evaluate the effectiveness of abrasive pretreatment on raisins. Abrasive
pretreatment contributed to reduce drying time and rehydration time. The
treated and untreated dried grapes were significantly different (p p