a method based on machine vision system (mvs) is hereby employed to evaluate grape drying through an assessment of the fruit’s shrinkage and quality during the dehydration. experimental data as well as captured images are obtained at an air velocity of 1.4 m s-1 and different drying temperatures (50, 60, 70ºc). the results indicated the effect of temperature on the moisture content, shrinkage a...

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,...

A five level four factors central composite rotatable design under response surface methodology was used to optimize process conditions of the foam mat drying process i.e. egg albumen (0%-12%), methyl cellulose (0.1%-0.5%), drying bed thickness (3-7 mm) and drying temperature (55-75°C) to develop grape bar with final moisture content of 14%±1% (dry-base). Contour and response graphs were genera...

Sustainable food production is one of the main goals of the modern world. Nowadays, there is a growing interest in the exploitation of the by-products generated from agriculture and food production as raw materials for obtaining high-value products, which can be used for various purposes in the pharmaceutical, cosmetics and food industries. During the winemaking process, about 20 % of the grape...

This study aimed to evaluate the freeze-drying process for obtaining grape juice powder by reverse osmosis using 50% grape juice pre-concentrated (28.5 °Brix) and 50% hydrocolloids (37.5% maltodextrin and 12.5% arabic gum). The morphology of the glassy food showed the absence of crystalline structure, which was the amorphous wall that protected the contents of the powder. The samples were store...

Two varieties of grapes, white grape and red grape grown in the Campania region of Italy were selected for the study of drying characteristics. Comparisons were made with treated and untreated grapes under constant drying condition of 50 C in a conventional drying system. This temperature was selected to represent farm drying conditions. Grapes were purchased from a local market from the same s...

in this study, the possibility of microwave finish drying for two types of dried grapes (natural and sultana) was investigated. the samples were washed in water bath at given temperature ranges (25 and 45 c) for 30 to 60 minutes. after dewatering the samples, they were dried using microwave (at two powers: 270 and 450 w) and hot air convective dryer (at 50 c). water gain (%), effective moistu...

An analytical ultrasound-assisted extraction (UAE) method has been optimized and validated for the rapid extraction of stilbenes from grape canes. The influence of sample pre-treatment (oven or freeze-drying) and several extraction variables (solvent, sample-solvent ratio and extraction time between others) on the extraction process were analyzed. The new method allowed the main stilbenes in gr...

drying is one of the most important steps in raisin processing. during this step, initial moisture content decreases up to 15-17% (db) for suitable storage. achieving optimum drying conditions can affect the processing time and improve raisin quality. temperature, air velocity and pretreatment are important factors in the quality of the grape drying process. in this research, the effect of temp...

in recent years immense interest has been focused on the use of solar dryers especially when taking into consideration economical and ecological aspects and increasing in fuel costs. the aim of this study was to compare the qualitative factors of raisins made by five different drying methods. at the first step, pretreatments were applied to grapes (var. sultanas) and then the grapes were dried ...