Stability of agro-industrial waste through the convective drying process

Abstract

Wastes obtained from the processing of agro-food products have a short shelf life, so they need to be preserved for further processing. One solution for the conservation of agro- industrial waste is to be subjected to the drying process. This solution has also the advantage that dry products take up less storage space, due to water removal. Material and methods. In this study, a series of industrial wastes resulting from the processing of vegetables and fruits were dried and were taken from the technological flow of the profile units in Romania (as Research-Development Station for Viticulture and Winemaking Iași - SCDVV Iasi, or SC. ContecFoods SRL, Tecuci). The resulting waste comes from the following technological stages: grape pressing (SCDVV Iasi), sorting, washing, cleaning, peeling, heat treatment of onions, eggplants, peppers, beets, carrots, cabbage (SC. ContecFoods SRL, Tecuci) Results and conclusions. The marc obtained in the grape pressing process was subjected to natural drying in a shed up to a humidity of 18-20%, after which the products were dried to constant humidity in a convective dryer that uses hot air as a drying agent. The humidity obtained after convective drying was on average 8-9% for all marc samples (five species). The samples collected from the technological flow were subjected to the convective drying operation using hot air, reaching a minimum constant humidity (from 85-90% to 10-14%, depending on the variety). In order to dry, the samples were chopped into 3-5 mm particles to increase the contact surface. After drying, the dried samples of marc and vegetables were finely grounded with a hammer machine and/or knife machine. The dried samples were stored, by variety, in paper bags in a dry environment. The drying process lasted between 8 and 14 hours, at 45 degrees Celsius, depending on the humidity of the analyzed samples.