Solar drying of apple and orange waste: Evaluation of a new thermodynamic approach, and characterization analysis

Abstract

During the industrial processing of agricultural products, the steps to be followed are more numerous and lead to the appearance of a varied range of waste, a source of pollution in the environment. However, this waste is an important source of energy for ruminants, which greatly benefit from it. This work is an experimental and thermodynamic study of the solar drying of apple and orange waste. In this work, we present a new approach for the thermodynamics study of drying apple and orange waste, as well as the evaluation of this waste as a complement in the feeding of ruminants. This evaluation has led to the study of the properties of four powders obtained by drying apple and orange waste with two methods, namely thin-film drying under the sun, and thin-film drying in the greenhouse solar dryer. Several experiments were carried out on the powders obtained, to study the effect of drying on their physical, physicochemical, microbiological, and microscopic properties. The goal is to know and determine the optimal drying method that provides us with dry, healthy, nutritious, and better quality food waste to be included in ruminant rations. According to the obtained results from this comparative study, it was found that the waste dried inside the greenhouse dryer is of better quality. The thermodynamic parameters derived from the proposed new approach are discussed and compared with literature results. The negative values of Gibbs free energy indicate that solar drying of apple and orange waste is a spontaneous process.