ANALYSIS OF OPEN SUN DRYING EXPERIMENTS

Open sun drying has lost its previous importance due to the fact that different factors affect its reliability and the quality of the products obtained. One of the set-backs for the analysis of solar drying experiments is their dependence on a non-controlled source of energy, i.e. solar radiation depends on climatic conditions and experiments are difficult to compare. It is thus necessary to investigate the advantages of a particular set up as well as the climatic influences. open sun drying could constitute the natural reference, allowing the comparison of different drying strategies. A new way of standardizing drying times, based on solar radiation input, is proposed, to allow better evaluation of the experiments. An equivalent time is defined, allowing comparison of experiments carried out under different circumstances. Carrots and potatoes were used in these experiments. The use of the average daily solar radiation 15.28 MJ m-2.d-1 in Palma de Mallorca (39.33-degrees-N, 2.37-degrees-E), is proposed for comparison purposes. An improvement of more than 12% in the explained variance was observed, the unexplained variance being lower than 1%.