Experimental Characterization and Mathematical Modelling of Natural Drying of Apricots at Low Temperatures

To mitigate reduced apricot fruit quality due to mildew, browning and sand dust from natural drying under low temperatures and humidity, we determined the characteristics of three different methods of drying (via hanging) and further established their mathematical models. Various comparative analyses of natural drying by laying apricots in an area of the Gobi Desert, subjecting them to ventilated drying in an air-drying house, and hanging them on trees were conducted. The least and most efficient methods were hanging on trees (302 h) and laying them in an area of the Gobi Desert (>192 h), respectively. The loss rate and the total sugar content were 5.26% and 70.16%, and up to 18.31% and 68.54% for fruits dried by ventilated drying in an air-drying house and those hung on trees, respectively. Fruits dried by ventilated drying in an air-drying house showed the least loss and the best comprehensive quality. Using experimental data from assessments of the drying methods, mathematical models were constructed and fitted to drying mathematical models of seven kinds of porous media. The Wang and Singh model had the best fitting degree, an error value of less than 0.05, and the regression that most accurately explained the drying mathematical model for apricots under natural conditions.