Experimental investigation on solar drying of salted greengages

The preserved greengage is a favorite dried fruit in China. In processing preserved greengages, the drying of salted greengages is a key and energy-consuming process. Traditionally, the drying of salted greengages mainly relies on natural sun drying and requires about 48 days. In this study, an attempt was made using solar driers with fresh fruit that have been mixed with some salt and preserved in a concrete pool for more than 2 months. A solar drier, consisting of 6 m² of solar air collectors, a greenhouse-like drying chamber and three fans powered by a solar module of 20W_p, was developed and examined, and a comparative experiment between solar drying and natural sun drying was conducted from 26 April to 12 June, 2003. The experiment found that, even in cloudy days, the temperature of the drying air inside the chamber was much higher than that of the ambient air, and solar drying of salted greengages was very effective. Thus the drying period was shortened from 48 days in natural sun drying to about 15 days. It was also found that the solar drying could eliminate a process that takes 20 days to desalt salted greengages to obtain the final product as required in the natural sun drying method.