Improving the Sun Drying of Apricots (Prunus armeniaca) with Photo-Selective Dryer Cabinet Materials

Photo-selective materials have been studied for their effects on the preharvest quality of horticultural crops, but little work has been done on potential postharvest processing effects. The aim of this work was to characterize the effects of 5 different photo-selective acrylic materials (used as the lid to a single-layer sun drying cabinet) on the drying rate and quality of apricots (Prunus armeniaca). Photo-selective cabinet materials that transmit light in the visible portion of the solar spectrum accelerate the apricots' drying rate in both the early period of drying and the course of drying as a whole. These materials do not significantly affect the measured quality metrics during the first day of sun drying. However, when drying is taken to completion, some minor but significant quality differences are observed. Infrared-blocking material produces dried apricot with lower red color, compared to clear, opaque black, and ultraviolet-blocking materials. Clear material produced dried apricot with significantly lower antioxidant activity, compared to black and infrared-blocking materials. Using appropriate photo-selective drying cabinet materials can reduce the required sun drying time for apricots by 1 to 2 d, compared with fully shaded drying. Ultraviolet-blocking material is recommended to maximize drying rate and minimize quality degradation. Practical Application This study showed how drying cabinet lid materials that transmitted and blocked different wavelengths from sunlight can speed the drying and improve the quality of dried apricots, increasing the amount of fruit that can be processed in a given length of time without sacrificing nutritional benefits. Apricot drying time could be reduced from 3 to 4 d (shade drying) to 1 to 2 d (drying with clear or ultraviolet-light-blocking materials). The cabinet material did not have an effect on brightness of the fruit or vitamin C content, but it did affect red color and antioxidant activity.