Innovative combined solar energy assisted air and hot air assisted radio frequency drying system was used to dry unsulphured, sulphured (1 kg/ton and 2 kg/ton sulphur) and pistachio hull extract treated apricots. Unsulphured and sulphured apricots dried under sun were used as the control samples. The effects of different storage temperatures (5, 20 and 35oC) on residual sulphur content, β-carotene and microbial stability characteristics of dried apricots were studied. Also, the effect of storage temperature on the total phenolic content of dried apricots pre-treated with pistachio hull extract was investigated. The obtained results showed that the loss of sulphur and β-carotene was less in the products stored at 5oC compared to the products stored at 20 and 35oC. Sulphur treatment significantly inhibited the loss of β-carotene during storage. The maximum decrease in phenolic content of dried apricots pretreated with extract, was observed in samples stored at 20°C. In addition, extract treatment provided an advantage in terms of storage considering the microbial quality. The combined drying system caused less sulfur loss compared to sun drying.
The effect of storage on some chemical and microbial properties of apricots dried with a combined solar energy assisted air and hot air assisted radio frequency drying system