Effects of tray drying, vacuum infrared drying, and vacuum microwave drying techniques on quality characteristics and aroma profile of orange peels

This study aimed to dry orange peels using tray drying (TD), vacuum infrared drying (VID), and vacuum microwave drying (VMD) techniques and to investigate the effects of different drying techniques on the drying kinetics, physical, chemical characteristics, and volatile compounds. The VMD raised the drying rate and the effective water diffusivity compared to the TD and the VID. It was detected that the TD, VID, and VMD at 50 degrees C required 300, 106, and 20.67 min, respectively. The VMD showed the highest vitamin C, total phenolic substance, total carotenoid content, whereas the TD indicated the lowest color values. A total of 63 volatile compounds which consist of 16 aldehydes and ketones, 4 esters, 34 terpenes, and 9 other types of compounds were determined in dried orange peels. It was determined that the VID technique caused the least destructing in volatile compounds, whereas the TD technique was the most destructive. Practical Applications Drying is a common preservation method used for the long-term durability of foods. Drying of orange peel conduces not only to decrease environmental problems but also to provide economic benefits. Dried orange peel is used in herbal teas and food products because it is rich in aromatic flavor and odor components. Orange peel was dried using tray drying, vacuum infrared drying, and vacuum microwave drying. The vacuum microwave drying increased the drying rate and effective water diffusivity to others. The vacuum microwave drying and vacuum infrared drying protected quality characteristics, and volatile compounds of orange peels. This study demonstrated that the waste orange peels could be dried with different drying methods and converted into products with high nutritional components.

Automated summary

This study compared the effects of tray drying, vacuum infrared drying, and vacuum microwave drying on orange peels, revealing that vacuum microwave drying was the most effective in preserving quality characteristics and volatile compounds. Vacuum infrared drying caused the least destruction to volatile compounds, while tray drying was the most destructive.