Drying of Garlic Slices (Allium Sativum L.) and its Effect on Thiosulfinates, Total Phenolic Compounds and Antioxidant Activity During Infrared Drying

This study was conducted to evaluate moisture transfer and changes of thiosulfinates, total phenolic compounds and antioxidant activity of garlic slices during infrared drying at temperatures from 50 to 80C and powers from 675 to 2,025 W. Drying time was significantly shortened with increasing infrared drying temperature. Thiosulfinates showed no significant changes versus moisture content during the whole drying period at 50, 60 and 70C, while a notable degradation of thiosulfinates was observed at 80C. Total phenolic compounds in garlic slices all rapidly decreased versus moisture content initially at all investigated drying conditions. Whereas the total phenolic compounds in dried garlic slices significantly enhanced with drying temperature from 50 to 80C at 1,575 W. Antioxidant activity increased during infrared drying, which was contradictory with the changes of total phenolic compounds and thiosulfinates.

Pratical Applications

This work are useful for the processing of garlic slices by infrared drying to obtain the optimum benefits of bioactive compounds present in this food product during drying. Infrared drying is reported as a promising method on foodstuff processing, which impinges on the material, penetrates it, and converts the infrared energy into heat. Therefore, it is more energy saving as well as reduce drying time. In this study, drying time was significantly shortened with increasing infrared drying temperature. A remarkable decrease of total phenolic compounds versus moisture content was observed during infrared drying. Meanwhile, thiosulfinates of garlic showed fluctuation over the moisture content decreased, except a notable degradation of thiosulfinates was observed at 80C. Conflicting results were found in antioxidant activity that a clear increasing trend with decreasing moisture content during infrared drying process.