Effect of Carbonic Maceration (CM) on the Vacuum Microwave Drying of Chinese Ginger (Zingiber officinale Roscoe) Slices: Drying Characteristic, Moisture Migration, Antioxidant Activity, and Microstructure

Abstract

Ginger is an important Chinese flavoring agent and a traditional herbal medicine. Traditional drying method for ginger may cause severe damage and destroy the chemical and physical qualities. Carbonic maceration (CM) is an efficient and low-cost technology, which can increase the mass transfer rate during drying process and improve the quality indices of ginger. The results showed that CM treatment could produce porous structure and increase the cell membrane permeability, which significantly increases the moisture diffusion and evaporation rate, especially the internal moisture diffusion. The total drying time can be shortened by 42.27 ± 2.78%. Due to the increase of cell membrane permeability, the plant extraction barrier was decreased; thus, the extracted active components were enhanced. Besides, the lower pH environment and inactivation of polyphenol oxidase (PPO) and peroxidase (POD) were also beneficial to increasing the phenol compound retention as well as antioxidant activities. The contents of 6-gingerol, 8-gingerol, 10-gingerol, and 6-shogaol were increased by 20.79%, 37.27%, 36.80%, and 68.53% respectively after CM treatment. The 2,2-diphenyl-1-picrylhydrazyl, ferric-reducing antioxidant power, and oxygen radical absorption capacity values were also increased by 1.33, 1.28, and 1.20 times respectively. Therefore, CM pretreatment could be a suitable alternative technique for improving drying characteristics and preserving nutritional values of agro-based product.