Drying ginger and preserving 6-gingerol content

Abstract

Ginger rhizome (Zingiber officinale Roscoe) is widely used as a spice or a folk medicine. 6-gingerol is the major bioactive component in fresh ginger and has numerous physiological effects. 6-gingerol is heat sensitive while cooking and drying will transform 6-gingerol to 6-shogaol. Therefore, 6-gingerol content is used to determine the quality of ginger after drying. A drying model called the Two layer model was tested for prediction of drying ginger and compared with a single layer model. In this study, two layer model was used to describe ginger drying process. 6-gingerol content was measured by using HPLC method. Several factors which could affect 6-gingerol content were reviewed and a 6-gingerol prediction model was established from the experimental data.

The results showed that the two layer drying model gave no significant improvement to describing the ginger drying process compared with the single layer model. Drying time and relative humidity (ranging from 10% to 40%) impacted 6-gingerol content, although drying temperature (ranging from 30°C to 60°C) had less effects on 6-gingerol content. It was found that 6-gingerol content was highly variable in fresh ginger, which making conclusions on models difficult.