Physicochemical properties and antioxidant activities of ginger (Zingiber officinale Roscoe) slices according to temperature and duration of hot water treatment

Abstract

This study was conducted to determine the optimal hydrothermal pretreatment conditions for manufacturing processed ginger products. Ginger slices heated at different temperatures (60-100°C for 1 h) for varying durations (1-5 h at 80°C) were compared in terms of their physiochemical properties, antioxidant activities, and functional compound contents. The pH and soluble solid content decreased with increasing hydrothermal treatment temperature. Browning occurred at temperatures > 80°C. The 2,2-diphenyl-1-picrahydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging were highest after heating at 80°C for 1 h, and the total phenolic compound content showed a similar trend. As the hydrothermal treatment temperature and duration increased, the 6-gingerol content decreased and the 6-shogaol content generally increased. Based on sensory testing of ginger jeonggwa (with sugar syrup) prepared using hot water-treated ginger slices, the optimal hot water treatments were conducted at 70 and 80°C for 1 h, with no significant difference between these temperatures in terms of smell, taste, and texture. Therefore, hydrothermal treatment of ginger at 70-80°C for 1 h was a suitable to improve the functionality and antioxidant ability while maintaining the sensory quality. Therefore, this may be used in the production of processed ginger.