Title: The changes of chemical quality of ginger during postharvest storage at chilling temperature
Abstract: Zingiber officinale is a tropical produce which is susceptible to chilling injury due to improper storage temperature management. Therefore, the objective of the study was to investigate the development of chilling injury (CI) in ‘Bentong’ ginger rhizome. Fresh ‘Bentong’ ginger rhizomes were harvested at 9-10 months and were stored at 5, 15 and 25°C for 0, 8, 16, and 24 days. The treatments were evaluated for the effects of storage temperatures and storage durations on postharvest chemical qualities of ginger rhizomes. The experiment showed significant interaction effects between storage temperature and storage durations for total flavonoid contents (TFC), total phenolic contents (TPC), 6- gingerol, 6-shogaol, and DPPH radical scavenging activity of the treated rhizome. Ginger stored at 15°C showed the highest TPC at 16 days of storage and then reduced throughout the storage as compared to the ginger stored at 5°C and 25°C. The 6-gingerol content increased from day 0 to day 16 and resulted in an optimum content at 66.7 mg/g fresh weight when it was stored at 15°C. 6-shogaol was identified in smaller quantities within the range of 1.52 to 3.11 mg/100 g of fresh weight. A similar trend was also observed in 6 -shogoal after 24 days of the storage. DPPH scavenging activity showed that storage at 5 and 25°C resulted in a decrease of DPPH inhibition along with storage durations. Therefore, it was suggested that the ginger was best kept at 15°C up to 16 days of storage in order to maintain the postharvest qualities and chemical properties of ginger.