Relationship between invertase activity and reducing sugar content of cold-stored Japanese processing potatoes

Invertase activities and sugar contents of four Japanese processing varieties (Norin-1, Toyoshiro, Hokkai-76 and Hokkai-82) were measured at intervals during storage at 5 and 12°C in order to invetigate the role of invertase activity in sugar accumulation during cold storage. The experimental data revealed that the invertase activity of potatoes stored at 5°C correlated significantly (r=0.81, p <0.01) with the reducing sugar content, whereas potatoes stored at 12°C showed no significant relationship (r=0.01, p>0.05) between the invertase activity and reducing sugar content. The invertase activity of cold-stored processing potatoes accounts for 66% of the variability in reducing sugar content, implying that invertase is one of the key enzymes for reducing sugar accumulation in cold-stored processing potatoes.