Application of glycosidase activity as a marker for characterizing and identifying vegetables

For the first time, glycosidase (EC 3.2.2.) activity was applied to characterize and identify vegetables. To measure glycosidase activity in vegetables, 4-methylumbelliferyl (4MU) glycoside (Gly) was employed as the fluorescence enzyme substrate. By using either a cuvette-type or a 96-well micro-plate-type fluorescence reader, 7 kinds of glycosidase, including α-d-glucosidase (α-Glc-ase), β-d-glucosidase (β-Glc-ase), β-d-galactosidase (Gal-ase), α-d-mannnosidase (Man-ase), N-acetyl-β-d-glucosaminidase (GlcNAc-ase), β-d-glucuronidase (GA-ase) and β-d-xylosidase (Xyl-ase) were measured by incubating extracts of vegetables in the presence of 4MU-Gly at pH 6.0 for 60 min at 38 °C. After optimizing, both methods were applied to food matrices that included 10 different vegetables. Results of the application to both domestic and imported garlic (Allium sativum) and broccoli (Brassica oleracea var. italica), revealed that the glycosidase activities of Man-ase and GlcNAc-ase showed significant differences (p < 0.01, n = 10) between domestic and imported varieties for both vegetables. Furthermore, the glycosidase activities in 30 heads of cabbage (B. oleracea L. var. capitata) itemized into 6 different cultivars were measured, and each profile was analyzed by employing a multivariate analysis. The results of their chemometric analyses showed that 29 out of 30 heads of cabbage were simultaneously and correctly discriminated into 6 different cultivars.