2.6. PG enzyme activity

The PG activity was measured with the method of Guo et al. (²⁰¹⁴). After extraction of 1 g of fruit tissue with 2 ml of cold Na acetate buffer (pH 6.0) and centrifugation at 15000 × g, 0.1 ml of the supernatant was mixed with 0.3 ml of 0.1% (w/v) polygalacturonic acid (Sigma‐Aldrich) in 0.2 ml of 40 mmol/L Na acetate and 0.4 ml of water, and incubated at 37°C for 60 min. Then, the vessel containing the sample was immersed in boiling water for 5 min, cooled on ice, and 10 ml of distilled water was added. The absorbance at 540 nm was determined with a spectrophotometer (Cary 100).