Changes of Ca forms and chelate-soluble pectin in cherry tomatoes treated with ultrasound and calcium lactate

The physicochemical properties, polygalacturonase and pectin methylesterase activity, calcium form, and structure of chelate-soluble pectin (CSP) in cherry tomatoes were studied. The total calcium and CSP contents for calcium with ultrasound assisted treatment (U + Ca) group were the highest at the end of storage. U + Ca improved the calcium content from 0.6486 g/kg to 07198 g/kg, and enhanced the permeation of Ca2+ into cell walls. Compared to control (CK), ultrasound (U) and calcium (Ca) groups, the fruit firmness of U + Ca group maintained at high level throughout the storage process. Soluble solids content of all groups had no significant difference at the end of storage. Titratable acidity of cherry tomatoes in U + Ca group was higher than that in CK and U groups at day 30. According to CSP structure analysis, its main configuration had no obvious change at the end of storage. Atomic force microscopy and weight average molecular mass analyses confirmed that U + Ca delayed the degradation of CSP. Our results indicated that U + Ca has application potential in maintaining the quality of cherry tomatoes during storage.