Inhibitory Effects of CaCl2 and Pectin Methylesterase on Fruit Softening of Raspberry during Cold Storage

Ran Yan,Weihao Wang,Maorun Fu,Wenxiao Jiao,Cong Han

doi:10.3390/horticulturae8010001

Abstract

Quality of raspberry fruit experiences a rapid decline after harvest due to its vulnerable texture and high moisture content. Application of calcium chloride (CaCl2) combined with pectin methylesterase (PME) is efficient in delaying fruit softening. In this study, the effects of exogenous CaCl2 alone or in combination with PME on the structure of the cell wall, the molecular properties of pectin, and the amount of free water of raspberry during postharvest storage were investigated. The results showed that CaCl2 combined with PME treatment could maintain fruit firmness and inhibit weight loss. The treatment of CaCl2+PME maintained the cell wall structure via sustaining middle lamella integrity and reducing the activities of cell wall-degrading enzymes, such as polygalacturonase, pectin methylesterase, β-galactosidase, α-L-arabinofuranosidase, and β-xylosidase. In addition, CaCl2+PME treatment could effectively increase the content of chelate-soluble pectin (CSP) and develop a cross-linked structure between Ca2+ and CSP. Moreover, CaCl2+PME treatment was of benefit in maintaining free water content. CaCl2 in combination with PME treatment could be a promising method for inhibiting softening and maintaining the quality of postharvest raspberry during cold storage.

Highlights

Quality of raspberry fruit experiences a rapid decline after harvest due to its vulnerable texture and high moisture content
Our study aimed to investigate the effect of the postharvest application of CaCl2 alone or combined with pectin methylesterase (PME) on the quality of raspberry fruit in order to reveal the underlying mechanisms regarding fruit softening in terms of cell wall metabolism, pectin molecular properties, and free water content
Exogenous PME combined with CaCl2 treatment significantly slowed down the reduction of firmness, and retarded weight loss when compared with the CaCl2 treatment alone and the control fruit during storage

Summary

Introduction

Quality of raspberry fruit experiences a rapid decline after harvest due to its vulnerable texture and high moisture content. Application of calcium chloride (CaCl2 ) combined with pectin methylesterase (PME) is efficient in delaying fruit softening. CaCl2 alone or in combination with PME on the structure of the cell wall, the molecular properties of pectin, and the amount of free water of raspberry during postharvest storage were investigated. The results showed that CaCl2 combined with PME treatment could maintain fruit firmness and inhibit weight loss. CaCl2 +PME treatment could effectively increase the content of chelate-soluble pectin (CSP) and develop a cross-linked structure between Ca2+ and CSP. CaCl2 in combination with PME treatment could be a promising method for inhibiting softening and maintaining the quality of postharvest raspberry during cold storage. Inhibitory Effects of CaCl2 and Pectin Methylesterase on Fruit Softening of Raspberry during Cold Storage.

Methods

Results

Discussion

Conclusion