Physiological mechanism in the cell wall of passion fruit peels: innate carbohydrate metabolism

Calcium chloride treatment is an effective preservative that is widely utilized for the purpose of maintaining the quality of harvested fruits. A 5% calcium chloride solution was utilized for the soaking of postharvested passion fruit stored under ambient conditions for a period of eight days. The textural properties, pectins, hemicellulose content, and enzyme activities in passion fruit peels were determined through a series of analytical procedures. These enzymes were found to be involved in the carbohydrate metabolism of the fruit peels. Furthermore, the data were subjected to correlation determination and principal component analysis. The findings demonstrated that the calcium ion treatment preserved the firmness, elasticity, glutenability, cohesion, resilience, and chewiness of passion fruit while regulating the alterations in pectin and hemicellulose content observed in the treated fruit peels. The treatment also resulted in a reduction in the activities of cell wall-metabolizing enzymes within the fruit peel, leading to a slowing down of the degradation of cell wall materials. The corresponding activities of polygalacturonase, pectin methylesterase, cellulase, and β-galacturonase in the fruit peels were found to be reduced following the treatment. It can therefore be concluded that the calcium chloride treatment is an effective method of maintaining the quality of passion fruit by regulating the carbohydrate metabolism in the fruit peels and achieving a fruit preservation effect.