Predicting storage time of passion fruit using pericarp change index: a study on size, mass and texture parameters

This study aims to explore the changing trends in external characteristics of passion fruit pericarp and their application in predicting shelf-life, assessing storage quality, and advancing the field of non-destructive testing. Through storage experiments, the evolving patterns of passion fruit pericarp during storage and correlations among relevant physical parameters were analyzed. Three attribute parameters, namely minor-axis diameter, hardness, and mass, were extracted from the characteristic parameters of passion fruit, exhibiting the strongest interrelationships with storage time variable. The findings indicate a negative correlation between storage duration and minor-axis diameter of passion fruit, while no correlation was observed with major-axis diameter. The pericarp's contraction behavior is influenced by both thickness reduction and internal collapse. Moreover, a linear correlation existed between hardness of pericarp layers. The minor-axis diameter was positively correlated with puncture force at two peak positions (R = 0.87, P < 0.01; R = 0.95, P < 0.01). Simultaneously, minor-axis positively correlated with thickness and mass (R = 0.97, P < 0.01; R = 0.98, P < 0.01). To better quantify the degree of pericarp change, a passion fruit pericarp change index was proposed. Using the index as an independent variable and storage duration as the dependent variable, an equivalent fruit age prediction model was established. The results show a coefficient of determination (R²) of 0.997 and a significance level of P < 0.05 between predicted and actual values. This research has the potential to provide a theoretical foundation and methodological framework for predicting passion fruit shelf-life in the context of food preservation and storage, and to offer practical support for real-world applications in the field.