Physicochemical indicators coupled with statistical tools for comprehensive evaluation of the novel infrared peeling on tomatoes

Abstract

The peelability of fruit is influenced by numerous factors; thus, it is critical to identify key factors to anticipate peelability. This study aimed to examine variations in peelability and key indices of tomatoes at various infrared (IR) parameters, and their quantitative relationships, using Pearson's correlation and multiple linear regression (MLR) statistical tools. Results showed that the peelability during IR treatment could be quantitatively reflected by content, esterification degree (DE), intrinsic viscosity of pectin, surface temperature, intracellular and extracellular resistance, and relative electrolyte leakage (REL). Among them, contributions of REL, pectin content, DE of pectin, and surface temperature to peelability were more significant. This is because as IR's time and temperature increased, tomatoes' surface temperature increased, leading to the degradation of pectin, and changes in DE of pectin and REL. This contributed to thermal softening of peel and decreased adhesions of cells, leading to skin loosening. Skin loosening along with accumulated pressure improved skin rupture, improving peelability. This peeling model was statistically significant (Adjust R2 = 0.971, Sig. of F-test <0.01), with no outliers, and residuals were independent and normally distributed. Overall, this model can simplify data collection, assist in determining more suitable infrared peeling parameters, and improve the peelability of tomatoes.