Prediction of ethylene permeance through perforated packaging films using a dimensionless correlation

Abstract

Ethylene is a ripening hormone biosynthesized by fruit and vegetables that can accumulate inside the package and accelerate ripening in fresh produce, which, in turn, affects its shelf-life. Perforating the fruit package material can facilitate the effective removal of ethylene gas through the transmission process. Excessive perforations will allow ethylene to completely escape, but will then invalidate the possibility of modified atmosphere packaging (MAP). In order to design MAP for climacteric fruits, it is therefore essential to quantify ethylene transfer through the package, and not only oxygen and carbon dioxide. While there is ample information on the transmission of water vapour, oxygen, and carbon dioxide in perforated MAP, little research has focused on ethylene. The objective of this study was to develop a dimensionless correlation for predicting ethylene permeance through a perforated film. The ethylene permeance ranged from 1.70 to 4.06 cm/s per perforation, depending on film thickness (0.002–0.003 cm), perforation diameter (0.05–0.095 cm), cooling air velocity (1–18 cm/s), and temperature (4–24 °C). The developed dimensionless correlation relates Stanton, Peclet and Schmidt numbers. The coefficient of determination (R2) of the dimensionless correlation developed with a first set of 36 data points was 99.62%. The dimensionless correlation developed was then validated with 2 sets of 12 data points each, with the model predictions fitting very well the experimental data of these validation trials (coefficient of determination R2 = 97.69%). The correlation is thus validated for axial Peclet numbers in the 0.01–0.35 range and radial Peclet numbers in the 0.4–11.1 range, while the Schmidt number barely varies in MAP conditions (being around 0.98). The perforation diameter was the most influential parameter on ethylene permeance, while cooling air velocity and temperature had a moderate impact, and film thickness had little effect.