Effects of relative humidity on ethanol vapour releases from hydrophilic filmbased sachet in active food packaging

H Kampawong,W Utto,R Pruthtikul

doi:10.26656/fr.2017.5(5).202

Abstract

Active food package incorporating an ethanol vapour-controlled release sachet has been known for its efficacies to delay microbial proliferation in fresh fruit and vegetable. High humidity inside the package could be utilized as a stimulus for conditional releases as a means to stabilize the sachet prior to being used. The present research was undertaken to investigate the effects of relative humidity on ethanol vapour release from the hydrophilic film-based sachet. The prototype 4-side sealed sachets were made of either ethylene vinyl acetate (EVA) or laminated film comprising EVA and Nylon/PE (designated as ENP). A gas chromatogram equipped with a flame-ionized detector (FID-GC) was employed to analyze ethanol vapour concentration levels released from both sachet types and accumulated in headspaces of sealed glass beakers having different relative humidity (RH) levels. For a given RH level, the concentrations in the headspaces containing the ENPbased sachets were lower than those containing the EVA-based sachets. Delays of ethanol vapour release up to 24 h were observed in the ENP-based sachet system, whilst these did not occur among EVA-based sachets. Both sachets could release ethanol vapour with faster rates and subsequently higher concentrations accumulated at the very high relative humidity level (90-99% RH), compared to lower RH levels (60-89% RH). However, the release rates and concentration levels accumulated in 60-75% RH were not different from those in 80-89% RH. Extents of water vapour uptake by films were relatively small when the films were kept at the lower RH levels, but these became exponentially increased when the RH levels were ≥90%RH. Experimental data on water vapour uptakes were well predicted by an exponential model (R2 0.92-0.99; and root mean square of errors (RMSE) 0.004-0.054). Overall, experiment findings indicate that the ENP film caused delayed ethanol vapour releases from the sachet. The relative humidity levels had significant effects on the releases from hydrophilic film-based sachets

Highlights

Modified atmosphere packaging systems (MAP, commonly known as passive MAP) have been used for packing fresh fruit and vegetables because of their simplicities and technical applications in slowing down quality changes (Malakar et al, 2020)
Differences in release patterns, as well as concentration levels accumulated, were because of the film’s property, namely film permeance to ethanol vapour (FPE) indicating extents of eases for which ethanol molecules can permeate through the film structure (Miyauchi et al, 1996; Utto et al, 2016)
It could be concluded that surrounding humidity levels had significant effects on ethanol vapour releases from the hydrophilic film-based sachet

Summary

Introduction

Modified atmosphere packaging systems (MAP, commonly known as passive MAP) have been used for packing fresh fruit and vegetables because of their simplicities and technical applications in slowing down quality changes (Malakar et al, 2020). There are increasing interests in incorporated ethanol vapour-controlled release sachet into the package. The ethanol vapour slowly is released from the sachet to package headspace, and subsequently interacts with the fresh produce packaging. The interactions subsequently lower microbial proliferation and other qualities including colour and aroma volatiles (Utto, 2014). Applications of ethanol vapour-controlled release sachets were tested and reported in a range of fresh fruit and vegetable including sweet cherries (Bai et al, 2011), freshly peeled shallots (Utto et al, 2018), cherry

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Conclusion