Influence of Packaging Material/Sealing on the Quality of Biscuits

Abstract

This investigation concentrated on determining the water vapor transmission rates (WVTR) of some of the packaging materials most commonly used to wrap biscuits (BOPP/pearlized BOPP, BOPP/BOPP, BOPP/ LDPE/ BOPP, BOPP/met-BOPP, BOPP/LDPE/met-BOPP, PET/met-BOPP)** and theoretical WVT-values were then calculated for the different types of package, based on the WVTR of the material and the total surface area of the packages exposed to ambient. The next phase of the project aimed at verifying whether or not the type of seal brings about an increase of the permeability to water vapor of the biscuit packages by comparing the theoretical value (WVTt) of the biscuit packages with the experimental (WVTp). Packages of biscuits were purchased from regular retail outlets in Brazil (9 different types of biscuit/6 manufacturers). The packages had been produced with three types of form-fill-seal machines. Among the packaging materials tested, those that contained a metallized BOPP-layer in their structure provided the best barrier against moisture (0.5 to 1.0 g water/m²/day) whereas the WVTR of all the other materials varied from 2.3 to 4.0 g water/m²/day at 38⁰C/90% RH. The packages sealed with rollpack and horizontal flowpack machines presented impaired seal integrity, particularly at the transversal seal, which caused the WVTp of the packages to be 1.1 to 3.0 times (depending on the material/manufacturer) higher than the corresponding theoretical WVTt values previously calculated. Vertical flowpack machines produced packages with seals of good integrity so the permeability of these packages depends directly on the type of packaging material used.

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