The effect of polymers used in packaging on the aroma of the packaged product has been little explored. Using a package-in-a-jar system, we are able to simultaneously measure volatile production by plant organ (Malus domestica Borkh. cv. Golden Delicious) and the permeability of the packaging film to those volatiles. In this system, apple fruit were placed into a glass container or sealed in a low-density polyethylene(LDPE) package and subsequently placed into a glass container. Air or a modified atmosphere was slowly passed through the glass containers such that the O2 level in the package was similar to that in containers with no package. The package and jar head spaces were sampled for CO2, O2, ethylene, and aroma volatile analysis by gas chromatography/mass spectrometry. The effect of temperature, atmosphere and film presence to some major volatile compounds was determined. When storage temperature increased from 0°C to 22°C the production rate of hexylacetate and 2-methyl butylacetate increased 11.27- and 17.15-fold, respectively. At 0°C, as O2 decreased in concentration from 10% to 5% (v/v), hexylacetate and butylacetate declined significantly; however, 2-methyl butylacetate was not affected. This can be taken to indicate the production of 2-methyl butanol for 2-methyl butylacetate formation is not as O2 concentration dependent as straight-chain alcohols. At the same O2 concentration, non-packaged fruit evolved greater amounts of all volatiles than packaged fruit. The flux of α-farnesene, hexylacetate and 2-methyl butylacetate was 26.6-, 1.7-, and 1.4-fold higher, respectively, for fruit in glass container. The sorption of α-farnesene and some other volatiles into LDPE film is evidently considerable, altering the aroma profile of packaged produce relative to a flow-through system.
Effects of modified atmosphere packaging on quality attributes and physiological responses of fresh-cut crisphead lettuce
