UBC Theses and Dissertations
Modified atmosphere packaging of sweet cherries Thomson, Carrie Ann
Modified atmosphere packaging (MAP) involves the storage of perishable commodities in atmospheres containing higher carbon dioxide and lower oxygen levels than in air. When combined with refrigeration temperatures, MAP techniques result in an appreciable extension of the post-harvest life of fruits and vegetables. Modified atmosphere packaging storage trials performed in this study involved packaging sweet cherries in four plastic films, covering a range of gas permeabilities, coupled with storage at 1 °C. Cherries packaged in plastic produce bags obtained from a local supermarket served as the control treatment for the experiment. A variety of chemical and physical characteristics of the stored fruit was analyzed and values were compared to those obtained for unstored fresh fruit. Deviation of values from those obtained for zero storage fruit was taken as a measure of cherry deterioration. Sensory analysis was performed for assessing cherry quality. Storage of cherries in films ranging from medium-high to high gas permeabilities resulted in internal aerobic atmospheres with elevated carbon dioxide levels. Cherries in these packages displayed superior quality retention over the storage period as compared to other treatments, and could be stored successfully for up to six weeks. While the control cherries retained their acceptable quality for about five weeks, mold growth was apparent after this storage time. Storage of cherries in medium-low permeability films resulted in the accumulation of very high levels of carbon dioxide within the packages. Cherries in these packages deteriorated more quickly than cherries stored in the higher permeability films, but remained marginally acceptable at the end of eight weeks of storage. Carbon dioxide levels rose and oxygen levels fell quickly in the low permeability film packages. The quality of the cherries in these packages diminished very rapidly, and fruit was unacceptable after four weeks of storage. It is proposed from these findings that the low oxygen and high carbon dioxide levels within the high and medium-high permeability packages slowed product respiration, thereby extending the effective storage period of the fruit. The inhibition of spoilage organisms under these atmospheres likely also played a role in mitigating quality changes.
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