The Effects of Packaging Film and Storage Temperature on the Internal Package Atmosphere and Fermentation Enzyme Activity of Sweet Potato Slices

Fresh-cut sweet potato slices were packaged in low- (PD900), medium- (PD961) and high-permeability (PD941) film bags, and were stored at 2 or 8C for 14 days. Changes in O2, CO2, ethanol and acetaldehyde concentrations in the headspace were monitored over 14 days. The activities of fermentation enzymes and the concentration of fermentation volatiles were measured from tissue extracts on days 0, 7 and 14. Storage at 8C was an excessively high temperature for fresh-cut sweet potatoes to maintain aerobic respiration for 14 days. Low-permeability film bags resulted in anaerobiosis at 2 and 8C. Medium-permeability film bags were able to maintain a higher O2 and a lower CO2 level than PD900 film bags at 2C. However, they behaved similarly at 8C. High-permeability film bags maintained an aerobic atmosphere during the 14 days of storage at both temperatures. PRACTICAL APPLICATIONS Consumer demand for convenience, ease of preparation and ready-to-eat forms of fresh fruit and vegetables have contributed to the significant market growth in the fresh-cut produce sector during the last several decades. However, minimally processed forms of sweet potatoes have only recently become available in the U.S. commercial produce trade. Many consumers perceive these value-added forms of sweet potatoes to be healthy food items, high in nutritional value. Utilization of selectively permeable modified atmosphere packaging (MAP) is standard in the distribution of fresh-cut produce. The success of MAP depends on the proper selection of the appropriate semipermeable polymeric film to match the product respiration rate and holding temperature. Polymeric films, which allow for the establishment of acceptable internal package O2 and CO2 atmospheres while maintaining aerobic respiration of the fresh-cut product, are the most desirable. Undesirably low O2 and/or excessive CO2 concentrations inside the package may result in anaerobic respiration of the product that is detrimental to edible quality. The results of this study provide useful information to fruit and vegetable processors on the appropriate semipermeable polymeric film package and holding temperature for maintaining fresh-cut sweet potato quality. Commercial foodservice firms targeting fresh-cut sweet potatoes as a convenience food will potentially benefit from the information in this article.