Optimization of bulk modified atmosphere packaging for long-term storage of 'Fuyu' persimmon fruit

An optimal design procedure for bulk modified atmosphere packaging (MAP) that would enable the long-term storage of 'Fuyu' persimmon fruit for export market was proposed in this study. Initially, the lower O2 limit of aerobic respiration was determined, based on the respiratory quotient breakpoint, and found to be 0.65 kPa. Next, the parameters of a Michaelis-Menten type respiration model were estimated, and they were used to predict the O2 consumption rate at 1.5 kPa, which was set as the target O2 partial pressure inside the package and is considered safe to avoid fermentation. Then, the values of the predicted respiration rate, the surface area of the packaging, and the sample weight were substituted into the mathematical model to calculate the gas composition change inside the package; as a result, the necessary O2 permeance of the packaging film material was estimated as 2.59 × 10−7 L m−2 s−1 kPa−1 for the prospective bulk packaging system. Finally, the efficacy of the designed bulk MAP on the quality changes in the fruit was practically examined by comparing the MAP performance to that of fruit in an individual package (having 60-μm thick low-density polyethylene film bag) and to that of non-packed fruit (i.e., control). All the samples were stored under conditions simulating the long-term storage and subsequent transportation of fruit from Japan to Thailand. The results revealed that the O2 concentration at a steady state in the designed bulk MAP could be established at 1.3-1.6 kPa, which successfully corresponded with the target value. Furthermore, losses in flesh firmness and color, and the external damage of fruits were reduced in the bulk MAP when compared to storage in the other two package treatments. Overall, the bulk MAP designed could be used for ca. 4 months storage of 'Fuyu' persimmon fruit and for its commercial application to maintain fruit quality and to export fruit to international markets.