Storage Quality of Enzymatically Peeled Baby Persimmons in High CO2 Controlled Atmospheres

Freshly peeled “baby” persimmons, 3-4 cm in diameter, were processed by enzymatic peeling of ‘Totsutanenashi’ cherry persimmon fruit (miniature of full size mature fruit), which is a bud mutation of ‘Hiratanenashi’ persimmon. The disinfectant treatment followed by an enzymatic peeling process of intact baby persimmon fruit involved a porous treatment of the peel, hot water dipping, protopectinase infusion, and rinsing under running tap water. The microbiological and physicochemical quality of enzymatically peeled baby persimmons was investigated during storage in air or high CO₂ atmospheres (10%, 15%, and 20%) at 10 °C. With intact baby persimmon fruit, the peel had 3.2 log cfu/g of bacteria and 3.7 log cfu/g of fungi and a diverse microflora, while microbial counts of the flesh were below the lower limit of detection (2.4 log cfu/g for bacteria and 3.0 log cfu/g for fungi). Treatment with electrolyzed water reduced the microbial counts of the peel to levels below the limit of detection. Microbial counts of baby persimmons remained undetectable throughout the enzymatic peeling process. When microbial contamination of enzyme-peeled and knife-peeled baby persimmons was compared, the diversity of bacterial and fungal flora was less in enzyme-peeled fruit than in knife-peeled fruit. High CO₂ atmospheres reduced the growth of mesophilic aerobic bacteria, coliform groups, lactic acid bacteria, and fungi of baby persimmons, with the reduction being greater in 15% or 20% CO₂. Bacterial and fungus counts were 4 to 5 logs lower in samples held in 20% CO₂ atmosphere than those in air after 6 days of storage. Diversity of the microflora was also much less in 20% CO₂ atmosphere than in air on day 6. High CO₂ atmospheres inhibited the development of brown discoloration in baby persimmons by day 4, but all samples developed browning to an unmarketable level on day 6. The color index (L* and C* values) and texture of all samples decreased during storage and were not affected by high CO₂ atmospheres. These results indicate that a 20% CO₂ atmosphere is desirable for enzymatically peeled baby persimmons to achieve effective microbial safety when held at 10 °C.