To maximize pomegranate quality fruit should be picked when fully ripe because they do not ripen off the tree. Pomegranate should be carefully maintained in cold storage after harvest because fruit are susceptible to chilling injury (CI). CI following exposure to temperatures below 5°C (41°F) during storage and transport for longer than 4 weeks is a major cause of deterioration during marketing. The incidence and severity of CI depends upon storage temperature, duration and cultivar (Photo 1). The minimum safe storage temperature is 5°C (41°F) for up to 8 weeks, if decay is not a problem. For longer storage, the temperature should be at 7^oC (45⁰F) to avoid chilling injury, but decay (Botrytis cinerea) and weight loss may become a limitation. A postharvest application of the fungicide Fludioxonil (Scholar) is approved for use on pomegranates with a 5ppm maximum residue limit to control decay development and prolong storage (Photo 2). However, pomegranates must be dipped in the fungicide solution because the botrytis spores are usually in the calyx area of the fruit, which are not adequately covered by postharvest spraying during packaging. After dipping surface moisture must be removed with a fan to eliminate free moisture on the fruit when stored in a box or bin. Under these storage conditions, pomegranates should be cooled to 7⁰C (45⁰F) as soon as possible after harvest and fungicide application. Fruit should be kept at 7⁰C (45⁰F) with relative humidity between 90-95% during storage and transportation to attain a postharvest-life longer than 8 weeks, depending on the cultivar.

Photo 1. Pomegranate chilling injury (CI) external symptoms include brown discoloration (scald) of the skin, pitting, and increased susceptibility to decay. Internal CI symptoms include brown discoloration of the white segments separating the arils and pale color (loss of red color) of the arils.

Photo 2. Gray mold (botrytis) on pomegranates

Author Information

Carlos H. Crisosto

Pomologist and Specialist, Plant Sciences Department, University of California Davis

Director of the Fruit & Nut Research & Information Center

chcrisosto@ucdavis.edu

References

•  Elyatem, S. M. and A. A. Kader. 1984. Post-harvest physiology and storage behavior of pomegranate fruits. Scientia Horticulturae 24:287-298.

• Kader, A. A., A. Chordas, and S. Elyatem. 1984. Responses of pomegranates to ethylene treatment and storage temperature. California Agriculture 38(7 & 8):14-15.

•  Palou, L., C.H. Crisosto, and D. Garner.  2007.  Combination of postharvest antifungal chemical treatments and controlled atmosphere storage to control gray mold and improve storability of ‘Wonderful’ pomegranates. Postharvest Biology and Technology 43: 133-142.

•  Hummer K.E., Pomper, K.W., Postman, J.D., Graham, C.J., Stover, E., Mercure, E.W., Aradhya, M., Crisosto, C.H., Ferguson, L., Thompson, M.M., Byers, P.,  and F. Zee.2012. Emerging Fruit Crops. Chapter 4, pp.97-147. In: (M. L. Badenes and D.H. Byrne, eds.) Fruit Breeding. Springer, NY, NY. 875 pp.