Leopold Center for Sustainable Agriculture

Progress in pawpaw processing project

Back to Leopold Letter Summer 2010

By Mary Adams, Outreach and Policy Coordinator

Patrick O’Malley, an ISU Extension commercial horticulture field specialist, has headed several Leopold Center Ecology Initiative projects that investigated the potential for growing pawpaws in various areas of Iowa. With information gained on how and where to produce pawpaws, O’Malley is taking the next step to determine the market potential for this crop in Iowa. He is starting the second year of a Leopold Center Marketing and Food Systems Initiative grant (M2009-20) “Enhancing Value and Marketing Options for Pawpaw (Asimina triloba) by Developing Pulp Separation and Preservation Techniques” to look at how Iowa farmers might take advantage of this unique fruit.

O’Malley is working closely with Lester Wilson of the ISU food science department to develop pulp separation and preservation techniques. Six hundred pounds of pawpaw fruit from the Louisa County orchard site were grown, picked and delivered to ISU last fall. The pulp separation from the fruits was carried out with an existing pulper at the Food Science and Human Nutrition Department’s Center for Crops Utilization Pilot Plant.

After several different modifications to the ISU pulper, researchers were able to efficiently operate the pulper for mechanically processing pawpaws without any damage to the seeds. After several attempts, the last run through the modified pulper produced a yield of 53 percent seed-and skin-free pulp. The researchers noted that enzymatic browning of the pulp occurred within minutes of processing, yielding a burnt orange color on the pulp exposed to air. Therefore, pulp should be processed or packaged as soon as possible. Samples of the peel, pulp and seeds were frozen at -20° C for later analysis of seed oil and quality of the pulp. Freezing and thawing of the whole pawpaw also were tested. Freezing does not seem to alter the pulp color, which will be evaluated after one year of frozen storage.

Plans are to refine the pulping methodology further with the 2010 pawpaw crop, characterize the pulp, test preservation techniques, and determine the best uses in food products. Researchers again will use the pawpaw fruits from the 220 trees at the Louisa County Conservation Chinkapin Bluff Recreation Area cultivar trial orchard. The pulp separation again will be carried out at ISU and will allow for tests to see if the final modifications made to the pulper last year can consistently produce the clean pulp needed for use in recipes.

Partners in this project include the Louisa County Conservation Board, which provides the land and mowing between rows of pawpaws. Red Fern Farm, currently the largest pawpaw grower in Iowa, represented by Tom Wahl, will provide consulting on growing and processing pawpaws and help with outreach. Ray Grogan, pawpaw grower Iowa/Arkansas, will help with maintenance and harvest of pawpaws. O’Malley will maintain the trees and harvest and conduct outreach, while Wilson, with student help, will work on mechanical processing methods, preservation and recipe development.

Back to Leopold Letter Summer 2010