Calcium salts help keep apples fresh.

Fresh-cut apple slices are the result of a cooperative research and development agreement between USDA-ARS scientists (Western Regional Research Center, Process Chemistry and Engineering Research Unit, 800 Buchanan St., Albany, CA 94710) and researchers at Mantrose-Haeuser Co. Inc. (Attleboro, MA). The refrigerated, packaged slices of apples last two to three weeks without browning or losing crispness.

Scientists have been working on ways to preserve fresh-cut fruit for several years. This commercial product retains the desirable characteristics of fresh apples without leaving a detectable residue, ARS researchers tell us. The key discovery by investigators was that certain calcium salts protect apple slices from color, taste or texture changes.

When you cut an apple, many physiological changes occur to the fruit tissue, including browning and the breakdown of cells. But this new treatment slows the process for at least two weeks. This time is crucial to allow the product to be packaged and shipped.

Convenience foods such as cut fruit and premixed salads are growing in popularity. According to the International Fresh-Cut Produce Association, ready-to-eat fruits and vegetables make up about 10% of produce sales, and in the United States they are worth up to $10 billion annually.

The equipment necessary to peel, core and slice the apples already exists. Scientists at Mantrose-Haeuser took the ARS findings and created a proprietary formulation using FDA-approved vitamins and minerals. They are marketing the product under the trade name NatureSeal for use by fresh-cut processors and the food-service industries. They are also developing treatments for other hard-to-keep produce, such as potatoes, carrots, peppers, onions and bananas. Patent. 5,939,117--Methods for preserving fresh fruit and product thereof. Issued Aug. 17, 1999. Inventors: Chao Chen, et al. Assigned to Mantrose-Haeuser Co. Inc. (Attleboro, MA) and The United States of America as represented by the Department of Agriculture (Washington, DC). This patent covers ways to preserve fresh fruit with fresh fruit preservatives that extend the shelf life of fresh fruit, particularly fresh-cut fruit. The preservative preserves the texture, flavor, appearance, crispness and color of the fresh fruit, particularly the exposed skin of the fresh fruit.

In a related area, we told you previously about research aimed at using vacuum infusion to improve the texture, appearance and other quality parameters of processed fruits, vegetables and berries. Vacuum infusion involves the removal of air from within vegetables by placing the product in a vacuum environment for 1 minute to 2 minutes at 0 bar to 2 bar. This treatment is followed by infusing or impregnating the product in a solution containing hydrocolloids, calcium or other solutes.

The vacuum infusion technology was able to improve the quality of thawed or pasteurized berries and fruits used for yogurt, marmalade and bakery fillings. The technique improved firmness and reduced drip loss. The technology can be used as a pre-treatment before freezing or pasteurizing a product to improve sensory characteristics.

Further information. On calcium salts: Dominic Wong or Attila E. Pavlath; phone: [phone]; fax: [phone]. On vacuum infusion: Virginie Mahdi, Technologie Marketing Innovation, TMI International, Le Britannia, 20 Bd. Eugene Deruelle, FR-69432 Lyon cedex 03, France; phone: [phone]; fax: [phone]; email: [e-mail].