Formulating for increased shelf life

Produce gains time

Research from the Southern Research Laboratories, New Orleans, of USDA’s Agricultural Research Service reveals that placing fruit under water during cutting can increase shelf life from 2-3 days to 6-8 days.

For produce in general, the addition of ascorbic acid and calcium to the water, at temperatures of about 150˚F, produces heat shock proteins that reduce the production of “wound proteins” and causes water and calcium to be imbibed into the cells. This firms prepared produce so it can be used as ingredients in salads or other prepared food applications. This technique allows fast food chains to add kid-friendly finger fruit with reduced loss of product.

Other antioxidants, including 4-hexylresorcinol, ascorbic acid and glutathione have been tested as a possible replacement for sulfites. Sulfites must be labeled because of their effect on the considerable portion of the population that suffers from asthma. Hexylresorcinol has been tested on fruits and vegetables, and is also used to control blackspot in fresh and frozen shrimp.

Bacterial control makes big strides

The battle against Listeria monocytogenes has given food science new tools in the quest for more shelf life. A variety of chemical additives can be added to hot dogs and deli meats to prevent recontamination of these products. Studies at the University of Florida found increased amounts of vitamin E in broiler feed increased antibody production in hens and pullets, protecting the birds against a variety of bacterial diseases.

“Supplementing turkey diets with vitamin E stimulates their immune responses, helping them clear the gut of the microorganisms such as Listeria that cause disease,” reports Irene Wesley, a microbiologist for the USDA’s Animal Disease Center.

Careful handling is required when processing foods that require extra shelf life without the use of intensive processes that normally kill bacteria. A production manager at Vienna Foods, Chicago, a firm that elected not to use chemical preservatives in processing its hot dogs, suggests careful attention to temperatures, maintaining clean and sanitized surfaces, purchasing clean raw ingredients and carefully supervising the process.

Specific, accurate measurements of ingredients such as antioxidants is essential, as is complete blending with raw ingredients to ensure the antioxidants will be maximally effective. Some of these natural antioxidants are not heat stable, so they must be added during a cool phase of the process. Oil-based antioxidants, such as vitamin E, can be dispersed in small amounts of fats or oils.

There is a number of new and improved methods of shelf-life extension. The challenge to processors is balancing satisfying the needs of the specific product with the demands of a more aware and more informed consumer.