Organic acid films optimize vegetable safety.

Fresh produce poses safety concerns because fruits and vegetables are often eaten raw or minimally cooked. An antimicrobial coating can provide a continuous barrier against pathogens that might otherwise survive on the surface of vegetables. These coatings should not have any negative impact on the sensory characteristics of a product.

Scientists at the University of Arkansas have demonstrated the antimicrobial activity of organic acid-incorporated soy protein films against three major foodborne pathogens--L. monocytogenes, S. gaminara and E. coli 0157:H7. They show how these films may or may not affect the sensory characteristics of fresh and fresh-cut vegetables.

Their objective was to evaluate the effect of organic acid coatings on the sensory attributes of the tomatoes and carrots. They found that tomatoes and carrots can be coated with organic acid films to improve microbial safety without affecting their sensory attributes.

Cherry tomatoes and baby carrots were coated with malic and lactic acid-incorporated soy protein film, and then stored at 5 C. The sensory properties of the products were evaluated using trained panelists. The color and texture of the coated produce were also measured with a colorimeter and texture analyzer.

With the soy protein coating, no beany flavor was perceived by the panelists. The various coatings generally did not affect the sensory properties of the tomatoes. In addition, sensory panelists did not find any significant differences in the hardness and cohesiveness of the coated and non-coated tomatoes.

Instrumental texture analysis showed that the malic acid-coated tomatoes had higher hardness values than the non-coated tomatoes after 14 days of storage. The lactic acid-coated baby carrots were not as sweet as the non-coated and soy-coated baby carrots after 14 days of storage. The coated carrots were darker than the non-coated carrots on the seventh and fourteenth day of testing. The soy protein film effectively prevented white blush from forming in baby carrots.

Further information. Navam Hettiarachchy, Department of Food Science, University of Arkansas, 2650 N. Young Ave. N 218, Fayetteville, AR 72704; phone: [phone]; fax: [phone]; email: [e-mail].