Antimicrobials optimize fresh produce safety.

Fresh and minimally processed fruits and vegetables are good sources of nutrition. But along with their greater availabililty comes an increase in the potential for pathogenic microorganism contamination. Determining how contamination occurs and finding ways to prevent it or decontaminate fruits and vegetables is a challenge facing the industry today. What makes this challenge more complex is maintaining a product's visual and olfactory qualities while at the same time making it safe to consume.

Naturally derived biological compounds and other natural products may find use in controlling pathogens in salads, dressings, purees, jams, jellies and juices. However, we're limited in our use of natural preservatives because of associated flavors that can alter the taste of food. Isothiocyanates have potent antimicrobial activity when used in packaged foods. Improving our understanding of how such compounds function and affect the survival and growth of microorganisms can lead to advances in maintaining the quality of foods naturally while preventing microbial contamination.

Essential oils have antimicrobial properties. These include essential oils from coriander, mint, vanillin, parsley and citrus fruit peels. Like carbonyl compounds, intense flavors from these natural chemicals may limit their use. Enzymes, such as oxidases, hydrogenases and catalase, have deprived nutrient availability to microorganisms. Proteases inactivate enzymes within microorganisms and disrupt growth.

Chemicals combined with high pressure, sonication, high-intensity pulsed light, pulsed electric fields and irradiation offer new ways to reduce pathogens in foods. Treatments should overcome problems experienced using conventional sanitizing processes, for example by targeting treatment to microbial attachment sites in fruits and vegetables and by treating products with surfactants, antimicrobial agents, hydrolytic enzymes and sonication. Such techniques might be used in conjunction with HACCP plans and good agricultural and manufacturing practices, including work force training.

Further information. John Cherry, USDA/ARS Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038; phone: [phone]; fax: [phone].