Dry fresh produce without losing volatiles.

Salsa's becoming a major seller. There are a variety of reasons for interest in salsa. There is an increased interest in ethnic and novel foods among consumers who want something different, including hot, spicy and bold flavors. There is a need for flavors to compensate for the loss of fat in low- and non-fat foods. There is a higher perceived value for a dish served with a condiment, such as salsa. There is a connection between salty snacks, such as tortilla chips, and the use of salsa.

Salsas are a combination of finely chopped fruits or vegetables flavored with a variety of different herbs, spices and other ingredients. The combined ingredients are not a puree but distinct pieces and are often uncooked. Tomato salsa can be made as a fresh condiment that needs to be refrigerated or as a processed, shelf-stable product. Because it is considered a high-acid food, tomato salsa can be produced using a high-pressure retort system or the hot-fill-hold method, which is preferred because it does not overprocess the product.

Fresh, tomato-based salsas often include cilantro as a flavoring ingredient. However, this product must be refrigerated and has a relatively short shelf life. Unfortunately, the volatiles that produce the aroma and flavor in this product have a low boiling point that normal heat processing exceeds. The flavor that cilantro imparts to fresh salsa is lost during normal processing conditions.

Scientists at California State University (Dried Foods Technology Laboratory, 2360 E. Barstow Ave., M/S 89, Fresno, CA 93740) have developed a microwave-vacuum (MIVAC) dehydration process that allows fresh fruits, vegetables and herbs to be dried to low moisture levels without losing their volatiles. This is accomplished through a combined microwave and vacuum dehydration process.

The process occurs inside a stainless steel vessel under vacuum. The vessel contains a conveyor system, a microwave and a radiant heat source. Dehydrating products under vacuum minimizes oxidation and lowers the boiling point of the water in food, making it possible for drying to occur rapidly at below 130 F. Low-temperature drying allows food to retain many qualities, such as color, flavor and nutrients, that are altered at greater temperatures.

The technique has been successfully used to produce dehydrated cilantro that maintains its fresh appeal. Given the growing demand for salsa and other condiments and the popularity of Mexican and other ethnic cuisines, it would be advantageous to produce a shelf-stable, processed product that contains cilantro without losing the volatile compounds that give fresh salsa its flavor appeal.

In experiments, cilantro was washed, sorted, picked, chopped and then soaked in citric acid to minimize enzymatic activity during processing. Treated cilantro was subjected to the MIVAC process. Dried cilantro was stored in air-tight, vacuum-sealed aluminum laminate packages with desiccant packaging until time for processing. Treated and prepared cilantro was added to salsa, and the product was processed using the hot-fill-hold method.

The cilantro product produced using the MIVAC technology was of high quality. It can be stored for prolonged periods of time as long as the vacuum seal is not broken. When the product is rehydrated, it possesses an aroma characteristic of fresh cilantro and might be added to salsa or other dishes to impart fresh cilantro character.

Investigators still must determine the initial and subsequent microbiological loads of the salsa. Consumer preferences for the salsa produced with and without cilantro as an ingredient must be further investigated, as should varying the degree of perceived heat (capsaicin) levels and the effects of cilantro in masking these heat levels. Companies can test products in a prototype MIVAC system operating at the university.

Further information. Carter Clary; phone: [phone]; fax: [phone].