INTRODUCTION

Consumer tastes are changing. More than 3,690 new condiments were introduced to supermarket shelves in the United States last year (Dornblaster, 1996), with salsa becoming the largest seller, surpassing catsup (Cousminer, 1996). Salsa sales increased to $675 billion in 1992 (Charlet, 1994) and are expected to climb further. Why is there this sudden increase in salsa? There are basically four reasons for this surge:

1. There is an increased interest in ethnic and novel foods among consumers who want something different, including "hot, spicy and bold flavors" (Toops, 1996);  
2. There is a need for flavors to compensate for the loss of fat in low- and non-fat foods (Cousminer, 1996; Hollingsworth, 1996);  
3. There is a higher perceived value for a dish served with a condiment such as salsa (Duran-Gutierrez, 1996);  
4. There is a connection between salty snacks such as tortilla chips and the use of salsa (Mogelonsky, 1995).

Salsas are a combinations of finely chopped fruits and/or vegetables flavored with a variety of different herbs, spices, and other ingredients. The combined ingredients are not a puree, but are distinct pieces and are often uncooked (Cousminer, 1996). This definition would also include chutneys and fruit or vegetable relishes.

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 (Cousminer, 1996), tomato salsa can be produced using a high-pressure retort system or the "hot-fill-hold" method (Ronsivalli and Vieira, 1992). The hot-fill-hold method is preferred because it does not "over- process" 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.

Cilantro is the green, leafy portion of the coriander plant also known as Chinese parsley (Labensky and Hause, 1995). Cilantro is a popular herb used in Chinese, Southeast Asian, Indian, Italian, Caribbean, South American, and Mexican cuisines. However, the volatiles that produce the aroma and flavor in this product have a low boiling point that normal heat processing exceeds. In other words, the flavor that cilantro imparts to fresh salsa is lost during normal processing conditions.

The microwave/vacuum (MIVAC) dehydration process developed by Dr. Carter Clary of the Dried Foods Technology Laboratory at California State University, Fresno allows fresh fruits, vegetables, and herbs  to be dried to low moisture levels without losing their volatiles. This is accomplished through the combined microwave, vacuum dehydration process. This process has already 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 the food processing industry and agriculture in general to produce a shelf-stable, processed product that contains cilantro without losing the volatile compounds that give fresh salsa its flavor appeal. It is the objective of this study to produce such a product.

The short-term impact of this research would be to make a shelf-stable, fresh-tasting tomato salsa available to the local community through the university farm market. The intermediate impact would be to make this same process and/or product available to the food processors throughout California for production of salsa and other unique cilantro-based products. The long-term implications are far reaching. The MIVAC process is a unique and exciting one that is being under-used by food processors, especially dried herb and spice manufacturers. The overall purpose of this study is to develop a "new" processed, shelf-stable salsa that retains the fresh characteristics of cilantro.

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METHODOLOGY

Bench-top Production

Production and testing of a Standardized or Control Formulation
The purpose of the first step of the current investigation was to produce a shelf-stable salsa without cilantro that was acceptable to consumers at the California State University, Fresno Farm Market (the target market). This salsa was to act as the control for all further research.

A "family recipe" from Mr. Ernesto Duran was adapted to meet the criteria for the project. Standard ingredients - canned or aseptically packaged 3/4" tomatoes and brined 1/2" jalapenos with a standard heat  index - were purchased to ensure uniformity in the control batches. All ingredients were carefully weighed and the weights recorded. Any adjustments to the formula were made only after careful screening using trained tasters. Product was sealed in glass jars using the hot-fill-hold method (Ronsivalli and Vieira, 1992).

To test the acceptability of the control salsa, a consumer acceptance test was performed at the California State University, Fresno Farm Market. Results were analyzed using a five percent significance level (Meilgaard, Civille, and Carr, 1991).

Production of a Salsa with "MIVACed" Cilantro
Production of cilantro stems and leaves - Initial work indicated that cilantro stems and leaves have different compositions. Therefore it is imperative to include both  in the formulations. Cilantro was washed, sorted, picked, chopped, and then soaked in citric acid to minimize enzymatic activity during processing. Treated cilantro was then subjected to the microwave/vacuum dehydration (MIVAC) process. Dried cilantro was stored in air-tight, vacuum-sealed aluminum laminate packages with desiccant packages until time for processing.

Production of  salsa with MIVACed Cilantro (treatment) - Treated and prepared cilantro was added to the salsa at initial rates of 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6% and 0.7%. This cilantro was added near the end of the cooking time to assure less loss of volatile components  but to allow enough time to destroy viable microorganisms during the thermal processing. The product was processed using the hot-fill-hold method as described above.

Sensory Testing of Treated Salsa (containing cilantro)
Threshold Testing of Salsa Containing Cilantro - MIVACed cilantro might be costly. Too much cilantro might also produce unacceptable quality in the finished salsa. It is therefore imperative to add enough cilantro to the salsa for people to enjoy the character it imparts without adding too much to prevent cost effectiveness or negative flavor inputs. A trained panel was enlisted to test the recognition threshold for the treated salsa. The recognition threshold is the level at which cilantro can be recognized as cilantro in the salsa.

Preliminary screening for the panel was performed using a Triangle Test for difference (Meilgaard, et al., 1991). Panelists were selected if they could detect the difference in salsa containing cilantro at a high level of  inclusion, 0.5%. Screened panelists were then trained to distinguish cilantro in salsa. Following training, panelists were tested using the Recognition Threshold Test (ASTM, 1995) under controlled conditions in the sensory booths at California State University, Fresno Sensory Laboratory. Results were analyzed at a five percent significance level (Meilgaard, et al., 1991).

Consumer Preference Testing - Cilantro was added to the salsa according to results obtained in the Threshold Test above. To test if consumers preferred salsa with or with-out cilantro, a consumer preference test was performed. To eliminate bias on the part of consumers, the initial test was conducted without giving consumers information about the difference between the control salsa (without cilantro) and the treated salsa (with cilantro). However, consumers, in many cases, perceived the difference as being due to the degree of heat in the product.

In order to better understand a preference for or against cilantro, a revised consumer preference test was performed, in which consumers were informed that the only difference in the two salsas being tested was the inclusion of cilantro in one sample. Results were analyzed at a five percent significance level (Meilgaard, et al., 1991).

Scale-up Production of Salsa at the Food
Processing Research Laboratory (FPRL)

The tested and approved salsa product was produced in the Food Processing Research laboratory at California State University, Fresno in 14-gallon batches. Ingredients were brought to temperature in a 50-gallon stainless steel, indirect steam kettle and pumped using a 1 and 1/2" Wakasah pump to a simplex type filler. Eight-ounce jars were filled and processed using the hot- fill-hold method. This product is currently being sold at the California State University Farm Market.

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RESULTS AND DISCUSSION

Bench-top Production

Production and testing of a Standardized or Control Formulation
A control formula for salsa without cilantro was produced (see Table 1). This formula was liked by more than 93 percent of the customers who tested it  at the California State University, Fresno campus market (see Figure 1). Significantly more people liked  the salsa than those who did not at a five percent significance level. Since the formula was liked by so many customers, it is apparent that the product could be sold at the market with or without the addition of cilantro. 

Table 1 - Standardized Control Salsa Formula (without cilantro)

Ingredient	Standard Batch Weight (grams)	Percentage
Tomatoes, canned or aseptic pack, 3/4” dice	781.0	77.2%
Onions, white, 1/2” dice	72.4	7.2%
Jalapeno peppers, brined, 1/2” slices*	157.8	15.6%

*ASTM Heat Unit Range 100-200 units

Production of a Salsa with MIVACed Cilantro
Production of cilantro stems and leaves - The cilantro product produced using the MIVAC technology is high quality and 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 many dishes to impart fresh cilantro character.

Production of salsa with MIVACed Cilantro (treatment) - Processed salsa containing various amounts of cilantro was produced, including 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6% and 0.7%. The products all had a fresh cilantro aroma that persisted after opening and refrigeration for prolonged periods of time. 

Sensory Testing of Treated Salsa (containing cilantro)
Threshold Testing of Salsa Containing Cilantro - The threshold testing was used as a screening process only. The information it provides cannot be generalized to the population. However, it is a good starting point for determining the amount of cilantro that should be used in the final product. The trained panel group threshold was 0.29% (see Figure 2). To account for the fact that this was a trained panel that was sensitive to cilantro odor and for any potential variation in perception levels, a higher level of cilantro was added to the final formulation, 0.5% (see Table 2).

Table 2 - Standardized Salsa Formula for Treated Salsa (containing cilantro)

Ingredient	Standard Batch Weight (grams)	Percentage
Tomatoes, canned or aseptic pack, 3/4” dice	781.0	76.9%
Onions, white, 1/2” dice	72.4	7.1%
Jalapeno peppers, brined, 1/2” slices*	157.8	15.5%
MIVACed cilantro, stems and leaves, chopped	5.0	0.5%

*ASTM Heat Unit Range 100-200 units

Consumer Preference Testing - The initial consumer preference test indicated that there was no difference in the preference for control (no cilantro) or treated  (with cilantro) salsas at the five percent significance  level (see Figure 3). This was difficult to believe since cilantro imparted such a distinctive character to the finished product.

Open ended responses to the preference survey indicated that many customers felt that the control salsa was much hotter than the treated product. Perhaps the cilantro had a masking effect on the product. The open ended responses indicated that by trying to control consumer bias by not telling the tasters that the only difference between the two products was the cilantro, it actually biased the tasters in another way. They perceived that the difference between the two products must be the capsaicin level (the amount of heat in the two products) and that must be difference the researchers were looking for. If this is the case, then consumers were indicating if they liked hot or mild salsa, not if they preferred cilantro in the salsa.

In order to determine if this is true, a second consumer preference test was performed. This time the tasters were informed that the only difference between the two salsas was the addition of cilantro to one of them. The results were very different from the first survey (see Figure 4). Fifty- three of 78 consumers preferred the treated salsa. Statistically, this is significant at the 5% level. This means that significantly more customers prefer the salsa containing cilantro over the salsa containing no cilantro.

Scale-up Production of Salsa at the Food
Processing Research Laboratory (FPRL)

The bench-top formula was scaled up from a 2.24 lb. batch (0.28 gallon) to a 112 lb. (14- gallon batch) (see Table 3). Scale-up was performed at the FPRL as described in the methodology section. Addition of the cilantro near the end of processing was critical to maintaining the quality and volatile character of the cilantro. This will be increasingly more important as the product is scaled-up to higher levels of 28- and 42-gallon batches. 

Table 3 - Fourteen Gallon Salsa Batch

Ingredient	Standard Batch Weight (pounds)	Percentage
Tomatoes, canned or aseptic pack, 3/4” dice	86.4	77.1%
Onions, white, 1/2” dice	7.8	7.0%
Jalapeno peppers, brined, 1/2” slices*	17.2	15.4%
MIVACed cilantro, stems and leaves, chopped	0.6	0.5%

*ASTM Heat Unit Range 100-200 units

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CONCLUSIONS

A successful salsa was produced using a standardized formulation, sensory testing, and scale-up procedures. This product is currently being sold at the California State University, Fresno Farm Market. Further research is needed to determine the effect of shelf-life on the quality of the shelf-stable product.

Microbiological work needs to be performed to determine the initial and subsequent microbiological loads of the salsa. Consumer acceptance of the newly formulated product containing cilantro will need to be periodically updated throughout the testing period using the consumer acceptance test and a significance level of five percent. Investigation into varying the amounts and types of ingredients should also be performed. Included in this investigation should be the effects of varying the tomato, onion, jalapeno and cilantro components in the salsa matrix.

Consumer preferences for the salsa produced with and without cilantro as an ingredient should be further investigated as should varying the degree of perceived heat (capsaicin) levels and the effects of cilantro in masking these heat levels. 

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REFERENCES

ASTM (American Society of Testing Methods). 1995. Standard practice for defining and calculating individual and group sensory thresholds from forced-choice data sets of intermediate size. E1432-91. Vol. 15.07.

Charlet, K. 1994. The heat is on! (new condiments). Prepared Foods, 163 (5), 75.

Clary, C. 1997. Personal communication. March, 1997.

Cousminer. 1996. Sales of salsa. Food Technology, 50(1), 70-73.

Dornblaser, L. 1996. Lightweights drive condiment category. Prepared Foods, Mid-April, 59-62.

Duran-Guiterrez, E. J. 1995. At the heat of salsa. Student report, Department of Enology, Food Science & Nutrition, California State University, Fresno, Fresno, CA.

Hollingsworth, P. 1996. Food shows spotlight subtle innovations. Food Technology, 50(7), 36.

Labensky, S.R. and Hause, A.M. 1995. On Cooking. Englewood Cliffs, NJ: Prentice Hall Publishers.

Meilgaard, M., Civille, G.V., & Carr, B.T. 1991). Sensory Evaluations Techniques, 2nd. ed.  Boca Raton, FL: CRC Press, Inc.

Mogelonsky, M. 1995. Sauces beyond salsa. American Demographics. 17(5): 10.

Ronsivalli, L.J. and Vieira, E.R. 1992. Elementary Food Science, 3rd ed.  pp. 311-313. New York: Chapman and Hall.

Toops, D., Kevin, K. 1996. New bytes. Food Processing, 57(8), 16.

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