Sensory evaluation useful in marketing fresh-cut produce

November 9, 2007

Quality is the No. 1 factor when it comes to increasing American consumption of fruits and vegetables. Consumers who are disappointed with a product won’t buy it again.
But quality – as defined by the average shopper – encompasses a variety of senses, including taste, texture and visual appearance.

“Flavor is very important and will determine if they will buy that product again,” said Adel Kader, professor emeritus in the department of plant sciences at the University of California, Davis. “That is what determines repurchases. The flavor satisfaction is key.”

When developing new fresh-cut products, Kader said to consider the sugar-to-acid ratio to find the balance that gives the most intense flavor. Generally, flavor is most intense when both the sugar content and acid content are high, he said.

“If you are shooting for one target, you should shoot for high sugars and moderate to high levels of acids and you will satisfy most people,” Kader said.

Taste and texture are what keep customers coming back, more so than the brand or price.
Shelf life is often considered more important than flavor by processors and retailers who want to reduce shrink, but Kader said that’s a mistake that will result in less satisfied customers.

“You have to get it through your head that you should not keep things based on appearance, you should keep them based on flavor,” he said.

That’s not to say that visual quality isn’t important. Packaging should be designed so that customers can see the cut product, and it should look as good as it tastes.

“Color is, of course, very important. It’s the first thing that gets our attention,” Kader said.

The quality of fresh-cut fruit and vegetables starts with the incoming raw product. The biggest challenge for growers is finding the balance between yield and quality, which makes the monitoring of incoming product important. If the material isn’t mature enough, its color and aroma will be reduced. If it’s overripe, it could lose firmness – resulting in a reduced shelf life.

“Even if you discover it at the time of cutting, it is a loss,” Kader said. “If you cut it anyway, you will have a serious deterioration of life.”

Sensory Testing

Fresh-cut companies put time and money into developing the best-tasting varieties, the best-looking packaging and the longest shelf life, but the research often stops there. Processors need to conduct more follow-through on their products to make sure they’re doing what they say they’re doing, said Hildegarde Heymann, a sensory scientist in the Department of Viticulture and Enology at the University of California, Davis.

Testing should be conducted during product development, and then follow-up testing should be done to verify shelf-life claims and to check for packaging problems such as leakers.

“Sensory evaluation is a technique that uses people to tell us about products,” Heymann said. “The techniques are always the same; the products are different.”

There are different tests that look for different answers. Some look for product differences, others look for quantitative or qualitative data and other tests look for hedonic responses to products.

There are two differentiation techniques used, called discrimination tests because they ask subjects to determine if two products are perceptibly different. The first is a Duo-Trio test that asks test subjects to match a reference sample to one or two test samples. The second discrimination test is called a Triangle test, where test subjects pick the one dissimilar item out of three test samples.
These tests are useful for testing shelf life, because test subjects would be able to pick out a product that isn’t reaching its shelf life when compared to fresh product.

“There is nothing in the test that tells you it is more yellow, only that it is different,” Heymann said.

A qualitative sensory evaluation uses a panel of testers who are trained to describe perceived attributes of a particular product. This type of test uses descriptions and definitions that have a chemical reference to determine what is considered “floral” or “sweet,” for example. The difficulty with a qualitative analytical sensory evaluation is test subjects have to be trained on the language so that everyone has the same definitions and scale to measure by.

A quantitative descriptive analysis method uses eight to 12 judges with three or four replications. The group has to be trained, as with a qualitative evaluation, but in this test the group comes to its own language during the testing process. After sampling the test product, the group will come up with a description of the product that can be charted based on the intensity of the flavors described.

The final sensory test is a consumer sensory evaluation. This asks for “hedonic” responses of how much the testers like or dislike a product.

“We’re looking at people and asking how they like something,” Heymann said.

Consumer responses will vary, because everyone tastes and smells differently. How they rate a product may depend on culture, experience or genetics, so results can’t be quantitatively measured.
“We have to be careful with this data, because it is subjective,” Heymann said.

The key to hedonic tests is to target consumers of the product. If a new product is aimed at children, test mothers and children to see how each feels about it.

“Don’t ask the people you work with whether they like the product or not,” she said.

Sampling

No matter what test is used, the key is to have as many test subjects as possible to get an accurate picture from a statistical data analysis. Dissimilar products are easy to differentiate, so only a small sample group is needed, but the more similar the product, the more judges are required.

“Power equals people,” Heymann said. “You are always better going with more individuals than with the same people over and over.”

The difficulty with sensory evaluation testing is that test subjects look for the right answer and can pick up subtle external cues to lead them to the right answer. Heymann spoke of one test conducted at the University of California, Davis, where a student cut one sample of cheese and a technician cut the other sample. The cuts were different enough that she was able to tell which sample was which without tasting them. On a second attempt at the same test, the samples were stored at different temperatures and she was able to differentiate them just by touching the cups holding the samples.

“If you think that’s obnoxious, your panelists are going to be more obnoxious,” she said.
Genetic differences also have an effect on sensory tests.

That’s why companies should make a firm commitment to sensory evaluation testing. It requires both money and time, so hire a full-time professional, Heymann said.

“It’s a well thought-through science that needs an expert.”

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