A car manufacturer wouldn’t dream of putting a new vehicle on the market — or unveiling changes to an existing model — without test-driving it first. Yet many manufacturers continue to introduce products without investing the time to thoroughly evaluate and understand their attributes.

No matter how innovative the concept or the packaging, a dairy product is doomed to failure if it does not deliver in terms of taste, appearance and consistency — or any one of the numerous other parameters that influence overall quality. Sensory analysis and quality testing provide the tools formulators need to understand their products and compete in today’s highly competitive market.

“The more product knowledge you have upfront, the better your chances are,” says Kathleen Rutledge, president and chief executive officer of Bartlesville, Okla.-based 21st Sensory Inc. “When you have 80 to 90 percent failure rates for new product introductions, it just seems short-sighted to spend a lot of money on packaging and the external of the product and not actually know much about the internal attributes.”

As its name applies, sensory analysis relies on the human senses to assess a product’s properties. Formulators can use its findings to optimize ingredient substitutions, understand how a product’s attributes compare to those of its competitors or even reduce costs.

“Sensory analysis is a discipline used to evoke, measure, study and interpret properties of materials such as food as perceived by the senses of sight, smell, taste, touch and hearing,” says Grace Brannan, Ph.D., sensory group leader for Givaudan Flavors Research and Development, Cincinnati. “Analytical instruments are very useful in determining similarities and differences in products. However, there is certain information such as consumer liking and interactions within and across characteristics that only a human panel can provide.”

Sensory analysis can be divided into analytical and affective analyses, says Brannan. Analytical sensory testing essentially uses a trained panel as an analytical instrument and combines physiology, psychology and methodology. Affective testing, on the other hand, relies on consumer feedback. Combined, these two areas of testing can provide the information dairy formulators need to better understand their products and markets.

Analytical sensory analysis encompasses activities such as descriptive analysis and difference testing, says MaryAnne Drake, Ph.D., an associate professor in North Carolina State University’s Department of Food Sciences. Affective sensory testing relies on consumer input from undertakings such as acceptability tests, preference tests and focus groups.

Gail Vance Civille, president of Chatham, N.J.-based Sensory Spectrum Inc., looks at analytical and affective sensory analyses as tools that reveal the “two halves of the truth” about a product. The first half of the truth uses descriptive panels or some form of discrimination tests to define the product’s sensory properties — how it looks, smells and tastes, as well as its textural attributes. The other half of the truth, she says, relies on consumer product perceptions.

“The art form is to put those two halves of the truth together to get at the whole truth,” Civille stresses. “You can’t ask consumers why they love a product, because they are inarticulate about sensory properties. So if you take the descriptive information you have — for example, this product has a higher saltiness, and this product has a lower acidity or whatever — and you put that together with liking information from the consumer using statistics, you end up getting a fairly good understanding of the whole truth.”

Although grading and judging still are used widely to assess general dairy product quality, “they really do not tell us about all the attributes and intensity of attributes in a product,” says Drake. Therefore, descriptive analysis — performed by a panel of trained sensory experts — is becoming more of a necessity in today’s very competitive global dairy market.

Drake developed sensory lexicons, or defined sensory analysis languages, for dairy products ranging from cheddar cheese to chocolate milk. Civille has collaborated with Drake on some of these projects, as well as on certain panel training.

Trained sensory panels can use a defined sensory language to help formulators understand, for example, exactly how their chocolate milk products compare with competitors’ versions and “what’s out there” in terms of flavor variability, says Drake. For chocolate milks, Drake’s panel uses a sensory language that boasts terms such as “malty,” “stale,” “cardboard” and “burnt.”

Effective training is essential to a sensory analysis panel’s ability to perform descriptive analysis, says Rutledge. Made up of people who have been tested and shown to have “at least basic sensory acuities,” each panel typically undergoes intensive training over a period of several months to learn to recognize and measure food characteristics. The panel then functions as an analytical instrument, she says, and its likes and dislikes are “immaterial” to the analytical work.

Rutledge says her company’s trained panelists “contribute the absolutes” to the product developer. “In our methodology, we use references along a scale that anchors the data of the panelists, so over time, from session to session, you can actually compare data sets,” she says. “They might taste a chocolate milk and then taste the references, and they can determine what position that chocolate impact falls along that scale. So then if the product developer looks at the consumer data (and sees) they want more chocolate, they can actually change the formulation, bring it back to the panelists and have them evaluate it again to see if that chocolate impact has moved up correspondingly.”

Givaudan Sensory, which supports the company’s Savory and Sweet Goods business, uses descriptive analysis to analyze various cheese varieties and understand the different profiles. The company uses the information to create “authentic signature profiles” for process cheese and seasoning blends, says Cindy Ward, Ph.D., senior sensory manager.

Trained panels also can perform difference testing to help dairy processors determine the impact an ingredient substitution might have on a given product.

“You can do a difference test to find out if the flavor is similar enough,” says Civille. “You can do statistical analysis to actually prove that it’s similar enough that only a very small portion of the population would ever notice.”
Difference testing also can substantiate matches to competitive flavors, notes Givaudan’s Ward.

On its own, however, such testing is rather limited, notes Lori Kruse, manager of Sensory Evaluation Services for St. Paul, Minn.-based Rtech Laboratories, a business unit of Land O’ Lakes Inc. The results tell formulators whether or not the respondents detect a difference, but they do not indicate the type or scope of that difference.

Descriptive analysis measures only the intensity of sensory attributes, not the acceptance of such characteristics, says Kruse. To gauge product acceptance, Rtech relies on consumer-type testing that includes product guidance, in-home usage and consumer acceptance assessments.

For product guidance testing, Rtech recruits Land O’ Lakes employees to provide acceptance measures of products. “This is usually first step prior to full-scale consumer testing,” says Kruse. “Product guidance testing results may be used to benchmark the acceptance of a product compared to competitors or to determine if a cost-reduced sample is as well liked as the current sample.”

In-home usage testing is appropriate for situations in which consumer usage is important to product acceptance, says Kruse. For example, a manufacturer might want to evaluate how a specific cheese performs in various consumer applications.

Although it might entail a greater financial investment, full-scale consumer testing can offer a high level of confidence in the results, notes Kruse. “It uses a large number of consumers specifically selected as those that purchase the product being evaluated,” she says. “Full-scale consumer testing may also be conducted in various regions of the country.”

Consumer testing works hand in hand with descriptive analysis, says Drake. Once a trained panel has used a defined sensory language to describe the chocolate milks’ flavors, mouthfeel and other attributes, the formulator then can provide a subset of those milks to consumers. Researchers then merge consumer-liking data with the objective analytical sensory information — the profiles of those products — using a technique called preference mapping.

Preference mapping, says Drake, “allows you to specifically identify, from an analytical perspective that you can understand, what drives consumer like and dislike, and what areas are out there that consumers want or need that are not being provided by existing products.”

The sensory area continues to expand and grow in sophistication. According to Ward, new research in statistics, physiology, psychology, psychophysics and molecular biology will help improve the understanding of how humans experience foods.

Through its “flavor preference research,” Givaudan applies advanced statistics and experimental design to link “product attributes with consumer data to generate product profiles and predict consumer liking,” says Ward. The company has applied this type of research to a wide variety of products, including chocolate milk, strawberry milk, macaroni and cheese, and strawberry yogurt, she says, to create “optimized flavors.”

Although innovations such as the “electronic nose” increasingly will be used to discriminate between good and bad samples and perform other tasks, instrumentation will never replace the human factor in sensory analysis, stresses Drake. “There’s never going to be a black box to replace the human perception of flavor.”

Drake, in collaboration with other researchers, microbial physiologists and cheesemakers, currently is trying to uncover ways to accelerate the formation of certain desirable flavors in cheese.

“This is really what the cheese industry has been after for a long time,” says Drake. “They want to be able to very specifically deliver the right flavors to the right consumers. Well we have to know how the bacteria form those flavors, and we have to know about cheese biochemistry, absolutely. But we also have to know what volatile compounds cause those flavors from a sensory perspective.”

While sensory testing can help dairy processors perfect product formulations, other quality tests help ensure that formulation will hold up under processing or storage conditions.

According to Fred Weber, president of Hamilton, N.J.-based Weber Scientific, such testing includes the evaluation of physical, chemical and microbiological kinetics and deterioration for shelf-life purposes; processing and sanitation related to psychotropic bacteria; processing preservation levels required; a product’s need for stabilizers and/or emulsifiers; composition and nutritive value; regulatory concerns and much more.

Fat and moisture analyses are essential for product consistency and cost control, says Bobbie McManus, process product manager for Matthews, N.C.-based CEM Corp.

“The ability to quickly determine the fat content enables the manufacturers of dairy products to efficiently and accurately verify the quality of incoming raw materials, check products in process and make fast adjustments,” says McManus.

CEM’s Smart Trac‘ system uses microwave energy and nuclear magnetic resonance (NMR) analysis to yield accurate fat and moisture test results in just minutes, says McManus. The product won the 2003 National Society of Professional Engineers New Product Award.

Laboratory HTST and UHT equipment and services such as those provided by Raleigh, N.C.-based MicroThermics allow dairy processors to do precisely mimic processing conditions. “We allow the formulator to process their product exactly the same way it’s processed in a production plant so they know the end-product identity,” says MicroThermics vice president David Miles, Ph.D.

MicroThermics’ equipment goes hand in hand with sensory analysis, notes Miles. Essentially, it can be used to match a previously agreed-upon sensory profile, or it can run numerous formulations of a product destined for subsequent sensory analysis. The equipment can run as many as 20 small-quantity batches a day.

New to the company’s product line is a direct/indirect processor that “does both steam injection and indirect heating all in one cabinet,” says Miles. “Processors can select the style of heating, the hold tubes, the number of heating and cooling stages, and more.”