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Analyzing Foods and Flavors

Revealing the flavor and function of foods calls for various analytical skills

by Rachel Petkewich
January 23, 2006 | A version of this story appeared in Volume 84, Issue 4

Susan Parker thought about apples differently before she joined Kraft Food Ingredients in Memphis. "In my first week, I compounded an apple flavor and it had nothing in it that was from an apple," recalls Parker, now a certified flavorist. She liked learning how to use different acid-water solutions to make the apple flavor "go from being kind of a light-green apple or a fresh apple taste to a juicy apple to a distinct green apple."

Parker, who has a B.S. in chemistry and completed some graduate work, found her forte in flavor chemistry. Other scientists examine food for much more than just taste. Analytical chemistry has facilitated the determination of how taste buds work, contributed to an understanding of why some people lack a sense of taste, and helped to answer many other food-related questions. In this article, scientists in industrial, academic, and government laboratories explain what skills and techniques they use to develop flavors, test food for safety, and establish methods to identify and quantify nutrients.

Whether sweet, savory, dairy, alcoholic, or pharmaceutical, flavors found in foods and consumer products are usually a complex mixture of volatile and other compounds, which explains why the analytical workhorses for flavor and food chemistry are gas chromatography (GC), liquid chromatography (LC), and mass spectrometry (MS).

University researcher and entrepreneur Daphna Havkin-Frenkel has used these techniques in studying vanilla, a flavor compound that she says isn't just a flavor for ice cream anymore. "Vanilla is a unique plant with much that remains to be studied and learned," she says.

Several large companies such as McCormick produce lines of vanilla flavors. Havkin-Frenkel started learning about vanilla at David Michael & Co. in 1989. Now, she splits her time between research at Rutgers University and her own company, Bakto Flavors. To do research in the flavor industry, she says, "one must be well-trained in the sciences," but she also recommends additional training in economics and finance. She holds a B.S. and an M.S. in agriculture, a Ph.D. in food science, and a master's in business administration.

Now in academia full time, Robert McGorrin spent 22 years in R&D in the processed food industry where he analyzed food flavors. Before becoming head of the food science and technology department at Oregon State University (OSU), Corvallis, six years ago, he worked at Quaker Oats Co. and Kraft Foods. He holds a B.S. in chemistry and M.S. and Ph.D. degrees in organic and medicinal chemistry. His research focuses on dairy flavors, which present various analytical challenges.

Credit: Getty Images
Group of people sitting at table, eating in restaurant
Credit: Getty Images

"The trick during analysis is to tease out these very trace amounts of flavor," he says. Traditional ways to isolate dairy flavors for analysis include vacuum distillations or purge-and-trap headspace. Both methods are labor-intensive and difficult to automate, so the food industry is interested in a flavor extraction method that can be automated and paired with an analytical identification technique that exhibits increased sensitivity, he says.

Better sample preparation techniques are also becoming routine for food analysis. Concentrating samples or eliminating the interfering substances in the food matrix is frequently done with solid-phase microextraction or an emerging method called stir bar sorptive extraction, where the stir bar is coated with a polymer that can absorb volatile analytes.

GC/MS techniques fit the requirements for increased sensitivity, and fast microprocessors enable rapid data searches for peak matching. "The power that a flavor chemist has at his or her fingertips has expanded tremendously even in the past five to seven years because of the speed at which spectral libraries can be scanned against to get a proper identification," McGorrin adds.

McGorrin's lab draws on other instrumental techniques including GC paired with infrared (IR) spectroscopy, for example, to confirm a functional group. Many food companies don't require that kind of enhanced instrumental power, he says, unless they are doing a sophisticated analysis such as looking for a novel flavor composition in a dairy fermentation product such as a unique cheese flavor or a cultured milk product.

Because people need to eat, job prospects in the food and beverage industries for those with analytical skills continue to look good. "The food industry is the world's largest industry, so the opportunities both on the basic research side as well as on the product development and quality control and manufacturing sides are pretty wide open," McGorrin says.

Jobs are available for all degree levels, but most are entry-level positions for graduates with B.S. and M.S. degrees. Recruiters and companies call McGorrin looking for students ready to graduate with the expertise they seek. They project that there will be openings for at least the next three to five years as the baby-boomer segment of the industry's workforce approaches retirement age.

McGorrin also reports that his department's undergraduate program has doubled in size in two years to 80 students. He attributes the growth to at least two factors: First, students have unique opportunities in beer brewing and winemaking, which are options to the core food science program. Specialized programs like these are found at only a few other universities across the country. Second, the public's interest in new cuisine is on an upswing, and this creates development opportunities for new foods. The department's Food Innovation Center in downtown Portland and the Seafood Laboratory in Astoria also offer real-world learning experiences.

"The Food Innovation Center works with entrepreneurs in the food industry and also seeks to work with specific food companies to bring products to market or make improvements to products that are of interest to primarily Oregon, Washington, and Idaho," he explains. OSU and the Oregon Department of Agriculture share responsibility for the center. The public can get involved, too: The center sponsors an annual contest open to all who want to submit food ideas to a panel of industry judges. The winner receives help with recipe refinement, package design, and marketing.

To solve various analytical problems, industry collaborates with Oregon's Seafood Lab. The albacore tuna industry, for example, wants the ability to rapidly assay fish on the boat as they are caught to make quick decisions on value. Then the low-quality fish could immediately be diverted to the canning industry, while the high-quality ones would go to restaurants or into fresh-frozen products for worldwide distribution, he explains. Other projects include examining potential safety issues with shellfish and oysters. For example, a high-pressure processing technique developed by the department is being used by the processed oyster industry to simultaneously kill bacteria and shuck raw oysters.

Various government labs also employ scientists for food analysis. One such example is the Beltsville Human Nutrition Research Center, in Maryland, which has the standout task of developing analytical methods for components or nutrients and bioactive compounds in the U.S. food supply. This lab is part of the Department of Agriculture's Agricultural Research Service.

James Harnly has been working in the lab for more than 25 years. After receiving a B.S. in chemistry, he went to work for a contractor to the old Atomic Energy Commission, analyzing trace metals in spent reactor fuels and purified radioactive components. Six years later, he enrolled at the University of Maryland, College Park, to get his Ph.D. in analytical chemistry. After conducting his project and completing his dissertation on work he did in Beltsville, he was hired there.

The lab's projects fall into two main areas. The first is developing methods for analyzing new compounds or newly interesting compounds, such as the complex analysis of flavonoids, a class of 7,000 phytochemicals. The second area is applying modern instrumental techniques to classic nutrients as a substitute for older microbiological assays or radioimmunoassays. Projects include, for example, developing a simultaneous method to identify eight water-soluble vitamins in one LC/MS or LC/ultraviolet run.

Credit: Getty Images
Credit: Getty Images

Lab members usually pick their projects. "Those decisions are based on going to meetings, talking to people, and input from our sister labs," Harnly says. The Nutrient Data Laboratory in Beltsville, which puts together USDA's nutrient database for standard reference, is one of those sister labs. The data lab points out gaps in the database such as what foods need to be analyzed or what methods require development, and the research lab follows up.

Occasionally, senior officials at USDA will assign a project. For example, recent biological studies indicate new nutritional importance for vitamin D, but there has always been a lack of a robust, accurate, precise, and fast analytical method to analyze for it, Harnly says.

Attaching significance to data requires more than knowing how to collect the information. Analysis from a statistical or chemometric point of view is helpful, Harnly says. When analyzing or extracting samples, information about biology, the nature of the sample's biochemistry, what is happening on the molecular level, and the nutritional impact of these foods is necessary, he adds.

Twenty people, including scientists and technical and administrative support staff, work in the Beltsville lab with Harnly. Every scientist has at least a bachelor's degree, but backgrounds differ. "It's not cut-and-dried that we would say we only need nutritionists or biochemists or analytical chemists," he says. The research scientists also have doctoral degrees in analytical, organic, or inorganic chemistry; biochemists have worked there in the past.

Even in this small lab, positions open up. In the past five years, five Ph.D. chemists were hired to fill vacancies from retirement or people moving to other positions, Harnly says. In addition, the lab hires "quite a few postdocs."

Although their individual objectives vary, food and flavor chemists often analyze the same chemicals found in food and attend some of the same conferences, Harnly says. The thiosulfonate compounds found in garlic serve as a perfect example of both function and flavor. "Sulfur-containing compounds are phytochemicals that have been implicated in having anticarcinogenic effects," he explains. "They are also interesting to the flavor chemists because they have a very strong influence on flavor."



In Good Taste

Compounding sweet, fruity flavors drew her in. Designing savory ones became her specialty. (Think green bell pepper and roasted tomato. Marinades. Brownies and cheesecake.) In September, research scientist Susan Parker added "certified flavorist" to her qualifications after completing requirements set forth by the Society of Flavor Chemists.

Parker holds a B.S. in chemistry. Halfway through a doctorate, she decided that elucidating the mechanisms inherent to organophosphorus chemistry wasn't for her. She put her analytical skills to use in commercial labs until seven years ago, when she got a job in Memphis at Kraft Food Ingredients, part of the Food Service Division of Kraft Foods.

"You cannot learn this job from a book, and you can't learn it from taking a class or two," Parker says. "It's not like taking instrumental analysis or organic chemistry where you get some basic skills; it's really some heavy on-the-job work."

The road to certification requires at least seven years in the industry working under a certified flavorist. After the first five years, the flavorist-in-training can take the oral apprenticeship exam. After two more years as an apprentice, the candidate can apply to take the oral certification exam. Two examiners can ask anything pertaining to topics outlined in a published syllabus. Questions range from government regulations around the world to dietary laws to what constitutes a natural or artificial flavor to information about the flavor profiles of more than 6,000 approved raw materials.

Becoming a certified flavorist has advantages. "It shows that you have a minimum level of knowledge in a wide variety of areas, because as a flavorist you can work in anything from fruit flavors to savory flavors to cheese flavors to alcohol flavors to pharmaceutical flavors and everything in between," Parker says.

Typically, she says, people have bachelor's degrees rather than a master's or Ph.D. simply because the first job is entry-level, technician-type work. She says the work can get frustrating.

Parker depends on her senses for most analysis. Raw materials are diluted in an appropriate solvent and evaluated at parts-per-million, parts-per-billion, or parts-per-trillion levels. "As you work on flavors you start to get how those raw materials fit together and so you start to understand how a combination gives you a certain kind of flavor profile," she explains. "A material may taste like chicken fat at one level, but maybe more like citrus at a higher or lower level."


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