Pictured above: Sarah Mayfield, an honors food science senior, develops new uses for a healthier shortening. | Photos by Russell Cothren
Imagine reaching for a piping hot biscuit or taking a forkful of crisp, flaky piecrust, knowing that each delicious bite will lower your bad cholesterol, raise your good cholesterol and maybe boost your metabolism to burn more calories. Sound too good to be true? It gets better: how about savoring a chocolate bar that promotes heart health and combats fat?
Sarah Mayfield, an Honors College student in food science, is working with Andrew Proctor in food science to make this dream a reality.
She has spent more than five months making shortening and, more recently, chocolate bars and chocolate paste using a new soy oil that Proctor produced, an oil containing conjugated linoleic acid (CLA). This new soy oil provides the recommended daily allowance of CLA in just one-half ounce, and besides being cholesterol-free and low in saturated fat, it has anti-obesity, anti-carcinogenic, anti-diabetic, and anti-arthritis properties.
Proctor’s research team has already produced a CLA-rich margarine that delivers 3.2 grams of CLA in just 185 calories. In a recent study by University of Arkansas System Division of Agriculture researchers, obese rats ate CLA-enriched feed, resulting in demonstrated health benefits. In 30 days, total serum cholesterol and LDL (“bad”) cholesterol were reduced by 50 percent, and a fat-burning gene was activated.
Given today’s obesity problems and the economic potential — soybeans are a $2-billion-a-year-crop in Arkansas — the search is on at the university to produce more CLA-rich food products with soy oil. And that’s where Sarah Mayfield comes in.
One spring day in the lab, Mayfield assembles the ingredients for her latest batch of shortening. The formulation is simple: melt together the fats, which include regular and CLA-enriched soy oils, then allow them to cool slowly while stirring. The combination of cooling and stirring causes the fats to crystallize and form a semi-solid substance that looks exactly like the shortening in your kitchen pantry. Unlike with traditional solid shortening, “crystalline structure, rather than a high concentration of saturated fats, is responsible for the texture,” Mayfield explains.
Nearby, a tray is filled with more than 70 shortening samples in plastic containers, each marked with different percentages of CLA-enriched and regular soy oils. Later in the afternoon Mayfield will ship them to the food science department at the University of Ghent in Belgium, where she will spend the summer subjecting the samples to a battery of tests.
“We’ll be looking at viscosity, hardness, color, and we’ll use X-ray crystallography to look at the crystal structure,” Mayfield said. “We’ll also use the DSC — differential scanning calorimetry — to see how much solid fat is in there. You don’t want it to be too low, or it would melt at room temperature.”
In addition to testing her shortening samples, Mayfield will work in the University of Ghent’s Cacaolab, where researchers are partnering with industry to create innovative chocolate products, improve chocolate-making processes, and stimulate the export potential of Belgian chocolate, renowned worldwide for its quality. There she plans to develop chocolate bars and a chocolate paste that use a combination of CLA-enriched soy oil and the customary palm oil to provide the fat.
Chocolate promises to be a bit trickier to work with than the shortening. Normal chocolate melts at body temperature, a unique property of its cocoa butter, a solid fat.
“With chocolate, it’s important to hit the sweet spot for the melting point,” Mayfield said. “When you put it in your mouth, you want it to melt right then. We’ll have to see if adding CLA changes that property – hopefully, it won’t.”
She will use the same battery of tests on the chocolate bars that she used for the shortening, in addition to testing for fracture force — the point, when bending, that the bar breaks — and for bloom, a film that develops on older or lower quality chocolate.
Once Mayfield returned to campus in fall 2014, she studied the oxidative stability of the shortening and chocolate over time. Fats go bad because they oxidize, which leads to rancidity and off odors and flavors. Unsaturated fats oxidize faster than saturated fats, so this test will be an important final step.
Mayfield also plans to start baking with the CLA-enriched shortening and conventional solid vegetable shortening and then compare the baked goods for crispiness and hardness. She’ll start with something simple, like pie crusts, which are easy to analyze.
It’s a good bet that when Mayfield is ready to taste test her baked goods and chocolates, she’ll have no problem finding volunteers.