Sensory tests of a mayonnaise-like product made from soy protein and rice bran oil got high marks from a consumer study in which people were asked to taste and evaluate the product developed by LSU AgCenter researchers.

The project began with recognition that a third of U.S. adults have some form of cardiovascular disease, said Witoon Prinyawiwatkul, an LSU AgCenter food scientist.

"Heart disease and stroke are leading causes of death," Prinyawiwatkul said. "Soy protein and rice bran oil can contribute to a diet low in saturated fat." The sensory testing was conducted by Karen Garcia, a graduate student who worked with Prinyawiwatkul while completing her master’s degree.

Garcia’s study began with 10 formulations of a spread made with rice bran oil and soy protein. The oil content ranged from 30 percent to nearly 60 percent, and the soy protein ranged from one percent to 11 percent. The study was conducted with 360 consumers on the LSU campus in Baton Rouge.

Tasters were asked if they liked the product, its appearance, its color, its mouth feel, its flavor and other sensory characteristics, Garcia said.

Commercial mayonnaise is made of soybean oil, egg yolks, vinegar and spices. The researchers’ product is made with rice bran oil, which has a cholesterol-lowering effect, and soy protein, which replaced the egg yolk. Without eggs, the unflavored product is cholesterol-free.

"Mayonnaise is one of the most popular U.S. condiments," Garcia said. But, she pointed out, the tested product can’t be called a true mayonnaise.

"To be called mayonnaise, a product has to contain at least 65 percent oil," Garcia said. "Most commercial mayonnaise is 70-80 percent oil."

The soy protein and rice bran oil product has far less oil, which means fewer calories.

Garcia said studies report rice bran oil can contribute to lower LDL, which is termed the bad cholesterol and a contributor to cardiovascular disease.

"We tried to come up with a partial solution to contribute to a diet low in saturated fat," Prinyawiwatkul said. "Rice bran oil has a cholesterol-lowering component, but we need to point out that soybean oil is not bad. Both rice bran oil and soybean oil have more than 80 percent unsaturated fats."

Rice bran oil contains gamma oryzanol – a functional food – which has been said to serve as an antioxidant and to contribute to lowering cholesterol, Prinyawiwatkul said. The oil also contains other plant sterols and the antioxidant tocotrienol.

In the taste test, 360 adult consumers were asked their impressions of the spreads. Then they were then asked, "Would you buy this product?" After they answered, the tasters were told about its potential health benefits and asked again if they would buy it, Garcia said. When they heard about the health benefits, that number increased by 13 percentage points.

In a follow-up study, 100 tasters were presented with the most popular formulation from the first test but with a twist. The product was offered with three flavorings – sour cream and onion, cheddar cheese and sour cream, and Monterey jack cheese. The preferred formulation included 37 per-cent rice bran oil and six percent soy protein.

With the addition of the flavorings, tasters’ willingness to purchase the product jumped to 65 percent, Garcia said. And after hearing about the health benefits, the number rose to 77 percent. On top of that, 97 percent responded "yes" when asked if they deemed the product "acceptable."

The product has a wide range of uses, the researchers said. Although it cannot be called mayonnaise, they call it a mayonnaise-type spread. With flavorings, it could be used as a condiment; the basis for a tuna, chicken, ham or other sandwich filling; a spread for crackers and as an added ingredient in any number of food recipes.

The spread can be an alternative healthy food, the researchers said. But because it contains a vegetable oil, it still has high calories.

"Soy protein provides functionality and, of course, health benefits," Prinyawiwatkul said.

Rick Bogren

(This article was published in the spring 2011 issue of Louisiana Agriculture.)