Beef burger with pineapple fiber could help combat obesity

Lean burger contains less unhealthy fat and fewer calories.

By Peter Moon  |  Agência FAPESP – Obesity is a serious epidemiological problem in Brazil, as evidenced by the growing prevalence of cardiovascular disease and diabetes. One of the main causes of obesity is the consumption of sandwiches sold by fast-food chains.

Processed foods contain large amounts of calories and fat, so reducing the amount of fat in burgers seems like a valid way to combat obesity. Hence the importance of a research project that set out to replace part of the animal fat in beef burgers with vegetable fat from canola oil and pineapple fiber.

The project was Miriam Selani’s PhD research at the University of São Paulo’s Luiz de Queiroz College of Agriculture (ESALQ-USP) in Piracicaba, Brazil, supervised by Solange Guidolin Canniatti Brazaca, a professor in ESALQ’s Agribusiness, Food & Nutrition Department, and supported by FAPESP. A paper describing the study has been published by the journal Meat Science.

A typical commercial beef burger contains 20%-30% fat by weight, including polyunsaturated and monounsaturated fats, which come from vegetables and are beneficial to human health because they lower the level of bad cholesterol (LDL) in the blood and raise the level of good cholesterol (HDL). However, it also contains saturated and trans fats from animal sources: these are unhealthy because they raise LDL levels and lower HDL levels. Saturated and trans fats can contribute to obesity and increased risk of cardiovascular disease, so they are priority targets for replacement with pineapple fiber and canola oil in “lean” beef burgers.

“We evaluated three sources of fiber for use in low-fat burgers: pineapple, mango and passion fruit bagasse, all byproducts of the juice industry,” Selani said. They eventually chose pineapple for its higher fiber content, which was expected to result in a lean burger with better texture and sensory quality. The beef used was chuck bought in from a local butcher.

The experiment involved cooking five different burgers on an electric hotplate: a conventional beef burger with 20% fat (250 calories per 100 g), a leaner burger with only 10% fat and no added fat substitutes (212 calories), another burger with 10% fat plus 1.5% pineapple byproduct (193 calories), a third burger with 10% fat plus 5% canola (217 calories), and a fourth burger with 10% fat plus 1.5% pineapple byproduct and 5% canola (209 calories). The burgers were well done in all cases.

The two burgers containing pineapple fiber, which retains water, lost less weight and kept more liquid during cooking than the conventional burger or the lean burger with only 5% canola. “As a result, the lean burgers with pineapple fiber were as succulent as the conventional burger with higher fat content,” Selani said.

Another interesting finding was the difference in size after cooking. The conventional burger shrank considerably, while the size of the burgers containing pineapple fiber did not decrease very much. A burger that maintains its size and shape after cooking has greater visual appeal for consumers.

Trained food tasters

A texturometer was used to analyze the texture of the burgers. “There were alterations in all treatments, but the burger with pineapple and canola was less different from the conventional product than the others,” Selani said.

Finally, eight trained food tasters helped with sensory analysis of the lean burger, appraising attributes such as color, flavor, odor and tenderness, as well as succulence, meaning the amount of liquid released at the start of mastication. The tasters found the burger with pineapple and canola to be similar to the conventional product in all the attributes appraised.

The study showed that a lean beef burger containing pineapple fiber and canola can be a viable substitute for the commercial “fatty” product. Its advantages are lower unhealthy fat content, fewer calories, and enhanced sensory quality due to the lower fat content.

Several stages still have to be completed before a lean burger is ready to be offered to the food industry. “Other tests are required, including shelf life,” Brazaca said. “The food industry is interested in novel ways of cutting the amount of saturated fat and sodium in its products. Other goals are increasing fiber content and developing healthier products generally. Manufacturers also want to reduce waste, which is costly to dispose of.”

The article “Effect of pineapple byproduct and canola oil as fat replacers on physicochemical and sensory quality of low-fat beef burger”, published in Meat Science, can be found at www.sciencedirect.com/science/article/pii/S0309174015301157.