Modified Yogurt Cultures Reduce Added Sugar And Increase Sweetness Naturally, But Is It Necessarily Healthier?
In the 21st century, when there are more overweight than underweight people in the world, many are trying to find ways to indulge in their favorite foods without packing on extra pounds. It’s well documented that sugar is a significant contributor to obesity, and the extra sugar added to foods is the worst of the worst. A team from Danish food ingredients company Chr. Hansen A/S has come up with a new sweetened yogurt they say can help solve this problem. They have manipulated the metabolic properties of yogurt-producing bacteria so the product comes out naturally sweeter, eliminating the need for some added sugar. However, the new product could actually be less healthy than the sweetened yogurts currently on supermarket shelves.
The study’s corresponding author, Dr. Eric Johansen, said the researchers’ trick was to engineer the bacteria not to consume glucose, a particularly sweet product of yogurt’s fermentation. Denmark, along with many other countries, defines yogurt as a product containing live cultures of Streptococcus thermophiles and the bulgaricus subspecies of Lactobacillus delbrueckii. When grown in milk, the two strains normally break down the disaccharide lactose into two monosaccharide components — glucose and galactose. Then, they eat the glucose and make more galactose. The microbial tweak eliminates lactose, so those intolerant to the milk sugar can eat the yogurt.
“We wanted to change them so that they would eat the galactose and spit out the glucose,” said Johansen, who is an associate vice president at the company, in a press release. “That required a number of changes in metabolism.”
First, the team grew the yogurt bacteria in a medium that contained the glucose analog 2-deoxyglucose, which is toxic to cells. By doing so, they made sure any surviving mutants would lack the ability to metabolize glucose. They then subjected the mutants to a second solution containing a higher level of 2-decoxyglucose, resulting in bacteria entirely lacking a glucose transport mechanism. They detailed the process in a paper published in the journal Applied and Environmental Microbiology.
The yogurt the newly modified bacteria make has almost no lactose, very little galactose, and is high in glucose. This natural sugar makes it sweet, and when the yogurt was presented to a taste panel with varying amounts of sucrose added, the team found that they could maintain the panel’s desired sweetness with 20 percent less added sucrose than usual.
“The sugar content of food is of increasing concern to health-conscious consumers, and dairy products are often criticized due to the presence of added sugar — sucrose,” Johansen said. “We reasoned that since glucose is considerably sweeter than lactose or galactose, bacteria that release galactose into the product could allow for a reduction of added sugar while maintaining the desired level of sweetness in the yogurt.”
Not everyone is convinced the new yogurt will help people eat more health consciously, however. Dr. Barry Sears, biochemist and president of the Inflammation Research Foundation, does not believe the yogurt is better for the body’s metabolism.
“This new product will make people more hungry than eating traditional yogurt because of the higher glucose levels,” he told Medical Daily via email. “Sucrose enters the bloodstream at a lower rate than glucose, so reducing sucrose while increasing glucose is self-defeating.”
Because glucose has a higher glycemic index than sucrose, he said, it would cause blood sugar to rise and fall more rapidly than normal yogurt, causing hunger.
“This new yogurt product is a glorified candy bar,” he said.
Researchers generally agree that fructose, including the high-fructose corn syrup, is the worst of the sugars. Glucose is a simple sugar that our bodies can use most efficiently, but as Dr. Sears outlined, it is not without its downfalls.
The researchers did not mention plans to begin producing their modified yogurt for consumers.
Source: Sorensen K, Curic-Bawden M, Junge M, Janzen T, Johansen E. Enhancing the Sweetness of Yoghurt Through Metabolic Remodeling of Carbohydrate Metabolism in Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus. Applied and Environmental Microbiology. 2016.