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Researchers at the University of Illinois have used a yeast-based approach to produce tagatose, a low calorie natural sweetener, likely to increase its commercial use.
The researchers, led by Yong-Su Jin, a professor of food science and human nutrition, have developed a yeast strain capable of metabolizing lactose to tagatose in amounts much larger than enzymatic manufacturing techniques. traditional. This means that it could be a cheaper alternative to sugar.
"Tagatose is a sweetener with almost identical tastes and textures of sucrose or table sugar, but tagatose has far fewer calories than sucrose – around 40% sucrose," Jin said. "In addition, it does not increase blood sugar levels as much as sucrose or fructose." The glycemic index of tagatose is equal to 3, which is well below that of sucrose 68 and 24 fructose. as such, tagatosis is less risky for developing type 2 diabetes and other diseases caused by a rapid and repeated rise in blood sugar. "
However, he stated that high manufacturing costs had hindered its commercial use. Although it is naturally present in fruits and dairy products, its concentrations are too low to effectively isolate tagatose.
Traditionally, a multistep enzymatic process is used to transform galactose – a component of lactose – into tagatose, but this method of manufacture is extremely inefficient. Only 30% of galactose is converted to tagatose, which forces manufacturers to use a costly process to remove tagatose from the galactose mixture.
The Jin team has managed to increase this yield to 90% by using a yeast-based process. They developed a yeast strain producing tagatose from lactose by making two genetic modifications: they released a gene that allowed the yeast to use galactose as a cellular fuel during lactose metabolism, and added two genes that convert galactose into tagatose.
Thus, when the yeast is fed with lactose, its own metabolism allows it to produce a solution containing 90% of tagatose. Yeast reactors also operate at scales much larger than enzyme-based ones, which could allow for an efficient mbad-production of the sweetener, according to Jin.
He added that the yeast-based process indirectly uses whey, which gives Greek cheese and yogurt manufacturers a way to get rid of the by-product.
"We hope that our process can be used to solve the problem of surplus whey.Our approach based on yeast fermentation allows a higher product ratio and the direct use of inexpensive dairy waste, we we expect a significant reduction in the production cost of tagatose. "
The team plans to use their yeast-based approach to make other products from lactose.
The research was published in the journal Nature Communications.
