D-Tagatose is a natural low-calorie sweetener, structurally similar to allose, and is a “diastereomer” of fructose. Tagatose belongs to the category of “rare sugars” and is found in trace amounts in nature, such as in fruits, cocoa, and dairy products.
Possessing Nearly Perfect Sucrose Sweetness
Tagatose’s sweetness is similar to sucrose, with a sweetness level of 92% of sucrose. It has virtually no off-flavors or aftertaste, and it produces about one-third of the calories of sucrose, with an energy value of 1.5 kcal/g. Moreover, Tagatose undergoes the Maillard reaction easily, caramelizing at lower temperatures, making it suitable for applications in dairy products, beverages, cereal products, candies, dried fruits, and other food sectors.
Approved for years, yet not widely adopted
Unlike allose, D-Tagatose was approved as a new food ingredient by the National Health Commission as early as 2014 for use in foods other than infant products, with no daily intake requirements. Additionally, in 2003, Tagatose received Generally Recognized as Safe (GRAS) certification from the U.S. FDA and was approved as a novel food ingredient by the European Union in 2006. However, despite these approvals over the years, its widespread adoption has been hindered due to the complex production process and high commercialization costs of Tagatose.
The traditional manufacturing method involves multiple enzyme-catalyzed reactions to convert lactose into Tagatose. However, this process can only convert about 30% of lactose, and the cost of separating Tagatose is high, resulting in a high retail price. According to data from the Dutch industry consulting firm FutureBridge, in 2020, the retail price of Tagatose was $26 per kilogram, while sucrose’s retail price was only 50 cents per kilogram. In addition, Linlu Biotechnology (Danjiangkou) Co., Ltd. stated that the current retail price of Tagatose is $250,000 per ton, and the company’s annual production is 3000-4000 tons, mainly for export.
In today’s rapidly growing sugar substitute market, Tagatose has been constrained by technological barriers, not only in China but also globally.
Whoever can lower the price will dominate the market
Persistence Market Research is confident about the future demand for rare sugars, predicting a 4.7% growth in the global Tagatose market from 2019 to 2027. Many startups are reconsidering and evaluating the Tagatose production process to make it easier to enter the market. In 2020, FutureBridge conducted a three-year review of sugar reduction development and identified Tagatose as a more competitively priced innovative ingredient.
So, whoever can lower the price will dominate the market. Currently, there are three main ways globally to expand Tagatose production capacity.
Expanding Enzyme-Catalyzed Conversion
The U.S. startup company Bonumose is committed to making Tagatose more affordable. Headquartered in Virginia, the company has developed a simultaneous enzyme-catalyzed conversion process claimed to be more efficient than traditional methods. Bonumose CEO Ed Rogers stated that they use multiple enzymes to simultaneously convert raw materials into a high yield of Tagatose. Starting from starch, they employ enzyme-catalyzed processes to produce Tagatose on a large scale, with a final yield of up to 90%. The raw materials they use are also inexpensive, such as leftover potato starch from the production of french fries or residual starch from pea protein isolation.
Bonumose secured a Series B funding round led by Hershey and sugar giant ASR Group to support the commercial production of Allose and Tagatose in 2022. The company plans to reduce the production cost of Tagatose to below $2 per kilogram.
In January of this year, ASR Group and Bonumose announced that Tagatose production had commenced at Bonumose’s new commercial production facility and advanced research laboratory. Starting from mid-February, ASR Group would provide initial shipments and samples of Tagatose.
Synthetic Biology
Synthetic biology technology based on yeast fermentation is another emerging method for potentially large-scale Tagatose production.
Researchers at the University of Illinois Urbana-Champaign designed a yeast strain through two genetic modifications to produce Tagatose from lactose. They first removed a gene, blocking the yeast from using lactose as a cell fuel in lactose metabolism. Then, they added two genes that convert lactose into Tagatose. The genetically engineered yeast solution contained 90% Tagatose, significantly higher than the traditional 30% yield. Additionally, the yeast reactor’s operational scale is much larger than enzyme-based reactors, enabling effective large-scale production of Tagatose.
Moreover, their method can utilize lactose in acidic whey to produce Tagatose. Whey is a significant byproduct in the manufacturing process of Greek yogurt. In addition to maximizing the value of the substrate, the researchers simplified product separation and purification, overall reducing production costs.
Utilizing Bacteria as Microbial Reactors
Researchers at Tufts University have proposed an innovative method using bacteria as miniature microbial reactors to produce Tagatose. This approach can increase the yield to 85%.
The preferred enzyme for manufacturing Tagatose from lactose is L-Arabinose Isomerase (LAI). However, lactose is not the primary target for LAI, resulting in low rates and yields in the reaction with lactose. LAI itself is not very stable, with a conversion rate of 39% at 37°C and 16% at 50°C before its degradation.
Researchers found that it is possible to produce a large amount of LAI enzyme using Lactobacillus plantarum and maintain its stability within the bacterial cell wall. When LAI is expressed in Lactobacillus plantarum, it continuously converts lactose into Tagatose. At 37°C, the conversion rate of lactose can be increased to 47%, and at 50°C, the conversion rate further rises to 83%.
However, transporting the initial component, lactose, into the cell is a challenge. To address this issue, researchers treated the cells with a very low concentration of detergent—just enough to cause the bacterial cell wall to leak. This allows lactose to enter the cell and release Tagatose from the cell, enabling the enzyme to convert lactose into Tagatose at a faster rate.
Diverse Applications, a Promising Future for Tagatose
As a functional monosaccharide, Tagatose has numerous advantages in energy metabolism, blood sugar reduction, improvement of gut microbiota, and cavity prevention. As a natural sweetener, Tagatose has a wide range of applications in the food industry.
Beverages
In beverages, Tagatose acts synergistically with other intense sweeteners (such as saccharin, steviol glycosides, aspartame, etc.) to eliminate metallic, bitter, and astringent aftertastes produced by these sweeteners, improving the taste of the beverage. As early as 2003, PepsiCo introduced a beverage called Slurpee that contained Tagatose. This marked the first commercial application of Tagatose, and the drink was sold at 7-11 stores. The Tagatose added by PepsiCo was supplied by Arla Foods.
Dairy Products:
As a low-calorie sweetener, a small amount of Tagatose can enhance the taste of dairy products. Additionally, it can be used in yogurt to increase the probiotic count while providing sweetness, thereby enhancing the nutritional value of yogurt.
Baked Goods:
The low-temperature caramelization characteristics of Tagatose make it easier than sucrose to achieve the desired color and a more aromatic flavor in baked goods. Furthermore, due to its low viscosity and easy crystallization, Tagatose can also be used in frosting.
Dambert Tagatesse introduced a gluten-free gingerbread cookie, incorporating Tagatose. This product, which is lactose-free and low in carbohydrates, is suitable for individuals with lactose intolerance and complies with ketogenic dietary requirements.
Confectionery & Chocolate:
Tagatose can be used as the sole sweetener in chocolate without requiring significant process changes, as its viscosity and heat absorption properties are similar to sucrose. However, due to its high cost and retail price, products using Tagatose are currently limited in the market.
In Conclusion
It’s important to note that the FDA classifies Tagatose as an added sugar. Bonumose had previously applied to the FDA to exempt Tagatose from added sugars, attempting to attract food and beverage manufacturers. The company argued that their simplified method of producing Tagatose using plant-based starch and enzymes challenges the fundamental principles behind the use of sweeteners and the added sugar label. Additionally, according to Bonumose’s research, Tagatose not only does not increase the risk of chronic diseases but also has positive health impacts.
Although the FDA agreed to Bonumose’s health studies, they pointed out that Tagatose has a calorie content that is too high (compared to Allulose) to be exempt from the label. Therefore, the FDA ultimately rejected Bonumose’s application.
References
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https://now.tufts.edu/2019/11/21/bacteria-help-make-low-calorie-sugar
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Wang, J. (2018). Production of the Sweetener D-Tagatose and Its Application in Foods.
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Tagatose to be classified as an added sugar when used in foods, US Food regulator rules.
