Functional beverages based on herbal and tea extracts: evaluation of bioactive phytochemical properties, nutritional value and effects on α-amylase and glucosidase inhibition

In recent years, the beverage aisle has transformed from a simple place to quench thirst into a landscape of functional options designed to do more than just hydrate. Consumers increasingly seek drinks that offer specific health benefits, such as improved focus, better sleep, or support for blood sugar management, often hoping to replace the need for swallowing large, unpleasant pills. This shift relies on the idea that nature provides a complex toolkit of plant compounds—substances like polyphenols found in tea leaves and herbs—that can interact with the human body in beneficial ways. Among the most promising of these interactions is the ability of certain plant extracts to slow down the digestion of carbohydrates. When we eat starch or sugar, our bodies use specific enzymes, acting like molecular scissors, to break these foods down into glucose for energy. If these scissors work too quickly, blood sugar can spike, a problem for many people. The question facing food scientists is whether a drink made from natural ingredients can gently slow these enzymes without sacrificing taste or safety, creating a beverage that is both enjoyable and biologically active.

Researchers at the Lodz University of Technology set out to answer this by crafting a series of functional beverages using clean-label ingredients, meaning they avoided artificial colors, flavors, and sweeteners. Instead of relying on processed additives, the team built their drinks around a base of water, tea, and herbs, sweetening them naturally with fresh apple or orange juice. They created seven distinct recipes, each targeting a different health goal. Some were designed to be calming and aid sleep, blending black tea with lemon balm and chamomile. Others aimed to boost energy and memory, combining green tea, matcha, ginseng, and ginkgo biloba. One variant even included whey protein to add a nutritional boost. To ensure these drinks could be stored safely, the researchers tested two preservation methods: ultrafiltration, which uses a fine filter to remove particles, and pasteurization, which involves heating the liquid to kill bacteria. They then put these beverages through a rigorous battery of tests to measure their nutritional value, their ability to fight oxidative stress, and, most importantly, their power to inhibit the enzymes responsible for breaking down carbohydrates.

The results revealed that these homemade formulations were far more potent than a standard commercial tea drink available in stores. The researchers found that the new beverages were rich in minerals and vitamins, particularly when made with fresh fruit juices, and contained significantly higher levels of beneficial plant compounds than the store-bought alternative. When it came to the specific goal of managing blood sugar, the drinks showed a clear ability to slow down the body's digestion process. The team measured how well the beverages could stop two key enzymes: one that breaks down starch and another that finishes the job by converting sugars into glucose. The drinks were generally more effective at stopping the second enzyme, which is the final step before sugar enters the bloodstream. Among all the recipes tested, a specific calming blend made with black tea, lemon balm, chamomile, and orange juice emerged as the most powerful. This particular drink, labeled as variant C2, was able to inhibit the final sugar-converting enzyme by more than 85 percent and the starch-digesting enzyme by nearly 60 percent. This suggests that a single serving of this drink could significantly slow the absorption of glucose, potentially helping to prevent sharp spikes in blood sugar levels after a meal.

However, the path from a fresh, potent mixture to a shelf-stable product was not without challenges. The researchers discovered that the method used to preserve the drink mattered greatly for its final properties. The process of ultrafiltration, while effective at removing sediment and extending the drink's life in the refrigerator, also stripped away some of the beneficial compounds, reducing the levels of tannins and antioxidants. In contrast, pasteurization, which involves heating the liquid, preserved the tannin content better but caused a significant drop in vitamin levels, particularly vitamin C, which is sensitive to heat. Despite these losses, the drinks remained stable for surprisingly long periods. The calming blend with orange juice remained organoleptically acceptable—meaning it still tasted and smelled good—for up to nine days when stored in a refrigerator after ultrafiltration, far outlasting many of the other variants which began to spoil or sour within a week. The study also noted that the choice of fruit juice influenced the drink's profile; apple juice tended to result in higher levels of polyphenols and a slightly different color compared to orange juice, though both provided natural sweetness without the need for added sugar.

Ultimately, the study demonstrates that it is possible to create a functional beverage that is both sensorially pleasing and biologically active, provided the right combination of ingredients and preservation techniques is chosen. The most successful recipe, the calming tea blend, not only offered the strongest inhibition of the enzymes that regulate blood sugar but also maintained a high level of antioxidant activity and a rich vitamin content. While the researchers caution that these findings are based on laboratory measurements and that further studies are needed to understand how these drinks behave inside the human body, the results are a strong indicator of potential. The work suggests that by carefully selecting natural ingredients like specific teas and herbs, and by choosing a preservation method that balances safety with nutrient retention, it is possible to develop drinks that offer genuine health benefits, such as supporting better sleep or helping to manage blood sugar, without relying on synthetic additives. The study concludes that these natural formulations, particularly those containing apple or orange juice, offer a promising alternative to commercial drinks, providing a way to hydrate the body while delivering a complex mix of minerals, vitamins, and bioactive compounds that work together to support overall health.