After brewing your morning tea or pouring coffee into your mug, you might not immediately want to toss out the leaves or grounds. So, don’t throw them away just yet. A new study has revealed that these leftovers can offer significant benefits.
A team of researchers from King Faisal University in Saudi Arabia has demonstrated that adding coffee grounds or tea leaves to baked goods can enhance their nutritional value and extend their shelf life. This, they believe, could provide additional health benefits.
The presence of bioactive compounds in these coffee and tea waste products also contributes to the potential antioxidant activity of the final product and inhibits microbial growth during storage.
What Scientists Knew at the Time of the Study
Tea and coffee are the most popular beverages worldwide, providing countless people with daily doses of anti-inflammatory agents, antioxidants, fiber, and even some bioactive compounds beneficial for cognitive and cardiovascular health.
Unfortunately, the way most of us prepare these drinks is quite wasteful. After extraction, about 90 percent of the original tea and coffee material ends up in the trash.
In recent years, scientists have been pondering possible ways to make better use of this waste, as reported by Science Alert.
One recent study found that adding charred coffee grounds to cement makes it 30 percent stronger.
But it’s not just the construction industry that could benefit from these byproducts. Researchers have also suggested using tea and coffee waste to enrich food products.
For instance, in 2020, a group of researchers studied the effects of adding spent coffee grounds to gluten-free cookies. They found that the nutritional value of the cookies increased as a result.
In another study, authors added used green tea to cupcake batter. Experts discovered that flavonoids remained in the tea leaves even after baking in the oven. (It’s worth noting that flavonoids are important plant compounds with potential anti-cancer, antioxidant, anti-inflammatory, and antiviral properties.)
What Scientists Learned
The new research from Saudi Arabian scientists built on the work of their predecessors. During their experiments, the team investigated whether tea or coffee retains antioxidants after boiling and grinding, and whether this material could be used to improve the nutritional value of baked goods and extend their shelf life.
The researchers boiled distilled water and soaked black tea and coffee in it for 10 minutes. Analysis of the dried grounds that formed afterward showed that they still retained a significant percentage of phenolic compounds, including flavonoids.
The tea waste contained about 73 percent of a powerful phenolic antioxidant that doctors recommend for people with high cholesterol, obesity, or heart disease.
The coffee grounds retained nearly 64 percent of chlorogenic acid—a well-known antioxidant that is also recognized for its health benefits.
Antioxidants remained in the final product even after processing the tea and coffee waste in the oven.
According to the researchers, after two weeks of storage, there was no significant microbial growth observed in the baked goods enriched with coffee and tea. This is due to the inhibitory effect of certain antioxidants on bacterial growth.
Thus, the results of the new study proved that used coffee and tea can be an effective natural way to enrich baked goods with additional nutrients and prolong their shelf life. The findings of the study were published in the journal ACS Omega.