Those little plastic containers of coffee cream may not look significant on their own, but when you consider how many of them are used and discarded every day … it adds up to a lot of waste. That's why Martha Wellner, when she was a PhD student at Germany's Martin Luther University Halle-Wittenberg, created milk-and-sugar capsules that dissolve completely when placed in hot liquid.
To make the capsules, a solution of milk and sugar is first placed in a mold. As that liquid cools, some of the sugar moves to the outside edges (along the contours of the mold), where it crystallizes. The milk-sugar solution in the middle remains in a liquid state, encapsulated by the crystalline outer shell.
Once the capsules are removed from the mold and stored at room temperature, the milk in them stays good for at least three weeks.
By tweaking parameters such as the type of sugar used, there are currently both highly-sweetened and lightly-sweetened versions of the capsules. That said, Martin Luther scientists are now working on an unsweetened version, that uses a substance other than sugar to form the shell. Additionally, Wellner points out that the technology could be used to encapsulate other liquids, such as fruit juice concentrate.
Although the university registered a patent for the process back in 2015, it's still waiting on regulatory approval, and is working on scaling the system up to industrial production levels.
A paper on the research was recently published in the journal Chemical Engineering & Technology.