system
Given the following post, respond as if you're commenting on Reddit:
human
What causes powder mixed into drinks (such as protein powder or Nesquick) to clump together in a globulous ball that is wet on the outside, but still dry and powdery on the inside?

I'm sitting here drinking my protein shake and although most of it has dissolved into warm water, there are large clumps of powder that somehow remain dry on the inside. As I drink, I find that I sometimes have to chew the powder, and it's dry and disgusting. To clarify, this is MET-Rx 100% Ultramyosin Whey protein powder. I've also noticed this with Nesquick; could it have something to do with chocolate? 

Thanks scientists! Laypeople, could you report in if you notice this phenomenon in other drinks with water and powder?
gpt
Proteins (especially mixtures of proteins) are often amphiphillic, meaning part of the molecule has an affinity for water (hydrophillic), and part for fat/oils (lipophillic or hydrophobic).  This means that they tend to orient themselves into structures known as micelles where the molecules all orient themselves to isolate their lipophillic ends away from the water, which can result in spherical, tubular, or sheetlike structures.  While micelles are a microscopic phenomena, a similar thing is what causes the clumps - along the protein powder-water interface there will be bi-layer sheet type structures where the hydrophillic parts of the molecules are facing the water, 'protecting' the rest of the clump for getting wet.  Additionally, since you are using warm water, the proteins can become entangled, so it makes it very difficult to break up the clump since the outer surface has essentially polymerized.

As others have said, the solution is to wet each of the solid particles individually first before dispersing them (eg, mix them in a small amount of water to form a paste), this will ensure that they disperse well.  Cold water will also help, since it will keep the proteins tightly coiled up and less likely to get entangled with each other.