Funny, I was just reading about this on
www.bulkmsm.com because I will be switching to the powdered form. I don't know about putting MSM in coffee, but the quote below says it dissolves better in warm water.
Your choice is really between putting a teaspoon of the stuff into your mouth (it tastes pretty bad) and then taking enough water or juice to wash it down -- or putting that teaspoon full into a glass of something. The "something" would normally be warm water, first, because MSM dissolves most quickly in warm water. Once it is dissolved you can then mix in more water, or add any beverage to disguise the taste. Disguising the taste? Tomato juice is the strongest disguiser!! Orange juice, or any juice will help hide the taste of the MSM. None of these juices will adversely affect the results of the MSM.