Chicken – Boiling lentils in chicken stock

Skimming is for aesthetic purposes.

The scum is denatured protein, mostly comprising the same proteins that make up egg whites. It is harmless and flavorless, but visually unappealing. Eventually, the foam will break up into microscopic particles and disperse into your stock, leaving it grayish and cloudy. The more vigorously your stock bubbles, the faster this process will occur.

If the grayness or cloudiness bothers you but skimming is not an option for some reason, you can always remove the micro-particulates later through the clarification process used to make consomme.

That's a good question, and I have no direct experience in using calcium chloride, however looking at the ingredients for many canned lentil products shows calcium chloride being a very common ingredient, so I would suspect it may work. It's got a very salty flavor though, so don't go overboard.

As a counterpoint adding salt to lentils during cooking is discouraged as it makes them tough, it's quite likely calcium chloride will have the same effect.

If you do try it please post your experience, I'd really like to hear how it works out.