My Tempeh looks strange. How do I know it's safe to eat?

Since tempeh is a naturally cultured soy product, color fluctuations are actually perfectly normal. Black spots on your tempeh (and the white stuff in-between) are normal and edible; tempeh is inoculated with Rhizophus oligosprorus, a species of mold used to ferment and bind the soybeans together. Think of it like yogurt, beer, or wine - all are fermented products completely safe to eat and drink.

If you’d like some more information, check out this link.