Junmai refers to pure rice (??) (non-additive) sake. Additionally, the junmai classification means that the rice used has been polished to at least 70 percent. While it's hard to over-generalize, junmai sake tends to have a rich full body with an intense, slightly acidic flavor. This type of sake can be particularly nice when served warm or at room temperature. Yamahai is a traditional way of making sake where, rather than adding lactic acid to deter microbes and bacteria from spoiling the fermentation, no lactic acid is added and thus the sake is left to ferment naturally.