There are a number of different flavours of, say, yogurts, and one of them is plain, without any added flavours besides what is needed to make the yogurt. In English this flavour seems to be often called "natural", the Finnish expression translates to "unflavoured", and there are also suitable words like "plain".
What would be a good Latin adjective to describe an unflavoured variety of a product like yogurt? I would prefer an adjective to a prepositional phrase like "without added flavours". I am not sure what would be an idiomatic approach here.