New knowledge on milk composition and quality is of essential importance to consumers as well as the industry. There are therefore considerable research efforts in milk worldwide. One of the major topics concerns milk’s content of different proteins and their importance to human health. Basically, milk consists of two protein types – whey and casein. Casein can be further divided into four categories. One of these, beta casein, attracts particular attention. Several beta casein types exist and A1 and A2 are the most common.