Agri-Mark Whey Protein Concentrate (WPC) and Dairy Product Solids (Whey Permeate) are manufactured at the cooperative's cheese manufacturing plant located in Middlebury, Vermont and sold worldwide. This is the only USDA FOOD grade manufacturing facility of WPC and Whey Permeate east of Wisconsin. With cheese making operations beginning in 1994 and whey processing added in September 2000, the plant's processing equipment incorporates the latest in cheese making and whey processing technology.

All of the milk used at Agri-Mark's three cheese manufacturing facilities is Grade A, the highest USDA quality standard for fluid milk in the USA. The plant processes whey from only the cooperative's cheese plants - it does not process any whey manufactured at plants not owned by Agri-Mark. This ensures most of the condensed whey solids are processed and in dry powder form within 8 hours or less of cheese manufacturing.

The Middlebury facility is approved by USDA, European Union, Kosher and Halal authorities.