In recent months, it has come to our attention that there has been an increase in quality problems caused by Heterofermentative lactic bacteria that are not from starter cultures. These bacteria have been found growing on biofilms in the pasteurizer regen section of milk HTST’s, in some silage inoculants, in dairy powders and liquids used to fortify milk for cheesemaking, and on individual farms with certain cleaning issues. Once these are in the milk, they can’t be removed by pasteurization and will carry through into the cheese and whey powder by-products.

The Center for Dairy Research (CDR) in Madison has seen an increase in quality defects in cheese including off flavors such as “sour” gas formation in retail packages of cheese and cracking defects in blocks of cheese. Many companies are starting to include specifications for low spore count non-fat powders, liquid condensed skim and UF milk products, and also whey powders used in many other foods.