Stability of Aflatoxin M1 During Manufacture and Storage of a Butter-like Spread, Non-fat Dried Milk and Dried Buttermilk.

Butter-like spread, non-fat dried milk and dried buttermilk were prepared from cream, skim milk and buttermilk that were naturally contaminated with aflatoxin M1 (AFM1). Four batches of butter-like spread were prepared from pasteurized cream in a home-style chum. Cream, buttermilk, spread and water from two rinses were monitored for weight and AFM1 content. Most of the AFM1 appeared in buttermilk or water from the first rinse. Butter-like spread and water from the second rinse had only small quantities of AFM1. During refrigerated storage for 1 month and frozen storage for up to 2 months, the AFM1 content was variable but toxin remained in the butter-like spread. Variability probably resulted from the analytical procedure rather than from actual changes in content of AFM1. Four batches of skim milk and three of buttermilk were freeze-dried and then stored at 22°C for up to 4 months. Both non-fat dried milk and buttermilk were reconstituted with water and were then extracted to recover AFM1. The AFM1 content remained stable in both products through drying and 4 months of storage.