>Moisture/Protein Ratios
Moisture/protein ratios-MPR-are commonly used in the U.S. to classify dried sausages and other meat products. These ratios express the percent moisture divided by the percent protein. Dried meat MPR values vary from 3.7:1.0 for Thuringer to as low as low as 0.75:1.0 for beef jerky. These MPR values are currently FSIS labeling standards and are historical in nature, representing average of a market basket survey of representative products exhibited at the time of initial classification for labeling. Although the MPR values do indicate the degree of product drying, they are not necessarily indicative of microbial safety or stability, as is the case with aw values. Nevertheless, FSIS, in its Food Standards and Labeling Policy Book, identifies criteria for a shelf-stable product based on MPR. Shelf-stable dry sausage must have an MPR ≤ 1.9:1 and semi-dry sausage must have an MPR ≤3.1:1 with a pH ≤5.0, or be commercially sterilized (unless another MPR is specified for a product).