White film on beef jerky occurs occasionally and can be of concern to customers. This was originally prepared by Dr. Jimmy T. Keeton in response to questions about this condition.
Possible causes of white film on beef jerky include:
Mold – The white film could be mold on the surface if the product is packaged where oxygen can get to the surface (i.e., packaged in a jar, or non-vacuumed bulk pack), not vacuum packaged, nor backflushed with nitrogen. Mold requires oxygen to grow and will not grow if oxygen is excluded from the product.
Salts or sugars – If too much salt or sugar is used in the brine/marinade formula, then when the product is dried, these ingredients concentrate and at a critical moisture level crystalize on the surface of the product. Brine formulations yield about 9 to 20% ingredients in the dried jerky product. Those products that have above 10% ingredients tend to have more problems with film formation. Usually, this is caused by the extra sugar that is added, but not always.
Tyrosine crystals – Tyrosine, an amino acid, may be the problem. Just as tyrosine crystals form in cheese as it is dried, they can form on the surface of meat also. Usually this occurs more on the sliced surfaces of country-style hams and a solid white film that looks like slime or mold, but is actually tyrosine. I have no suggestions for solving this problem.
Sodium nitrite – Some processors have reported that sodium nitrite percipitates on the surface of jerky if “hard” water with excessive amounts of iron is used to formulate brine. This would appear as a white film and would be rare, but possible.
Jerky too dry – If the jerky is dried excessively, concentrating the ingredients can sometimes cause crystalization of the ingredients and a white film on the surface. Back off on the drying cycle to see if this helps.