Looking for a good way to reduce bacterial growth in refrigerated colostrum? Then you might want to try potassium sorbate, a common food preservative.

Research published in the July 2005 Journal of Dairy Science shows that bacteria counts in refrigerated colostrum were much lower after 96 hours when preserved with potassium sorbate compared to untreated colostrum.

Researchers at the University of Minnesota examined the total plate count and total coliform count of four treatment groups: 1) untreated, refrigerated colostrum, 2) untreated colostrum stored at ambient temperature, 3) refrigerated colostrum treated with potassium sorbate and 4) treated colostrum stored at ambient temperature

Here are some of the highlights from the study:

  • Bacteria counts — both total plate count and total coliform count — in the preserved, refrigerated colostrum declined by 24 hours and stayed low during the 96-hour study period.
  • Total plate count was lower in the preserved, refrigerated colostrum than in any of the other treatment groups at 24, 48 and 96 hours of storage.
  • After 96 hours, total plate count averaged 3,548 colony-forming units (cfu) per milliliter for preserved, refrigerated colostrum versus 1,479,108 cfu per mL for untreated, refrigerated colostrum.
  • After 96 hours, total coliform count averaged 2,455 cfu per mL for preserved, refrigerated colostrum versus 812,831 cfu per mL for untreated, refrigerated colostrum.

The researchers say more studies are needed to analyze the cost-benefit of using potassium sorbate in colostrum. During the study, they mixed a 50-percent potassium sorbate solution with colostrum immediately after harvest to create a 0.5-percent final solution, says Sandra Godden, lead investigator and veterinarian at the University of Minnesota. Cost was about 50 cents per calf.

July 2005 Journal of Dairy Science