Preparation and stability of milk somatic cell reference materials

Area of Science:

• Dairy Science
• Analytical Chemistry
• Biotechnology

Background:

• Accurate milk somatic cell count (SCC) is crucial for dairy herd health and milk quality assessment.
• Existing calibration sets for electronic somatic cell count (ESCC) methods may have limitations in range and uniformity.
• Development of reliable reference materials is essential for validating SCC measurement techniques.

Purpose of the Study:

• To develop a novel method for producing milk SCC reference materials using gravity separation.
• To evaluate the stability of these reference materials under refrigerated (4°C) storage.
• To assess the impact of freeze-thaw cycles on the integrity of skim and whole milk SCC reference materials.

Main Methods:

• Whole raw milk was pasteurized and subjected to gravity separation at 4°C for 22 hours to concentrate somatic cells.
• Skim milk was produced via centrifugation and further processed using gravity separation.
• Stock solutions of varying SCC levels in skim and whole milk matrices were prepared and preserved with bronopol.

Main Results:

• Gravity separation proved effective in isolating and concentrating somatic cells for reference material production.
• Refrigerated (4°C) milk SCC reference materials demonstrated stability for at least a two-week period.
• Frozen and thawed reference materials indicated potential for extended shelf-life, though whole milk showed a slight decrease in ESCC post-thawing.

Conclusions:

• Gravity separation offers a viable method for creating a diverse range of milk SCC reference materials.
• Liquid SCC reference materials are suitable for use for up to two weeks when stored at 4°C.
• Further research is required to establish optimal conditions for long-term frozen storage of SCC reference materials.