Visual Demerit and Microbiological Evaluation of Beef Carcasses: Methodology

Area of Science:

• Food microbiology
• Meat science
• Analytical chemistry

Background:

• Assessing aerobic bacterial populations on beef carcasses is crucial for food safety.
• Existing methods for bacterial enumeration can be labor-intensive and time-consuming.
• Developing repeatable and automated methods is essential for efficient quality control in meat processing.

Purpose of the Study:

• To develop and validate a repeatable, automated method for estimating aerobic bacterial populations on beef carcass surfaces.
• To assess the variability of bacterial counts across different carcasses and sampling sites.
• To investigate the association between visual demerits and bacterial contamination levels.

Main Methods:

• Identification of ten sample cluster sites (CS) based on visual demerits on 200 beef carcasses.
• Collection of excision samples from the centers of identified CS.
• Enumeration of aerobic bacterial populations using most probable number growth units per cm² (MPNGU/cm²) on hydrophobic grid membrane filters (HGMF).
• Automated interpretation of HGMF for bacterial quantification.

Main Results:

• The developed method demonstrated high repeatability, with over 90% of the total variance attributed to between-sample variation.
• Significant variation in bacterial counts was observed between individual carcasses and adjacent sample sites.
• A weak but statistically significant association was found between visual demerit scores and bacterial counts at the sampled sites.

Conclusions:

• The automated HGMF method provides a repeatable and efficient approach for estimating aerobic bacterial populations on beef carcasses.
• Variance component estimates are valuable for optimizing sample size calculations in future carcass evaluation studies.
• Further research can refine this method for routine application in meat inspection and quality assurance programs.