Comparison of Bacterial Swab Samples Given Different Storage Treatments ¹

Area of Science:

• Food microbiology
• Meat science
• Microbial sampling techniques

Background:

• Microbial contamination of beef is a significant food safety concern.
• Effective sampling methods are crucial for assessing microbial load on meat surfaces.
• Understanding the impact of storage conditions on microbial viability is essential for accurate assessment.

Purpose of the Study:

• To compare the efficacy of phosphate buffer and peptone broth as diluents for beef swab samples.
• To evaluate the effect of refrigerated storage time on the recovery of microorganisms from swab samples.
• To determine optimal conditions for preserving microbial viability in swab samples from beef.

Main Methods:

• Six paired sides of U.S. Good beef were swabbed for microbial analysis.
• Beef sides were subjected to different temperature storage regimens (25°C then 1°C, or continuous 1°C).
• Swab samples were stored at 5°C for varying durations (1-120 hours) before incubation.

Main Results:

• No significant difference (P>.05) was observed between phosphate buffer and peptone broth as diluents.
• Refrigerated storage (1°C) of swab samples led to reduced microorganism recovery at 24, 48, and 72 hours.
• Elevated temperature storage (25°C) followed by refrigeration impacted microbial recovery.

Conclusions:

• Both phosphate buffer and peptone broth are effective diluents for beef swab sampling.
• Refrigerated storage of swab samples significantly impacts microbial recovery, necessitating prompt analysis.
• Optimizing sample handling and storage is critical for accurate microbial assessment in beef safety studies.