On the compositing of samples for qualitative microbiological testing.

Area of Science:

• Food Microbiology
• Analytical Chemistry
• Regulatory Science

Background:

• Legislative microbiological criteria for foods necessitate increased testing by laboratories.
• Increased testing leads to consideration of sample compositing for efficiency.

Purpose of the Study:

• To summarize statistical and practical aspects of compositing sample units for food compliance testing.
• To evaluate the permissibility of compositing replicate sample units for microbiological criteria assessment.

Main Methods:

• Statistical analysis of compositing versus individual sample testing.
• Consideration of 'fit for purpose' methodology for sensitivity in composite samples.

Main Results:

• No statistical difference exists between testing multiple small units or fewer larger composite units if the method is appropriate.
• Compositing is valid only if the method can detect target organisms in the larger quantity.

Conclusions:

• Sample compositing is a statistically valid approach for food microbiological compliance testing.
• Method validation for sensitivity with composite samples is crucial for accurate results.