Overview

Food Classification

Food Category II

30 individual 25 g analytical units or 2 composite units of 375 g if applicable.

Sampling

This is different for Salmonella vs. aerobic bacteria.

Salmonella

Collect Sample Units

Skipping because there is no transfer to a lab.

Sample analytical units randomly from the plants.

Collect Analytical Units

In most cases, two composite units of 375 g each is acceptable.

Individual leaves should be selected from a random selection of plants.

If there's not enough produce, a complete and partial composite unit should be selected.

If there's still not enough produce, sample a partial composite unit, though this is risky.

All composites, partial or complete, should be preenriched at a 1:9 sample-to-broth ratio.

Refrigerate perishable samples and samples supporting microbial growth.

Aerobic Bacteria

Collect Sample Units

Skipping because there is no transfer to a lab.

Sample analytical units randomly from the plants.

Collect Analytical Units

Analyze samples as indicated in current compliance programs.

Analysis

Storage

Refrigerate unfrozen perishable samples at 0-4°C not longer than 36 h.

Thawing

Not applicable.

Mixing

"Use analytical unit size and diluent volume recommended for appropriate Bacteriological Analytical Manual method being used."

Use a 50 g analytical unit of liquid or dry food to determine aerobic plate count value and most probable number of coliforms.

Other analytical unit sizes (e.g., 25 g for Salmonella) may be recommended, depending on specific analysis to be performed.

Weighing

Tare high-speed blender jar; then aseptically and accurately (± 0.1 g) weigh unthawed food (if frozen) into jar.

If entire sample weighs less than the required amount, weigh portion equivalent to one-half of sample and adjust amount of diluent or broth accordingly.

Total volume in blender must completely cover blades.

Blending & Diluting

Add 450 ml Butterfield's phosphate-buffered dilution water to blender jar containing 50 g analytical unit and blend 2 min.

• This results in a dilution of 10-1.

Make dilutions of original homogenate promptly, using pipets that deliver required volume accurately.

Do not deliver less than 10% of total volume of pipet. For example, do not use pipet with capacity greater than 10 ml to deliver 1 ml volumes; for delivering 0.1 ml volumes, do not use pipet with capacity greater than 1 ml.

Prepare all decimal dilutions with 90 ml of sterile diluent plus 10 ml of previous dilution, unless otherwise specified.

Shake all dilutions vigorously 25 times in 30 cm (1 ft) arc in 7 s.

Not more than 15 min should elapse from the time sample is blended until all dilutions are in appropriate media.