Staphylococcus aureus Burden in Frozen, Precooked Tuna Loins and Growth Behavior During Typical and "Worst-case"...

Area of Science:

• Food safety
• Microbiology
• Seafood processing

Background:

• The FDA recommends a 3-hour cumulative exposure limit for seafood processing above 70°F to prevent Staphylococcus aureus (SA) and staphylococcal enterotoxin (SE) production.
• This limit is impractical for tuna processing, hindering essential post-thawing activities and lacking tuna-specific evidence.

Purpose of the Study:

• To generate industrial data on SA growth and SE production risk during tuna processing under typical and worst-case conditions.
• To inform the development of an accurate maximum cumulative exposure time for tuna processing facilities.

Main Methods:

• Analysis of 48,933 certificates of analysis (COAs) for SA detection frequency and microbial load.
• Monitoring SA levels during nine production days under typical conditions.
• Challenging the system over three production days with extended holding times (up to 5 hours) at 78.8°F in open and sealed cans.

Main Results:

• SA detection frequency was 2.14%; quantitative analysis highlighted the need for method validation and supplier communication.
• Typical processing showed consistent SA control (<2 log CFU/g increase) between thawing and retort staging.
• Extended holding in open cans significantly increased SA populations, confirming SE production risk.
• Extended holding in sealed cans significantly reduced SA growth.

Conclusions:

• The current 3-hour FDA guidance is insufficient for practical tuna processing.
• Extended holding times in sealed cans do not pose a significant SA growth risk.
• Data supports relaxing the maximum cumulative exposure time beyond the current 3-hour recommendation for tuna processing.