Seafood Safety

1. Seafood Safety Joong-Han Shin, Barbara Rasco & Dong-Hyun Kang Department of Food Science and Human Nutrition Washington State University Tyler Greeson, ClearSprings Foods

2. Current Hot Issues • Mercury in fish (California Proposition 65 case) • Environmental contaminants and pollution • GM foods (they’re back…) • Food additives (colorants) • Microbial contamination

3. Risks of microbial contamination in aquatic food products • Raw molluscan shellfish – Vibrio spp., bacterial toxins, fecal pathogens • Raw fish – Parasites and various bacteria (killed by heating)

4. Risks of microbial contamination in aquatic food products • Ready-to-eat and smoked fish - • Listeria monocytogenes • Vibrio spp. • Clostridium botulinum (regulatory issue) • Mesophiles from humans or warm blooded animals (Salmonella spp., E. coli)

5. Listeria monocytogenes • Gram-positive bacterium, motile by means of flagella • Isolated from soil, sediments, estuaries, and other environmental sources • Grows at temperatures as low as –0.1°C and hıgh salt (up to 10%)

6. Listeriosis • Asymptomatic or mild flu-like symptoms • Immunocompromised:septicemia or meningoencephalitis • Infants: spontaneous miscarriage, stillbirth, development of meningitis within a few days of birth • Fatality: elderly and children if untreated

7. Listeria in foods • The vast majority of cases are sporadic, making epidemiological links to food very difficult (CDC, 1987)

8. Projected number of Listeria outbreaks • 2,500 cases per year. Possibly 500 deaths • Overall prevalence in RTE food supply is 1.8% (31,705 tested) • Highest levels >102/g in lunch meat and smoked fish

9. Listeria in seafoods • The incidence of L. monocytogenes in cold-smoked or cured salmon ranges from 6 to 50% • FDA/USDA risk assessments estimates are that 15% of all smoked fish is contaminated with L. monocytogenes • 17% of vacuum-packed crawfish tails and 25.8% of lightly pickled fish are contamınated

10. Listeria contamination patterns • Rate of contamınatıon of raw finfish for smoking range from 2 to 30% • 12% of raw shellfish and 8% of raw crab • 28-44% of environmental samples (floor, surfaces, drains) from smoked fish plants • 4.5% of meat processing plant refrigerators • 3.1% retail refrigerators

11. Temperature abuse makes Listeria problem worse • 26% of refrigerators average >8C (France) • 33.3% of refrigerators > 7ºC (UK) • 55% of domestic and 32% of retail store refrigerators > 9ºC (Greece) • Refrigerators of 70% elderly consumers >6ºC (UK)

12. Regulation of Listeria • zero tolerance for L. monocytogenes in cooked and ready-to-eat food by USDA-FSIS and FDA • Both agencies at theır dıscretıon, can hold or detain products at the food processing plant, request a voluntary recall or seize products. Numerous seafood producers have ınıtıated recalls, even ın cases where there have been no ıllnesses.

13. Recent recalls of trout products • Food recall involves: cost of product, cost to cover, lost markets, and damage of company’s reputation. • Direct costs of recall are ~10% of total

15. Seafood packaging • FDA concern with safety of vacuum packaging • Modified atmosphere packaging (MAP) • MAP alter the gaseous environment in the immediate vicinity of the product • Slows microbial growth and enzyme activity • MAP may inhibit the growth of L. monocytogenes in fish at refrigerated temperatures

16. Methods • L. monocytogenes strains ATCC 19114, 7644, 19113 • Raw and smoked rainbow trout (Oncorhynchus mykiss) • Enumeration on modified Oxford medium and plate count agar

17. Methods • Packaging method - air-packaging - vacuum packaging - nitrogen gas flushing - nitrogen flushing & vacuum packaging • Storage at 3°C or 7°C (mild thermal abuse) • Sensory evaluation

18. Effect of MAP on growth of L. monocytogenes in fresh trout (3°C)

19. Effect of MAP on growth of L. monocytogenes in fresh trout (7°C)

20. Effect of MAP on growth of endogenous microflora in fresh trout (3°C)

21. Effect of MAP on growth of endogenous microflora in fresh trout (7°C)

22. Aroma changes in fresh trout aroma during storage (3 & 7°C)

23. Effect of MAP on growth of L. monocytogenes in smoked trout (3°C)

24. Effect of MAP on growth of L. monocytogenes in smoked trout (7°C)

25. Effect of MAP on growth of endogenous microflora in smoked trout (3°C)

26. Effect of MAP on growth of endogenous microflora in smoked trout (7°C)

27. Aroma changes in smoked trout during storage (3 & 7°C)

28. Conclusions • 3  C: L. monocytogenes in fresh and smoked trout remained at initial levels during storage. MAP had no effect. • 7  C: L. monocytogenes increased up to 2 log in fresh trout, 4 log in smoked trout during storage. MAP had no effect. • MAP did not prevent the growth of endogenous microflora

29. Conclusions • Fresh trout: aroma of Nitrogen & Nitrogen-Vacuum packaging remained acceptable for 20 days. Product would be spoiled before Listeria levels would become high. • Smoked trout:acceptable aroma for 30 days.

30. Conclusions • Smoked trout with moderately high initial levels of Listeria (log 2) could be unsafe in 10-15 days at mild thermal abuse (7oC) and not appear to be spoiled.