# Presentation: 201157

## CONTROL OF FOODBORNE PATHOGENS IN MEAT PRODUCTS BY SANITATION, DRYING AND ANTIMICROBIALSJohn N. SofosColorado State UniversityJohn.Sofos@colostate.edu

## SANITIZER INACTIVATION OF ACID-ADAPTED AND NONADAPTED LISTERIA MONOCYTOGENES BIOFILMS

- Objective
- To evaluate the antimicrobial effects of sodium hypochlorite (200 ppm, pH 10.4), pH-adjusted (pH 6.8) sodium hypochlorite (200 ppm), a quaternary ammonium compound (200 ppm), and peroxyacetic acid (150 ppm) on biofilms produced by previously acid-adapted or nonadapted *Listeria monocytogenes* inoculated in fresh beef decontamination washings.

## Stainless steel attached cells; fresh beef washings (15oC, 2 days) inoculated  with Listeria monocytogenes

**2**

- Closed symbols = acid-adapted cells; open symbols = nonadapted cells

- Stainless steel attached cells; fresh beef washings (15oC, 2 days) inoculated  with *Listeria monocytogenes*

## Deattached cells; fresh beef washings (15oC, 2 days) inoculated with Listeria monocytogenes

- Closed symbols = acid-adapted cells; open symbols = nonadapted cells

- Deattached cells; fresh beef washings (15oC, 2 days) inoculated with *Listeria **monocytogenes*

## Conclusions

-  Previous acid adaptation did not affect biofilm formation or inactivation.
-  Intact biofilms were more resistant to inactivation than biofilm cells (deattached) removed into suspension.
-  Peroxyacetic acid was more effective on the attached cells of the natural flora than those of  *L. monocytogenes*.
-  Peroxyacetic acid was relatively less effective on biofilm cells in suspension than on attached biofilm cells when compared with the other sanitizers.
-  Sodium hypochlorite adjusted to pH 6.8 was more effective than when unadjusted (pH 10.4).

## FATE OF LISTERIA MONOCYTOGENES IN FRESH MEAT DECONTAMINATIONFLUIDS AT 4 AND 10oC 

- Objective
- 	To evaluate the potential for survival and growth of acid-adapted, partially acid-adapted or nonadapted *Listeria monocytogenes* in acid or nonacid (water) spray-washings of fresh beef at low temperatures to simulate conditions encountered in the meat industry.

## Behavior of Listeria monocytogenes in meat washings

- Behavior of *Listeria monocytogenes* in meat washings

## Conclusions

- Limited survival of *L. monocytogenes* for at maximum 4 days may be expected in undiluted acidic (lactate or acetate) meat decontamination washings, or mixed with water washings, when the resulting pH is less than 4.0.
- Acid-containing washings with a pH above 4.0 may support survival and potential growth for extended times, while in nonacid (water) washings the pathogen may increase to high numbers.

## FRESH BEEF DECONTAMINATION AND POPULATIONS OF LISTERIA MONOCYTOGENES DURING VACUUM-PACKAGED STORAGE (4oC, 10oC) 

- TREATMENTS
- Control
- Water (pH 6.7, 55C)
- Water (pH 6.7, 75C)
- Lactic acid (2%, pH 2.3, 55C)
- Acetic acid (2%, pH 2.8, 55C)

## Acid-adapted Listeria monocytogenes in vacuum packaged beef Not-treated:    , Water (55°C):   , Water (75°C):   , Lactic acid (55°C):     or Acetic acid (55°C):      

- 2

*a*

*a*

*a*

*a*

*a*

*a*

*a*

*a*

*a*

*a*

*a*

*b*

*b*

*b*

*b*

*b*

*b*

*b*

*b*

*b*

*b*

*b*

*b*

*b*

*b*

- Acid-adapted *Listeria monocytogenes* in vacuum packaged beef Not-treated:    , Water (55°C):   , Water (75°C):   , Lactic acid (55°C):     or Acetic acid (55°C):**      **

## Acid-adapted Listeria monocytogenes in vacuum packaged beef Not-treated:    , Water (55°C):   , Water (75°C):   , Lactic acid (55°C):     or Acetic acid (55°C):      

- 2

*d*

*b*

*b*

*c*

*a*

*d*

*d*

*c*

*a*

*b*

*c*

*c*

*b*

*a*

*a*

*b*

*b*

*a*

*a*

*a*

*c*

*b*

*b*

*a*

*a*

## Conclusions 

- Application of organic acids (acetic or lactic acid) to meat can reduce levels of contamination and then inhibit growth of *L. monocytogenes* during storage at 4 or 10C.
- Although 75C water decreased the initial population of *L. monocytogenes* on meat, growth of the pathogen occurred during storage.
- Prior acid-adaptation of this strain did not enhance growth on meat treated with acid or water.
- This study emphasizes the importance of long-term residual effects of acid and water decontamination treatments and storage temperatures on meat safety.

## EVALUATION OF PROCESSES TO DESTROY ESCHERICHIA COLI O157:H7 AND LISTERIA MONOCYTOGENES IN WHOLE MUSCLE HOME DRIED BEEF JERKY

- Objectives
- 	To determine the survival of inoculated *E. coli* O157:H7 populations during preparation of whole muscle beef jerky with and without marinade and acids.

## Escherichia coli O157:H7

*Escherichia coli* O157:H7
- Beef Jerky

- 2

- 62.5oC

- 62.5oC

- 62.5oC

- 62.5oC

- 68.3oC

- 68.3oC

- Closed symbols = TSA
- Open symbols = SMAC

## Escherichia coli O157:H7

*Escherichia coli* O157:H7
- Beef Jerky

- 2

- 62.5oC

- 62.5oC

- 62.5oC

- 62.5oC

- 68.3oC

- 68.3oC

- Closed symbols = TSA;
- Open symbols = SMAC

## Escherichia coli O157:H7

*Escherichia coli* O157:H7
- Beef Jerky (68.3oC)

- Closed symbols = TSA
- Open symbols = SMAC

- 2

- Water = 94oC, 15 sec

- Marinate/store at 4oC, 24 h

- Season/store at 4oC, 24 h

- Hot brine = 78oC, 90 sec

- Acetic acid (2.5%), 57.5oC 20 sec

## Escherichia coli O157:H7

*Escherichia coli* O157:H7
- Beef Jerky (68.3oC)

## Escherichia coli O157:H7

*Escherichia coli* O157:H7
- Beef Jerky (62.5oC)

## Bacterial counts (TSA+0.1% pyruvate) on jerky (dried at 60.0oC) inoculated with E. coli 0157:H7

- Bacterial counts (TSA+0.1% pyruvate) on jerky (dried at 60.0oC) inoculated with *E. coli* 0157:H7

- 5.0 log reduction

## Survival Of L. monocytogenes on beef jerky—(PALCAM) 

- Survival Of *L. monocytogenes* on beef jerky—(PALCAM)

- 5.0 log reduction

## Conclusions

- The traditional marination procedure did not result in a 5 log reduction of either pathogen.
- In addition, the traditional marination procedure may provide protection/resistance of pathogens during drying.
- In general, application of pre-drying treatments or modified marination was more detrimental to either pathogen than the control or traditional procedures and more detrimental to *Listeria monocytogenes* than *E. coli* O157:H7.
- Bacterial injury may be occurring during drying.

## TREATMENTS TO CONTROL POST-PROCESSING CONTAMINATION BY LISTERIA MONOCYTOGENES ON PORK FRANKFURTERS AND SLICED BOLOGNA STORED AT 4oC IN VACUUM PACKAGES

- Objective
- 	To evaluate antimicrobials or their combinations in the formulation of frankfurters, or as dipping solutions for bologna slices, against surface inoculated *Listeria monocytogenes* after peeling/slicing and before vacuum packaging.

## Bologna slices inoculated with Listeria monocytogenes and then immersed (1 min)

- 2

- Bologna slices inoculated with *Listeria monocytogenes* and then immersed (1 min)

## Bologna slices inoculated with Listeria monocytogenes and then immersed (1 min)

- 2

- Bologna slices inoculated with *Listeria monocytogenes* and then immersed (1 min)

## Bologna slices inoculated with Listeria monocytogenes and then immersed (1 min)

- 2

- Bologna slices inoculated with *Listeria monocytogenes* and then immersed (1 min)

## 2

## Bologna slices inoculated with Listeria monocytogenes and then immersed (1 min)

- 2

- Bologna slices inoculated with *Listeria monocytogenes* and then immersed (1 min)

## Conclusions 

*Listeria monocytogenes* inoculated (2-3 log CFU/cm2) on bologna slices before vacuum packaging reached high populations (> 7 log CFU/cm2) in 10-20 days of storage at 4oC.
- Immersion of inoculated bologna slices in acetic acid (2.5 and 5%), lactic acid (5%), sodium diacetate (5%) or potassium benzoate (5%) inhibited *Listeria monocytogenes* for over 90 days at 4oC.
- Lower immersion concentrations of lactic acid (2.5%) and sodium diacetate (2.5%), or immersion in sodium acetate (2.5 and 5%), and sodium lactate (5 and 10%) exhibited lower levels of inhibition.

## Conclusions 

- Results of this study revealed that post-processing contamination with *L. monocytogenes* may be controlled in cured meat products by post-processing exposure to solutions of acetic, lactic, benzoic or sorbic acid or their salts.
- Sensory evaluation studies should be performed, however to refine the concentrations needed and to determine their effects in product shelf-life before the commercial application of any of the effective treatments of this study.
- Evaluation of antimicrobial effects at abusive temperature is also suggested and technological innovations are needed for commercial application of the treatments.

## Frankfurters with antimicrobials included in the formulation inoculated 

- 2

- Frankfurters with antimicrobials included in the formulation inoculated
- with *Listeria monocytogenes*

## Inoculated frankfurters dipped in hot (75oC) water; open symbols = 1 frankfurter/bag; closed symbols = 2 frankfurters/bag

- 2

- Inoculated frankfurters dipped in hot (75oC) water; open symbols = 1 frankfurter/bag; closed symbols = 2 frankfurters/bag

## Frankfurters with antimicrobials included in the formulation inoculated 

- 2

- Frankfurters with antimicrobials included in the formulation inoculated
- with *Listeria monocytogenes*

## Conclusions 

*Listeria monocytogenes* inoculated (2-4 log CFU/cm2) on frankfurters after peeling exceed 7 log CFU/cm2 after 20-35 day at 4oC in vacuum packages.
- Permissible concentrations of sodium acetate and sodium diacetate (both at  0.25% of the total formulation weight) were inhibitory to  *Listeria monocytogenes* inoculated on frankfurters post-processing for up to 30 days at 4oC.
- The permissible concentration of sodium lactate (3% of the total formulation weight) inhibited growth of the pathogen for 50 to 70 days during storage at 4oC under the experimental conditions.

## Conclusions

- Increase of the permissible concentrations of sodium acetate to 0.5% did not affect growth of *L. monocytogenes* for more than 20 days, while by doubling their permissible concentrations,  sodium diacetate and sodium lactate exhibited complete control for 120 days at 4oC.
- As applied, post-packaging thermal pasteurization (75-80oC/30-90sec) had variable effects in reducing initial contamination and was not effective or reliable in controlling growth of L. monocytogenes during storage, especially when two frankfurters were included in a package.

## Conclusions 

- The increase in the permissible concentrations of antimicrobials in frankfurters could be avoided by combining a lower level of sodium lactate (1.8%) with sodium acetate (0.25%) or sodium diacetate (0.25%); these combinations inhibited growth of the pathogen for up to 120 days at 4oC.
- Post-packaging thermal treatment may enhance the inhibitory activity of the combined antimicrobials during storage at 4oC.
- Use of adequate levels of antimicrobials or their combinations, in the formulation of cooked meat products, needs to be evaluated for effects on product quality and shelf-life, and for antimicrobial effects at abusive temperatures.

## ACKNOWLEDGEMENTS

- Faculty
- K.E. Belk
- P.A. Kendall
- J.A. Scanga
- G.R. Schmidt
- G.C. Smith
- Post Docs:
- J. Samelis
- J. Ikeda
- M. Calicioglu
- Research Associate
- M.L. Kain

- Graduate Students:
- A. Abushelaibi
- S. Albright
- C. Anderson
- T. Bacon
- G. Bedie
- J. Burnham
- E. Derrickson
- T. DiPersio
- S. Lakkakula
- J. Ransom
- K. Segomelo
- J. Stopforth
- Y. Yoon

- Funding:
- USDA-CSREES
- Colorado Agricultural Experiment Station
- National Pork Producers Council