Post-Packaging Pasteurization:Will it work with country-cured hams?

Benjy Mikel

Professor/ Coordinator

Food Sciences

Listeria and 10240.4
        - Is Listeria in your plant?
        - Probably
        - Is it on your RTE product?
        - Hopefully not
        - What measures can you take?
        - Sanitation
        - Anti-microbials
        - Post-packaging pasteurization

Risk Management Strategies
        - Eliminate L. monocytogenes from the environment  of processing plants that produce ready-to-eat foods
        - Use a pasteurization processes to destroy L. monocytogenes
        - In-pack pasteurization, or
        - Immediately before packaging
        - Use product formulations that prevent the growth of L. monocytogenes

USDA-FSIS Alternatives
        - Alt 1.	Post-lethality AND Antimicrobial Agent
        - Alt 2.	 Post-lethality OR Antimicrobial Agent
        - Alt 3.	Sanitation Only

Post-Packaging Heat/Pasteurization 
        -  Heat re-applied to package 	surfaces to destroy any surface cross contamination.
        -  Immerse pkg. in hot water
        -  Surface steam (205F, 15 sec)
        -  Hot air or infrared.

        - Pasteurization for 2 or 4 min at 96.1 C reduced LM by 2 and 4 logs (Gill et al., 2002)
        - Reheat 60-90 sec @195-205 F
        - Steam or H2O
        - Goal: 2-3 mm of product to 160 F for 15-30 sec
        - Immediate chill and 3-4 log reduction
        - Shelflife- increase 25-33%

Post-Packaging Heat Disadvantages 
        -  Difficult to heat all surfaces
        -  May adversely affect package.
        -  Product changes with heat (color, texture, purge, etc.)
        -  Expensive
        -  Apply heat/moisture in refrigerated 	room (condensation, etc.)

Comparison of Pasteurization Methods
        -   Hot Water Bath     Advantages:  Simple method.

	Disadvantages: Process time, approx. 8 minutes.	Increases internal product temperature.	Lack of uniform surface heat distribution.	Heating large volumes of water. 

	Steam ChamberAdvantages:  Simple method.

	Disadvantages:Long processing time, approx. 15 minutes.Increases internal product temperature. 

	Lack of uniform surface heat distribution.Poor energy utilization. Circulating WaterAdvantages:  Short processing time (3 minutes) does not affect product characteristics.

	Very uniform surface heat distribution.Most efficient energy utilizationClose ratio of water/product.

Steam Surface Pasteurization

Top film

Discharge

Cut                        Seal                         Cool            SSP           Load            Form          Preheat

					            heat 

					         treatment

SSP step = 1.5 sec of high pressure steam

Machine Configuration

Film Travel Direction

Graphics and information provided by ALKAR-RapidPak, Inc.

Steam Surface Pasteurization
        - Hot dogs inoculated with indicator microorganism
        - SSP treatment = 1.5 seconds
        - 4-log reduction for single-layer package configuration
        - Actual Listeria monocytogenes inoculated-pack tests (102 per package) resulted in zero positives
        - Double-layer package tests in progress
        - Preliminary findings show 2.0 - 2.5 log reduction 

Graphics and information provided by ALKAR-RapidPak, Inc.

In Package Pasteurization

Log cycle reduction of Listeria monocytogenes at 96.1°C

Data and images supplied by Drs. James Marsden and Randall Phebus, Kansas State University

		Water Temp		Time (sec)		Product Temp

UK Shrink Tank Study
||
||
| 205 | 30 | 152 |
| 200 | 30 | 154 |
| 195 | 30 | 162 |
| 195 | 30 | 151 |
| 212 | 30 | 173 |
| 200 | 30 | 157 |
| 195 | 30 | 148 |
| 195 | 30 | 152 |
| 202 | 60 | 158 |
| 206 | 60 | 164 |
| 195 | 60 | 163 |
| 201 | 60 | 168 |
| 202 | 60 | 161 |
| 207 | 60 | 160 |
| 210 | 60 | 168 |
| 210 | 60 | 178 |