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MECHANICS OF CHILLING RTE MEAT PRODUCTS

MECHANICS OF CHILLING RTE MEAT PRODUCTS. Better be completely safe…. Seth Pulsfus Alkar Technical Development. Brine Chiller. Fast chilling delivers safer RTE products. Requirements to stabilize heat-treated meat and poultry products. Non cured meats

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MECHANICS OF CHILLING RTE MEAT PRODUCTS

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  1. MECHANICS OF CHILLING RTE MEAT PRODUCTS Better be completely safe… Seth Pulsfus Alkar Technical Development

  2. Brine Chiller

  3. Fast chilling delivers safer RTE products Requirements to stabilize heat-treated meat and poultry products • Non cured meats • From 130 to 80F  1.5 hr; then from 80 to 40F  5 hr Or • From 120 to 55oF  6 hr; continue until 40F • Cured meats • From 130 to 80F  5 hr; then from 80 to 45F  10 hr Appendix B objective: prevent the growth of spore-forming bacteria (Clostridia)

  4. Fast chilling offers other benefits to your operations • Prevent deterioration of products characteristics • Improve production output • Reduce water evaporation due to slow cooling (shrink) • Improve cooking yields • Reduce cooking yields variation • Improve slicing and peeling performances • Reduce re-work and “tankage” • Improve operating costs • Reduce in-process inventory • Increase production output • Optimize floor space utilization • Increase energy efficiency

  5. Purpose of this presentation • Review the parameters affecting the chilling process • Describe the different equipment utilized to chill RTE meat products • Explain how to evaluate chilling processes in regard to Appendix B

  6. OUTLINE Validation of Chilling Processes Chilling Equipment Design Chilling Process Parameters

  7. Chilling involves a 2-stage heat transfer 1- Heat migrates from the product center to the surface conduction 2- Heat transfers from the surface to the cooling medium  convection Product cross-section Product cross-section Transfer speed depends on product’s characteristics Transfer speed depends on medium’s characteristics

  8. Product’s “heat transfer” properties are characterized by 4 physical variables • Specific heat (Cp) = related to product molecular structure • characterize how easy it is to change product’s temperature • Thermal conductivity (k) = speed of heat transfer • Affected by product’s moisture content: water conducts heat better than fat • Latent heat = energy required to change phase i.e. to freeze the product • Product’s geometrical shape • The thicker the product, the longer the chilling

  9. Latent heat is a critical variable when fast chilling large pieces • Use of very cold medium  crust freezing • During freezing product’s temperature does not decrease = change of phase from water to ice • High energy requirement • Use of “equilibration” step when chilling Freezing

  10. Example: freezing of Ground Turkey chubs 10 lb chubs, 4.3” diameter, -10 F. Glycol Product Core Period of Latent Heat Glycol Time (hours)

  11. Example: crust freezing and equilibration process

  12. Thermal Properties of Meat Products % Solids % Water Cp k Latent Heat (kJ/kg . °C)(W/m . °C) (kJ/kg) Bacon 61 29 0.60 0.28 74 Bologna 35 65 0.86 0.31 86 Franks 40 60 0.86 0.31 86 Ham 51 49 0.68 0.28 87 Turkey 32 68 0.79 0.29 106

  13. Chilling media are characterized by their heat transfer coefficient MethodCoefficient (W/m2 . K) Air - Free convection 5 - 25 - Forced convection 10 - 200 Liquid - Free convection 20 - 100 - Forced convection 50 - 10,000

  14. OUTLINE Validation of Chilling Processes Chilling Equipment Design Chilling Process Parameters • Product thermal characteristics and shape • Heat transfer coefficient  medium, method

  15. Holding Cooler: free air convection

  16. High-Performance Air Chiller: forced air convection Heat exchanger Exhaust

  17. Brine chiller: forced liquid convection Heat exchanger Brine shower Storage tank Brine receptor tank

  18. Chilling efficiency: Brine > Blast > Cooler 7# Pressed Ham, 10” x 6” x 3.5” 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 Temperature (F) 12 0 1 2 3 4 5 6 7 8 9 10 11 Time (hours)

  19. Strengths Lower initial cost Ease of maintenance Simplicity of design Weaknesses Inefficiency of air Longer cooling time Less uniform Higher shrink Strengths High Efficiency Less than 1% shrink Faster chill time (vs. cooler) Energy savings (vs. cooler) Product compatibility Weaknesses Higher initial cost Longer chill time (vs. brine) More floor space (vs. brine) Maintenance (vs. cooler) The choice of chilling equipment depends on products characteristics, processes,… Air chilling Air blast chilling

  20. Strengths High efficiency 50 - 70% faster 0% shrink Less floor space 30 - 65% less energy Reduced inventory Weaknesses Higher initial cost Maintenance / cleaning Cost of solution Brine disposal Product compatibility Brine Low cost Most products Limited life 0°F minimum Corrosive Glycol High cost Impervious casings Indefinite life; > 25% glycol = bactericidal -20°F minimum Non-corrosive Absorbs moisture Less prevention And operation capabilities Brine or glycol? Liquid chilling

  21. OUTLINE Validation of Chilling Processes Chilling Equipment Design Chilling Process Parameters • Chilling efficiency: brine > blast > holding cooler • Choice depends on products, processes, operation capabilities • Product thermal characteristics and shape • Heat transfer coefficient  medium, method

  22. Using a “safe harbor” chilling process whenever possible makes life easier • Comply with FSIS stabilization Performance Standards • Time/temperature records will do • Customize a chilling process • Use literature or peer reviewed methods Or • Conduct challenge studies using C. perfringens as model

  23. How to analyze a chilling process record It does! Method 1 • Does this chill pass? • Method 1. • 130° to 80°F in 1.5 hr • 80° to 40°F in 5 hr • Method 2. • 120° to 55°F in 6 hr • Continue to 40°F

  24. How to analyze a chilling process record It does! Method 1 • Does this chill pass? • Method 1. • 130° to 80°F in 1.5 hr • 80° to 40°F in 5 hr • Method 2. • 120° to 55°F in 6 hr • Continue to 40°F

  25. How to analyze a chilling process record It does! M1 for brine chill @ 25F M2 for air chill @ 12F • Does this chill pass? • Method 1. • 130° to 80°F in 1.5 hr • 80° to 40°F in 5 hr • Method 2. • 120° to 55°F in 6 hr • Continue to 40°F

  26. SUMMARY Validation of Chilling Processes Chilling Equipment Design • Use “safe harbor” processes • Analyze chill curve Chilling Process Parameters • Chilling efficiency: brine > blast > holding cooler • Choice depends on products, processes, operation capabilities • Product thermal characteristics and shape • Heat transfer coefficient  medium, method

  27. MECHANICS OF CHILLING RTE MEAT PRODUCTS Better be completely safe… Alkar Technical Development

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