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Safety & Health

Process Effects on Microbiological Contaminant Levels

Process Effects on Microbiological
Contaminant Levels

Phares O. Okelo, Ph.D.
Center for Veterinary Medicine/FDA

AFSS Public Meeting
May 22, 2007

Process Effects on Microbiological Contaminant Levels - Slide 1

Slide 2

Outline

Ingredient/feed manufacturing processes

Process effects on contaminant levels

Some examples

Process Effects on Microbiological Contaminant Levels - Slide 2

Slide 3

Ingredients and Manufacturing Processes (swine diet)

Ingredient NameIngredient
Origin
Manufacturing Processes
Corn
(ground)
CornGround or Chopped (entire corn kernel)
Soybean meal
(solvent extracted)
SoybeanGrinding the flakes which remain after removal of most of the oil by solvent extraction
Fish meal
(select menhaden)
FishClean, dried, ground tissue of undecomposed whole fish or fish cuttings. May have part of oil extracted.
Spray-dried animal blood cellsWhole animal bloodSeparating and spray drying red and white blood cells
Spray-dried wheyMilkSeparating whey from coagulum Spray-drying of whey (whey – fluid from the coagulum from milk, cream or skimmed milk. A portion of the milk fat may have been removed)
 
 Animal, BeefRendering or extraction of beef tissue
Process Effects on Microbiological Contaminant Levels - Slide 3

Slide 4

Ingredient/Feed Manufacturing Process Categories

Thermal
Physical
Chemical
Other

Process Effects on Microbiological Contaminant Levels - Slide 4

Slide 5

Ingredient-Contaminant-Process Interactions

Manufacturing Process

Ingredient

Contaminant

Process Effects on Microbiological Contaminant Levels - Slide 5

Slide 6

Ingredient-Contaminant-Process Interactions ‘cont.

Initial
Contaminant
Levels

------->

Manufacturing
Process

------->

Final
Contaminant
Levels

Process Effects on Microbiological Contaminant Levels - Slide 6

Slide 7

Microbiological Contaminants

FungiBacteria
Penicillium spp.Salmonella enterica
Aspergillus spp.E. coli O157:H7
Fusarium spp.Mycobacterium spp.
 Bacillus spp.
 Clostridium spp.
 Pseudomonas spp.
 Staphylococcus spp.
Process Effects on Microbiological Contaminant Levels - Slide 7

Slide 8


Manufacturing Processes - Thermal

(Temp, time, moisture)

  • Spray-drying
  • Drum/tube-drying
  • Fluid-bed drying
  • Pelleting
Process Effects on Microbiological Contaminant Levels - Slide 8

Slide 9

Manufacturing Processes – Thermal
(spray-dried animal blood cells)

  Red blood cells    
       
Whole liquid porcine blood Separation Plasma concentration by filtration  
       
    Spray-drying,
Air in: 249 – 271 oC
Air out: 66 – 74 oC
Dwell time: ~ 10 min
  
       
    plasma meal 8 – 10 % mcf Other processes
Process Effects on Microbiological Contaminant Levels - Slide 9

Slide 10

Manufacturing Processes - Physical

(psd, temp, press, time)

  • Grinding
  • Pressing
  • Centrifugation
  • Membrane separation
  • Mixing
Process Effects on Microbiological Contaminant Levels - Slide 10

Slide 11

Manufacturing Processes - Chemical

(aw, time, pH, temp, conc)

  • Preservatives
  • Anti-microbial activity
  • Fermentation
Process Effects on Microbiological Contaminant Levels - Slide 11

Slide 12

Manufacturing Technologies and Inactivation Kinetics

N = Noe-kt
Where:
N = number of viable bacterial cells after t seconds
No = number of bacterial cells at the start of thermal process
t = duration of thermal process, s
k = activation constant of the organism (death rate), dimensionless

Process Effects on Microbiological Contaminant Levels - Slide 12

Slide 13

Manufacturing Technologies and Inactivation Kinetics (DT value)

DT value
The time (min) required to kill 90% of viable vegetative cells or spores at T (oC)
DT (min)

No 0.1No

T oC

Process Effects on Microbiological Contaminant Levels - Slide 13

Slide 14

Manufacturing Technologies and
Inactivation Kinetics (DT value ‘cont.)

DT = [2.303/exp(ln ko – Ea / RT)]
where:
ko = the pre-exponential factor, dimensionless
Ea = activation energy of the organism, (J mol-1)
R = the universal gas constant, (8.314 J mol-1 K-1)
T = absolute temperature of thermal process, K

Process Effects on Microbiological Contaminant Levels - Slide 14

Slide 15

Manufacturing Technologies and
Inactivation Kinetics ‘cont.

N = Noe-(ln ko–Ea/RT)t
Where:
N = # of viable bacterial cells after t seconds
No = # of bacterial cells at start of thermal process
ko = the pre-exponential factor, dimensionless
Ea = activation energy of the organism, (J mol-1)
R = the universal gas constant, (8.314 J mol-1 K-1)
T = absolute temperature of thermal process, K
t = duration of thermal process, s

Process Effects on Microbiological Contaminant Levels - Slide 15

Slide 16

Manufacturing Processes – Thermal
(spray-dried animal blood cells)

102-103 cells/g Mycobacterium avium Red blood cells    
       
Whole liquid swine blood Separation Plasma concentration thru membr. filtration T ~ 45-50 oC at droplet surface while in drying chamber
       
Some pigs at slaughter house show porcine tuberculosis – Mycobacterium avium infection   Spray-drying,
Air in: 249–271 oC
Air out: 66 – 74 oC
Dwell time: ~10 min
  
       
    8 – 10 % mcf animal plasma meal Other processes
Process Effects on Microbiological Contaminant Levels - Slide 16

Slide 17

Inactivation of M. avium – (spray-dried animal blood cells)

T (oC)T (K)k*DT oC (s)*DT oC (min)Spray Dryer Dwell Time (min)Log
Reduction (dimension
-less)
Percent Reduction (%)
45318.153.08291E-057.5E+041.2E+0310.00.011.8
50323.150.0002086551.1E+041.8E+0210.00.0511.8
55328.150.0013322631.7E+03>2.9E+0110.00.3555.0
60333.150.0080460482.9E+024.8E+0010.02.1099.2
65338.150.0460764835.0E+018.3E-0110.012.01100.0
*predicted DT values for M. avium sp. paratuberculosis
Process Effects on Microbiological Contaminant Levels - Slide 17

Slide 18

Manufacturing Technologies and Inactivation Kinetics (HHP)

MicroorganismMedium

Temp

(oC)

Press

(MPa)

DpValue

(min)

Salmonella seftenbergChicken23a340a7.1a
Pseudomonas
flourescens
Minced beef20b150b24b
aMetrik et al., 1989
bCalrez et al., 1993
Process Effects on Microbiological Contaminant Levels - Slide 18

Slide 19

Expert Opinion – Microbes (process effects)

If the microbiological contaminant is present in the
specified feed ingredient, will the processing step in
question 1) increase, 2) reduce, or 3) have no effect
on the level of the microbiological contaminant?

(Please restrict your estimates to effects occurring only during the specific
processing step.)

Process Effects on Microbiological Contaminant Levels - Slide 19

Slide 20

Expert Opinion – Microbes (magnitude of effect)

What is the estimated magnitude, in terms of
percentages, of that effect (e.g., 50% reduction,
200% increase, etc.)?

Process Effects on Microbiological Contaminant Levels - Slide 20

Slide 21

Expert Opinion – Microbes (expert’s certainty on estimate)

How certain are you in your estimation? Please
use the following scale:
 

  • 1 = very uncertain (just a guess)
  • 2 = uncertain
  • 3 = medium certainty
  • 4 = fairly certain
  • 5 = very certain (I know what I am talking about!)
Process Effects on Microbiological Contaminant Levels - Slide 21

Slide 22

Microbes Inactivation (Expert Opinion Table)

Process Effects on Microbiological Contaminant Levels - Slide 22

Conta-
minant

Thermal Processes (T)

Cooking/
Rendering

Drying

Distillation

Pelleting

Notes
PESCertaintyPESCertaintyPESCertaintyPESCertainty
Fungi         
Penicillium
spp.
         
Aspergillus
spp.
         
Fusarium
spp.
         
Bacteria         
Salmonella enterica         
         
Staphylo-coccus
spp.
         
PES = Processing Effect Score (magnitude of effect, e.g., 50% reduction, 200% increase, etc.)
 

Slide 23

Manufacturing Processes - Thermal

(Temp, time, etc)

  • Spray-drying (~45-55 oC, few min)
  • Drum/tube-drying (~35-40, few min)
  • Fluid-bed drying (~35-40, few min)
  • Pelleting (~66-100 oC, 30-140+ seconds)
Process Effects on Microbiological Contaminant Levels - Slide 23

Slide 24

Post Processing Operations (Effects on Level of Microbes)

  • Storage
  • Transportation
  • Feeding Practices

    Criteria for estimation of effects of these operations on the levels of microbes
    in ingredients and feed is being developed.

Process Effects on Microbiological Contaminant Levels - Slide 24

Slide 25

Final Level of Microbes in Feed

The overall estimate of levels of microbes in the feed will be based on
the following factors:

  • Initial levels in ingredients
  • Composition of contributing ingredient in diet (%)
  • Processing effects
  • Daily consumption
Process Effects on Microbiological Contaminant Levels - Slide 25

Slide 26

Microbe Inactivation - Levels After Processing (M. avium)

Whole liquid blood 

T Effects

 

P Effects

  
    

 |

  
102 - 103 cfu/g Mycobacterium avium   

C Effects

 

 

 

 

 

 

 

 

 

 

 

Other Ingredients

 

Mixing

 

Pelleting

 

 

 

 

 

 

 

 

 

 

 

Final level in feed:
x cfu/g
 

 

Final level in feed:
0 cfu/g

Process Effects on Microbiological Contaminant Levels - Slide 26

Slide 26

Microbe Inactivation - Levels After Processing (M. avium)

Whole liquid blood 

T Effects

 

P Effects

  
    

 |

  
102 - 103 cfu/g Mycobacterium avium   

C Effects

 

 

 

 

 

 

 

 

 

 

 

Other Ingredients

 

Mixing

 

Pelleting

 

 

 

 

 

 

 

 

 

 

 

Final level in feed:
x cfu/g
 

 

Final level in feed:
0 cfu/g

Process Effects on Microbiological Contaminant Levels - Slide 26

Slide 27

Process Effects on Microbiological Contaminant Levels - Slide 27

Expert Opinion Worksheet Microbiological Contaminant

Conta-
minant

Thermal Processes (T)

Cooking/
Rendering

Drying

Distillation

Pelleting

PES

Certainty

PES

Certainty

PES

Certainty

PES

Certainty

Salmo-
nella

93±9.6

5±0.5

33±27.7

3

48±47.3

3±0.8

78±38.6

4±1.4

E. coli

93±9.6

5±0.5

33±27.7

3

48±47.3

3±0.8

78±38.6

4±1.4

Process Effect Score (PES, %): - Increase; - Decrease; NE - No Effect

Certainty: 1–Very uncertain; 2-Uncertain; 3-Medium certainty; 4-Fairly certain; 5-Very certain

 
Slide 28

Swine Diet Ingredients


Processes

Salmonella

E. coli

FCP
% pos, mean

EOW
(PES/C)

FCP
% pos, mean

EOW
(PES
/C)

Corn, ground

Grind or chop

7.69

4

0

4

Soybean Meal,
solvent extracted

Solvent extraction, grind

7.69

75

0

95

Fish Meal,
select menhaden

Clean, dry, ground, mechanical extraction

72

90

0

95

Spray dried blood cells

Spray dry

72

90

0

95

Dried whey

Coagulate, separation,
dry

72

75

0

75

Choice white grease
&
Fat

Render

72

95

0

95

DDGS

Grind, ferment,, distill, dry

7.69

75

0

75

Process Effects on Microbiological Contaminant Levels - Slide 28

Slide 29

Summary

  • Start with diet with known ingredients & composition,
  • a list of list of identified microbiological contaminants
  • Assess effects of key manufacturing processes on contaminant levels
    using established techniques (and available data on: process parameters,
    microbe levels, expert opinion, etc.)
  • Use model to estimate final contaminant levels in mixed feed
Process Effects on Microbiological Contaminant Levels - Slide 29

Slide 30

Questions ?

Process Effects on Microbiological Contaminant Levels - Slide 30