1. Raw Materials and Their Impact on the Extrusion of Aqua Feeds
Presented by:
Brian Plattner, PE
Wenger Manufacturing, Inc.

2. Fundamentals of Extrusion Processing
Recipe
Hardware
Software
Product Specifications

3. Raw Materials
Raw materials and their characteristics are always the most important extrusion variable.

4. Particle Size Analysis of Typical Aquatic Feeds
U.S. Standard Sieve
Openings in Microns
Percent on Sieve 20 30 40 50 60 80
Pan
850
600
425
300
250
180
1.00
3.00
28.0
29.0
21.0
14.0
4.0
Geometric Mean Diameter: 327 Microns
Geometric Standard Deviation: 1.58

5. Benefits of Proper Particle Size
Improved product appearance
Reduced incidence of die orifices plugging
Ease of cooking
Reduced product breakage and fines
Increased water stability
Improved retention of liquid coatings due to small cell structure

6. Guidelines for Grind of Recipe
Maximum particle size = 1/3 of die opening
Not to exceed 1.5mm grind
800 micron mm

7. Particle Size Analysis of Two Grinding Processes of Extruded Feed
US Sieve
Opening (microns)
1.5 mm grind (%)*
425 micron grind (%)** 20
840
0.50 30
590
3.51 40
420
37.75 50
297
40.16
36.75 60
250
10.44
34.31 70
210
5.12
13.60 80
177
3.15
100
149
3.55
140
105
4.37
Pan
2.51
4.26
*Mean Diameter = 316µm, 66,768 particles/g
**Mean Diameter = 224µm, 519,365 particles/g

8. Effect of Grind Size on Extruded Feed Processing on X85 System
Bulk Density (g/l) at Given Rate
SME (kWh/t) at Given Rate and Bulk Density
Rate (kg/h) at Given Bulk Density
1.5 mm
316
46.8
357
425 microns
232
42.3
513

9. Effect of Grind on Floating Aquatic Feed
200
400
600
800
1000
1200
1400
1600
1800
2000
Time (Seconds)
Viscosity (cP) 20 40 60 80
100
120
Temperature (C)
3.5 g solids
25 ml water
Temperature
3/64" Grind
2/64" Grind
40 Mesh Grind

10. Recipe Preparation Grind ingredients to proper particle size
Weigh individual ingredients
Particle size and density of each ingredient should be similar
Premix by hand the micro-ingredients (anything less than 1% of total recipe) and add a carrier (part of a major ingredient) if necessary to bring premix size up to 3% of total recipe
Add major ingredients, then premix (from #4) to mixer and mix 3-5 minutes. Add any liquids slowly and then mix another 3-5 minutes
Final grind, if required
Use sifter and/or magnet to detect and remove foreign material

11. PROTEIN Plant Sources Animal or Marine Sources
Soy, Legumes, Wheat/corn glutens, cereal grains
Good functional properties
Lower cost
Amino acid profile may require supplementation
Animal or Marine Sources
Meat, Fish, Poultry, Blood, Gelatin
Poor functional properties unless fresh or spray dried
Higher costs
Good amino acid profile

12. Vegetable Proteins in Salmon, Trout, and Shrimp Diets
Maximum Substitution for Fish Meal (%)
Disadvantages
Maize Gluten Meal 40
Yellow pigmentation of flesh
Wheat Gluten 25
High Cost
Soybean Meal 50
Palatability and Growth Inhibitors
Soy Concentrate 75
Canola Meal 67
Low Protein Content
Hardy (January 1999) Feed Management Magazine

13. Benefits of Vegetable Proteins in Aquatic Diets
More expansion potential for floating diets
More binding potential for improved durability
Reduced ingredient costs
Lower incidence of white mineral deposits in screw and die area
Higher oil absorption levels possible in coating operations
Reduce dependence on fish meal

14. Effect of Vegetable Protein Levels On Extrusion Moisture15 17 19 21 23 25 27 29 31 10 20 30 35 40
Vegetable Proteins in Recipe (%)
Extrusion Moisture (%)

15. Soybean Meal Nutrient Level Comparison
Dehulled
Solvent Extracted
49.0
3.3
1.2
Non-dehulled
Solvent Extracted
44.0
7.0
1.2
Full Fat Soy
37.5
7.4
17.4
Crude Protein (%)
Crude Fiber (%)
Oil (%)

16. Addition of Slurries to Extrusion System
Maximum particle size not to exceed 1.5 mm
Fish ensilage slurries pumped into DDC
Fat/oil slurries heated to 60°C
Moisture is limiting factor for most slurry additions
Enzyme treatments reduce viscosity

17. Wet slurries pumped into DDC preconditioner and extruder barrel (head #2)

18. Positive Displacement Wet Slurry Pump System slaved to Dry Recipe Rate

19. Maximum Wet Slurry Addition to Single Screw Extrusion Systems*
% moisture in wet slurry
Maximum slurry addition (% of total)
Maximum slurry addition (% of dry)
% slurry in final dried product
66.7
25.0
33.3
10.9
40.0
41.8
71.8
32.4
50.0
33.4
21.8
60.0
27.8
38.5
14.6
70.0
23.9
31.4
9.5
80.0
20.9
26.4
5.6
* Maximum moisture addition to Single Screw Systems is 16.7%

20. Maximum Meat Addition to Twin Screw Extrusion Systems*
% moisture in wet slurry
Maximum slurry addition (% of total)
Maximum slurry addition (% of dry)
% slurry in final dried product
66.7
30.0
43.0
13.7
40.0
50.0
100.0
26.3
60.0
33.3
18.1
70.0
28.6
40.1
11.8
80.0
25.0
6.9
* Maximum moisture addition to Twin Screw Systems is 20.0%

21. Protein denatures at 60 - 700C
As protein denatures, it becomes insoluble (non-functional)
Starch gelatinizes at C
As starch gelatinizes it becomes soluble

22. STARCH Raw potato starch magnified 450 X Carbohydrate - energy source
Assists expansion
Improves binding and pellet durability
Found in two forms
Amylose
Amylopectin
% levels in aquatic food
Raw potato starch magnified 450 X

23. Effect of Extrusion on Starch
Gelatinizes starch
Improves digestibility in most species
Forms starch-lipid complexes
Increases binding characteristics
Increases susceptibility to enzyme hydrolysis

24. Recommended Starch Levels in Aquatic Feeds
Type
Floating
Sinking
Minimum Starch (%) 20 10

25. Starch Content of Common Cereal Grains
Corn
Winter Wheat
Sorghum
Barley
Oats
Unpolished Rice
% Starch (Dry Basis) 73 65 71 60 45 75

26. Heat of Gelatinization for Various Starches
Heat of Gelatinization (cal / gram)
Starch Source
Size (microns)
Amylose Content (%)
High Amylose Corn
Potato
Tapioca
Wheat
Waxy Corn
7.6
6.6
5.5
4.7 55 20 22 28
5-25
15-121
5-35
1-35

27. Minimum Moisture Levels Necessary to Initiate Starch Gelatinization
Starch Source
% Moisture
Wheat
Corn
Waxy Corn
High Amylose Corn 31 28 34
Lower moistures during extrusion require higher extrusion temperatures to achieve same level of cook.

28. Rice as a Starch Source
Small, tightly packed starch granules that hydrate slowly
Becomes sticky when it gelatinizes
Choose long grain varieties over medium and short grain varieties as they are much less sticky when cooked
Rice is very digestible even when cook values are low
Rice bran may contain up to 40% starch

29. Corn as a Starch Source Good expansion Excellent binding
Sticky at high levels (>40%)

30. Wheat as a Starch Source
Good binding
Good expansion
Can be sticky if overcooked
Contains gluten (good binder)
Most widely available starch source
Often utilized as wheat flour which has most of the bran removed

31. Tubers as a Starch Source (Potato & Cassava)
Excellent binding (at 5% levels)
Requires less total starch in diet
Good expansion
Often precooked
Smooth pellet surface
Increased cost

32. Effect of Extrusion on Starch
Process
Raw Recipe
Preconditioner
Extruder
Dryer
% Cook
15.5
31.6
92.8
96.7

33. Purposes of Fat in Feeds
Energy Source
Increases Palatability
Provides Essential fatty acids
Carrier for Fat Soluble Vitamins

34. Fat Sources Animal Fat Poultry Fat Marine Oils
Blended Animal and Vegetable Fats
Feed Grade Vegetable Fats
Must use FAH (fat acid hydrolysis) method for determining fat levels in extruded products.

35. Effect of Fat Levels on Product Quality (Single Screw Systems)
Level of Fat in Extruded Mix
Effect on Product Quality
<7%
7-12%
12-17%
Above 17%
Little or no effect
For each 1% of Fat Above 7%, the final bulk density will increase 16 g/l
Product will have little or no expansion, but will retain some durability
Final product durability may be poor
Add 5% to above figures for twin screw systems

36. Effect of Internal Levels of Fat on Expansion of Extruded Feeds
% Added
Fat
Bulk Density
(g / l) 5 10 15
256
309
408
533

37. Internal Fat vs. Pellet Durability75 ) 70 2 65 60 55
Maximum Compressive Stress (g / mm 50 45 40 35 30 6 8 10 12 14 16 18 20 22 24 26 28 30
Internal Fat (%)

38. To Maximize Fat Inclusion Levels
Formulate with ingredients high in indigenous fats (example: flax meal)
Heat fats to C prior to inclusion
Add late in the process
Maintain starch / function protein levels
Increase thermal and/or mechanical energy inputs
Increase moisture levels during extrusion

39. Ingredient
Moisture
(%)
Protein
Fat
Starch
Fish meal, Menhaden
8.0
62.0
9.8
0.0
Corn gluten meal
60.0
2.3
0.1
Soy Bean Meal
9.5
49.0
1.2
Broken rice
10.5
7.1
0.4
68.0
Wheat flour
11.5
12.0
3.0
65.0
Potato Starch
7.5
7.8
4.3
Fish Silage
75.5
20.6
2.6

40. Vitamin & Pigment Retention
Vitamin/Pigment Retention Depends On:
Raw material formulation
Temperature
Moistures
Retention times
An average of 10 to 15 percent of vitamins and pigments are lost during extrusion. Compensation is made by overages. Heat stable forms are preferred.

41. Preservation System Required for Soft Moist Aquatic Feeds (Final product moisture of 16-28%)
Lower Aw (water activity) below with humectants at 10-12% levels
Reduce pH to with acids at 1-2% levels or with fish silage/solubles
Add mold inhibitors at % levels

42. Effect of Extrusion on Microbial Populations
Microbe
Raw Recipe
After Extrusion
TPC (CFU/g)
Coli form
Mold count
Clostridium
Listeria
Salmonella
240,00
22,600
54,540
16,000
positive
negative
9,300
<10
negative

43. Thermal Destruction Studies for Pathogenic Organisms1 10
100
1000
10000
130
150
170
Time (Seconds)
Thermal Plastic Spores
E. Coli
Salmonella
Listeria 70 90
110
Temperature (C) 30 50

44. Effect of Extrusion Temperature on Fumonisin Toxin Levels
(Katta, Jackson, Sumner, Hanna, Bullerman, Cereal Chem. 76(1):16-20, 1999) 20 25 30 35 40 45 50 55 60 65 70
140
150
160
170
180
190
200
Extrusion Temperature (C)
Fumonisin B 1
Recovered (%)

45. Effects of Heat Processing on Insect Survival
Temperature (°C)
Effect
>62
50-60
45-50
30-35
25-32
Death in less than 1 minute
Death in less than 1 hour
Death in less than 1 day
Max temperature for reproduction
Optimum for development
Feed Management, January 2001, Vol. 52, No. 1, pg 27

46. After Ripening Factor
Biochemical changes occurring after harvest are influenced by storage time.

47. By-Products Starch / Filler Sources Protein Sources Wheat Bran
Wheat Midds (Pollards)
Rice Bran
Protein Sources
Co-Products such as DDGS

48. By-Products By-Product Moisture (%) Protein Fat Fiber Sorghum DDG 9.5
30.3
12.5
10.7
Dried Brewers Grains
(Barley)
24.0
5.0
15.5
Wheat DDG
7.5
38.5
8.2
6.2
Corn DDG
8.5
32.0
11.0
6.0

49. Effects of Adding Rework to Recipe (5 to 10 percent levels)
Darker color
Less expansion, higher bulk density
Higher levels of cook
More defined shape

50. Better Shape Definition
Bulk Density
Product Hardness
Smooth Skin
More Uniform
RECIPE
+ Starch
+ Oil (Internal)
+ Fiber
+ Functional Protein
+ Non-Functional Protein
+ Rework - + ? + - +
(1)
(2) ? + ? +
(1) Function of grind and particle size
(2) Large cell structure