Fundamentals of Extrusion Processing - Aquafeed.com - … · Raw Materials and Their Impact on the Extrusion of Aqua Feeds May 2007 Aqua Feed Horizons -- Victam 2007 3 Benefits of

Raw Materials and Their Impact on the Extrusion of Aqua Feeds May 2007

Aqua Feed Horizons -- Victam 2007 1

Raw Materials and Their Impact on the Extrusion of Aqua Feeds

Presented by:

Brian Plattner, PEWenger Manufacturing, Inc.

RecipeHardwareSoftwareProduct Specifications

Fundamentals of Extrusion Processing



Raw Materials

Raw materials and their characteristics are always the

most important extrusion variable.

Particle Size Analysis of Typical Aquatic Feeds

203040506080

Pan

850600425300250180

0

1.003.0028.029.021.014.04.0

U.S. Standard Sieve

Openings in Microns

Percent on Sieve

Geometric Mean Diameter: 327 MicronsGeometric Standard Deviation: 1.58



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

Guidelines for Grind of Recipe

• Maximum particle size = 1/3 of die opening• Not to exceed 1.5mm grind

800 micron 1.5 mm



4.264.373.553.15

13.6034.3136.75

425 micron grind (%)**

2.51Pan10514014910017780

5.122107010.442506040.162975037.75420403.51590300.5084020

1.5 mm grind (%)*

Opening (microns)

US Sieve

Particle Size Analysis of Two Grinding Processes of Extruded Feed

*Mean Diameter = 316µm, 66,768 particles/g**Mean Diameter = 224µm, 519,365 particles/g

51342.3232425 microns

35746.83161.5 mm

Rate (kg/h) at Given

Bulk Density

SME (kWh/t) at Given Rate and

Bulk Density

Bulk Density (g/l) at Given

Rate

Grind

Effect of Grind Size on Extruded Feed Processing on X85 System



Effect of Grind on Floating Aquatic Feed

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 200 400 600 800 1000 1200Time (Seconds)

Visc

osity

(cP)

0

20

40

60

80

100

120

Tem

pera

ture

(C)

3.5 g solids25 ml water

Temperature

3/64" Grind

2/64" Grind

40 Mesh Grind

Recipe Preparation1) Grind ingredients to proper particle size2) Weigh individual ingredients3) Particle size and density of each ingredient should be

similar4) 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

5) 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

6) Final grind, if required7) Use sifter and/or magnet to detect and remove foreign

material



PROTEIN

Plant SourcesSoy, Legumes, Wheat/corn glutens, cereal grains

• Good functional properties• Lower cost• Amino acid profile may require supplementation

Animal or Marine SourcesMeat, Fish, Poultry, Blood, Gelatin

• Poor functional properties unless fresh or spray dried• Higher costs• Good amino acid profile

Vegetable Proteins in Salmon, Trout, and Shrimp Diets

Low Protein Content67Canola Meal

High Cost75Soy Concentrate

Palatability and Growth Inhibitors50Soybean Meal

High Cost25Wheat Gluten

Yellow pigmentation of

flesh40Maize Gluten Meal

DisadvantagesMaximum Substitution for Fish Meal (%)Vegetable Protein

Hardy (January 1999) Feed Management Magazine



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

Effect of Vegetable Protein Levels On Extrusion Moisture

151719212325272931

10 15 20 25 30 35 40

Vegetable Proteins in Recipe (%)

Ext

rusi

on M

oist

ure

(%)



Soybean Meal Nutrient Level Comparison

Crude Protein (%)

Crude Fiber (%)

Oil (%)

DehulledSolvent Extracted

49.0

3.3

1.2

Non-dehulledSolvent Extracted

44.0

7.0

1.2

Full Fat Soy

37.5

7.4

17.4

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



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

Positive Displacement Wet Slurry Pump System slaved to Dry Recipe Rate



Maximum Wet Slurry Addition to Single Screw Extrusion Systems*

5.626.420.980.09.531.423.970.0

14.638.527.860.021.850.033.450.032.471.841.840.010.933.325.066.7

% slurry in final dried product

Maximum slurry addition

(% of dry)


(% of total)

% moisture in wet slurry

* Maximum moisture addition to Single Screw Systems is 16.7%

Maximum Meat Addition to Twin Screw Extrusion Systems*

6.933.325.080.011.840.128.670.018.150.033.360.026.366.740.050.040.0100.050.040.013.743.030.066.7

% slurry in final dried product


(% of dry)


(% of total)

% moisture in wet slurry

* Maximum moisture addition to Twin Screw Systems is 20.0%



• Protein denatures at 60 - 700C• As protein denatures, it becomes insoluble

(non-functional)• Starch gelatinizes at 55 - 750C

• As starch gelatinizes it becomes soluble

STARCH

• Carbohydrate - energy source• Assists expansion• Improves binding and pellet

durability• Found in two forms

AmyloseAmylopectin

• 10 - 60 % levels in aquatic food Raw potato starch magnified 450 X



Effect of Extrusion on Starch

• Gelatinizes starch• Improves digestibility in most species• Forms starch-lipid complexes• Increases binding characteristics• Increases susceptibility to enzyme hydrolysis

Recommended Starch Levels in Aquatic Feeds

Type

Floating

Sinking

Minimum Starch (%)

20

10



Starch Content of Common Cereal Grains

Cereal Grain

CornWinter WheatSorghumBarleyOatsUnpolished Rice

% Starch (Dry Basis)

736571604575

Heat of Gelatinization for Various Starches

Starch Source

Heat of Gelatinization (cal / gram)

AmyloseContent (%)

Size (microns)

High Amylose Corn

Potato

Tapioca

Wheat

Waxy Corn

7.6

6.6

5.5

4.7

4.7

55

20

22

28

0

5-25

15-121

5-35

1-35

5-25



Minimum Moisture Levels Necessary to Initiate Starch Gelatinization

WheatCornWaxy CornHigh Amylose Corn

31312834

Starch Source % Moisture

Lower moistures during extrusion require higher extrusion temperatures to achieve same level of cook.

Rice as a Starch Source

1) Small, tightly packed starch granules that hydrate slowly

2) Becomes sticky when it gelatinizes3) Choose long grain varieties over medium

and short grain varieties as they are much less sticky when cooked

4) Rice is very digestible even when cook values are low

5) Rice bran may contain up to 40% starch



Corn as a Starch Source

1) Good expansion2) Excellent binding3) Sticky at high levels (>40%)

Wheat as a Starch Source

1) Good binding2) Good expansion 3) Can be sticky if overcooked 4) Contains gluten (good binder)5) Most widely available starch source6) Often utilized as wheat flour which has most

of the bran removed



Tubers as a Starch Source(Potato & Cassava)

1) Excellent binding (at 5% levels)2) Requires less total starch in diet3) Good expansion4) Often precooked5) Smooth pellet surface6) Increased cost

Effect of Extrusion on Starch

ProcessRaw RecipePreconditionerExtruderDryer

% Cook15.531.692.896.7



Purposes of Fat in Feeds

• Energy Source• Increases Palatability• Provides Essential fatty acids• Carrier for Fat Soluble Vitamins

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.



Effect of Fat Levels on Product Quality (Single Screw Systems)

<7%7-12%

12-17%

Above 17%

Little or no effectFor each 1% of Fat Above 7%, the final

bulk density will increase 16 g/lProduct will have little or no expansion,

but will retain some durabilityFinal product durability may be poor

Level of Fat in Extruded Mix Effect on Product Quality

Add 5% to above figures for twin screw systems

Effect of Internal Levels of Fat on Expansion of Extruded Feeds

05

1015

% AddedFat

Bulk Density(g / l)

256309408533



Internal Fat vs. Pellet Durability

30

35

40

45

50

55

60

65

70

75

6 8 10 12 14 16 18 20 22 24 26 28 30

Internal Fat (%)

Max

imum

Com

pres

sive

Str

ess

(g /

mm

2)

To Maximize Fat Inclusion Levels

• Formulate with ingredients high in indigenous fats (example: flax meal)

• Heat fats to 40 - 600C 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



65.03.012.011.5Wheat flour

75.5

7.5

10.5

9.5

8.0

8.0

Moisture (%)

60.04.37.8Potato Starch

0.02.620.6Fish Silage

68.0

0.0

0.1

0.0

Starch(%)

0.47.1Broken rice

1.249.0Soy Bean Meal

2.360.0Corn gluten meal

9.862.0Fish meal, Menhaden

Fat(%)

Protein (%)

Ingredient

Vitamin & Pigment Retention

Vitamin/Pigment Retention Depends On:Raw material formulationTemperatureMoisturesRetention 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.



Preservation System Required for Soft Moist Aquatic Feeds

(Final product moisture of 16-28%)

• Lower Aw (water activity) below 0.70 with humectants at 10-12% levels

• Reduce pH to 4.0 - 4.5 with acids at 1-2% levels or with fish silage/solubles

• Add mold inhibitors at 0.2-0.5% levels

Effect of Extrusion on Microbial Populations

Microbe

240,0022,60054,54016,000 positive negative

9,300<10<10<10negativenegative

TPC (CFU/g)Coli form Mold countClostridium ListeriaSalmonella

Raw Recipe After Extrusion



1

10

100

1000

10000

130 150 170

Tim

e (S

econ

ds)

Thermal Plastic SporesE. ColiSalmonella SenftgenberListeria Monocytogenes

70 90 110Temperature (C)

30 50

Thermal Destruction Studies for Pathogenic Organisms

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)

Fum

onis

in B

1R

ecov

ered

(%)



Effects of Heat Processing on Insect Survival

>6250-6045-5030-3525-32

Death in less than 1 minuteDeath in less than 1 hourDeath in less than 1 dayMax temperature for reproductionOptimum for development

Feed Management, January 2001, Vol. 52, No. 1, pg 27

Temperature (°C) Effect

After Ripening Factor

Biochemical changes occurring after harvest are influenced by storage time.



By-Products

• Starch / Filler SourcesWheat BranWheat Midds (Pollards)Rice Bran

• Protein SourcesCo-Products such as DDGS

8.5

7.5

9.5

9.5

Moisture (%)

6.0

6.2

15.5

10.7

Fiber(%)

11.032.0Corn DDG

8.238.5Wheat DDG

5.024.0Dried Brewers Grains

(Barley)

12.530.3Sorghum DDG

Fat(%)

Protein (%)

By-Product

By-Products



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

+ Starch+ Oil (Internal)+ Fiber+ Functional Protein+ Non-Functional Protein+ Rework

-+?-++

Bulk DensityRECIPE

Product Hardness

Smooth Skin

More Uniform

Better Shape

Definition

+--+--

++

(1)(2)++

?+???+

?++?++

(1) Function of grind and particle size(2) Large cell structure

Documents

Fundamentals of Extrusion Processing - Aquafeed.com - … · Raw Materials and Their Impact on the Extrusion of Aqua Feeds May 2007 Aqua Feed Horizons -- Victam 2007 3 Benefits of