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

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Raw Materials and Their Impact on the Extrusion of Aqua Feeds

Presented by:

Brian Plattner, PEWenger Manufacturing, Inc.

Recipe Hardware Software Product 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

U.S. Standard Sieve

Openings in Microns

Percent on Sieve

Geometric Mean Diameter: 327 Microns

Geometric 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

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

Particle Size Analysis of Two Grinding Processes of Extruded Feed

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

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

Grind Bulk Density (g/l) at Given

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

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

Time (Seconds)

3.5 g solids25 ml water

Temperature

3/64" Grind

2/64" Grind

40 Mesh Grind

Recipe Preparation

1) 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 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

Vegetable Proteins in Salmon, Trout, and Shrimp Diets

Vegetable ProteinMaximum Substitution for

Fish Meal (%)Disadvantages

Maize Gluten Meal 40Yellow

pigmentation of flesh

Wheat Gluten 25 High Cost

Soybean Meal 50Palatability and

Growth Inhibitors

Soy Concentrate 75 High Cost

Canola Meal 67Low Protein

Content

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

10 15 20 25 30 35 40

Vegetable Proteins in Recipe (%)

Soybean Meal Nutrient Level Comparison

Crude Protein (%)

Crude Fiber (%)

Oil (%)

Dehulled

Solvent Extracted

Non-dehulled

Solvent Extracted

Full Fat Soy

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*

% moisture in wet slurry

Maximum slurry addition

(% of total)

(% 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 50.0 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%

Maximum Meat Addition to Twin Screw Extrusion Systems*

% moisture in wet slurry

(% of total)

(% of dry)

% slurry in final dried product

66.7 30.0 43.0 13.7

40.0 50.0 100.0 40.0

50.0 40.0 66.7 26.3

60.0 33.3 50.0 18.1

70.0 28.6 40.1 11.8

80.0 25.0 33.3 6.9

* 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

Amylose Amylopectin

• 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

Floating

Sinking

Minimum Starch (%)

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)

Amylose Content (%)

Size (microns)

High Amylose Corn

Potato

Tapioca

Waxy Corn

15-121

Minimum Moisture Levels Necessary to Initiate Starch Gelatinization

Waxy Corn

High Amylose Corn

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 expansion

2) Excellent binding

3) Sticky at high levels (>40%)

Wheat as a Starch Source

1) Good binding

2) Good expansion

3) Can be sticky if overcooked

4) Contains gluten (good binder)

5) Most widely available starch source

6) 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 diet

3) Good expansion

4) Often precooked

5) Smooth pellet surface

6) Increased cost

Effect of Extrusion on Starch

Process

Raw Recipe

Preconditioner

Extruder

% Cook

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)

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

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

% Added

Bulk Density

(g / l)

Internal Fat vs. Pellet Durability

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

Internal Fat (%)

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

Ingredient Moisture

Protein

Starch

Fish meal, Menhaden 8.0 62.0 9.8 0.0

Corn gluten meal 8.0 60.0 2.3 0.1

Soy Bean Meal 9.5 49.0 1.2 0.0

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 60.0

Fish Silage 75.5 20.6 2.6 0.0

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.

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

240,00

22,600

54,540

16,000

positive

negative

TPC (CFU/g)

Coli form

Mold count

Clostridium

Listeria

Salmonella

Raw Recipe After Extrusion

130 150 170

Thermal Plastic SporesE. ColiSalmonellaListeria

70 90 110

Temperature (C)

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)

140 150 160 170 180 190 200

Extrusion Temperature (C)

Effects of Heat Processing on Insect Survival

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

Temperature (°C) Effect

After Ripening Factor

Biochemical changes occurring after harvest are influenced by storage time.

By-Products

• Starch / Filler Sources Wheat Bran Wheat Midds (Pollards) Rice Bran

• Protein Sources Co-Products such as DDGS

By-Product Moisture

Protein

Sorghum DDG 9.5 30.3 12.5 10.7

Dried Brewers Grains

(Barley)9.5 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

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) Function of grind and particle size

(2) Large cell structure

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

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