Food extrusion. Traditional and new trends

Osvaldo H. CampanellaAgricultural and Biological EngineeringWhistler Carbohydrate Research CenterPurdue University

The IPAT Equation

. .I P A T=I : Environmental Impact (e.g. resource depletion, waste

accumulation)P : PopulationA : Affluence (Average amount of technology units per

personT : Technology, or the amount of environmental impact

per unit of technology

Sustainability in the XXIth Century

( )3

1. .

i

ii

I P A T=

=

=∑The “Weighed” IPAT Equation

i

= 1 Highly Industrialized Countries

= 2 Nations in Rapid Development

= 3 Poor Nations

Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press)

Importanceof sustainabletechnologies

Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press)

Sustainability in the XXIth Century

Is extrusion processing a sustainable technology?

PROFIT PEOPLE

PLANET

SUSTAINABLEDEVELOPMENT

Ecological Dimension

Social Dimension

Economical Dimension

Is extrusion processing a sustainable technology?

People/Social Dimension• Provide the needs of the poor?• Extrusion accessible to all level of technical education• Social Acceptance ?• Safety, smell, occupational health? Positive impacts• Noise? Within legal limitsPlanet/Ecological Dimension• Depletion of abiotic resources? Positive impact • Depletion of biotic resources? Positive impact• Global warming; photochemical ozone pollutants? Positive Impact• Acidification and thermal pollution? Positive impactProfit/economic dimension• Non-renewable resource depletion? Fossil fuel depletion? Positive impact• Drinking water depletion? Positive impact• External costs for concerns to the ecosystem? No concerns identified• Capital or operational expenditures? Positive impact

Emerging sustainableprocessing technology

Mature sustainableprocessing technology

Threatened processing technology

0 + ++ +++

Condemned processing technology

TEC

HN

OLO

GY

SUST

AIN

AB

ILIT

Y

0

+

++

MARKET ATTRACTIVENESS

+++

Decision-making graph for sustainability-driven technology development

Process Intensification Concept

“Novel equipment, processing techniques, and process development methods that, compared to conventional ones, offer substantial improvements in (bio)chemical manufacturing and processing”.

Stankiewicz and Moulijn (2000). Chemical Engineering Progress, Process Design Trends, January, pp. 22-34Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press)

SME: Specific Mechanical EnergyWAI: Water Absorption IndexWSI: Water SolubilityGELATINISATIONDEXTRINISATION (Molecular Degradation)

PRODUCT PARAMETERS•Product Moisture•Product Temperature•Bulk Density or Expansion•Morphology

ShapeSizeUniformity

•Texture/Sensory•WSI/WAI

WSI: Water Solubility IndexWAI: Water Absorption Index

•Gelatinisation•DextrinisationSYSTEM PARAMETERS

•SME•Residence Time•Thermal Energy•Product Temperature•Product Pressure•Melt Viscosity

PROCESS PARAMETERS•Feed Rate•Water Addition•Screw Speed•Screw Profile•Cutter Speed•Barrel temperature

PROCESS PARAMETERS Associated to Raw Material•Composition: Oil, starch, protein, fiber•Moisture•Particle Size•Additives

SYSTEM DISTURBANCES•Screw Wear•Ambient Conditions

PROCESS PARAMETERDie Profile •Open Area•Flow Resistance

Expansion

Is extrusion processing a sustainable technology?

EXTRUSION PROCESSING ADVANTAGES

• Lost Cost• Large Product Range• Energy Efficient• No Effluents

Raw Cereal and other Ingredients

Screw pumps the material Inside the barrel

Cooking by Electrical, Steam jacketed, Induction “magnetic” heating

Residence Time10 seconds – 1min

Forming and expansion

Unit Operations• Feeding• Conveying• Mixing• Shearing• Cooking• Forming• Drying and Cooling Water Evaporation

GLASS TRANSITIONG

lass

tran

sitio

n te

mpe

ratu

re o C

Moisture Content (%)

GLASSY STATE

RUBBERY STATE

Increasing temperature

Increasing moisture

MATERIAL TRANSFORMATION CONCEPT

Glass Transition Region

MOISTURE

TEM

PER

ATU

RE

TRANSFORMATIONS OF RAW MATERIALS DURING EXTRUSION

LIQUID (AMORPHOUS)

GLASS

Wetting and MixingDry Material

HeatingExpansion Glass Transition

Temperature

DESIGN OF A MULTIPURPOSE SMALL EXTRUDER

Initial Motivation• Mission to Mars• 6-8 months outbound• 600 days surface stay• 6-8 months return

Lift cost to Mars:~$200,000/kg

Actual Use• Small (Farm) Scale Inexpensive Extruders

(and Screw Press) in underdeveloped countries

Extrusion Pressing Drying Grindingsoybeans

soy flour

First Extrusion

meal

oil

Second Extrusion

Extrusion Drying

soy flour

Texturized soy protein

Design a multipurpose small and inexpensive extruder/expeller

LARGE SCALE “MODEL” EXTRUDERTriple F - Model RC 2000

Modeling an Extrusion Process

( ) :pdTC Tdt

ρ λ τ⋅ = ∇ ⋅ ∇ + ∇u u

0∇⋅ =u0pτ∇ ⋅ −∇ =

Energy Transfer

Length

Pres

sure

Momentum Transfer

Rheology

Rheology

Design a multipurpose small extruder

Rheological Model For Soy Flour

0 852 1 373 0 3730 7 0 5 7. . .M T olog . log ( a a a ) .η γ=− ⋅ ⋅ ⋅ +

1.23 - T 0.020 a log T =

2.13-b)12.55(M a log M +=b -0.00034 T 0.0223= ⋅ +

0.088 - A)Content (Oil 9.3 a log o +=A -0.001347 T 0.06866= +

2.0 2.5 3.0 3.5 4.0 4.5 5.00.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

log

(Visc

osity

)

log (aM x aT x ao x Shear Rate)

Temperatures = 50oC - 90oCMoistures = 30% - 42%Oil = 0% - 12.2%

Experimental validation Large Scale Extruder

Extruder geometry: Db=138.94 mm, L=934 mm, H=17.08 mm,θ = 6.9◦

Operating conditions:N = 620 rpmMass flow rate:M = 184.8 g/secMaterial: Soy flour

Final performance comparisonTemperature rise

(C)Die pressure (bar) Power consumption

(kW)Industrial Extruder

97.8 19.7 57.4

Model Prediction

96 17.5 58.9

Extrusion temperature validation

50

100

150

200

250

3 4 5 6 7 8Port number

Tem

pera

ture

(o C)

Experimental dataSimulation

Design of the Small (60 lb/h) extruder

EXTRUSION-POROSIFICATION TECHNOLOGY

The Extrusion-Porosification Technology is aimed to:

• Create porous powders with better rehydration time• Reduce conversion costs (energy, capital)• Overcome some limitations of spray drying & drum

drying technologies• Process complete formulations without further

mixing• Leverage in-built extrusion flexibility

cream

MilkStorage Separation Heating

MultipleEffect

Evaporation

Spray Drying

Fluidized BedDrying

50 9312% Solids 96

Typical Skim Milk Powder Process

Effect of solid content in the feed on the energy consumption for the evaporation of water in the spray drying process.

Solids in the feed(%)

Energy consumption(kJ/kg powder)

10 24,00020 10,50030 6,20040 4,00050 2,700

Energy Saving

VISCOSITY OF PROTEINS AND OTHER MACROMOLECULESLimitations of spray drying

Visc

osity

10 3020 40 50

NewtonianBehavior

Time-independentnon-Newtonianbehavior

Time-dependent“thixotropic”non-Newtonianbehavior

Solids Concentration (%)0 10 20 30 40 50 600

20

40

60

80

100

B

rook

field

Vis

cosi

ty a

t 25o C

Solids Concentration (%)

Whey Protein Skim milk Whey Protein Concentrate

Maximum concentrationpermissible for spray drying

EXTRUSION-POROSIFICATION TECHNOLOGY

Process Modification

Simplified flowsheet for the extrusion-porosifiedmilk powder manufacturing process

Extrusion-textured foam obtained from 38% dry solids milk protein concentrate

Typical SEM picture of an extrusion-porosifiedmilk powder particle

Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press) - (courtesy of CLEXTRAL, France)

Characteristics of the Products

0 20 40 60 80 1000.0

0.1

0.2

0.3

0.4

0.5

Ener

gy C

onsu

mpt

ion

kg s

team

/kg

of in

com

ing

milk

Percent Solids (%)

Spray Drying Process

Extrusion-Porosification Process

Energy Analysis

Characteristics Extrusion-porosifiedpowder

Standard values

Moisture (%) 2.5 – 3.9 < 4Fat (%) 27 – 28 27 – 29Insolubility Index (mL) 0.1 – 0.2 < 0.5Titratable acidity (%) 0.1 < 0.15Flavour & Odour Good GoodAppearance & Colour Normal NormalpH (10% solution) 6.73 – 6.77 > 6.6Free fat (%) 3.2 – 6.7 < 5Peroxide value (meq. O2/kg fat) 0.3 < 1Water activity 0.22 – 0.27 < 0.5Density (kg/L) 0.41 – 0.44 > 0.4

Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press) - (courtesy of CLEXTRAL, France)

Characteristics of extrusion-porosifiedwhole milk powder

Reactive Extrusion

Raw MaterialsPlant Proteins

Animal Proteins

Plant Proteins

Cereals

Starches

Wood

Oilseeds

MoleculesAlcohol/solvents

Chemicals

Oil and Lubricants

Surfactants

Chemicals

Paper

Green ChemistryResearch/Development Output

Concept – Use the micromixing capabilities oftwin-screw extruders along chemical reactions

Process ComparisonSodium Caseinate

Reactive Extrusion

TraditionalProcess

Water Content (%)

16-28 70-80

Temperature, oC

120-140 70-80

Time 15-20 sec 30-45 min

Energy Cost 60 -70 100

Capital Cost ~ 50 100Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press)

Neutralization ReactionsReactive Extrusion

“Batch”Production of Sodium caseinate

Wet acid casein+ water

Grinding

Diluted alkali

Drying Spray or rollerdryer

Dissolutionand

Neutralization

Grinding

Caseinate powder

Casein/water mixture

Extrusion Process

SodiumHydroxide

Extruder

Caseinate powder

• Casein can be fed dry or wet• 10-30% moisture content after

alkali is added• Functional properties aredifferent (e.g. emulsification)

• Higher solid contents are handled• Less labor and floor space

Roller Dryer

Production of Sodium Caseinate

Concept – Use the micromixing capabilities oftwin-screw extruders along chemical reactions

Some Twin screw geometries

Rectangular Channel Model

y

z

dcosπφ

bV sin tanφ φ−

sVcosφ

−

1cξ

1ξ

C

1ξ 1cξ

Cross-channel section – velocity profile Down-channel section – velocity profile

Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press)

zx

y

Mixing and Deformation of material

Moving down the channel

Single screw extruder as a bioreactorfor sago starch hydrolysis

amylase−α

Starch + enzyme60-120oC

Conditions• Feed Moisture• Enzyme concentration• Mass Temperature

Govindasamy, Campanella and Oates, 1997. Food Chemistry

Results• Water Solubility Index (WSI)• Water Absorption Index (WAI)• Degree of Gelatinization (DGR)• Dextrose Equivalent (DE)

Extrusion

Reactive Extrusion

Influence of feed moisture and enzyme concentration on DE of sago starch extrudates produced in a single screw extruder

Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press)

High moisture twin screw extrusion of sago starch. Saccharification

amylase−α

Product• DE• WSI (Water Solubility Index)• % Saccharification

Twin Screw ExtruderBatch

Reactor

Amyloglucosidase

Rx times 8hrs

Starch

Rx time 30-40 secs

Twin Screw Extruder

Starch

amylase−α

Amyloglucosidase

Product• DE• WSI (Water Solubilty Index)• % Saccharification

Rx time 30-40 secs

Reactive Extrusion-Reactor Approach

Reactive Extrusion Approach

Influence of enzyme concentration and barrel temperature on DE of extrudate produced by twin screw extrusion at 39.5%

moisture content at 130rpm

Bouvier and Campanella (2013). Extrusion Processing Technology. J. Wiley (In press)

amylase−α

Zone 4Zone 3

Effect of enzyme concentration (AMG), moisture content and stage of addition of the enzyme in a twin screw extruder on WSI

The examples described shows that Extrusion Technology can be considered a Process Intensification technology getting more interest particularly due to more incentives for the development of sustainable technologies. • Process intensification/Extrusion can promote continuous

processing instead of batch, or semi-batch processing. Higher throughputs with equivalent or even smaller volume devices result from continuous processing, hence leading to higher process productivity, smaller plants, safer processing, and reduced capital and operating costs.

• Process Intensification/Extrusion develops and promotes multifunctional processing equipment

• Process Intensification/Extrusion accelerates fundamental process phenomena such as physical transfer phenomena and chemical reactions.

SUMMARY

GRACIAS POR SU ATENCION