Optimization of caramel flavour generation upon extrusion cooking

13th Weurman Flavour Research Symposium

Zaragoza, September 27-30, 2011

generation upon extrusion cooking

Tomas Davidek, Silke Illmann, Andreas Rytz, Hélène Chanvrier, Greet Vandeputte, Heike

Schuchmann, Josef Kerler and Imre Blank

Nestle PTC Orbe

Flavour is one of the major drivers of consumer preference

However, there are many other factors of similar importance

Colour, structure, texture, Nutritive value, safety, Convenience, packaging, …

2

Flavouring can be achieved by

- adding compounded and/orreaction flavours

- generating flavours upon food processing, e.g. extrusion

Louis-Leopold Boilly, Les Cinq Sens (The Five Senses), 1823.

Extrusion with direct expansionProduct structure created by extrusion

Flour Mix (~10% H2O)

Water, Oil, ...

The cereal is expanded to its

3

SteamExpansion

10%

~15–20%

~5-10%

Moisture:

110–180°C80–170 bars

Average residence time: 20–30 seconds

The cereal is expanded to its final size at the extruder outlet

Downstream processing

Flavour generation upon extrusion

Extrusion Heat load (T, t) Screw speed, SME Moisture Number of barrels Slurry vs. dry addition…

Recipe Ingredients Specific precursors Concentration, ratio Catalyst pH…

4

……

Manifold interactions, Systematic & multidisciplinary Effects difficult to predict approach, Experimental design

O

OHO

CH3CH3

Favourable conditions

• low moisture• high pH• T > 120°C

4-Hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol) as a target compound generated from sugars

Objective

Study the effect of extrusion parameters and recipe composition on furaneol formation from rhamnose and lysine

NH2 OH

O

NH2 O

OHO

CH3CH3

+ Recipe & Process

parameters

5

Identify recipe and processing conditions during extrusion of rice flour favouring the formation of caramel flavour while considering physico-chemical properties of the final poduct

Optimised recipe and processing conditions

Experimental setup: Key product attributes affected by recipe and extrusion parameters

Recipe parameters • pH

• Ratio Rha/Lys

• Phosphate

Extrusion parameters• Moisture levels

• Screw speed

• Temperature

• Residence time

Mixing

Extrusion 500400300Screw speed (rpm)

150135120Temp. (°C)

0.1340.035PO4 (mol/kg)

232017Moisture (%)

75Barrel length

3:13:0Rha:Lys

7.76.4pH

SME

6

• Residence time

• Slurry vs. dry

Drying

Milling

Final product

Product characterisation

• Texture

• Crispness

• Colour

• Flavour

• Acrylamide

• Starch degradation

• Granulometry

• Viscosity

• Sensory

Fractional factorial design:- 32 instead of 576 trialsModelling furaneol yield & rhamnose degradation by estimating - all main effects and - two-factor interactions of 3 recipe & 5 process parameters

SlurryDryAddition

Holistic approach: Analytical characterisation of samples from experimental design

List of analysis:• Residual rhamnose (HPLC/DAD)• Furaneol (GC/MS)• Acrylamide (HPLC/MS)• Chemical composition (NIR)• Moisture (MNR)• Molecular weight profile of starch (GFAS = Gel Filtration Analysis of Starch)

Flavour Recipe/process parameters Other key product attributes

7

• Molecular weight profile of starch (GFAS = Gel Filtration Analysis of Starch) • Molecular weight profile of debranched starch (SEC = Size Exclusion

Chromatography) • Molecular weight profile of proteins (HPSEC = High Performance Size

Exclusion Chromatography) • Colour• Viscosity (rheometer, RVA profile)• Granulometry (laser diffraction)• Texture: X-ray tomography

• Porosity (cells size & cell walls distributions, degree of anisotropy)• Crispiness (average drop off, force Max)

• Texture: Spoon test• Sensory evaluation

• Trained panel (14 panelists)

• Product– Extruded powder (85%)

– Sugar (15%)

• Reconstitution– 12.4g product

– 100mL milk at 70°C

Sensory assessment Reconstituted products from experimental design

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

tEasySwallowaLump

tSmooth

BurntNutty

aDarkCaramelToasted

Range covered by A01-A32 (vs. REF)

Text

ure

& A

pp

eara

nce

Range of sensory attributes

Wide diversity of sensory perception

8

– 100mL milk at 70°C

• 32 Products evaluated vs. reference

• Identification of statistically relevant trends

Parameters units Low Medium High

pH 6.4 7.7Rha:Lys 3:0 3:1Phosphate mol/kg 0.035 0.134Moisture % 17 20 23Screw speed rpm 300 400 500T °C 120 135 150length barrel short longAddition dry slurry

ToastedProcessy

OffOverall

acidWholeGrain

Mushroom

astringentbitter

aftertaste

t1Thick

tThicktFluffy

t1WettabilitytSemolina

CookedMilkyRice

Vanillasweet

Fla

vor

Text

ure

& A

pp

eara

nce

16

20

Fu

ran

eo

l dry

/ m

ol%

Correlation matrixNo correlation between Furaneol level and SME

32 samples produced in experimental design

Resulting in products with sufficiently different properties

9

0

4

8

12

20 30 40 50 60 70 80 90 100

SME measured / Wh/kg

Fu

ran

eo

l dry

/ m

ol%

Correlation matrixFuraneol vs SME

ab

C

Furaneol ext

Furaneol dry

12

16

20

Fur

ane

ol d

ry (

mo

l%)

Furaneol is positively correlated with the degradation of rhamnose and colour development

10

SME measured

SME calculated

Visco5min

ViscoMax

ViscoMaxTime

Visco5/3min

L

h

Rha extRha dry

0

4

8

12

20 30 40 50 60 70 80 90 100

SME measured (Wh/kg)

Fur

ane

ol d

ry (

mo

l%)

Acrylamide

SME is negatively correlated with viscosity

and colour development

Furaneol formation Free AA, moisture, T and phosphate are most critical

-6 -4 -2 0 2 4 6

pH 6.4pH 7.7

Rha:Lys 3:0Rha:Lys 3:1

Phosphate 0.035 mol/kgPhosphate 0.134 mol/kg

Furaneol ext / mol% Furaneol dry / mol%

Conversion of rhamnose to furaneol can be modulated through changes of extrusion and/or recipe

11

17% H2O20% H2O23% H2O

300 1/min400 1/min500 1/min

120 °C-Long120 °C135 °C150 °C

DrySlurry

changes of extrusion and/or recipe parameters

Acrylamide Temperature is most critical

-75 -50 -25 0 25 50 75

pH 6.4pH 7.7

Rha:Lys 3:0Rha:Lys 3:1

Phosphate 0.035 mol/kgPhosphate 0.134 mol/kg

Acrylamide

-6 -4 -2 0 2 4 6

pH 6.4pH 7.7

Rha:Lys 3:0Rha:Lys 3:1

Phosphate 0.035 mol/kgPhosphate 0.134 mol/kg

Furaneol ext / mol% Furaneol dry / mol%

12

17% H2O20% H2O23% H2O

300 1/min400 1/min500 1/min

120 °C-Long120 °C135 °C150 °C

DrySlurry

17% H2O20% H2O23% H2O

300 1/min400 1/min500 1/min

120 °C-Long120 °C135 °C150 °C

DrySlurry

Colour generation

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

tEasySwallowaLump

tSmooth

Range covered by A01-A32 (vs. REF)

Colour range

Colour developmentModulate colour in product through recipe

Browning reactions

pH 6pH 7

Colour (C)

* High pH

pH 6Rha/Lys 3:0

pH 7Rha/Lys 3:1

13

tSmooth

BurntNutty

aDarkCaramelToasted

ProcessyOff

Overallacid

WholeGrainMushroomastringent

bitteraftertaste

t1ThicktThicktFluffy

t1WettabilitytSemolina

CookedMilkyRice

Vanillasweet

Sen

sory

im

pac

t

Colour range

-6 -4 -2 0 2 4 6

pH 7

Rha:Lys 3:0Rha:Lys 3:1

Phosphate lowPhosphate high

17% H2O20% H2O23% H2O

300rpm400rpm500rpm

120°C-Long120°C135°C150°C

DrySlurry

** Lysine

* High pH

Key

par

amet

ers

Light Dark

SME Temperature, moisture, screw speed are most critical

-15 -10 -5 0 5 10 15

pH 6.4pH 7.7

Rha:Lys 3:0Rha:Lys 3:1

Phosphate 0.035 mol/kgPhosphate 0.134 mol/kg

SME measured / Wh/kg SME calculated / Wh/kg

No effect of recipe parameters on SME

14

17% H2O20% H2O23% H2O

300 1/min400 1/min500 1/min

120 °C-Long120 °C135 °C150 °C

DrySlurry

Higher SME is achieved with low moisture, high screw speed, low temperature and long extruder.

Structure and Texture Moisture and temperature are most critical

-1500 -1000 -500 0 500 1000 1500

pH 6.4pH 7.7

Rha:Lys 3:0Rha:Lys 3:1

Phosphate 0.035 mol/kgPhosphate 0.134 mol/kg

Visco5min / mPas ViscoMax / mPas

-15 -10 -5 0 5 10 15

Cell walls / µm

Structure = f (SME)Texture = f (SME)

ProcessProcess

15

Phosphate 0.134 mol/kg

17% H2O20% H2O23% H2O

300 1/min400 1/min500 1/min

120 °C-Long120 °C135 °C150 °C

DrySlurry

StructureWide variety of structures obtained

Rha:Lys 1:0Rha:Lys 3:1

0.035 mol/kg PO40.134 mol/kg PO4

17% H2O20% H2O

Cell walls (um)

600

800

1000

1200M

ean

cel

l siz

e (u

m)

16

-20 -10 0 10 20

20% H2O23% H2O

300 1/min400 1/min500 1/min

120 °C-Long120 °C135 °C150 °C

DrySlurry

Main effect

0

200

400

600

70 75 80 85 90

Porosity (%)

Mea

n c

ell s

ize

(um

)

12 mm

Long ChainDP~50

Short ChainDP~25

Rice Flour

Moisture % 8-13

Starch %d.b. 88-92

Total fibers %d.b. 0.3-1Proteins %d.b. 6-9Fat %d.b. 0.5-1Ash %d.b. 0.3-1

A28

40

50

60

70

80

90

100

Car

bo

hyd

rate

s (g

/100

g)

Total Amylopectin Intermediate1

Intermediate2 Amylose

A04

0

10

20

30

40

50

60

70

80

90

100

1000 10000 100000 1000000 10000000 100000000

Molecular weight

Car

bo

hyd

rate

s (g

/100

g)

Total Amylopectin Intermediate1

Intermediate2 Amylose

Amylopectin

High MW

Am

ylo

pec

tin

, h

igh

MW

In

term

edia

te d

epo

lym

eriz

ed

Lo

w M

W In

termed

iate gen

erated, am

ylose co

nstan

t

SME 92 SME 35

Texture: Starch degradation Depolymerisation of amylopectin increases with SME

17

A17

0

10

20

30

40

50

60

70

80

90

100

1000 10000 100000 1000000 10000000 100000000

Molecular weight

Car

bo

hyd

rate

s (g

/100

g)

Total Amylopectin Intermediate1

Intermediate2 Amylose

A31

0

10

20

30

40

50

60

70

80

90

100

1000 10000 100000 1000000 10000000 100000000

Molecular weight

Car

bo

hyd

rate

s (g

/100

g)

Total Amylopectin Intermediate1

Intermediate2 Amylose

0

10

20

30

40

1000 10000 100000 1000000 10000000 100000000

Molecular weight

Car

bo

hyd

rate

s (g

/100

g)

Am

ylo

pec

tin

, h

igh

MW

In

term

edia

te d

epo

lym

eriz

ed

Lo

w M

W In

termed

iate gen

erated, am

ylose co

nstan

t

Low MW

Amylose

SME 92 SME 35

A28

40

50

60

70

80

90

100

Car

bo

hyd

rate

s (g

/100

g)

Total Amylopectin Intermediate1

Intermediate2 Amylose

A04

0

10

20

30

40

50

60

70

80

90

100

1000 10000 100000 1000000 10000000 100000000

Molecular weight

Car

bo

hyd

rate

s (g

/100

g)

Total Amylopectin Intermediate1

Intermediate2 Amylose

Amylopectin

High MW

Am

ylo

pec

tin

, h

igh

MW

In

term

edia

te d

epo

lym

eriz

ed

Lo

w M

W In

termed

iate gen

erated, am

ylose co

nstan

t

SME 92 SME 35

0

20

40

60

80

100

0 50 100SME

Sta

rch

(%

)

Amylopectin

High MWintermediate

Low MW intermediate

Starch degradation MW = f (SME)

0

1000

2000

3000

4000

5000

6000

0 2 4 6 8 10 12V

isco

sity

(m

Pa.

s)Time (min)

SM

E 9

2S

ME

35RVA 50°C, 50rpm

21g+170mL milk

Viscosity = f (MW)

18

A17

0

10

20

30

40

50

60

70

80

90

100

1000 10000 100000 1000000 10000000 100000000

Molecular weight

Car

bo

hyd

rate

s (g

/100

g)

Total Amylopectin Intermediate1

Intermediate2 Amylose

A31

0

10

20

30

40

50

60

70

80

90

100

1000 10000 100000 1000000 10000000 100000000

Molecular weight

Car

bo

hyd

rate

s (g

/100

g)

Total Amylopectin Intermediate1

Intermediate2 Amylose

0

10

20

30

40

1000 10000 100000 1000000 10000000 100000000

Molecular weight

Car

bo

hyd

rate

s (g

/100

g)

Am

ylo

pec

tin

, h

igh

MW

In

term

edia

te d

epo

lym

eriz

ed

Lo

w M

W In

termed

iate gen

erated, am

ylose co

nstan

t

Low MW

Amylose

SME 92 SME 35

High H2OHigh T

Low H2OLow T

Effect of recipe/extrusion parameters Options for flavour optimization

Rha:Lys 3:1

Phosphate high

17% H2O

500rpm

150°C

1

2

3

4

%F

ura

ne

ol-

dry

Temperature affects

Free amino acid and phosphate affect furaneol, but not SME

19

pH 6pH 7

Rha:Lys 3:0

Phosphate low

20% H2O

23% H2O

300rpm

400rpm

500rpm

120°C-Long

120°C135°C Dry

Slurry

-4

-3

-2

-1

0

-20 -15 -10 -5 0 5 10 15 20

SME-measured

%F

ura

ne

ol-

dry

Temperature affects both furaneol and SME150°C → more viscous

Moisture affects both furaneol and SME17% → less viscous

Conclusions

Critical parameters for generation of furaneol from rhamnose during extrusion:

• Furaneol generation is affected both by recipe parameters (Lys, PO4) and extrusion parameters (T, moisture)

• Temperature and moisture affect both furaneol formation and texture (→ SME)

• Recipe parameters permit furaneol modulation w/o impact on texture

• Lower pH will limit colour and acrylamide development w/o affecting furaneol formation

20

formation

• Addition of amino acid will enhance furaneol while limiting acrylamide formation

Full factorial design