School of Food and Nutritional Sciences

University College Cork

Ireland

School of Food and Nutritional Sciences

University College Cork

Ireland

Professor Elke Arendt

Advances in gluten free cereal research,

Coeliac Disease

What is coeliac disease?

Autoimmune disease

Intolerance to gluten

Changes to the lining of the

upper part of intestine

Malabsorption

Possible causes

Genetic predisposition

Environmental factors

Immunological based

inflammationIceberg model depicting prevalence of

coeliac disease from Feighery (1999)

CD is a multi-organ autoimmune

disease caused by gluten intolerance

adapted from Rewers 2005

Treatment – Gluten free diet

Wheat Barley Rye ?Oats

Eragrostis tef

Teff

Eleusin

coracana

Finger millet

Cereals Allowed:

GF Cereals and Pseudocereals

Oryzoidae

Rice

Panicoideae

zea mays

Maize

Sorghum bicolor

Sorghum

Pennisetum

glaucum

Perl Millet

Setaria Italica

Italien Millet

Fagopyrum

esculentum

Buckwheat

Amaranthus

cruentus

Amaranth

Chenopodium

quinoa

Quinoa

Pseudocereals

Consumers benefitting from a gluten free diet

Coeliac Disease patients

( 1 to 2 % of the population)

Gluten sensitivity (10 to 20 %)

Wheat protein allergies (very small %)

Autism

Irritable Bowel Syndrome and Crones

Disease (approx. 20 %)

Skin-disorders

Life style choice

Special diets

Relations from above patients

9 out of 10 consumers buying GF-foods

are not Coeliac patients

Gluten free Market study

100 bread products from 15 countries

Free-from market: 300% growth since 2000

Growth rate of 25% per year

Only 1 out of 10 consumers buying GF-products

are coeliac patients

Marketing study UCC

Dry, crumbly mouth feel and off-flavor

Lack of Nutrients, high in fat

Rapid staling (mostly starch based)

Expensive

Long shelf life

Nutritional Information

Volume

Texture

Sensory evaluation

Price

Nutritional Composition of GF Breads

Gluten free white bread Wheat bread

Calories 196 kcal 311 kcal 219 kcal

Fat 1.7 % 15.6 % 1.4 %

Protein 1.1 % 6.6 % 8.7 %

Carbohydrates 35.0 % 62.7 % 43.0 %

Fibre 0.1 % 8.3 % 2.8 %

wheat flour + water

mixing

proofing

baking

GF flour + water

mixing

proofing

baking

Bread-making

Wheat vs. Gluten-free

CLSM of bread crumbs

CLSM of dough/batter

Gluten-free flours

New Generation Gluten-free bread development

Functional ingredients

Novel processing approaches

EnzymesLactic acid bacteria

Hydrocolloids Dough improversCereals Pseudo-cereals

High fibre

ingredients

Malting

Starches

School of Food and Nutritional Sciences

University College Cork

Ireland

Gluten free cereals and their characterization

Eragrostis tef Teff

Eleusin coracanaFinger millet

Gluten free cereals

OryzoidaeRice

Panicoideaezea mays

Maize

Sorghum bicolorSorghum

Pennisetumglaucum

Proso Millet

Avena sativa L.Oats

Fagopyrum

esculentum

Buckwheat

Amaranthus cruentus

Amaranth

Chenopodium quinoaQuinoa

Pseudocereals

Potential nutritional deficiencies

On diagnosis On GF diet On long-term

GF diet

Protein/calorie

Fibre

Fe, Zn, Cu, Mn

Vit D, Vit K

Ca, Mg

Folate, B12

Thiamin

Niacin

Pyridoxine

Riboflavin

Se, Carnitine

Fibre

Fe, Zn

Vit D

Ca, Mg

Folate, B12

Niacin

Riboflavin

Fibre

Folate, B12

Niacin

Pyridoxine

based on data provided by Kennedy et al.

Evaluation of technological and nutritional properties of gluten-free raw materials and end products

Nutrition

•Protein

•Aminoacids

•Fat

•Starch

•Fibre

•Folate

•Minerals

•Polyphenols

Technology

• Rheology

• Bioanalyser

• Rapid Viscoanalyser

• Enzyme activities

• Rheofermentometer

• Particle size

• Waterholdingcapacity

• Differential scanning calorimetry

Product quality

• Loaf volume

• Moisture

• Water activity

• Crumb texture

• Crumb structure

• Staling

• Microbial shelf life

• Bake loss

• In vitro digestibility

• Sensory evaluation

• Ultrastructure

Gluten-free flours – nutritional value 4%10%

13%

72%

1%

Whole wheat

2%

11%

13%

73%

1%

Wheat

2% 6%

14%

78%

0%

Maize4%

12%

13%

69%

2%

Buckwheat1%

7%

13%

78%

1%

Rice4%

13%

10%

71%

2%

Teff

7%7%

10%

75%

1%

Oat

3% 5%

11%

80%

1%

Sorghum

9%

14%

12%63%

2%

Quinoa

School of Food and Nutritional Sciences

University College Cork

Ireland

Nutritional Quality of GF grains

Protein content [%] Dietary fibre content [%]

Calcium content [mg/100g]Iron content [mg/100g]

Hager, A.-S., A. Wolter, et al. (2012). "Nutritional properties and ultra-structure of commercial gluten free flours from different botanical sources compared to wheat flours." Journal of Cereal Science 56(2): 239-247.

1834 33 30

180

132

77

37

96

Folic acid [µg/100g]

Gluten-free flours – baking properties

120

95 90 85

67 63

0

20

40

60

80

100

120

Wat

er

leve

l [%

bas

ed

on

flo

ur]

Oat represents exception: sensory score and loaf quality comparable to

wheat bread

Quality of gluten free breads inferior to wheat counterparts regarding taste attributes, loaf

volume, crumb texture, microbial shelf life, staling

SEM micrographs (1500/2000x) of wheat flour (a); dough (b), and bread (c).

a b c

SEM micrographs (1500/1000x) of maize flour (a), dough (b), and bread (c)

a b c

•c

SEM micrographs (2200/2300x) of quinoa flour (a), dough (b) and bread (c)

a b c

Evaluation of technological and nutritional properties of gluten-free starches

Composition

•Moisture

•Total starch

•Amylose

•Amylopectin

•Damaged starch

•Protein

•Alpha- Amylase

•Beta-Amylase

Morphology

Pasting,

Visco-elastic properties

• Rapid Viscoanalyser

• Rheometer

Bread analysis

• Loaf volume

• Moisture

• Crumb texture

• Crumb structure

• Bake loss

18

•Scanning electron microscopy

•Confocal laser scanning microscopy

19

Starch Size (µm)

Potato starch 4- 25 ; 31- 87

Tapioca starch 4– 20

Corn starch 3- 21

Rice starch 3- 7

Wheat starch 4- 14 ; 17- 30

Scanning electron micrographs. Magnification 1000x. Scale bar represent 10µm

Granules sizes of the

different starches

Potato starch Rice starchCorn starch

Wheat starch Tapioca starch

Potato starch

Impact of starch on model bread quality

Wheat starchRice starchCorn starchTapioca starch

Starches show very different behaviour and composition

Bread quality is dependent on the type of starch used.

School of Food and Nutritional Sciences

University College Cork

Ireland

Hydrocolloids and LAB producing EPS

Hydrocolloids

• Group of polysaccharides

• Sources include trees, plants, seaweed and bacteria

• used in food products to control

rheology and texture

stabilise emulsions

organoleptic properties

• produce highly viscous solutions, form gels with varying texture

Commonly found Hydrocolloids in

GF-cereal products

Gluten free model systems:

With HPMC

• Gas retention

• High volume

• Porous structure

No HPMC

• Weak structure

• Poor volume

• Dense, heavy texture

Impact of Hydrocolloids

ExopolysaccharidesEPS produced by LAB

EPS are extracellularly secreted microbial polysaccharides

Their amount and chemical structure depend on microorganism and substrate

Cereal associated lactic acid bacteria (LAB) are known to produce EPS in

large quantities

Two classes of EPS: homo- and heteropolysaccharides

HeteropolysaccharideComposed of repeated subunitsRepeating units consists of three to eight monosaccharidesSynthesised intracellularly from sugar nucleotide precursorsLow yield: <2g/l

HomopolysaccharideComposed of one type of monosaccharides (Glucose or Fructose)Synthesised by extracellular glycansucrases using sucroseUp to 50g/l

Laser-scanning electron microscopy of EPS LAB producing EPS

Sourdough technology: Hydrocolloids (LAB - EPS)

Exopolysacarideproduce LAB

EPS are extracellularl secreted microbial polysaccharides

Their amount and chemical structure depends on the microorganism and the growth substrate

Cereal associated LAB are known to produce EPS in large quantities

Dry, crumbly mouth feel and rapid staling

• LAB screening for EPS producer and EPS isolation

• Physicochemical characterisation (monomer composition, type of linkage, MW)

• GF sourdough fermentation (growth condition, optimisation, metabolic profile, EPS formation)

Experimental design

In vitro screening

In vitro characterisation

In situ investigation

LAB EPS production – Effect on bread

Wheat (EPS +) sourdough bread Wheat (EPS -) sourdough bread

Control Sourdough EPS producer

Effect on bread

Improves volume

Reduces staling

(5*106 –

4*107)(104)

(16.9*106)

(105 –

2*105)

Weisella cibaria MG1 EPS production in GF sourdoughsStructural characterization (SEC/FFF/MALS/RI)

In collaboration with Prof Gänzle and Dr Galle, University of Alberta, Canada

(MRS/Suc +) 36 g/l EPS

(MRS/Suc -) No EPS

In vitro screening

In situ (GF-SD)

• production

• isolation and

• characterization

4,2

3,2

1,1 0,9

4,7

0,00,51,01,52,02,53,03,54,04,55,0

Buckwheat Quinoa Sorghum Teff Wheat

g/

kg d

ou

gh d

wb

Sourdough fermentation – improvement of texture & taste

Breads produced with 20% sourdough fermented with Weissella cibaria

Strain produces Exopolysaccharides

0

0,5

1

1,5

2

2,5

3

3,5

4

Spec

ific

vo

lum

e [m

L/g]

Ctrl Bread

SD Bread

05

101520253035404550

Cru

mb

har

dn

ess

[N]

• Specific volume was significantly improved only in wheat breads• Crumb hardness reduced in all breads but sorghum• Staling rate reduced in teff and buckwheat bread• Improved sensory profile with addition of sourdough

In collaboration with Prof Gänzle and Dr Galle, University of Alberta, Canada

School of Food and Nutritional Sciences

University College Cork

Ireland

Enzymes and their impact on gluten free model breads

Enzymatic processing of GF flours

Production of reactive

cross-linking agents

LACCASE

radical-generating oxidation of

aromatic compounds

GLUCOSE OXIDASE

formation of H2O2 in conjunction

with glucose oxidation

• Cross-linking of AX by esterification of

FA residues

• Formation of S-S bridges

• Formation of S-S bridges

• Gelation of water-soluble pentosans

Protein hydrolysis

BAKING APPLICATION IN GF SYSTEM

ENDOPROTEASE

Hydrolysis of internal peptide

bonds

•Increase of polar groups

• Decrease average MW

• Changes in molecular conformation

• Improve foaming properties

• Reduce interference with starch gel

phase

Three different approaches have been considered

Direct enzymatic catalysis

TRANSGLUTAMINASE

formation of isopeptide bonds

Enzymes and their influence on GF -bread

Screening of the effect of enzymes on gluten free cereals

Transglutaminase, Laccase, Glucose oxidase & Protease

Characterisation the impact on rheological properties

Fundamental rheology, viscometry, creep-test, rapid visco-analyser

Impact of bread characteristics and ultra structure

Texture profile analysis, image analysis, rheo-fermento-meter, laser scanning microscopy,

electron-microscopy

Understanding of the interactions

Capillary electrophoresis, size exclusion

chromatography, NIR, HPLC, SDS, 2D electrophoresis

0

1000

2000

3000

4000

5000

6000

7000

0 1 2 3 4 5 6 7

time (h)

G', G

'' (

Pa

) .

G' 10 U/g G'' 10 U/g

G' 1 U/g G'' 1 U/g

G' 0 U/g G'' 0 U/g

Transglutaminase – Different GF-Raw-material

-No

changes

NoneSorghum

-No

changes

NoneTeff

-No

changes

NoneOats

+G’ ↓

G’’ ↓

Positive

Corn

+G’ ↑

G’’ -

Positive

Brown rice

+G’ ↑

G’’ -

Positive

Buckwheat

LaserRheologyStructurRaw-material

Frequency (Hz)

0.1 1 10

|G*|

(P

a)

10

100

1000

10000

10

15

20

25

30

-20

0

20

40

60

80

100

120

0 10 20 30 40 50 60

retention time (min)

mA

U

control

incubated

A BA B

TGase processing of GF flours

Fundamental

rheology of batters

SE-HPLC of protein

fractions

2D gel of protein

fractions

Buckwheat

Untreated Treated

In collaboration with Prof Vogel and Dr Behr, TU – Munich, Germany

School of Food and Nutritional Sciences

University College Cork

Ireland

In vitro starch digestibility and estimated glycaemic index of various gluten-free breads upon sourdough addition

• Extent of increase of blood glucose concentration

• Characterisation of carbohydrate-containing foods into categories (Atkinson’s table 2008)

35

Glycaemic index

www.rogerspeakperformers.com

The GI is defined as the incremental area under the curve (AUC) of the blood glucoseconcentration upon ingestion of a carbohydrate-containing food relative to reference food(glucose, GI glucose=100, or white wheat bread, GI white wheat bread=100) (Jenkins et al.1981)

Factors influencing glycaemic response

Baking

In vitro multi-enzyme dialysis

Sourdough

Sourdough breads

Control breads

Pepsin α-amylase Glass beads

buffer

sample

10-11 kDa

Weissella cibaria

Lactobacillus plantarum

Brennan 2008

In vitro glycaemic index – Control breads

37

Sorghum, teff:Higher gelatinisation temperatures

Oat-, sorghum- and teffHigher dietary fibre content

Decrease GI

Quinoa:Smallest granules

Higher enzymatic starch susceptibility

Lowest amylose content Reduced recrystallization

Buckwheat:Low dietary fibre content

Quinoa <1-2 µmBuckwheat, Teff 5 µmSorghum 10 µmWheat 6/15 µm

Size

Increase GI

71°C Teff 69°C Sorghum

66°C Buckwheat61°C Wheat 58°C Quinoa56°C Oat

Gelatinisation

Influence on in vitro GI – Starch properties

38

0

20

40

60

80

100

120

Wheat Teff Sorghum Quinoa Oat Buckwheat

Control W.cibaria MG1 L.plantarum FST1.7

20% sourdough addition: Reduced GI for wheat breadGluten-free breads: Only in teff and sorghum with Lactobacillus plantarum

Influence of sourdough on glycaemic index

The right mix

Hydrocolloids

Sourdough

Protein Source

GF Cereals

rich in fibre &

micro-nutrientsHigh fibre

ingredients

WaterStarch

Enzymes

Malt

School of Food and Nutritional Sciences

University College Cork

Ireland

Commercial Gluten Free Bread

Nutritional Information

Typical values per 100g of dry product

Energy 219 kcal 296 kcal 204 kcal 196 – 311 Kcal

Protein 8.7g 8.4g 6.6 g 1.1 – 8.4 g

Carbohydrates

Of which sugar

43g

2.42g

41.1g

3.0g

34.2 g 35.0 – 62.7

1.13 g

Fat

Of which saturates

1.4g

0.4g

13.0g

0.9g

2.8 g 1,7 -15,6

Fibre 2.8g 9.7g 8.0 g 0,1 – 8.3

Sodium 0.45g 0.63g 0.62 g

Range based on market study

Comparison of GF-breads and wheat bread

Consumer studies showed that GF bread developed in UCC could not be

distinguished from wheat bread

It is possible to produce a Gluten free bread comparable to wheat bread

Further Reading

Department of Food and Nutritional Sciences,

University College Cork, Ireland

Thank you very much

for your attention!