John Taylor
Institute for Food, Nutrition and Well-being and
Department of Food Science University of Pretoria [email protected]
TRADITIONAL
AFRICAN
CEREAL FOODS
AND BEVERAGES
HOW THEY CAN HELP US DEVELOP
BETTER GLUTEN-FREE PRODUCTS
Until the “Age of Discovery” starting in the 15th Century Most People in the World
did not know Wheat and Barley
People in the Americas, Asia and Africa Developed Sophisticated Technologies
to Optimise the Processing of their Local Grains
Bacteria from a traditional African soured beverage (strain of Lactobacillus plantarum)
Lactic acid bacteria on starch granules in sorghum fermentation
50
60
70
80
90
100
110
0 50 100 150 200 250
Brewing time (min)
Tem
pera
ture
(o
C)
MASH IN
COOKING
MASHING
Fungal alpha-amylase
Simplified General Process
for Brewing Sorghum Lager/Stout using Raw Sorghum, Sorghum Malt and
Commercial Enzymes
Sorghum Malt or Thermostable Alpha-amylase
Proteases Cellulases
+
Raw Sorghum
Starchy adjunct Cooking and Mashing processes
After cooking – The adjunct it is returned back to the mash vessel (foreground)
Mashing is then carried out overnight
Sorghum malt
Warm Water
What Were The Ladies Doing In the Mashing Process?
Step 1: Add sorghum malt to warm water with stirring
Enzyme Extract
Cooked Starchy Solids
Step 5: Allow to cool somewhat Add cooked starchy solids back to enzyme extract
“Recently, a decantation mashing procedure was devised to convert sorghum malt more efficiently”
1. The mash is carried out at 45oC for 30 min
2. The active enzymic wort (amylase enzyme rich solution) is
decanted
3. The starchy-grist residue is heated to 80oC or 100oC to gelatinize the starch
4. The mash is then cooled and the decanted enzymic wort is re-added to achieve a conversion (starch hydrolysis) temperature of 65oC”
From: G.H. Palmer et al. 1989. MIRCEN J Appl. Micro. Biotech 5: 265
Effect of Different Mashing Conditions with Sorghum Malt
Taylor, JRN.1992. J. Amer. Soc. Brew. Chem. 50:13
(from β-amylase) (from α-amylase)
Decoction
LACTIC ACID
FERMENTATION
Sourdough Technology
Traditional in Africa
For Making Breads with
Non-wheat Cereals
- Sorghum, Maize, Millets,
Rice, Teff
Traditional KISRA
flatbread from Sorghum
- Sudan
OLD? DOUGH-MAKING TECHNOLOGY
INJERA FLOWCHART
KEY INJERA TECHNOLOGIES
• Mixed yeast LAB sourdough fermentation • Pre-gelatinise part of the dough
Yetneberk S. et al. Cereal Chem. 2004.
Sourdough Fermentation Increases Maize Bread Loaf Volume
- Much larger gas cells and open crumb structure
Falade A T et al. J. Cereal Sci. 2014.
Effect of Sourdough fermentation on Mixolab dough profile
Edema, M.O. et al. 2013.
Starch/Stärke
Sorghum ferm Wheat-(standard) Sorghum unferm B Fonio 2 ferm B Fonio 1 ferm B Fonio 2 unferm B Fonio 1 unferm W Fonio 1 ferm W Fonio 2 ferm W Fonio 1 unferm W Fonio 2 unferm
Sorghum and Fonio Compared to Wheat
Dough
Bread
Sourdough fermentation produces a more cohesive maize dough - Larger more uniform gas bubbles/cells
in the dough and bread
Straight dough With yeast
Chemically acidified dough With yeast
L. plantarum fermented dough With yeast
Sourdough fermented dough With yeast
L. plantarum fermented dough No yeast
Sourdough fermented dough No yeast
Falade A T et al. J. Cereal Sci. 2014.
1
101
102
103
104
105
106
Pa
G'
100
101
10-3
10-2
10-1
100
101
102
%
Strain
CSD
Anton Paar GmbH
spontaneously fermented maize dough without yeast 1c 1
PP25-SN25508; [d=2 mm]
G' Storage Modulus
l.plantarum fermented maize dough without yeast1b 1
PP25-SN25508; [d=2 mm]
G' Storage Modulus
myny2b 1
PP25-SN25508; [d=2 mm]
G' Storage Modulus
chny3a 1
PP25-SN25508; [d=2 mm]
G' Storage Modulus
d
c b
a
102
103
104
105
G''
100
101
10-3
10-2
10-1
100
101
102
%
Strain
CSD
Anton Paar GmbH
spontaneously fermented maize dough without yeast 1c 1
PP25-SN25508; [d=2 mm]
G'' Loss Modulus
l.plantarum fermented maize dough without yeast1b 1
PP25-SN25508; [d=2 mm]
G'' Loss Modulus
myny2b 1
PP25-SN25508; [d=2 mm]
G'' Loss Modulus
chny3a 1
PP25-SN25508; [d=2 mm]
G'' Loss Modulusd
b
a
c
100
101
102
103
104
Pa
10-3
10-2
10-1
100
101
102
%
Strain
CSD
Anton Paar GmbH
spontaneously fermented maize dough without yeast 1c 1
PP25-SN25508; [d=2 mm]
Shear Stress
l.plantarum fermented maize dough without yeast1b 1
PP25-SN25508; [d=2 mm]
Shear Stress
myny2b 1
PP25-SN25508; [d=2 mm]
Shear Stress
chny3a 1
PP25-SN25508; [d=2 mm]
Shear Stress
b a
d c
B
A
Elastic modulus Loss modulus Shear stress
103
104
105
106
Pa
G'
20 30 40 50 60 70 80 90 100 110 120 130 140 150 160°C
Temperature T
G', G''
Anton Paar GmbH
msscny4a 1
PP25-SN25508; [d=2 mm]
G' Storage Modulus
lpny1 1
PP25-SN25508; [d=2 mm]
G' Storage Modulus
myny2b 1
PP25-SN25508; [d=2 mm]
G' Storage Modulus
chny3b 1
PP25-SN25508; [d=2 mm]
G' Storage Modulus
a b
c d
102
103
104
105
Pa·s
| *|
20 30 40 50 60 70 80 90 100 110 120 130 140 150 160°C
Temperature T
G', G''
Anton Paar GmbH
msscny4a 1
PP25-SN25508; [d=2 mm]
| *| Complex Viscosity
lpny1 1
PP25-SN25508; [d=2 mm]
| *| Complex Viscosity
myny2b 1
PP25-SN25508; [d=2 mm]
| *| Complex Viscosity
chny3b 1
PP25-SN25508; [d=2 mm]
| *| Complex Viscosity
a b
c d
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
0.7
0.75
0.8
tan( )
20 30 40 50 60 70 80 90 100 110 120 130 140 150 160°C
Temperature T
G', G''
Anton Paar GmbH
msscny4a 1
PP25-SN25508; [d=2 mm]
tan( ) Damping Factor
lpny1 1
PP25-SN25508; [d=2 mm]
tan( ) Damping Factor
myny2b 1
PP25-SN25508; [d=2 mm]
tan( ) Damping Factor
chny3b 1
PP25-SN25508; [d=2 mm]
tan( ) Damping Factora
d c
a
b
b
c
a
d
c
b
a
d
c a
c d
a c b
d
b
d c b
a
b
d
Tan delta Complex viscosity Elastic modulus
a: Maize dough. b: Chemically acidified maize dough. c: L. plantarum fermented maize dough. d: Multiple strains starter culture fermented maize dough
Effects of L. plantarum fermentation or multiple strains starter culture fermentation - Rrheological properties of maize dough A: strain sweep analysis parameters B. Temperature sweep analysis parameters
Falade AT et al. J Cereal Sci. 2014
b
b
c d
e f
10µm 10µm
10µm 10µm
10µm 10µm 10µm 10µm
Effect of Sourdough Fermentation on
Fonio Starch Granules
Unfermented Fermented
Edema MO et al. 2013 Starch/Staerke
MODIFY MAIZE ZEIN WITH LACTIC/ACETIC ACID
A = Unmodified Zein + Starch flour after mixing
B = Modified Zein + Starch flour after mixing; C = Dough properties
D = Alveograph dough bubble of Modified Zein + Starch dough
Sly AC et al. 2014. J Cereal Sci
FUTURE OF GLUTEN–FREE
PRODUCTS IN AFRICA
Combine Traditional and Modern Technologies
Beers and non-alcoholic cereal beverages • Reduce gelatinization temperature of tropical cereal starches
• Optimise tropical cereal malt beta-amylase activity
• Improve tropical cereal protein and cell wall digestibility
• Lactic acid fermentation
Breads and Baked Goods • Application of flour improvers – Enzymes etc
• Use of Hydrocolloids and Gums
• Develop novel dough-making technologies – To handle batters
• Co-proteins – Legume proteins + Cereal proteins
• Sourdough fermentation
See – Forthcoming Special Issue of the Journal of Cereal Science
“Functionality of Cereal Based Non-gluten Dough Systems” Edited by John Taylor and Cristina Rossell
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