traditional african food technologies
TRANSCRIPT
John Taylor University of Pretoria, South Africa
Traditional African Food TechnologiesSolutions to 21st Century Africa’s Challenges
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Gauteng – South Africa
NASA Satellite View June 2002
Image specially taken for for Second UN World Summiton Sustainable DevelopmentHeld in Johannesburghttps://www.jpl.nasa.gov/spaceimages
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1985 1990 1995 2000 2005 2010 2015
Urb
an p
op
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tio
n (
mil
lion
s)
Wh
eat
imp
ort
s (t
on
s x
10
00
)
Year
Wheat imports
Urban
GHANA – Wheat imports and Urban population trends(FAOStat data)
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1985 1990 1995 2000 2005 2010 2015
Urb
an p
op
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tio
n (
mil
lion
s)
Wh
eat
pro
du
ctio
n a
nd
imp
ort
s (t
on
s x
10
00
)
Year
Wheat production
Wheat imports
Urban population
NIGERIA – Wheat imports/production and Urban population trends1988-2013 (FAOStat Data)
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1985 1990 1995 2000 2005 2010 2015
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(m
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ins)
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s p
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d im
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(10
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Year
Maize production
UrbanPopulation
Wheat production
Wheat importsSorghumproduction
SOUTH AFRICA – Cereal Production and Import and Urban Population trends (FAOStat data)
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THE HYPOTHESES
1. Sub-Saharan Africa can only achieve Food Security through greatly expanded cultivation and utilization of staple Food Crops that are well-adapted to increasingly Hot and Arid climatic conditions
2. There is an Urgent need to develop Technologies to Economically Process these “Climate Smart Food Crops” into Food Products that meet the Nutritional and Lifestyle needs
of Africa’s increasingly young and urban population
3. Much can be learnt from Africa’s Traditional food and beverage Processing Technologies and Products
- What is called Indigenous Knowledge (IK)
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“Okafor (Nigerian Bakery Association head) lamented that six years on, the initiative has clearly failed
He said: "The fund was to be used to for the development of cassava bread which includes training, equipping of 5,000 bakers,
As we speak, only 1,584 bakers have been trained, only 151 bakeries have been partially equipped in a very unacceptable circumstances”
NIGERIA ABANDONED ITS
CASSAVA-WHEAT BREAD DEVELOPMENT PROGRAMME IN 2018
(From AllAfrica.com 26 April 2018)
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WHY ARE THESE INITIATIVES NOT SUCCESSFUL?
Model for Glutenin Network ElasticityLétang C. et al. 1999. J Food Eng 41:121
Startof mixing
Optimummixing
“Loops” of glutenin polymers - Glutenin Relaxed
“Trains” of gluteninpolymers H bonded together- Gluten Stretched
Loop
Wilde P. 2012 In: Breadmaking:Improving Quality. S.P. Cauvain (Ed.)
During fermentationThe Gas bubbles in Dough Expand
The Lamellae (film)between the Bubbles Comes thinner
Elastic response of GlutenRestores film
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• In Wheat bread dough with gas bubble expansion at Advanced stages of fermentation and Early stages of baking - Only Liquid Lamellae separate the Bubbles
- Bubbles are unstable• As there is no Gluten in Non-wheat doughs Lamellae between the bubbles is
essentially a liquid - Even during Early stages of fermentationHence, non-wheat doughs foams are very unstable
Gan Z et al. 1995.J Cereal Sci 21:215.
DOUGH LIQUID FILM HYPOTHESIS
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WATER → TEFF or SORGHUMor FINGER MILLET
FLOUR(or combination)
↓DOUGH MAKING(Knead by hand)
↓STARTER CULTURE
(Ersho) (from previous fermentation,
5% on flour basis)
→MIXED YEAST
AND BACTERIA (Sourdough-type )FERMENTATION
↓DIVIDE DOUGH
(3:1)→ COOK PART
OF DOUGH (Absit)(Starch Gelatinization)
↓↓ COOL
(to 45oC)↓
ADD WATER (To make batter)
← ADD BACK TO DOUGH
↓FERMENTATION
(Sourdough type)(2-3 hours)
↓POUR BATTER ONTO
BAKING GRIDDLE(50 cm. diam clay griddle (Metad)
→ BAKE(Close lid,
Bake for 2 min)
Injera making Process Highlighting Traditional
Technologies Steps
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SOURDOUGH FERMENTATION
IS ATTRIBUTED TO HAVE MANY POSITIVE EFFECTS
ON BREAD QUALITY
Acidification - Modifying bread structure-forming polymers Reduction – Breaking of protein S-S bondsAmylase and protease activities -Partial breakdown of structure-forming polymers Exopolysaccharide production -Acting as hydrocolloids
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SOURDOUGH FERMENTION OF SORGHUM + POTATO STARCH BREAD
Bread made with HydrocolloidBread made with Hydrocolloid + Sorghum Flour first Sourdough fermented with L. plantarum
Schober et al. 2007. J Agric Food Chem
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CLSM of crumb of sorghum + potato starch bread Made with b) Chemical acidificationc) Sourdough
“Results suggest that a Strong Starch Gel, without interference of aggregated protein, is desirable for Non-wheat bread”
SEC of Sorghum SourdoughDough Liquid and Protein Extracted with SDSa) Before fermentation, b) After fermentation
Schober et al. propose that positive effect of sourdough fermentation on non-wheat bread crumb structure is actually due to breakdown the storage proteins
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Effect of SourdoughFermentation on Sorghum
and FonioMixolab dough profile
Edema, M.O. et al. 2013.Starch/Stärke
Sorghum FermWheat (standard)Sorghum Unferm
Black Fonio 2 FermBlack Fonio 1 FermBlack Fonio 2 UnfermBlack Fonio 1 Unferm
White Fonio 1 FermWhite Fonio 2 FermWhite Fonio 1 UnfermWhite Fonio 2 Unferm
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b
b
c d
e f
10µm 10µm
10µm 10µm
10µm 10µm 10µm 10µm
Effect of SourdoughFermentation on Fonio Starch Granules
Unfermented Fermented
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Maize flour dough Stress-Relaxation curves
Regular doughAcidifedL. plantarum sourdoughMultiple strains sourdough
Good Evidence to support Sourdough Starch Modification by Sourdough
Dough treatment
Gelatinisation onset temp.
(oC)
Gelatinisation peak temp.
(oC)
Gelatinisation endset temp.
(oC)
Enthalpy(Delta H)
(J/g)
Regular dough
74.43a 81.09bc 88.68a 0.38a
Acidified dough
73.83a 82.05c 89.84a 0.49a
L. plantarumsourdough
72.87a 79.81b 89.84a 1.06b
Multiple strains starter culture
71.39a 77.28a 88.13a 1.13b
Thermal properties of the maize doughs
Falade AT et al. 2014. J Cereal Sci.
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Effects of Acidification and SourdoughFermentation onMaize dough and Bread Structure
Falade AT et al. 2014J Cereal Sci.
Dough
Bread
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The Custard (Batter) Breadmaking ProcessInclusion of Cooked (Pre-gelatinized) Flour – As a Hydrocolloid
1 January 1988The Nigerian Government
Banned the Importation of Wheat
The Nigerian Federal Institute of Industrial Research
Developed 70% Maize/Sorghum/Millet-
30% Cassava Batter Bread
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D.S Murty and K.A. Kumar of ICRISATTraditional uses for Sorghum and Millets
Roti“Sometimes a small quantity of Four Cooked in Water is added to the dry flour during dough preparation. The Gelatinization of part of the flour improves the Elasticity and
Cohesiveness of the Dough and produces a roti with improved quality”
1995
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Raw Maize flour+Pre-gelatinized maize flour
1 6 sheeting passes
Raw Maize flour only
5 40 sheeting passes
Making non-wheat flourDoughs using sheeting
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SORGHUM DOUGH SHEETING AND INCLUSION OF PRE-GELATINIZED FLOUR
a b c d
a) No pre-gelatinized flour, (b) 10% pre-gelatinized flour, c) 20% pre-gelatinized flour, (d) 30% pre-gelatinized flour
Magabane et al. (unpublished)
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Number of Sheeting passes1 2 3 4 5 7
5 mm 5 mm 5 mm 5 mm 5 mm 5 mm
What happens to the pre-gelatinized flour when the dough is sheeted
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Maize Pan breads made with Pre-gelatinised flour + either Gluten or Zein (Maize prolamin protein) or Sourdough or Zein + Sourdough
Strands of zein
Maize flour + pre-gelatinised maize flour +Sourdough
Maize flour + pre-Gelatinised maize flour+Sourdough + Zein
“Papery”Gas cellWalls
Linear Gas cell Walls
Proof height 18.5BLoaf height 39.3bc
Proof height 26.5CLoaf height 42.5bc
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CONCLUDING REMARKS
• Not possible to produce a Consumer-acceptable Conventional Pan-type Bread using CSFC flours retailing at “R10” a loaf
• For sub-Saharan Africa to become Food Secure we must utilise its CSFCsto produce our staple foods and beverages
• To succeed - We can learn much from Indigenous Knowledge of CSFC foods and their technologies – If it is not lost first
• Traditional African Foods and Beverages and their Technologies should be a Food Science and Technology degree module in Africa’s universities
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