sorghum in respect of their potentialcopy injera …...2018/06/11 · injera for softness and...
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Grain and Flour Quality of Ethiopian Sorghum in Respect of their Injera Making
Potential
Senayit Yetneberk, Lloyd W. Rooney, John R. N. Taylor and H.L. de Kock
EIAR UP
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Introduction• Injera is an Ethiopian fermented leavened
flat bread made from various cereal flours
• It is characterized by having “eyes” (honeycomb-like holes) on its top surface
Sorghum injera(TI 76#23)
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Introduction (continue)
• Tef is preferred for the best quality injera for softness and rollability
• Staling is a common problem to almost all baked products from sorghum
• Notwithstanding this, nearly 80% of the sorghum produced in Ethiopia is used for the production of injera (Gebrekidan and GebreHiwot, 1982)
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Objectives 1. To confirm the role of grain quality in
sorghum injera making
2. To determine the sorghum grain physico-chemical factors involved in injera making quality
3. To establish objective indicators for rapid evaluation of sorghum cultivars in terms of injera making quality
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Materials • Twelve sorghum cultivars grown in two growing
seasons at the Melkassa Agricultural Research Center, Ethiopia
• A white tef cultivar DZ-01-196 with excellent injeramaking quality is used for comparison
o These cultivars had differentendosperm texture and pericarp color
o Four cultivars had pigmented testaDO NOT C
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Measured parameters
• Kernel characterization• Flour characterization• Evaluation of injera quality attributes
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Kernel characterization
• Thousand kernel weight (TKW) • Glume color • presence of a pigmented testa • Pericarp thickness • Endosperm texture
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Kernel characterization (continues)
• Grain hardness using o Extraction rate using TADD mill o Endosperm corneousness by image
analysiso Endosperm visual evaluation
• Test weight (hectolitre weight)• Pericarp thickness image analysis
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Flour characterization
• Water solubility index • Water absorption index • Pasting property • Flour gel property
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Evaluation of injera quality attributes • A descriptive sensory analysis for objective
measurements of the attributes of injera
• Instrumental texture analysis of fresh and stored injera
o Over a storage period of 48 hrs using a three-point bending rig attachment
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Endosperm corneousness (image analysis)
o Endosperm texture varied from floury to vitreous
o Vitreous sorghum cultivar had a high extraction rate (89.7%) after abrasive decortication
Germ
Germ
Germ
CR:35:5
PGRC/E 69341
SC-108
Floury
Intermediate
More vitreousDO NOT C
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al
Differences in pericarp thickness (image analysis)
CR:35:5
SC-108
Pericarp thickness ranged from thin to thick
Pericarp thickness affects
o Milling performance
o Flour quality
o Storage property
P
P
P
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-5
0
5
10
15
20
0 5 10 15 20 25 30
Double compression of sorghum and tef flour gel aged for 24 hrs at 4 ▫C sorghum (76 TI#23) ……. and tef (DZ 01 196) ____
o The breaking point of sorghum flour gel was much lower compared to tef flour gel
o Tef flour gel almost returned back to its undeformed condition
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Steps in injera preparation
Fermentation (48 hours)
Gelatinization
Second fermentation (2-3 hrs)
Mixing with water + addition of ersho
Sorghum flour
Baking
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IS-777
AW
Seredo
CR:35:5
3443-2-op SK-82-022
Gambella 1107
PGRC/E #69349
SC-423
SC-108
Tef
-6 -4 -2 0 2 4 6
PC 1: 43.65%
-6
-4
-2
-
0
2
4
6
PC 2: 26.48% 76TI #23
PGRC/E #69441
IS-777
AW
Seredo
CR:35:5
3443-2-op SK-82-022
Gambella 1107
PGRC/E #69349
SC-423
SC-108
Tef
-6 -4 -2 0 2 4 6
PC 1: 43.65%
-6
-4
-2
0
2
4
6
PC 2: 26.48% 76TI #23
PGRC/E #69441
IS-777
AW
Seredo
CR:35:5
3443-2-op SK-82-022
Gambella 1107
PGRC/E #69349
SC-423
SC-108
Tef
-6 -4 -2 0 2 4 6
PC 1: 43.65%
-6
-4
-2
-
0
2
4
6
PC 2: 26.48% 76TI #23
PGRC/E #69441
IS-777
AW
Seredo
CR:35:5
3443-2-op SK-82-022
Gambella 1107
PGRC/E #69349
SC-423
SC-108
Tef
-6 -4 -2 0 2 4 6
PC 1: 43.65%
-6
-4
-2
0
2
4
6
PC 2: 26.48% 76TI #23
PGRC/E #69441
white-bs red-bs
eye size
eye even
gritty
sour-atsweet-at
bitter-at
-1.0 -0.5 0.0 0.5 1.0
-1.0
-0.5
0.0
0.5
1.0
PC 2 : 26.48%
red-ts
bitter
sticky
soursweet
white-ts
eyedis
shin
yflu
ffy
rollablesoft
white-bs red-bs
eye size
eye even
gritty
sour-atsweet-at
bitter-at
-1.0 -0.5 0.0 0.5 1.0
-1.0
-0.5
0.0
0.5
1.0
PC 2 : 26.48%
red-ts
bitter
sticky
soursweet
white-ts
eyedis
shin
yflu
ffy
rollablesoft
white-bs red-bs
eye size
eye even
gritty
sour-atsweet-at
bitter-at
-1.0 -0.5 0.0 0.5 1.0
-1.0
-0.5
0.0
0.5
1.0
PC 2 : 26.48%
red-ts
bitter
sticky
soursweet
white-ts
eyedis
shin
yflu
ffy
rollablesoft
white-bs red-bs
eye size
eye evengritty
sour-atsweet-at
bitter-at
-1.0 -0.5 0.0 0.5 1.0
-1.0
-0.5
0.0
0.5
1.0
PC 2 : 26.48%
red-ts
bitter
sticky
soursweet
white-ts
eyedis
shin
yflu
ffy
rollablesoft
white-bs red-bs
eye size
eye even
gritty
sour-atsweet-at
bitter-at
-1.0 -0.5 0.0 0.5 1.0
-1.0
-0.5
0.0
0.5
1.0
PC 2 : 26.48%
red-ts
bitter
sticky
soursweet
white-ts
eyedis
shin
yflu
ffy
rollablesoft
white-bs red-bs
eye size
eye even
gritty
sour-atsweet-at
bitter-at
-1.0 -0.5 0.0 0.5 1.0
-1.0
-0.5
0.0
0.5
1.0
PC 2 : 26.48%
red-ts
bitter
sticky
soursweet
white-ts
eyedis
shin
yflu
ffy
rollablesoft
white-bs red-bs
eye size
eye even
gritty
sour-atsweet-at
bitter-at
-1.0 -0.5 0.0 0.5 1.0
-1.0
-0.5
0.0
0.5
1.0
PC 2 : 26.48%
red-ts
bitter
sticky
soursweet
white-ts
eyedis
shin
yflu
ffy
rollablesoft
white-bs red-bs
eye size
eye evengritty
sour-atsweet-at
bitter-at
-1.0 -0.5 0.0 0.5 1.0
-1.0
-0.5
0.0
0.5
1.0
PC 2 : 26.48%
red-ts
bitter
sticky
soursweet
white-ts
eyedis
shin
yflu
ffy
rollablesoft
Plot of the first two principal component loading vectors of sensory attributes
Plot of the first two principal component scores of the cultivars
o Principal components (PCs) are orthogonal directions of maximum variance in the original dataDO N
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1hr
24 hr
48 hrPGRC/E #69349
Effects of storage time on maximum force required to bend
injera from sorghum (PGRC/E #69349)
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Tef
3443-2op
76TI #23
AWSK82-022
Effects of cultivars on maximum force required to bend injera
after 48 hrs of storage
Tef injera had a higher score of 8.2 for softness in a sensory evaluation
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Significant correlationsParameter Sensory textural attributes and
correlation coefficients
Maximum force required to bend injera
(texture analysis)
(after 24 hr of storage)
(after 48 hr of storage)
vs
vs
Rollability –0.47*
Softness –0.51*, rollability –0.52*,
grittiness 0.54**
Hardness (TADD) vs Softness –0.70***, rollability –0.66***
Endosperm texture (visual rating) vs Softness 0.59**
Vitreousness (image analysis) vs Softness –0.59**
Test weight (hectoliter weight) vs Softness –0.61**, rollability –0.54**DO NOT C
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Significant correlations (continues)Parameter Sensory textural attributes and
correlation coefficients
RVA parameters
Peak viscosity (flour) vs Stickiness 0.46*
Final viscosity (flour) vs Shininess 0.48*
Setback viscosity (flour) vs Shininess 0.50*
Hot-paste viscosity (flour) vs Stickiness 0.50*
Water solubility index (flour) vs Fluffiness 0.48*
Water absorption index (flour) vs Stickiness 0.45*, fluffiness –0.70***
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Conclusion• Cultivars with floury endosperm, relatively
lower test weight with low extraction rate were positively correlated with soft and rollable sorghum injera texture
• Water solubility index of the flour was positively correlated with fluffiness of injera
• These parameters have potential to be used as indirect indices in predicting the quality of sorghum injera in ESIPDO N
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Proposed selection criteria at early generation stage
Parameter/method Acceptable ranges Remarks
Pigmented testa (Chlorox Bleach Test) Absent These methods require
small sample size and
are predictive tests for
injera making potential
Pericarp color (visual rating) White preferred
Endosperm texture (visual rating) 3-5
Water solubility index (whole flour) ≥2.5 g/100 g
Water absorption index (whole flour) ≤1.5 g/g
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Proposed selection criteria at advanced generation stage
Parameter/method Acceptableranges
Remarks
Hardness (TADD) (extraction rate) 56.0-79.0%The sample size from advanced lines is large enough to prepare the actual product
Test weight (hectolitre weight) 71.0-75.0 kg/hl
Sensory textural attributes of fresh injera
Softness Score of ≥6.7
Stickiness Score of ≤2.0
Fluffiness Score of ≥6.8
Roll ability Score of ≥7.2
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Proposed selection criteria at advanced generation stage
Parameter/method Acceptableranges
Remarks
Grittiness Score of
≤2.7 The sample size from
advanced lines is large
enough to prepare the
actual product
Maximum force required to
bend injera (texture analysis)(after 24 hr of storage) ≤0.27 N
(after 48 hr of storage) ≤0.33 N
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Future research needs• It is required to test a larger number of sorghum
lines, about 15-20 cultivars across 2-3 locations
• Test exclusively soft and hard endosperm sorghum cultivars to more clearly understand the effect of grain endosperm texture
• In-depth study on the structural properties of starch components of the cultivars with high and low staling properties is required
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Acknowledgements
• The South African National Research Foundation for sponsoring me to attend this conference
• The organizing committee for inviting me to present my work
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