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Physicochemical characteristics of grain and flour in 13 tef [Eragrostis tef (Zucc.) Trotter] grain varieties

  • Botswana University of Agriculture and Natural Resources

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In view of the limited information on tef grain and flour quality factors, 13 tef (Eragrostis tef) grain varieties were characterized for grain physical, proximate%, amylose% and flour starch pasting. The grain length (width) were ranged 1.30 (0.67)-0.51 (0.10) [mean = 1.17 (0.59)-0.61 (0.13)] mm, grain mass retained on 600 + 300 microns were about 98% and thousand kernel weight (TKW, g) were between 0.285-0.241 (mean = 0.264). The % proximate compositions are of typical for tef grain reported elsewhere. Both amylose% [25.8-20.0 (23.0)] and amylograph flour starch pasting showed that no waxy-or amylo-type starch traits in the varieties. The pasting temperature (PT) is high, because tef is a tropical C4 cereal. Tef flour starch showed less thickening ability, more shear tolerance and slow setback compared to maize starch. A variety (DZ-01-1285) with least grain protein (GPC) showed highest peak (PV), cold (CPV) and setback (SB) viscosities. The GPC was negatively weak correlated with PV (r = –0.461, p< 0.01), hot paste viscosity (HPV) r = –0.365 (p< 0.05) and break down (BD) (r = –0.360, p< 0.05) as similar reported for wheat flour starch pasting. Negative correlation (p < 0.01) between amylose%: PT (r = -0.606) and pasting time (Pt) (r = -0.460) were observed as with the normal cereal starches. However, in tef flour starch pasting, a subtle increase in the amylose% was weakly correlated toward increase of amylograph setback viscosity (SB, gelation tendencies) in part probably because of interferences of other flour components on the gelation tendency of amylose.
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Journal of Applied Sciences Research, 3(12): 2042-2051, 2007
© 2007, INSInet Publication
Corresponding Author: Geremew Bultosa, Department o f Food Science and Post harvest Technology, Box 22, Haramaya
University Campus, Ethiopia,
E-mail: Fax: 251-025-5530325 or 251-025-5530331
Physicochemical Characteristics of Grain and Flour in 13 Tef
[Eragrostis tef (Zucc.) Trotter] Grain Varieties
Geremew Bultosa
Department of Food Science and Post harvest Technology, Box 22,
Haramaya University Campus, Ethiopia.
Abstract: In view of the limited information on tef grain and flour quality factors, 13 tef (Eragrostis tef)
grain varieties were characterized for grain physical, proximate%, amylose% and flour starch pasting.
The grain length (width) were ranged 1.30 (0.67)-0.51 (0.10) [mean = 1.17 (0.59)-0.61 (0.13)] mm, grain
mass retained on 600 + 300 microns were about 98% and thousand kernel weight (TKW, g) were between
0.285-0.241 (mean = 0.264). The % proximate compositions are of typical for tef grain reported elsewhere.
Both amylose% [25.8-20.0 (23.0)] and amylograph flour starch pasting showed that no waxy- or amylo-
type starch traits in the varieties. The pasting temperature (PT) is high, because tef is a tropical C4 cereal.
Tef flour starch showed less thickening ability, more shear tolerance and slow setback compared to maize
starch. A variety (DZ-01-1285) with least grain protein (GPC) showed highest peak (PV), cold (CPV) and
setback (SB) viscosities. The GPC was negatively weak correlated with PV (r = –0.461, p< 0.01), hot
paste viscosity (HPV) r = –0.365 (p< 0.05) and break down (BD) (r = –0.360, p< 0.05) as similar
reported for wheat flour starch pasting. Negative correlation (p < 0.01) between amylose%: PT (r = -
0.606) and pasting time (Pt) (r = -0.460) were observed as with the normal cereal starches. However, in
tef flour starch pasting, a subtle increase in the amylose% was weakly correlated toward increase of
amylograph setback viscosity (SB, gelation tendencies) in part probably because of interferences of other
flour components on the gelation tendency of amylose.
Key w ords: Amylograph, Amylose, Eragrostis tef, Flour starch pasting, G rain plumpness, Injera,
Proximate composition
Tef [Eragrostis tef (Zucc.) Trotter] is indigenous
cereal crop in Ethiopia with largest share of area
(22.7 %, 2.4 million hectares) under cereal cultivation
and third (i.e. after maize and wheat) in terms of grain
production (16.3 %, 24.4 million quintals) . Tef grain
flour is widely used in Ethiopia for making injera
(staples for the majority of Ethiopians, a fermented,
pancake-like, soft, sour, circular flatbread), sweet
unleavened bread, local spirit, porridges and soups .
Tef grain commands premium price among other
cereals cultivated in Ethiopia. There is a growing
interest on tef grain utilizations because of nutritional
merits (whole grain), the protein is essentially free of
gluten the type found in wheat (alternative food for
consumers allergenic to wheat glutens) . The grain
proteins are also presumed easily digestible because
prolamins are very small . Tef grain micronutrient
is also apparently high , particularly in iron, a result
of agronomic practices used in Ethiopia and
fermentation on injera making . Because of this, the
prevalence of iron deficient anemia among tef injera
consumers in Ethiopia is low.
Information on the injera natures , nature of
micro-organisms involved in the tef fermentation for
injera making and changes in the physicochemical
properties with fermentation and on injera
baking are available. Various studies
[26,30,31,32] [35,34]
showed that in its injera making and keeping quality
features, tef grain appeared superior among other cereal
grains. Up to the year 2002, 13 tef grain varieties were
released by the Ethiopian tef improvement program for
production in the different agroecological locations in
Ethiopia . The fundamental physicochemical and
functional properties of tef starches that predicts the
processing and preservation of tef grain products seems
available for only five tef varieties .
Problem: Predictive grain and flour quality factors for
tef grain are limited and there are some complaints
also that tef grain varieties are not the same in their
injera making and keeping quality features (some poor
and some good).
J. Appl. Sci. Res., 3(12): 2042-2051, 2007
Objectives: To assess tef grain and flour characteristics
of the 13 varieties, particularly tef grain plumpness
(sizes, %mass on various test sieves and test weight),
proximate composition, flour starch amylose%, pasting
and correlation among the properties.
Tef Grain Samples: Thirteen (Table 1) released tef
grain varieties were collected from the harvest of
2004-05 of Debre Zeit tef improvement program
(DZTIP) form the breeder seed (Debre Zeit Agricultural
Research Center, Ethiopia). The grain sample was
manually cleaned by siftings and winnowing to ensure
is free from chaffs, dust and other impurities.
Grain physical characteristics:
Grain Size, % Mass on Test Sieves and Thousand
Kernel Weight (TKW): Grain samples (ca. 500g)
were sieved for 5 min with the help of a test sieve
shaker (Wykeham France Engineering Ltd., England)
through a range of sieves (250, 300, 600, 710 & 1000
microns) connected in tandem. Grain size (length and
width) on each test sieves were determined by digital
caliper (±0.01mm). Grain mass (%) was determined
after measuring the mass retained on each test sieves
on electronic balance (± 1mg). Thousand-kernel weight
was determined on analytical balance (± 0.1mg) after
counting 1000 tef grains by a seed counter (Numigral
II Chopin seed counter, France). The results on grain
size, grain mass% and TKW were reported on 12.5%
moisture basis.
Grain Proximate Composition and Flour Starch
Proximate Composition: Tef grain samples were
milled by disk attrition mill to whole flour to the
fineness level used traditionally for injera making at
the cottage tef grain-milling house (Dire Dawa,
Ethiopia). The flour was then kept in an air tight
sealed plastic bucket at refrigeration temperature
(ca 5 C) over the analysis duration. Moisture was
determined by drying approx. 2.5g flour samples by
air draft drying oven method at 130 C for 1h
(AACC Method No 44-15A) . Ash was determined
after ashing about 3g flour samples in a muffle furnace
at 550 C for over 24 h until ashing was complete
(AACC M ethod No 08-01) . Grain protein content
(GPC) was determined by taking approx. 0.3g flour
sample by micro-Kjeldahl method of nitrogen analysis
(AACC M ethod No 46-11) and urea was used as a
control in the analysis. %Protein = %N x 6.25. Crude
fat was analyzed after HCl acid (25 + 11) hydrolysis
of about 2g flours sample and extraction of the
released lipids with petroleum ether (16mL x 3)
(AACC M ethod No 30-10) . Crude fiber was
determined by taking approx. 3g flour samples as the
portion of carbohydrate that resisted dilute sulfuric acid
(1.25%) and dilute alkali (1.25%) digestions followed
by subsequent sieving (75 microns), washing, drying
and ignition (AACC Method No 32-10) .
Flour Starch Amylose%: Amylose (%) was analysed
colorimetrically by iodine binding with amylose by
taking 30-40 mg flour samples according to Charastil
. Normal maize (Merck UniLAB, code: 587 14 00)
and tef (DZ-Cr-37) starches of 27.8 and 27.2%
amylose, respectively were used as a control .
Amylose (%) was determined from the standard (0-
100% amylose of 10% variations) calibration curve.
Data were evaluated on moisture and protein
percentages free basis.
Brabender Amylograph Tef Flour Starch Pasting:
The Amylograph was obtained on 10% flour (db) basis
with Micro Visco-Amylograph (Brabender® OHG
2003, Brabender M easurement and Control Systems,
Germany) operated at 250 revmin , held at 30 C for
-1 O
1min, heated to 90 C for 5min. at a rate of 7.5 C per
min., held at 90 C for 5min. and cooled to 50 C at a
rate of 7.5 C per min. From the resulting amylograph
pasting curve, temperature at initial viscosity increase
(PT, C), pasting time (Pt, min), peak viscosity (PV,
BU), hot paste viscosity (HPV, BU) (minimum
viscosity recorded during holding duration at 90 C),
breakdown viscosity (BD, BU) (PV - HPV), cooled
paste viscosity (CPV, BU) (viscosity at the end of
cooling period) and setback viscosity (SBV, BU)
(CPV- HPV) were determined by Micro Visco-
Amylograph software (Windows version 72300,
Brabender M easurement and Control Systems,
Statistical Analysis: At least three replicate data were
analyzed by one-way analysis of variance (ANOVA),
means were compared at p < 0.05 using DMRT and
Pearson correlation coefficients (r) were calculated
among the properties by using SPSS 10.0.1 statistical
package (SPSS Inc., 1989-1999, Chicago, USA).
Grain Size, %Mass on Test Sieves and TK W: Tef
grain sizes are extremely small. The size variations
assessed after passing through test sieves (1000, 710,
600, 300 and 250 microns) showed that virtually no
grain had remained on 1000 micron. The length (L,
mm) and width (W, mm) on the highest (710 micron)
and the least (300 and 250 m icrons) were reported in
this paper (Table 1). T he varieties had grain length
J. Appl. Sci. Res., 3(12): 2042-2051, 2007
Table 1: Grain characteristics (size, mass (%) on test sieves and TKW ) of the 13 released tef varieties
Ma ss (%)#
Variety (C olor)-Relea se year Size# --------------------------------------------------------------------------------------- TK W (g)#
L (W) (mm) 710 microns 600 microns 300 microns 250 microns
DZ-0 1-354 (P ale white)-19 70* 1.29cd (0.67)d -0 .62ab(0 .13)a-d 0.73 ± 0.0 5bc 51.7 5 ± 0.6 8cd 47.48 ± 0.65e 0.05 ± 0 .01a 0.278 ±0.00 3d-f
DZ-0 1-99 (bro wn)-197 0 1.30d(0 .62)c -0.5 1a(0.12 )a-d 1.31 ± 0.07e 55.64 ± 0.14h 4 2.87 ± 0 .05c 0.0 5 ± 0.0 1a 0.283± 0.003e -f
DZ-0 1-196 (V ery w hite)-1970 1.17a-c (0.60 )a-c-0.83 (0.41) Ä3.33 ± 0.07i 61.79 ± 0.27j 34.82 ± 0.33a - 0.266±0.006c-e
DZ-0 1-787 (P ale white)-19 78 1.20 b-d (0.62 )bc -0.93 (0.40) Ä0.47 ± 0.06a 53.96 ± 0.56fg 45.30 ± 0.61d - 0.268±0.009cd
DZ-Cr-44 (White)-1982 1.14ab(0.56)a -0.66b(0.10)a 0.81 ± 0.10c 59.70 ± 1.13i 39.22 ± 1.09b 0.11 ± 0.01a 0.241±0.003a
DZ-Cr-82 (White)-1982 1.10ab(0.57)ab -0.64ab(0.14)cd 1.58 ± 0.10f 45.98 ± 0.90a 52.24 ± 0.94g 0.59 ± 0.81b 0.260±0.006bc
DZ-Cr-37 (White)-1984 1.17a-c (0.56)ab-0.65ab(0.15)d 1.83 ± 0.03g 54.60 ± 1.00gh 43.44 ± 1.00c 0.05 ± 0.01a 0.261±0.008bc
DZ-Cr-255 (White)-1993 1.13ab(0.60)a-c -0.68b(0.15)d 1.12 ± 0.05d 52.73 ± 0.57de 45.98 ± 0.64d 0.10 ± 0.01a 0.252±0.009ab
DZ-01-974 (White)-1995 1.11ab(0.58)a-c -0.60ab(0.14)cd 0.56 ± 0.04a 48.90 ± 0.21b 50.42 ± 0.26f 0.06 ± 0.01a 0.253±0.008ab
DZ-C r-358 (W hite)-199 5 1.16 a-c(0.57 )a-c -0.54a b(0.14)b -d 1.72 ± 0.25 fg 53.04 ± 0 .67ef 45.1 5 ± 0.90 d 0 .08 ± 0 .06a 0.269 ±0.00 3c-e
DZ-01-1281 (White)-2002 1.12ab(0.59)a-c -0.68b(0.15)cd 2.88 ± 0.09h 53.17 ± 0.29ef 43.70 ± 0.23c 0.17 ± 0.01a 0.262±0.005bc
DZ-01-1285 (White)-2002 1.05a(0.58)a-c -0.58ab(0.12)a-c 0.59 ± 0.06ab 51.51 ± 0.77c 47.67 ± 0.70e 0.18 ± 0.01a 0.250±0.003ab
DZ-01-1681 (Dark brown)-2002 1.23b-d(0.59)a-c -0.58ab(0.11)ab 1.36 ± 0.03e 51.34 ± 0.19c 47.13 ± 0.17e 0.07 ± 0.01a 0.285±0.020f
Mean 1.17 (0.59) -0.61(0.13) 1.12 ± 0.05 52.73 ± 0.57 45.34 ± 5.5 0.12 ± 0.23 0.264 ± 0.010
Range 1.30(0.67) -0.51(0.10) 3.33-0.47 61.79- 45.98 52.24-34.82 0.01-0.59 0.241-0.285
*Persona l communication from tef improvement program of the DZARC & B elay et al. (2005). #Values within the same column with different letters are
significantly different (p < 0.05) and are means of at least 3 determinations. Grain length (L) and width (W) are values on maximum (710) and minimum (250)
microns sieve ; Ä is value on 300 microns sieve ; TKW is thousand kernel w eight.
(width) ranged 1.30 (0.67)-0.51 (0.10) with mean of
1.17 (0.59) -0.61 (0.13). In earlier works, lengths (mm)
were reported to be ranged: 1.7-0.9 (width = 1.0-0.7
mm) . However, Umeta & Parker had noted
[17] [32]
length to be 1.2-1.0 mm. Also the DZTIP tef breeding
recent progress report had classified tef sieve-size
grades on 350, 425, 500, 600 and 710 microns ,
which is familiar to this finding. On 710 micron, the
highest grain length was for DZ-01-99 and the least
was for DZ-01-1285. In tef grain varieties DZ-01-196
and DZ-01-787 no thoroughs on 300 micron were
recorded. The % tef grain mass retained on 710 micron
test sieve was small (3.33-0.47) with mean 1.12 ± 0.05
and the highest %mass was recorded for DZ-01-196
and the least was for DZ-01-787 and DZ-01-974
(p< 0.05). The %mass on 600 micron had ranged
61.79-45.98 with mean 52.73. Tef grain DZ-01-196 is
most preferred for market because of its grain size and
white color and the highest %mass on 600 micron
was observed in this variety and the least was for
DZ-Cr-82. On 300 micron, the % mass retained had
ranged 52.24-34.82 with mean 45.34; the highest
was for DZ-Cr-82 and the least was for DZ-01-196.
The mean grain mass retained on 600 + 300 microns
was about 98%. The mass that had passed through 300
microns and retained on 250 microns were very small
The TKW for the varieties had ranged 0.285-
0.241g with mean 0 .264g, which is in the range
(0.42-0.19 g) reviewed for tef grain in . The highest
TKW was observed among DZ-01-354, DZ-01-99 and
DZ-01-1681 and the least was among DZ-Cr-44, DZ-
Cr-255, DZ-01-974 and DZ-01-1285 (p< 0.05). On the
preliminary report of Tefera & Sorrells , with an
increase in the grain size an increase in TKW and
grain yield was the trend. On this basis and the report
in probably size among tef grain populations few
might be larger than this finding or in part might be a
manifestation of the moisture level variations.
Grain Proximate Composition and Flour Starch
Amylose%: The proximate composition and amylose%
of the 13 released tef grain varieties are given in
Table 2. The moisture had ranged 11.22-9.30% with
mean 10.53% , which is in the no rmal range for field
dried tef grain . The grain protein (GP) of the
varieties are ranged 11.1-8.7% with mean 10.4%.
The GP in DZ-01-354, DZ-01-99, DZ-01-787,
DZ-Cr-44, DZ-Cr-82, DZ-Cr-37, DZ-Cr-255 and
DZ-01-1281 was the highest; and in DZ-01-1285
was the lowest (p < 0.05). The GP for tef varieties
were reviewed to range 13-9% with mean 11 % .
Belay et al. had reported for these 13 released tef
varieties in the range of 12.4-8.7% with mean 11.0%
and the highest was for DZ-01-99 and the least
was as for this finding (i.e. DZ-01-1285). The ash
content had ranged 3.16-1.99% with mean of 2.45%.
Ash in the brown tef varieties (DZ-01-99 = 3.16% and
J. Appl. Sci. Res., 3(12): 2042-2051, 2007
Table 2: Proximate composition and flour starch amylose % of the 13 tef grain varieties
Variety Moisture (% ) Grain protein (% )& Ash (% )& Crude fat (%)& Crude fibre (%)& Am ylose (%) from flour&
DZ-01-354 11.07± 0.02hi* 10.6 ± 0.7c-f 2.18 ± 0.0b 2.1 ± 0.2a 3.3 ± 0.2c-e 25.8 ± 0.7d
----------------------------------------------------------------- ---------- ---------- --------------------------------------------------------------------------------------------------
DZ-01-99 10.83± 0.13fg 10.8 ± 0.3d-f 3.16 ± 0.0f 2.1 ± 0.0a 3.8 ± 0.3e 22.9 ± 1.2bc
--------------------- ---------- ---------- ---------------------- ------------------------------------------------------------------------------------------------------------------------
DZ-01-196 9.69± 0.03b 10.4 ± 0.6b-e 2.14 ± 0.0b 2.4 ± 0.7ab 3.2 ± 0.2bc 22.1 ± 1.0bc
------- ------- -------------- ------- --------------------------------------------------------------------------------------------------------------------------------------- ------- ------
DZ-01-787 10.85± 0 .12fg 10.4 ± 0.5c-f 2.06 ± 0.0a 2.5 ± 0.5ab 3.5 ± 0.1c-e 23.8 ± 2.1cd
-------------------------------------------------------------------------------------------------------------------------------------- ------- -------------- ------- -------- ------- ------
DZ-Cr-44 9.30± 0.04a 10.7 ± 0.0c-f 2.82 ± 0.1d 2.6 ± 0.6ab 2.7 ± 0.1ab 25.6 ± 0.3d
---------------------------------------------------------------------------------------------------------------------------- ---------- ---------- ---------------------------------------
DZ-Cr-82 10.79 ± 0.14f 10.6 ± 0.3c-f 2.15 ± 0.0b 3.0 ± 0.4b 3.5 ± 0.2c-e 22.3 ± 1.6bc
-------------------------------------------------------------------------------- ---------- ---------------------- ---------- -------------------------------------------------------------
DZ-Cr-37 11.15± 0.08i 11.0 ± 0.2ef 2.54 ± 0.0c 2.0 ± 0.3a 3.3 ± 0.4cd 22.7 ± 0.6bc
---------------------------------------------------------- ---------- ---------------------- ---------------------------------------------------------------------------------------------
DZ-Cr-255 10.24± 0.08d 11.1 ± 0.1ef 3.10± 0.1f 2.5 ± 0.6ab 2.6 ± 0.2a 20.0 ± 0.4a
------------------------------------ ---------- -----------------------------------------------------------------------------------------------------------------------------------------
DZ-01-974 10.33± 0.10d 10.0 ± 0.5bc 2.16 ± 0.0b 2.1 ± 0.2a 3.5 ± 0.3c-e 22.7 ± 0.6bc
------- ------- -------------- ------- --------------------------------------------------------------------------------------------------------------------------------------------- -------
DZ-Cr-358 10.49 ± 0.06e 10.1 ± 0.2b-d 1.99 ± 0.0a 2.2 ± 0.0ab 3.5 ± 0.4c-e 22.4 ± 0.5bc
------- ------------------------------------------------------------------------------------------------------------------------------------- ------- -------- ------- -------------- -------
DZ-01-1281 11.22± 0.11i 11.1 ± 0.2f 2.52 ± 0.0c 2.5 ± 0.7ab 3.4 ± 0.5c-e 22.7 ± 1.4bc
--------------------------------------------------------------------------------------------------------------------- ---------- ---------------------- ---------- ------------------------
DZ-01-1285 9.96 ± 0.06c 8.7 ± 0.1a 2.02 ± 0.0a 2.5 ± 0.6ab 3.1 ± 0.4bc 24.2 ± 2.1cd
------------------------------------------------------------------------------------- ---------- ---------------------- ---------- --------------------------------------------------------
DZ-01-1681 10.96± 0 .04gh 9.7 ± 0.3b 2.99 ± 0.0e 2.0 ± 0.0a 3.7 ± 0.1de 21.2 ± 0.5ab
------------------------------------------------------------------------- ---------- ---------- ------------------------------------------------------------------------------------------
Mean 10.53 ± 0 .58 10.4 ± 0.7 2.45 ± 0 .42 2.3 ± 0.5 3 .3 ± 0.4 23.0 ± 1 .8
----------------------------- ---------------------- ---------- --------------------------------------------------------------------------------------------------------------------------
Range 11.22-9.3 0 11.1-8.7 3.16-1.99 3.0-2.0 3.8-2.6 25.8-20 .0
------- ------- -------------- ------- --------------------------------------------------------------------------------------------------------------------------------------------- -------
Maize s tarch (n=7) 28.4 ± 2 .0
------- ------------------------------------------------------------------------------------------------------------------------------------- ------- --------------------- -------- -------
Tef (D Z-Cr-37) starc h (n=7) 27.7 ± 1 .9
*Values within the same column with different letters are significantly different (p < 0.05) and are means of at least three determinations.
Values are on dry m atter basis
DZ-01-1681 = 2.99%) and in DZ-Cr-255 was
comparatively high and in tef varieties DZ-01-787, DZ-
Cr-358 and DZ-01-1285 appeared lowest (p < 0.05). A
review report of the ash level in tef grain had ranged
3.00-2.66% with typical value 2.8% . Apart from the
genetics, the ash levels in tef grain are influenced by
the agronomic practices used (i.e., by the degree of tef
grain unseen surface contamination mostly from the
threshing floor) . Tef grain used in this study were
from breeders and comparatively clean than purchased
from the market, hence the slightly less ash level
observed in this study are probably related to this
scenario. The crude fat had ranged 3.0-2.0% with mean
of 2.3% and the value is similar with the review report
of 3.09-2.00% of previous works . The highest crude
fat was for DZ-Cr-82 and the lowest was among DZ-
01-354, DZ-01-99, DZ-Cr-37, DZ-01-974 and DZ-01-
1681 (p < 0.05). Eventhough, germ in tef is known to
occupy large proportion as in other small grain its
crude fat is known to be not as such high. The crude
fiber (CF) had ranged 3.8-2.6% with mean 3.3%.
Apparently the crude fiber observed in these 13
varieties are almost similar with the earlier report of
3.5-2.0% with typical value 3.0% . The CF was high
among tef varieties DZ-01-354, DZ-01-787, DZ-Cr-82,
DZ-01-974, DZ-Cr-358 and DZ-01-1281 and was
highest in brown tef varieties (DZ-01-99 = 3.8% and
DZ-01-1681 = 3.7%) (p < 0.05). The CF for DZ-Cr-44
and DZ-Cr-255 were the lowest. Tef is consumed as a
whole grain, bran and cell wall materials were reported
not affected as such on tef fermentation on injera
making . The CF comprises materials that had
resisted digestions (dilute acid and base). These are
presumably major contributor for the dietary fiber of
characteristic large sto ols bulk on tef injera
The tef flour starch amylose% had ranged 25.8-
20.0% with mean 23.0%. Amylose in maize and tef
(DZ-Cr-37) starches analyzed along with the tef flour
varieties were 28.4% and 27.7% , respectively.
The amylose% in four tef starch varieties (DZ-01-99,
DZ-01-196, DZ-Cr-37 and DZ-01-1681), which their
flour included in this work were reported to range
28.8-27.2% . The lower % amylose observed in tef
flour than in tef starch of the same variety is because
other trace flour components in the flour sample
somehow slightly interferes and suppresses the starch
sample dissolution and the iodine binding with amylose
J. Appl. Sci. Res., 3(12): 2042-2051, 2007
of the blue color formation similar as reported in other
cereals . In addition, ash, fat and fiber contributions
to the total mass% sampled were also not precluded.
Among the tef flours the highest amylose% was for
DZ-01-354, DZ-01-787, DZ-Cr-44 and DZ-01-1285
and the lowest were for DZ-Cr-255 and DZ-01-1681
(p < 0.05). The starch in these 13 tef varieties
appeared normal type and no amylo- or waxy- starches
were observed and the flour starch pasting also support
this (Table 3, Figure 1). In tef grain food products, like
in tef porridges (marqaa), unfermented tef breads
(bixxille), pancakes, biscuits, soups and cookies, all
these tef grain varieties would be expected to have a
normal short stiff paste texture that would slightly vary
from each other probably by the influence of the
narrow range amylose% variations.
Brabender Amylograph Tef Flour Starch Pasting:
The pasting character predicts the processing qualities
(cooking temperature and time, thickening ability,
temperature-pressure-shear induced viscosity
breakdowns, gelling and retrogradation tendencies over
the storage durations) of starch based raw material food
ingredients. The pasting character is fundamentally
determined by the starch granule composition and its
nature (ultra-structures) and is also influenced by the
non-starch flour components. The pasting data and
pasting curves for the 13 tef grain flour starch varieties
are shown in Table 3 and Figure 1, respectively.
The pasting temperature (PT, C) (approx.
gelatinization temperature) had ranged 75.9- 67.7 with
mean 72.7. The pasting temperature is high because tef
is a C4 tropical cereal grain. The P T found in this
work is somehow similar to the reported RVA pasting
temperatures (74.8 -72.1 C) for five tef starches and
O [8]
to the starch gelatinization temperatures (64-82 C =
DSC method and 68-80 C = Kofler hot stage
method) . The highest PT was for tef varieties DZ-Cr-
82 and DZ-01-1681 and the lowest was for DZ-Cr-44
(p< 0.05).
The TKW of the varieties (Table 4) were
positively correlated with PT (r = 0.457, p< 0.01) and
pasting time, pt (r = 0.370, p< 0.05) but negatively to
the BD (r = -0.352, p< 0.05). The PT was reported
high for high amylose and vice versa among normal
starches . In this work also significant (p < 0.01)
negative correlation between amylose and PT (r = -
0.606) and between amylose and pasting time (Pt, r =
-0.460) were observed. The highest PT for DZ-Cr-82
and DZ-01-1681 (among low amylose %) and the least
for DZ-Cr-44 (among high amylose %) are most
probably related to this. The pasting time (Pt, min)
(cooking time) were ranged 6.1-5.2 with mean 5.6. The
lowest Pt was among DZ-01-354, DZ-Cr-44, DZ-01-
974 and D Z-01-1285 and the highest was for DZ-Cr-
82, DZ-01-1281 and DZ-01-1681 (p < 0.05). The
varieties Pt was slightly higher than the RVA Pt
reported (5.10-3.43 min) for five tef starches .
The peak viscosity (PV, BU) had ranged 191.3-
126.0 with mean of 158.0. The highest PV was for
DZ-01-354 and DZ-01-1285 and the lowest was for
DZ-Cr-82. The PV indicates the thickening ability and
water holding capacity of the pasted flour and reflects
the eating quality of the food products to be made.
The PV in wheat was reported be influenced positively
by the prime starch level primarily and to a lesser
extent negatively by the protein level (i.e., due to
competition for water p er se on starch gelatinization) in
sound wheat . A reduced starch amylose in the starch
granule, due to the genetic related decrease in the
granule-bound starch synthase enzyme (GBSS: ADP
glucose starch glycosyl transferase EC: was
correlated to high PV , eventhough in some work
[36] [24]
not unequivocally observed (i.e., high amylose of high
PV) for wheat starch pasting. In rice with reduced
amylose high PV was reported for varieties of wide
amylose range (28.2-6.3%) . In sorghum also high PV
was correlated with reduced amylose . In this work,
a significant positive correlation (r = 0.588, p< 0.01)
was observed between flour starch amylose and the
flour PV. It seems in normal tef (no amylo- and waxy-)
flour starch amylograph pasting, high PV is contributed
by other tef starch characters and other flour
components, but not by subtle reduced starch granule
amylose, since with narrow amylose variation (5.8%)
tef is behaving high PV with high amylose. The GPC
was negatively correlated with PV (r = –0.461, p<
0.01), HPV (r = –0.365, p< 0.05) and BD (r = –0.360,
p< 0.05) similar as reported for wheat by .
The minimum viscosity (HPV, BU) recorded
during the high temperature (90 C) of 5 min. holding
duration had ranged 157.0-115.0 with mean 134.0. The
HPV (holding strength) is the minimum apparent
viscosity recorded upon continuous shear thinning of
the gelatinised system at high temperature for defined
duration and reflects the degree of the disintegration of
the swollen systems and alignments of amylose and
other linear flour components in the direction of the
shear. The HPV is positively significantly (p < 0.01)
correlated with PV (r = 0.814) and CPV (r = 0.772),
whereas the correlation to amylose was positive but not
significant. The highest HPV viscosity was observed
for DZ-01-354 and DZ-01-1285, which have high PV.
The least HPV was observed in DZ-Cr-44 and DZ-Cr-
82 (p < 0.05). Breakdown viscosity (BD, BU) had
ranged 48.0-10.5 with mean of 24.0. The highest shear
stabilities (lowest BD) were observed among DZ-01-
196, DZ-Cr-82 and DZ-Cr-255 followed by DZ-Cr-
37, DZ-01-1281 and DZ-01-1681. The least (highest
BD) was for DZ-Cr-44 followed by DZ-01-1285,
J. Appl. Sci. Res., 3(12): 2042-2051, 2007
Table 3: Pasting properties of 13 tef grain flour varieties
Variety PT ( C) Pt (min) PV (BU) HPV (BU) BD (BU) CPV (BU) SB (BU)
DZ-01-354 71.0 ± 0.0bc 5.4 ± 0.0a-c 189.0 ± 4.6g 157.0 ± 3.5f 32.0 ± 1.7e 246.3 ± 1.5e 89.3 ± 2.1ab
DZ-01-99 73.7 ± 0.1g 5.7 ± 0.3de 148.0 ± 1.0c 125.7 ± 1.5b 22.3 ± 0.6c 232.7 ± 4.6cd 107.0 ± 3.6c
DZ-01-196 72.6 ± 0.4f 5.4 ± 0.0bc 142.7 ± 2.5bc 129.3 ± 3.5bc 13.1 ± 1.2ab 213.0 ± 4.6ab 83.7 ± 1.2a
DZ-01-787 71.6 ± 0.0de 5.4 ± 0.0bc 165.5 ± 2.1e 136.0 ± 2.6d 29.5 ± 2.1de 222.5 ± 0.7bc 86.5 ± 0.7ab
DZ-Cr-44 67.7 ± 0.3a 5.2 ± 0.1a 163.0 ± 3.5de 115.0 ± 4.0a 48.0 ± 2.0g 203.3 ± 3.8a 88.3 ± 2.5ab
DZ-Cr-82 75.7 ± 0.5J 6.1 ± 0.0f 126.0 ± 2.0a 115.3 ± 1.5a 10.7 ± 2.1a 204.7 ± 17.2a 89.3 ± 15.7ab
DZ-Cr-37 74.6 ± 0.4h 5.9 ± 0.3e 158.7 ± 7.6d 143.0 ± 6.6e 15.7 ± 1.2b 255.3 ± 9.5e 112.3 ± 3.2cd
DZ-Cr-255 73.5 ± 0.6g 5.5 ± 0.0cd 137.5 ± 0.7b 127.0 ± 1.4b 10.5 ± 0.7a 227.0 ± 1.4bc 100.0 ± 0.0bc
DZ-01-974 71.2 ± 0.1cd 5.4 ± 0.0a-c 173.0 ± 2.6f 143.7 ± 1.2e 29.3 ± 1.5de 243.3 ± 2.1de 99.7 ± 1.5bc
DZ-Cr-358 71.8 ± 0.1e 5.4 ± 0.0bc 162.0 ± 3.6de 134.0 ± 2.6cd 28.0 ± 1.7d 225.7 ± 7.6bc 91.7 ± 5.5ab
DZ-01-1281 75.1 ± 0.1i 6.1 ± 0.0f 147.0 ± 3.5c 131.0 ± 4.6b-d 16.0± 1.7b 252.3 ± 11.7e 121.3 ± 15.9de
DZ-01-1285 70.6 ± 0.2b 5.3 ± 0.0ab 191.3 ± 2.9g 152.7 ± 1.2f 38.7 ± 2.5f 284.3 ± 2.5f 131.7 ± 3.5e
DZ-01-1681 75.9 ± 0.2J 6.1 ± 0.0f 146.0 ± 1.7c 130.7 ± 1.2b-d 15.3 ± 0.6b 216.0 ± 2.0ab 85.3 ± 3.1a
Me an (Tef flour) 72.7 ± 2.4 5.6 ± 0.3 158.0 ± 19.1 134 .0 ± 12.9 2 4.0 ± 1 1.4 233.2 ± 23.7 99.2 ± 16 .0
Range (Tef flour) 75 .9-67.7 6.1-5.2 191.3 -126.0 157.0-1 15.0 48.0-10 .5 284.3-2 03.3 131 .7-83.7
DZ-0 1-99 starc h 70.5 ± 0.4 5.6 ± 0 .0 29 0.0 ± 1 .4 2 50.0 ± 2.8 40.0 ± 1.4 292.0 ± 1.4 42.0 ± 1.4
Ma ize starch 72 .5 ± 0.4 6.0 ± 0.1 418.0 ± 2.8 324.0 ± 1 .4 9 4.0 ± 1.4 413.5 ± 2.1 89.5 ± 0.7
*Values within the same column with different letters are significantly different (p < 0.05) and are means of at least 3 determinations. Where : PT = pasting
temperature, Pt = pasting time (cooking time), PV = peak viscosity, HPV = hot paste viscosity, BD = Break down viscosity, C PV = cold paste viscosity and SB
= set ba ck viscosity.
Fig. 1: Amylograph pasting curves for starches (s) (maize and DZ-01-99) and 13 tef flour (f) starch varieties
DZ-01-354, DZ-01-787 and DZ-01-974. The BD
measures the differences between PV and HPV
achieved during the high temperature (90 C for 5 min)
holding duration and shows the relative differences of
shear thinning and degree of disintegration of the
swollen systems. Tef starch and its flour starch pasting
are shear tolerant and thus had a potential for use in
foods processed under high shear conditions. The BD
was significantly (p< 0.01) correlated positively with
amylose (r = 0.667) and PV (r = 0.755) and negatively
with TKW (r = -0.352, p< 0.05), GPC (r = -0.360, p<
0.05), PT (r = -0.900, p< 0.01) and Pt (r = -0.743, p<
The cold paste viscosity (CPV, BU) had ranged
284.3-203.3 with mean 233.2. The highest CPV was
for DZ-01-1285 and the least was for DZ-01-196, DZ-
Cr-44, DZ-Cr-82 and DZ-01-1681. T he CP V is
significantly (p< 0.01) correlated positively with PV
(r = 0.630), HPV (r = 0.772) and SB (r = 0.860).
The SB (BU) had ranged 131.7-83.7 with mean 99.2.
The highest SB was for DZ-01-1281 and DZ-01-1285
and the least was among DZ-01-354, DZ-01-196, DZ-
01-787, DZ-Cr-44, DZ-Cr-82, DZ-Cr-358 and DZ-01-
1681 (p< 0.05). T he CPV and SB predict the degree of
gelation and the gradual reterogradation tendencies on
cooling and storage of the flour starch pasted system.
J. Appl. Sci. Res., 3(12): 2042-2051, 2007
Table 4: P earson correlation coeff icients amon g the gra in and flour qu ality factors in tef grain
Property TKW GPC Ash Fat Fibre Amylose PT Pt PV HPV BD CPV SB
TKW 1.000
-------------------------------------------------------- ---------- ---------------------- ---------- -------------------------------------------------------------------------------------
GPC .008 1.000
-------------------------------- ---------- ---------- ---------------------- -------------------------------------------------------------------------------------------------------------
Ash .116 .376* 1.000
------- ------- -------------- ------- -------- ------- -------------------------------------------------------------------------------------------------------------------------------------
Fat -.404* .110 -.044 1.000
------- ------- -------------- -------------------------------------------------------------------------------------------------------------------------------------- -------------- -------
Fibre .577** -.146 -.100 -.099 1.000
------- ------------------------------------------------------------------------------------------------------------------------------------- ------- -------- ------- -------------- -------
Amylose -.095 -.099 -.287 .029 -.084 1.000
----------------------------------------------------------------------------------------------------------------------------------------- ---------- ---------- --------------------------
PT .457** .230 .249 -.129 .457** -.606** 1.000
------------------------------------------------------------------------------------------------------- ---------- ---------- ------------------------------------------------------------
Pt .370* .260 .303 -.081 .464** -.460** .917** 1.000
----------------------------------------------------------------------------- ---------------------- ---------- --------------------------------------------------------------------------
PV -.136 -.461** -.398* -.203 -.101 .588** -.665** -.653** 1.000
----------------------------------------------------------------- ---------- ---------- --------------------------------------------------------------------------------------------------
HPV .110 -.365* -.435** -.330* .086 .281 -.188 -.310 .814** 1.000
----------------------------- ---------------------- ---------- --------------------------------------------------------------------------------------------------------------------------
BD -.352* -.360* -.175 .033 -.266 .667** -.900** -.743** .755** .234 1.000
------- ------- -------------- ------- -------- ------------------------------------------------------------------------------------------------------------------------------------- -------
CPV -.131 -.294 -.233 .-.287 .013 .195 -.062 -.121 .630** .772** .183 1.000
------- ------- --------------------------------------------------------------------------------------------------------------------------------------------- ------- -------- ------- ------
SB -.285 -.139 .004 -.157 -.051 .061 .060 .070 .278 .340* .082 .860** 1.000
Where: TKW is thousand kernel weight; GPC is grain protein content; PT is the pasting temperature; Pt is the pasting time; PV is the peak
viscosity; HPV is hot paste viscosity; BD is breakdown viscosity; CPV is cold paste viscosity and SB is setback viscosity. *Significant at p<
0.05 and **significant at p < 0.01
Tef starch was known to have less thickening ability,
shear tolerance and slow setback than commercial
normal maize starch on the RVA pasting and similar
is also seen in the Brabender amylograph pasting
(Table 3 and Figure 1). Tef starches were also known
to have slow reterogradation tendencies on the
refrigeration and freeze storages and freeze-thaw cycle
treatments than the maize starches . The correlation
of CPV and SB with amylose in tef flour starch
pasting was positive but insignificant, because in part
gelation tendency of amylose is suppressed by other
flour components. In addition to the known tef starches
slow starch reterogradation tendencies, probably such
weak SB (gelation tendencies) in the flour is also in
part a contributor for tef injera good keeping qualities
than injera made from other cereal flours.
Conclusions: Quality factors in tef grain and flour for
injera making are not clearly addressed to this date.
Traditionally: plump (non-shriveled), clean and non-
sprout damaged tef grain milled to optimum level of
fine powder are preferred in injera making. The grain
composition in the 13 tef grain varieties are of typical
for tef grain reported elsewhere with no amylo- or
waxy-type starch traits. The slight variations in the
pasting characteristics might be used to assess the
injera making and keeping quality variations and in
other tef grain foods. The dependency of SB (gelation
tendencies) on amylose in tef flour starch pasting is
found weak. It seems tef flour starch pasting is
different in this aspect from normal cereals like wheat,
rice, sorghum and maize.
The D ZTIP for providing tef grain varieties,
the Ethiopian Institute of Agricultural Research and
the IFS-O PCW (E/3173-2) for the financial support;
and colleagues at the department of Food Science
and Post harvest T echnology, H aramaya University
for their technical support are acknowledged for
this work.
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... The starch content of teff grain determined by the AOAC procedure was (65.65%). [16] reported that complex carbohydrates make up 80 percent of teff grain, it has a starch content of approximately 73 percent making teff a starchy cereal. Moreover, [17] reported that the total carbohydrate content of teff grain was reported to be 85.6% with starch content ranging from 74 to 75.5%. ...
... The crude fiber content was found to be (8.61%). Comparable results were obtained by [19] who reported that the crude fibre content in teff (8.0%) is far higher than when compared to some fruits, nuts, pulses and cereals such as corn and rice [16]. Stated that the crude fiber, total and soluble dietary fiber content of teff is several folds higher than that found in wheat, sorghum, rice, and maize, which could be attributed to the factor that whole grains have higher fiber content than decorticated ones. ...
... The data showed that there was no significant difference between treatments except in week six which showed a significant difference (P<0.05), in all weeks there is a gradual increase in feed intake with the increase in the level of substitution. This increase in feed intake may be due to the superiority of teff grain over sorghum grain, firstly, the teff grain is a starchy cereal with starch content accounting for 75% [16], with amylose content ranging from 20 to 30% [17], secondly, the protein content of the teff grain is superior to sorghum grain in term of quantity and quality, some researchers like [18] stated that the protein content of teff grain may reach 20% and in this study, the protein content is found to be 15% which is far higher from sorghum (10.48%) reported by [20], moreover, the quality of teff protein is better than sorghum, [13] stated that Teff's fractional protein composition revealed that the gluten (45%) and albumins (37%) are the major protein storages while prolamins are a minor constituent (less than 12%). Prolamine is a poor-quality protein with low digestibility [18], in addition to that, the amino acid composition in teff is well-balanced, a relatively high concentration of lysine amino acid is found in teff [21]. ...
Full-text available
This study aimed to determine the effect of the substitution of sorghum grain with teff grain (Eragorestis teff) on the performance of broiler chicks. The teff plant has been grown in Ethiopia and is used to prepare a kind of food called injera. The seeds were brought from the Sudanese Ethiopian Border. A total of 160 one-day-old, unsexed broiler chicks (Ross 308) were used. The birds were distributed randomly into 16 pens (10/pen) as replicates, in a completely randomized design. The experimental diets were formulated by substitution of sorghum grain with teff grain at a level of 0, 10, 15 and 20%. The chemical constituents of teff grain were measured by two methods (AOAC) and (NIR) Near-Infrared spectroscopy. The parameters measured were feed intake (FI), body weight gain (BWG), feed conversion ratio (FCR), carcass weight (CW), the weight of internal organs (liver, gizzard, pancreas, neck and heart), and serum contents (cholesterol, glucose and triglyceride). The CP percentage of teff grain was 7.96%, the starch content was (65.65%), and the fiber content was (8.61%). For chick's performance, the birds fed 20% teff consumed more feed (3403.0g), gained more weight (2040.5g), had the highest carcass weight (1733.8) and had the best FCR (1.66) than the control. For blood biochemical, the group of birds that fed 20 % teff grain 44 recorded the highest value of Glucose (113.0) and the lowest value of triglyceride (107.0) and Cholesterol (128.8). It could be concluded that the teff grain is superior to sorghum in terms of chemical constituents and broiler chicken's performance and could be a good substation for the sorghum if it is established in Sudan.
... It's high in B-vitamins and minerals, and it has larger quantities of critical amino acids than wheat and barley, making it a great source of those nutrients (Bultosa, 2016). Depending on availability and abundance, injera can be made from a variety of cereals, including teff, barley, sorghum, maize, and wheat, or a combination of some of these cereal flours (Bultosa, 2007). ...
... Injera prepared from composite flours with a larger proportion of 74% teff, 24% sorghum, and 3% fenugreek had a higher ash level. This was explained by the presence of ash in fenugreek seed flour at higher amount (up to 3.38) (Sowmya and Rajyalakshmi, 1999), followed by teff flour (up to 3.16) (Bultosa, 2007) than in sorghum (up to 2.29%) (Masresha and Belay, 2020). The ash content was obtained highly significant difference in model and linear mixture (p < 0.0001) ( Table 9). ...
Full-text available
❓ What's the best injera blending ratio? How about increasing the proportion of fenugreek flours in injera made from teff-sorghum-fenugreek mixing ratios? ▶ Learn the findings from Mr. Melaku Tafese Awulachew and Dr. Kumsa Delessa Kuffi's #preprint: 📖 Optimization and Modeling of Teff, Sorghum and Fenugreek Flour Mixing Ratios for Better Quality Characteristics of injera by Using D-Optimal Mixture Design
... In the current work, we characterized the ash produced from teff husk of four varieties from Ethiopia. Teff (Eragrostis tef) is an indigenous and one of the major cereal crops in Ethiopia [21]. In 2012, teff shares about 22.6% (about 3,098,887 ha) of arable land, and it is the third (after maize and wheat) crop in terms of annual cereal crop production in Ethiopia [22,23]. ...
... The crop generates about 5000 kg/ha of straw which makes an annual teff straw generation of 15.5 million tonnes/year [23]. Teff is a fine-stemmed and tufted annual crop characterized by a large crown, a shallow diverse root, and many shoots system [21]. There are more than 40 teff varieties in Ethiopia [24]. ...
Utilization of biomass is important both for economic and environmental projection purposes. To use biomass for industrial applications as well as to reduce its pollution load on environment, it is important to characterize and determine the compositions of the biomass. In this work, the proximate and chemical analyses of straws of four (Dagim, Filagot, Kora and Kuncho) Teff (Eragrostis tef) varieties were investigated with three replications. The thermographic and FTIR of the teff straws and the ashes were also studied. The volatile matter contents of the teff straws were 78.80, 77.00, 80.20 and 80.60% for the Dagim, Kuncho, Kora and Filagot varieties, respectively. The ash contents of the straws were 6.34% for Dagim, Kuncho and Kora while the value is 6.00% for Filagot. The fixed carbon contents of the straws were 14.86, 16.67, 13.47 and 13.40% for Dagim, Kuncho, Kora and Filagot varieties, respectively. The silica contents of the teff straw for the Filagot, Kora, Dagim, and Kuncho varieties are 5.92, 5.66, 4.94, and 4.70%, respectively. This corresponds to 92.21, 91.59, 77.19 and 87.20% silica contents in the ashes produced from Filagot, Kora, Dagim, and Kuncho varieties, respectively. The results show that the proximate and chemical composition of ash produced from teff straws show slight differences. Moreover, the silica content of the teff straw is comparable with the values reported for rice husk and wheat straw. Thus, teff straw can be used for the production of silica.
... Therefore, technologists and industries are giving more attention to other gluten-free whole grains with high nutritional profiles that can address the needs of people suffering from celiac disease and health-conscious consumers in general. Tef is among these grains for which worldwide interest and acceptance is growing rapidly, because of its attractive nutritional profile characterized by a well-balanced content of all essential amino acids, high content of minerals, polyphenols and dietary fiber [3,4]. A proximate composition study completed on 13 tef grain varieties showed that tef grain contains: moisture, 9.30-11.22% ...
... (mean 2.3%); and crude fiber 2.6-3.8% (mean 3.3%) [3]. Table 1 presents the treatment conditions used in this work and the identification of the samples used throughout the text. ...
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In recent years, many efforts are being made to produce tef-based food for its nutritive and health-promoting advantages. Tef grain is always whole milled because of its tiny grain size and whole flours contain bran (pericarp, aleurone, and germ) where major non-starch lipids could be deposited along with the lipid-degrading enzymes: lipase and lipoxygenase. As lipoxygenase shows little activity in low moisture, the inactivation of lipase is the common objective for most heat treatments to extend the shelf life of flours. In this study, tef flour lipase inactivation kinetics via hydrothermal treatments assisted using microwaves (MW) were studied. The effects of tef flour moisture level (12%, 15%, 20%, and 25%) and MW treatment time (1, 2, 4, 6, and 8 min) on flour lipase activity (LA) and free fatty acid (FFA) content were evaluated. The effects of MW treatment on flour pasting characteristics and the rheological properties of gels prepared from the treated flours were also explored. The inactivation process followed a first-order kinetic response and the apparent rate constant of thermal inactivation increased exponentially with the moisture content of the flour (M) according to the equation 0.048·exp (0.073·M) (R 2 = 0.97). The LA of the flours decreased up to 90% under the studied conditions. MW treatment also significantly reduced (up to 20%) the FFA level in the flours. The rheological study confirmed the presence of significant modifications induced by the treatment, as a lateral effect of the flour stabilization process.
... Most local Ethiopian homes prepare the grains themselves as porridge or stir-fried (Arendt & Zannini, 2013). Ethiopians create injera, a flatbread with a soft, pancake-like texture, on a large scale (Bultosa, 2007). ...
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Teff (Eragrostis tef) is a whole grain that is gluten-free and rich in nutrients, which has increased the popularity of goods based on it. Sorghum (Sorghum bicolour L.) is a vital nutritious crop and is mostly used for porridge-like traditional foods. Most cereals and starch-based foods can benefit from adding soybean (Glycine max) as a source of high-quality, low-cost protein and polyunsaturated fatty acids to increase the quantity and quality of their protein content. Although low in sulphur, it contains the amino acids methionine and cysteine and is rich in calcium, iron, and several B vitamins. Therefore, this present study aims to optimize the level of incorporation of teff, sorghum and soybean grain and flour blends to prepare value-added traditional foods such as injera, porridge and malt-based porridge through evaluation of organoleptic acceptability. The control, type I, type II and type III formulations were developed using teff, sorghum and soybean blends. The result suggests that blending teff, sorghum, and soybean in a ratio of 50:30:20 significantly improved sensory quality and fell in the group of "liked very much". These types of traditional food preparations can be eaten and liked by all age groups. This present study showed that the blending ratio and processing conditions such as soaking, fermentation and malting involved in traditional food preparations like injera, porridge and malt porridge significantly influenced sensory characteristics of blended grain or flour and also improved the sensory quality of developed foods.
... Teff [Eragrostis tef (Zuccagni) Trotter] is a native cereal grain to Africa and is used as a staple crop in Ethiopia, Eritrea, Djibouti, Sudan's south-eastern region, and northern Kenya [1]. Teff is the most intensively produced cereal grain for human consumption in Ethiopia, followed by maize [2]. ...
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Teff [Eragrostis tef (Zuccagni) Trotter] is an indigenous crop in Ethiopia, and Amhara region is the predominant teff producing region in the country. This study was aimed at developing an analytical methodology useful to determine the geographical origin of teff produced in the Amhara Region, based on multielement analysis combined with multivariate statistical techniques. For this, a total of 72 teff grain samples were collected from three zones (West Goj-jam, East Gojjam, and Awi) and analysed for K, Na, Mg, Ca, Mn, Cu, Fe, Co, Ni, Zn, Cr, and Cd contents using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The digestion and ICP-OES analysis method were accurate, with percentage recovery ranging 85.5 to 109% across the different metals analysed. Principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to discriminate samples based on their production regions. Magnesium, Ca, Fe, Mn, and Zn were the most discriminating elements among the samples. The LDA model provided 96% correct classification of samples into production regions and varietal types, with an average prediction ability of 92%. Hence, the multielement analysis combined with statistical modeling can be used in the authentication of the geographical origin and varietal type of teff from Amhara region.
... Samples: WF-wheat flour, TF-teff flour, WSF-watermelon seed flour, DWSF-watermelon seed pomace flour; Figure Table S1: Current literature data on the content of minerals as well as total protein and fat in teff and watermelon seeds and/or flours; Table S2: Correlations between the analyzed rheological parameters; Table S3: Current literature data on the total phenolic content and antioxidant activity of teff and watermelon seeds and/or flours; Table S4: Calibration parameters and results of the evaluation of linearity (regression coefficient (R2), goodness-of-fit (gof), means ± standard deviation), limit of detection (LOD), limit of quantification (LOQ), reproducibility (relative standard deviation-RSD), and recovery (means ± standard deviation) of melatonin determination in teff, watermelon seed flour and watermelon seed pomace flour. References [64][65][66][67][68][69][70][71][72][73] are cited in the Supplementary Materials (Tables S1 and S3). Data Availability Statement: Data associated with this work will be freely available upon request. ...
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Demonstrated limitations in the mineral and nutritional composition of refined flours have led to calls for the possibility of enriching them with health-promoting supplements, such as high-value non-cereal seeds. Teff and watermelon seeds have been found suitable for the production of gluten-free flour, but so far, their potential to enrich conventional baking flours has not been comprehensively studied. Hence, the present study aimed at farinographic evaluation of dough based on refined wheat flour with additions of whole white teff (TF) and watermelon seed (WSF) and pomace (DWSF) flours (tested levels 10%, 20%, and 30%), as well as possibly extensive chemical characterization of the plant material tested, including LC-MS/MS, GC-MS, total phenolics, flavonoids, melatonin, and antioxidant potential. Most of the rheological traits were improved in the flour mixtures compared to the base white flour: development time and quality number (above 1.6-fold increase), softening and stability time (up to 1.3-fold change), and water absorption (up to 6%). Overall, the best results were achieved after the addition of watermelon seed pomace. The DWSF material was characterized by the highest levels of P, Mg, Na (7.5, 1.7, 0.4 g/kg, respectively), and Fe and Zn (124 and 27 mg/kg), while TF was the richest in Ca (0.9 g/kg) and Mn (43 mg/kg). Protein and fat levels were significantly higher in watermelon seeds compared to teff (about double and up to 10-fold, respectively). Phytochemical analyses highlighted the abundance of phenolics, especially flavones, in TF, WSF and DWSF flours (244, 93, and 721 mg/kg, respectively). However, the value of total polyphenols was low in all materials (<2 mg GAE/g), which also correlates with the low antioxidant potential of the samples. Watermelon seed pomace was characterized by significantly higher melatonin concentration (60 µg/kg) than teff (3.5 µg/kg). This study provides new information on the chemical composition and application opportunities of teff and watermelon seeds.
Protein-energy malnutrition is unacceptably high among children in developing countries due to inadequate required nutrients and poor quality of complementary foods characterized by low protein and energy density and often monotonous. Thus, this research was aimed at examining the potential of including dabi teff, the underutilized/forgotten crop into pre-processed local food crops viz., germinated maize, roasted barley, roasted field pea, dehulled oats and linseed to develop energy and protein-dense optimized novel complementary food with improved sensory acceptability. Nutrisurvey software was employed to define ranges and they were constrained at 20–35% dabi teff, 0–30% field pea and 5–20% maize, while the rest were set constant at 25% barley, 15% oats and 5% linseed. Eleven experimental runs were generated from the six mixture components using D-optimal mixture design, Stat-Ease Design Expert ® software version 11. A 5-point Hedonic scale was used to evaluate the sensory attributes. ‘Scheffe’ regression was used to fit and test model adequacy and numerical multi-response optimization was performed to identify optimal points using the Design expert. Field pea and linseed contained significantly higher (P
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Tef (Eragrostis tef) is an orphan crop that is widely grown in East Africa, primarily in Ethiopia as a staple crop. It is becoming popular in the Western world owing to its nutritious and gluten-free grains and the forage quality of its biomass. Tef is also considered to have a high antioxidant capacity based on cell-free studies. However, the antioxidant activity of tef has never been validated using a physiologically relevant cell model. The purpose of this study was to investigate the antioxidant capacity of tef grain extracts using a mammalian cell model. We hypothesized that the tef grain extracts are capable of modulating the cellular antioxidant response via the modulation of glutathione (GSH) biosynthetic pathways. Therefore, we evaluated the antioxidant activity of purified tef grain extracts in the human acute monocytic leukemia (THP-1) cell line. Our findings revealed that the organic fraction of grain extracts increased the cellular GSH level, which was more evident for brown-colored tef than the ivory variety. Moreover, a brown-tef fraction increased the expressions of GSH-pathway genes, including γ-glutamate cysteine ligase catalytic (GCLC) and modifier (GCLM) subunits and glutathione reductase (GR), an enzyme that plays a key role in GSH biosynthesis, suggesting that tef extracts may modulate GSH metabolism. Several compounds were uniquely identified via mass spectrometry (MS) in GSH-modulating brown-tef samples, including 4-oxo-β-apo-13-carotenone, γ-linolenic acid (methyl ester), 4,4′-(2,3-dimethyl-1,4-butanediyl)bis-phenol (also referred to as 8,8′-lignan-4,4′-diol), and (3β)-3-[[2-[4-(Acetylamino)phenoxy]acetyl]oxy]olean-12-en-28-oic acid. Tef possesses antioxidant activity due to the presence of phytochemicals that can act as direct antioxidants, as well as modulators of antioxidant-response genes, indicating its potential role in alleviating diseases triggered by oxidative stresses. To the best of our knowledge, this is the first report revealing the antioxidant ability of tef extracts in a physiologically relevant human cell model.
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The formal tef seed sector covers a few varieties and supplies a small volume of seed to the market. The participation of the private sector is low, and the public seed system is facing several resource and institutional constraints. Thus, it cannot satisfy the existing diversified and huge seed demand. The government’s lack of confidence in the private sector usually results in a vicious circle of justifying public involvement in markets, thus, reducing the incentive and confidence of the private sector, and thereby resulting in further justification for government entry (Jayne et al., 2002; Djurfeldt et al., 2006). Therefore, a strong seed sector can contribute to a country’s economic development, when it adopts vibrant, pluralistic and market-oriented approaches. Each seed system in Ethiopia has its specific contribution to the development of the tef seed system. Thus, seed sector development strategies should develop programs upon integrating the formal, informal and intermediary seed systems. The co-existence of the different seed systems should be embraced not only because they mutually benefit from each other but also due to the fact that farmers and their communities cannot depend on one system per se. There is a lot of scope for strengthening the seed system of tef. In particular, technological backstopping, developing partnerships with the private sector, and developing capacity at the local level deserve special attention. The current varietal release system is not independent from the varietal development sector, and the process has severe capacity constraints. Post-release duties and rights of the crop variety owners are not enforced due to capacity constraints. Therefore, the establishment of an autonomous regulatory entity at the federal level that will also be responsible for conducting varietal evaluation, release, registration, and Plant Variety Protection (PVP) is crucial. There is also a need to complete revision of the draft regulations based on the new Plant Breeders’ Rights Proclamation No. 1068/2017 for immediate implementation. 445 Chapter 18: Seed Systems In spite of the availability of better tef technologies suitable for different ecologies in Ethiopia, the majority of tef EGS multiplication is handled by Debre Zeit Agricultural Research Center (DZARC). This centralized breeder seed maintenance and EGS multiplication practices by DZARC need better be decentralized to regional research centers and seed producers with suitable ecologies. Moreover, there is a need to increase the capacity of regional breeding institutions to produce higher quantities coupled with interventions to enforce contract based EGS production and use farmers' land for EGS production. Besides, expanding access to EGS of private seed companies’ access through issuing and enforcing an open and transparent application process is also important. Seed companies can improve the production of EGS in the case of limited public capacity. The seed production and supply data have shown that an increasing proportion of farmers use tef commercial seed for quality considerations. However, there are problems with the selection of tef varieties due to lack of information on the available technologies. Thus, empowerment of farmers with information through popularization and demonstration about commercial tef seed and new varieties, and strengthening of the system to protect farmer seed users would need to go a long way in developing the seed system. Certified seed production volume does not match farmers’ demand due to the absence of sound seed demand and distribution mechanism. Hence, the government needs to strengthen national seed demand estimation and local market assessment. So far, several farmers' seed producer associations involved in tef seed production have been legally established in the country. Therefore, due attention needs to be given to bring community-based seed production into picture by encouraging the engagement of innovative farmers into seed production and marketing. Hence, the implementation of the QDS quality assurance system should get due attention, and needs to be supported through decentralized farmer/village-based seed production and marketing. It is fundamental to mention that lack of a market environment reduces incentives to maximize the quality and quantity of seed availed. Efforts are made to scale up direct seed marketing (DSM) districts, and this has risen from 33 during its commencement to 228 districts in 2019. Moreover, the current involvement of private sectors in tef seed production and marketing has been growing. Currently, the seed marketing directive is in the process of validation to relax the seed marketing system. Therefore, the operationalization of the directive would help to strengthen the competitiveness of tef seed marketing system.The seed sector in Ethiopia is suffering from an inadequate quality assurance system and insufficient access to seed processing equipment. A public-private partnership business modality needs to be identified so as to develop an independent seed regulatory body that can provide services to customers.
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Starch was extracted from 10 sorghum genotypes and physicochemical properties (amylose content and pasting, textural, and thermal properties) were evaluated. The amylose content was 24-30%. DC-75 starch had the highest peak viscosity (380 Rapid Visco Analyser units). Gelatinization peak temperature occurred over a narrow range (67-69 degreesC). Genotypes Kasvikisire and SV2 produced white starches. Starches from other genotypes were different shades of pink. The starch noodles prepared were, accordingly, either white or pink. Cooking enhanced the pink coloration of noodles. Cooking loss, noodle rehydration, and elasticity were evaluated. Cooking loss was low (mean 2.4%). Noodle elasticity was highly correlated with starch pasting properties of hot paste viscosity (HPV) (r = 0.81, P < 0.01) and cold paste viscosity (CPV) (r = 0.75, P < 0.01). Noodle rehydration was significantly correlated to the initial swelling temperature of starch (T-i) (r = -0.91, P < 0.001) and gelatinization peak temperature (T-p) (r = 0.69, P < 0.05). The findings suggest a potential area of food application for sorghum genotypes of different grain colors. Evaluation of starch properties could be a good starting point for selecting sorghum genotypes with superior noodle-making properties.
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Participatory variety selection (PVS) was carried out in two of the major tef-growing woredas (districts) of Ethiopia, Ada and Akaki, in 2003 and 2004. The objectives were to identify farmers' selection criteria, to increase farmers' awareness and their access to improved tef varieties, to enable farmers to assess the performances of improved tef varieties of their choice and to accelerate seed dissemination of farmers' chosen varieties through farmer-to-farmer exchange mechanisms. Seed colour was the overriding selection criterion. Farmers overwhelmingly selected the very white seed variety DZ-01-196 (Magna) for market purposes, indicating that tef is a cash crop. Farmers also selected brown-seeded tef, but for home consumption. There was no evidence of connection between seed colour and desirable agronomic traits, or nutritional quality (protein content). Factors other than seed-colour were of secondary concern to farmers. When market demands become the dominant selection criteria, PVS should not be an end by itself: rather, it complements the formal breeding system. The results imply that tef performance evaluation trials need to be separated on a colour-group basis, and any new successful variety in the two woredas should be superior to DZ-01-196 not only in grain yield but also in seed-colour quality. A faster, more efficient and reliable pure-seed supply system than the traditional farmer-to-farmer exchange mechanism is required in order for farmers to continue planting improved varieties, which might be better achieved through small-scale commercial producers and/or cooperatives.
Starch isolated from five grain tef (Eragrostis tef) varieties was characterized and compared with commercial maize starch. Grain tef starch is formed of compound granules, comprising many polygonal shape (2-6 μm in diameter) simple granules. The crude composition is similar to that of normal native cereal starches. The amylose content ranges from 24.9 - 31.7%. Gelatinisation temperature range was 68.0-74.0-80.0 °C, typical of tropical cereal starches, and resembling the temperature range of rice starch. The mean intrinsic peak viscosity (269 RVU), breakdown viscosity (79 RVU), cold paste viscosity (292 RVU) and setback viscosity (101 RVU) determined were considerably lower than that of maize starch. Tef starch has higher water absorption index (WAI) (mean 108%) and lower water solubility index (WSI) (mean 0.34%) than maize starch.
The pasting behavior of flour from several Australian rice (Oryza sativa L.) cultivars, differing in amylose content and grown in three different locations and three seasons, were determined using the Rapid Visco Analyser. Genotype, growth season, and growth location all affected the pasting behavior of rice flour. The amylose content of the same cultivar was significantly higher in the coolest growing season, resulting in RVA traces with lower peak viscosity and higher setback than samples with lower amylose content. When the same cultivar of rice was grown in different locations in the same season, there were no significant differences in the total starch, protein, lipid, and amylose content of the flour, but there were significant differences in the pasting behavior. This indicates that environmental as well as genetic factors influence the pasting behavior of rice flour. Flour from parboiled and quick-cooking rice did not paste and had low viscosities compared with unprocessed rice. Results from this study showed that the pasting behavior of rice flour was related to genotype and was influenced by environmental factors that brought about subtle changes in the grains that were not picked up by chemical analyses.
Injera, a pancake-like fermented bread prepared from white or red tef (Eragrostis tef) flour, is the traditional staple food of Ethiopia. The fate of the major components of the bran and endosperm during the two-stage fermentation and baking has been examined by light and electron microscopy. Angular starch granules released from compound grains during milling showed a range of erosion effects typical of enzymic degradation during fermentation. The appearances of bran and embryo fragments, cell walls and protein bodies were unaffected by fermentation or baking. Microorganisms, the natural contaminants of tef grains, produced strands of fibrillar material during fermentation that bound the flour particles together. Apart from the presence of polyphenolic material in the testa cells of red tef, no structural differences were observed between red and white grain during the preparation of Injera, The portion of dough that was thinned, boiled and returned to the mixture for the second fermentation period contained swollen gelatinised starch. During cooking, the starch within the injera was totally gelatinised to form a steam-leavened, spongy starch matrix, in which fragments of bran and embryo, micro-organisms and organelles were embedded. The protein bodies played no role in the formation of the matrix-gas bubble interface.
Starch isolated from five grain tef (Eragrostis tef) varieties was characterized and compared with commercial maize starch. Grain tef starch is formed of compound granules, comprising many polygonal shape (2—6 μm in diameter) simple granules. The crude composition is similar to that of normal native cereal starches. The amylose content ranges from 24.9—31.7%. Gelatinisation temperature range was 68.0—74.0—80.0 °C, typical of tropical cereal starches, and resembling the temperature range of rice starch. The mean intrinsic peak viscosity (269 RVU), breakdown viscosity (79 RVU), cold paste viscosity (292 RVU) and setback viscosity (101 RVU) determined were considerably lower than that of maize starch. Tef starch has higher water absorption index (WAI) (mean 108%) and lower water solubility index (WSI) (mean 0.34%) than maize starch.
Chemical and physical properties of starch granules isolated from five grain tef (Eragrostis tef) varieties were characterised and compared with those of maize starch. Endogenous starch lipids extracted with hot water-saturated n-butanol and total starch lipids extracted with n-hexane after HCl hydrolysis were 7.8 mg/g (mean) and 8.9 mg/g (mean), respectively, slightly lower than in the maize starch granules. The starch phosphorus content (0.65 mg/g) was higher than that of maize starch but virtually the same as reported for rice starch. The starch granule-swelling factor was lower than that of maize starch and extent of amylose leaching was higher. The starch X-ray diffraction pattern was characteristic of A type starch with a mean crystallinity of 37%, apparently lower than the crystallinity of maize starch and more similar to that reported for rice and sorghum starches. The starch DSC gelatinisation temperature was high, like for other tropical cereals; To, Tp, Tc and ΔH were in the range 63.8—65.4, 70.2—71.3, 81.3—81.5 °C and 2.28—7.22 J/g, respectively. The lower swelling, apparently lower percentage crystallinity and lower DSC gelatinisation endotherms than maize starch suggest that the proportion of long amylopectin A chains in tef starch is smaller than in maize starch.
Bacillus sp. A-001, which produced large amounts of amylase, was isolated from fermenting tef (Eragrostis tef) on tryptone soya agar supplemented with 1% starch. The organism grew between pH 4.5 and 10.5 with an optimum at 7–7.5. Growth occurred between 20 and 55°C but the optimum was about 35–40°C. At optimum medium pH (7.5) and a temperature of 35°C the organism entered the stationary phase after about 72 h and amylase production was at its highest (9.6 units ml-1) at this time. Enzyme activity was optimal at pH 5.5 and 40°C and showed good thermal stability; it required 110 min to lose 50% of its activity at 70°C. The enzyme hydrolysed native starch (flour from tef, corn and kocho) to various oligosaccharides, including maltotriose, maltose and glucose.