Food

Chemistry
Food Chemistry 95 (2006) 9–18
www.elsevier.com/locate/foodchem

Pasting properties of starch and protein in selected

cereals and quality of their food products
a,* b
Sanaa Ragaee , El-Sayed M. Abdel-Aal
a
Department of Food Sciences, College of Food Systems, UAEU, P.O. Box 17551, AL-Ain, UAE
b
Food Research Program, Agriculture and Agri-Food Canada, Guelph, Ont., Canada

Received 23 August 2004; accepted 6 December 2004

Abstract

In an attempt to improve intake of dietary fibre and antioxidants and quality of whole grain products, whole grain meals from
barley, millet, rye and sorghum were evaluated individually and in blends with wheat flour in terms of starch pasting properties and
protein heat damage, during cycles of heating and cooling in RVA tests. The whole grain meals were blended with either hard or soft
wheat flour and processed into bread, cake, cookie or snack products. The products were then evaluated with regard to physical
properties and acceptability. Significant differences were observed between cereals in starch peak, breakdown and setback viscosities
as well as in protein peak viscosity. The results showed that RVA could be used to help formulate cereal blends with certain pasting
properties. Substitution of wheat flour, with 15% of barley, rye, millet or sorghum whole grain, did not have significant detrimental
effects on physical properties or acceptability of pita bread. Additionally, replacement of wheat flour with up to 30% of barley, rye,
millet or sorghum whole grain meal had no significant effects on quality of cakes or cookies. A multigrain snack-like food was also
developed as a healthy product and was highly acceptable in a sensory test. The developed product would help enhance consump-
tion of whole grain foods, resulting in improved intake of fibre and health-enhancing components.
Ó 2005 Elsevier Ltd. All rights reserved.

Keywords: Wheat; Barley; Millet; Rye; Sorghum; Flour; Wholemeal; Blends; RVA; Pasting properties; Pita bread; Cookie; Cake; Multigrain snack;
Sensory properties

1. Introduction Kushi, & Folsom, 1998b). In general, cereal products

are recognized sources of dietary fibre and many bioac-
At present, dietary guidelines recommend an increase tive components, such as lignans, phenolic acids, phy-
in the consumption of whole grain cereal products due tosterols, minerals, tocopherols and tocotrienols. These
to their role in reducing the risk of degenerative chronic substances are mainly concentrated in the germ and out-
diseases. Several epidemiological studies have shown er layers of the kernel (Glitsø & Bach Knudsen, 1999;
that consumption of whole grain cereals is associated Hegedüs, Pedersen, & Eggum, 1985; Liukkonen et al.,
with reduced incidences of diabetes (Liu et al., 2000; 1997). In order to maintain these substances in the
Pereira et al., 2002), cardiovascular diseases (Jacobs, end-products, whole grain flours and/or fortified flours
Marquart, Slavin, & Kushi, 1998a, 1998b) and certain are recommended for the production of health-enhanc-
cancers (Jacobs, Marquart et al., 1998a, Jacobs, Meyer, ing or functional foods.
In many nations, including the developed countries,
*
Corresponding author. Tel.: +1 971 3 706 4549; fax: +1 971 3 767
the consumption of whole grain products is far below
5336. the recommendations (Adams & Engström, 2000) with
E-mail address: s.ragaee@uaeu.ac.ae (S. Ragaee). no exception for the Gulf region. In most of the Gulf

0308-8146/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.foodchem.2004.12.012
10 S. Ragaee, El-Sayed M. Abdel-Aal / Food Chemistry 95 (2006) 9–18

countries, a diet rich in food of animal origin, fat and su- abrasive debranner mill model TM05 (Satake Corpora-
gar is mainly being consumed (Al Kanhal, AL-Mohizea, tion, Japan). The grains were ground using a Cyclone
AL-Qthaimeen, & Akmal Khan, 1999; Dashti, Al-Awadi, Sample Mill (UDY Corp., Fort Collins, CO) equipped
Sawaya, Al-Otaibi, & Al-Sayegh, 2003). Additionally, with a 1.0 mm screen. The whole grain meal and wheat
white Arabic flat bread, white toast bread and highly flour samples were kept in a refrigerator prior to analy-
polished rice are the main staple foods in the Gulf re- sis and processing.
gion. Such food products provide a low dietary fibre in-
take, which results in higher incidences of constipation 2.2. Analytical methods
and related diseases, such as diverticulitis, appendicitis,
piles, diabeties, and obesity among children, adults 2.2.1. Pasting properties of starch
and elderly in the Gulf region (Eid & Bourisly, 1986; Pasting properties of starches in the whole grain
Hamadeh & Khalifa, 1998; Madani, Al-Amoudi, & meals and wheat flours and their blends were measured
Kumosani, 2000). In one study (Ragaee, Abdel-Aal, & on a Rapid Visco Analyser (RVA-4), using the RVA
Noaman, 2005), barley, pearl millet, rye and sorghum General Pasting Method (Newport Scientific Pty. Ltd.,
were adapted to grow in the United Arab Emirates Warriewood, Australia). A sample of 4.0 g of wholemeal
(UAE) environment, and were found to contain reason- or 3.5 g of wheat flour (14% moisture basis) was trans-
able levels of dietary fibre, minerals and antioxidants, ferred into a canister and approximately 25 ± 0.1 ml dis-
showing good potential as functional food ingredients, tilled water were added (corrected to compensate for
i.e. to replace part of wheat flour in wheat-based food 14% moisture basis). The slurry was heated to 50 °C
products. and stirred at 160 ppm for 10 s for thorough dispersion.
Despite growing interest in the health aspects of The slurry was held at 50 °C for up to 1 min, and then
whole grain products, good sensory properties still re- heated to 95 °C over 7.3 min and held at 95 °C for
main a key priority as a consumer choice criterion. Pro- 5 min, and finally cooled to 50 °C over 7.7 min. The
cessing could have negative or positive effects on pasting temperature (the temperature where viscosity
bioavailability of some nutrients (Clydesdale, 1994; Sla- first increases by at least 25 cp over a 20 s period), peak
vin, Jacobs, & Marquardt, 2000), but good organoleptic time (the time at which peak viscosity occurred), peak
characteristics are a prerequisite for the consumption of viscosity (the maximum hot paste viscosity), holding
whole grains. Processing must, first of all, provide prod- strength or trough viscosity (the trough at the minimum
ucts that have suitable form and good sensory proper- hot paste viscosity), final viscosity (the viscosity at the
ties. The objectives of the present study were to end of test after cooling to 50 °C and holding at this
investigate pasting properties of starch and protein of temperature), breakdown (peak viscosity holding
barley, pearl millet, rye and sorghum whole grain meals, strength or trough viscosity) and setback (final viscos-
individually and in blends with wheat flour, the basic ity holding strength) were calculated from the pasting
ingredient in making many staple foods, using a Rapid curve, using Thermocline version 2.2 software Newport
Visco Analyzer (RVA). This should help to better Scientific Pty. Ltd. (Warriewood, Australia).
understand functionality of starch and protein during In a separate experiment, stirring number (SN, the
processing of whole grain products. The wholemeal/ viscosity at 3.0 min) was measured by the RVA, as de-
flour blends were processed into several common food scribed in the applications manual using the RVA Stir-
products, including pita or flat bread, cake, cookie and ring Number Method. The SN is an indication of
snack foods. Quality and acceptability of the products amylase activity and is highly correlated with falling
were evaluated using objective and subjective methods. number. The higher SN values indicate lower amylase
activity.

2. Materials and methods 2.2.2. Quality of protein by RVA

Properties of proteins in the whole grain meals and
2.1. Materials flours were measured by the RVA Flour Ethanol Method
(Newport Scientific Pty. Ltd., Warriewood, Australia).
Three cereal crops, including barley (Hordeum volg- The properties of the RVA second peak were used to
are L.), pearl millet (Pennisetum glaucum L.) and sor- determine properties of proteins during cycles of heating
ghum (Sorghum bicolor L.), were grown at the and cooling in aqueous ethanol. Second peak tempera-
Experimental Farm, College of Food Systems, UAE ture, peak time, peak viscosity, final viscosity and break-
University. Rye was obtained from the Department of down (peak viscosity final viscosity) were calculated
Plant Sciences, University of Saskatchewan, Canada. using Thermocline version 2.2 software.
Bread and pastry wheat flours were kindly provided All RVA experiments were run in duplicate and the
by the National Flour Mills CO. (L.L.C.), Jabel Ali, coefficient of variation of viscosity properties was less
UAE. Barley and sorghum were dehulled on a Satake than 5% at any point along the curve.
 S. Ragaee, El-Sayed M. Abdel-Aal / Food Chemistry 95 (2006) 9–18 11

2.3. Processing methods sured by the rapeseed displacement method. The bread
was placed in a container of known volume (total vol-
2.3.1. Bread-making ume, Vt). The container was then topped up with rape-
Pita bread was made according to the method de- seed; after that, the bread was removed and the volume
scribed by Abdel-Aal, Sosulski, Youssef, and Shehata of rapeseed was recorded (Vs) (Abdel-Aal et al., 1993).
(1993), in which 100 g (14% moisture basis) of wheat Loaf volume was calculated as the difference between
flour (control sample) or blended flour (wheat flour plus the total volume and volume of rapeseed, i.e. (Vt Vs).
whole grain meal), 2.0 g active dry yeast, 1.5 g salt and Similarly, cake volume was measured. Specific volume
water calculated according to water absorption of each was calculated from loaf volume and loaf weight or cake
flour or blend were mixed. The maximum replacement volume and cake weight. For cookies, diameter and
level for each whole grain meal in the blends (the level height were measured.
that had no dramatic effects on quality of pita bread)
was determined using a set of preliminary baking exper- 2.5. Acceptability of end products by hedonic method
iments at several replacement levels, namely 0, 10, 15,
20% of each whole grain meal (results are not shown). All product samples were coded and evaluated for de-
The maximum acceptable replacement level (determined gree of liking or disliking on a 9-point hedonic scale,
to be 15% w/w) was identified on the basis of bread char- using descriptive categories ranging from like extremely,
acteristics (namely sensory properties, loaf diameter, through neither like nor dislike, to dislike extremely.
loaf height, and layer separation). For each blend, three The samples were presented randomly in identical con-
batches of dough were prepared and each batch was di- tainers and the panellists (15 staff) were asked to check
vided into four dough pieces prior to proofing and bak- the appropriate category on the scale. The descriptive
ing, giving a total of 12 loaves of pita bread per each categories were converted to numerical scores that were
cereal/wheat blend. subjected to analysis of variance, as outlined in Watts,
Ylimaki, Jeffery, and Elias (1989).
2.3.2. Cake- and cookie-making
Cakes and cookies were made according to the Amer- 2.6. Statistical analysis
ica Association of Cereal Chemists, Approved Methods,
10-90 & 10-52, respectively (AACC, 2003). A series of The data were subjected to analysis of variance and
preliminary baking experiments at several replacement correlation analysis using Minitab software (version
levels (0%, 10%, 20%, 30%, 40%) of each whole grain 12, Minitab inc., State College, PA) to determine differ-
meal was carried out to determine the maximum ences in pasting properties and amylase activity among
replacement level which had no significant effect on flour and whole grain samples.
the quality properties of each product (results are not
shown). Based on the quality results, a 30% replacement
level was found to produce acceptable products. 3. Results and discussion

2.3.3. Snack food product 3.1. Pasting properties of starches

A new formula using a blend of barley, millet, rye and
sorghum whole meals plus wheat flour was used to make The RVA pasting properties of wheat flours, whole
a multigrain snack food product. The formula consisted grain meals and their blends are presented in Table
of 100 g (14% moisture basis) of 10% of each cereal and 1. The shape of the pasting curve differed depending
60% of wheat flour, 1.5 g active dry yeast, 1.0 g salt and on type of cereal flour and whole grain meal (Fig. 1).
water calculated according to water absorption of the Significant differences were observed, among the cereal
blend. The ingredients were mixed for 3 min, followed samples tested, in their behaviour during heating and
by dough fermentation for 20 min at 30 °C and 85% rel- cooling in excess of water. Among flours and whole
ative humidity. The fermented doughs were cut into grains, soft wheat flour samples had the highest peak
equally small balls (about 2 cm in diameter) and allowed viscosity (PV), trough viscosity (TV), and final viscosity
to proof for 15 min at 32 °C and 90% relative humidity. (FV), while hard wheat flour exhibited much lower val-
The fermented balls were baked in a microwave oven or ues of PV, TV and FV than did soft wheat flour. Past-
deep fried for few seconds and sprinkled with salt. ing temperature and peak time were rather similar in
the flours and whole grain meals, except for sorghum,
2.4. Volume of food products which required a longer time (13.0 min) to reach max-
imum viscosity. This might be due to the lower rate of
Each baked product was allowed to cool to room absorption and swelling of starch granules, as can be
temperature (left for about one hour after baking) prior seen in Fig. 1. The PV of barley whole grain meal
to quality measurement. The volume of bread was mea- was comparable to that of hard wheat flour, millet
12 S. Ragaee, El-Sayed M. Abdel-Aal / Food Chemistry 95 (2006) 9–18

Table 1
Average RVA starch pasting properties of wheat flours, whole grain meals and their blends
Cereal grains Pasting temp. Peak time Peak viscosity Trough viscosity Final viscosity Breakdown viscosity Setback viscosity
(°C) (min) (cp) (cp) (cp) (cp) (cp)
Flours
Hard wheat 94.9 9.1 1335 560 1402 775 (58)a 842 (60)b
Soft wheat 95.0 8.9 2599 1181 2531 1419 (55) 1351 (53)
Whole grains
Barley 94.9 8.8 1355 366 1061 989 (72) 695 (66)
Millet 94.8 8.5 1130 656 2452 474 (42) 1796 (73)
Rye 95.0 8.6 1084 757 1770 328 (30) 1014 (57)
Sorghum 94.9 13.0 821 819 2126 2 (<1) 1307 (61)
Hard wheat blends (85% wheat flour + 15% l whole grain)
+ Barley 86.0 9.0 1426 512 1404 915 (64) 892 (64)
+ Millet 86.9 9.1 1363 588 1826 775 (57) 1238 (68)
+ Rye 85.9 9.1 1596 658 1686 838 (53) 1028 (61)
+ Sorghum 86.6 9.0 1476 738 1941 738 (50) 1203 (62)
Soft wheat blends (85% wheat flour + 15% cereal whole grain)
+ Barley 80.7 9.0 2073 732 1870 1341 (65) 1139 (61)
+ Millet 83.9 9.0 1956 808 2588 1148 (59) 1780 (69)
+ Rye 81.6 9.0 2370 1050 2370 1320 (56) 1347 (57)
+ Sorghum 83.5 9.0 2432 1237 2835 1195 (49) 1598 (56)
a
Values in parentheses are percentage of breakdown.
b
Values in parentheses are percentage of setback.

3000 Soft wheat

Hard wheat
Barley
Millet
2500
Rye
Sorghum
Viscosity (cp)

2000

1500

1000

500

0
0 5 10 15 20 25

Time (min)

Fig. 1. RVA pasting curves of starches in wheat flours and cereal whole grain meals.

and rye slurries, showing intermediate degree of PV, During the holding period of the viscosity test, the
whereas sorghum slurry exhibited a low PV. None of material slurries are subjected to high temperature and
the whole grain cereals had a similar viscosity profile mechanical shear stress which further disrupt starch
to hard or soft wheat flour. The results suggest that granules in the grains, resulting in amylose leaching
the cereal whole meal materials would behave differ- out and alignment. This period is commonly associated
ently during cooking and processing. The high content with a breakdown in viscosity. The ability of starches to
of starch in wheat flours compared to whole grain withstand heating at high temperature and shear stress is
meals may contribute, to some extent, to the higher an important factor in many processes. High values of
pasting viscosity. Additionally, differences in the breakdown are associated with high peak viscosities,
protein composition in these cereals could also affect which in turn, are related to the degree of swelling of
pasting viscosity and properties (Batey & Curtin, the starch granules during heating. More starch granules
2000; Morris, King, & Rubenthaler, 1997). with a high swelling capacity result in a higher peak
 S. Ragaee, El-Sayed M. Abdel-Aal / Food Chemistry 95 (2006) 9–18 13

viscosity. This was the case in the soft wheat sample, The starch pasting properties of cereal whole grain
which had a higher peak viscosity (2599 cp) and break- meals, in blend with wheat flour at 15% replacement le-
down (1419 cp) than all other samples, followed by bar- vel, showed significant effects on pasting behaviour of
ley whole grain meal and hard wheat flour (peak wheat flours (Table 1). For example, breakdown and
viscosities were 355 and 1335 cp and breakdown viscos- setback viscosities, as a percentage of peak and final vis-
ities were 989 and 775 cp, respectively). On the other cosity, respectively, became more consistent in the
hand, sorghum whole grain meal had the lowest peak blends. Additionally, replacing part of the wheat flour
viscosity (821cp) and breakdown (2 cp). The peak vis- with whole grain meals resulted in a decrease or increase
cosity often correlates with quality of end-product and in peak viscosity, depending on flour type (hard or soft),
also provides an indication of the viscous load likely and also showed synergistic effects between starches in
to be encountered by a mixing cooker. Unlike wheat the blend. In general, pasting properties of wheat flour
flours, the whole grain meals examined were stable to can be manipulated by replacing part of wheat flour
heat and mechanical shear, except for barley. with cereal whole grain meals. The replacement level
During cooling, re-association between starch mole- and type of non-wheat cereal would be determined
cules, especially amylose, will result in the formation of based on the desired pasting properties and end-uses.
a gel structure and, therefore, viscosity will increase to
a final viscosity. This phase is commonly described as 3.2. Amylase activity
the setback region and is related to retrogradation
and reordering of starch molecules. The low setback Stirring number of cereal flours and whole grain
values indicate low rate of starch retrogradation and meals was determined as an indirect measurement of
syneresis. There were significant differences in setback amylase activity. Significant variations in stirring num-
values between cereal flours and whole grain meals. ber were observed between cereal grains (Fig. 2). Soft
When the setback was calculated as a percentage of fi- wheat flour had the highest stirring number (lowest
nal viscosity, soft wheat and rye had lower setback per- amylase activity), followed by barley whole grain meal.
centages, followed by hard wheat, sorghum and barley Sorghum and millet had the highest amylase activity,
at intermediate setback, and finally millet at 73% as indicated by their lower stirring numbers. Hard wheat
setback. flour and barley whole grain meal were intermediate in
The results of RVA starch pasting properties indicate amylase activity. The level of amylase activity in grains
that peak viscosities of barley, millet and rye whole influences viscosity of starch, and thus pasting proper-
grain meals are somewhat comparable to that of hard ties of their flours during processing. Several factors
wheat flour with better paste stability, except for barley, (such as pH, temperature, presence of minerals) can be
and could be used to replace part of the wheat flour in used to control amylase activity and pasting properties
several food formulas. Sorghum had the lowest peak vis- of cereal flours and wholemeals.
cosity but it showed the highest paste stability, as indi-
cated by the lowest breakdown. This indicates that 3.3. Quality of proteins
sorghum whole grain meal may have good potential as
a food ingredient for food exposed to heat treatment Little information is available on using RVA for
at high temperature and mechanical stirring. measuring quality of cereal proteins. RVA was used in

4000

3000
Stirring number (cp)

2000

1000

0
Hard wheat Soft wheat Barley Millet Rye Sorghum

Fig. 2. Stirring number of wheat flours and cereal whole grain meals.
14 S. Ragaee, El-Sayed M. Abdel-Aal / Food Chemistry 95 (2006) 9–18

an attempt to determine quality of proteins in cereal flour in PTm, PV, FV and breakdown, indicating signif-
grain flours and whole grain meals on the basis of pro- icant variations in protein properties when subjected to
tein damage when it is heated in aqueous ethanol. The heating and cooling treatments. Significant differences
viscosity of proteins subjected to heating and cooling cy- were also observed among cereal whole grain meals in
cles were measured as a function of time, temperature PT, PTm, PV, FV and breakdown, showing different re-
and mechanical shear. The second peak of the RVA sponses of proteins in these cereals. These results suggest
curve was used to determine protein properties, includ- that RVA can differentiate between cereal flours and/or
ing peak time (PT), peak temperature (PTm), peak vis- whole grain meals in terms of protein quality and
cosity (PV), final viscosity (FV) and breakdown. characteristics.
Significant differences in these parameters were observed Wheat flours and barley whole grain meal slurries
between wheat flours (hard versus soft) and among cer- had higher second peak viscosities than did other flour
eal whole grain meals (Table 2). Additionally, the shape and whole grain samples. The peak viscosity was ob-
of the second peak was unique for each cereal (Fig. 3). served during the cooling cycle at somewhat similar
Hard wheat flour significantly differed from soft wheat times (peak time 19–20 min). This may be explained

Table 2
Average RVA protein heat damage properties of wheat flours, whole grain meals and their blends
Cereal grains Peak temp. (°C) Peak time (min) Peak viscosity (cp) Final viscosity (cp) Breakdown viscosity (cp)
Flours
Hard wheat 40.7 19.0 1766 246 1520
Soft wheat 30.0 21.5 2578 822 1756
Whole grains
Barley 66.8 19.8 2117 1249 868
Millet 49.0 17.1 1004 108 896
Rye 34.1 21.0 1558 675 883
Sorghum 44.0 18.2 387 129 258
Hard wheat blends (85% wheat flour + 15% whole grain)
+ Barley 42.1 19.0 1975 595 1380
+ Millet 48.5 17.0 2064 324 1740
+ Rye 43.0 18.5 2009 443 1566
+ Sorghum 46.0 19.5 1889 344 1545
Soft wheat blends (85% wheat flour + 15% whole grain)
+ Barley 39.1 20.0 2415 620 1795
+ Millet 48.0 18.0 2669 411 2258
+ Rye 38.5 20.0 2490 669 1821
+ Sorghum 42.9 19.0 2468 379 2089

3000
Soft wheat
Hard wheat
2500 Barley
Millet
Rye
Sorghum
2000
Viscosity (cp)

1500

1000

500

0
0 10 20 30 40

Time (min)

Fig. 3. RVA heat damage curves of proteins in wheat flours and cereal whole grain meals.
 S. Ragaee, El-Sayed M. Abdel-Aal / Food Chemistry 95 (2006) 9–18 15

by similar storage proteins in wheat and barley, namely, (Fig. 4). This correlation may indicate degree of starch
prolamines or alcohol-soluble proteins. Rye, which be- gelatinization, level of protein denaturation and their
longs to the same tribe as wheat and barley, also had interaction. This phenomenon warrants further investi-
a relatively higher second peak viscosity than had millet gation using a large number of cereal grains to better
or sorghum. Still, there were substantial differences be- understand interaction of protein and starch during
tween millet and sorghum in the second peak viscosity. heating and cooling cycles.
Significant differences were also observed in the final
and breakdown viscosities among cereal whole grain 3.4. Physical properties and acceptance of end products
meals. It seems that RVA can be used to characterize
proteins in non-wheat cereal grains. This requires fur- Incorporation of 15% of barley, millet, rye or sor-
ther investigation to better understand RVA data in ghum whole grain meal into a baking formula of pita
relation to quality of these grains. Little or no informa- bread had very little effect on bread specific volume or
tion is reported on using RVA to study protein quality loaf height as compared with the control bread sample
of non-wheat cereal grains. Protein quality of wheat (100% wheat flour) (Fig. 5). The blends produced breads
flour/cereal wholemeal blends was different from wheat that were characterized by good-looking appearance,
flours, the base material in the blends. In the case of two-layers or pocket-type bread and were comparable
hard wheat blends, the viscosity of proteins changed to the control bread, except for having a darker colour,
due to replacing part (15%) of the flour with cereal particularly in the case of millet and sorghum breads.
whole grain meals. For soft wheat blends, addition of Colour of bread varied, depending upon the type of
barley and rye resulted in reduction in PTm, while addi- non-wheat cereal incorporated in the blend. The
tion of millet and sorghum increased PTm. Peak times wheat/sorghum blend produced breads having the dark-
were almost similar in soft wheat blends and flours, est crust, perhaps due to high concentration of the red
while peak and final viscosities were reduced compared pigments in the outer layers of the grains. The crusts
to soft flour alone, except for peak viscosity of millet of the breads made from wheat/millet and wheat/rye
blend. It seems that replacing part of wheat flour with blends were slightly darker than the control breads,
cereal whole grain meal not only changes pasting prop- while the crust of the bread baked from wheat/barley
erties of starch, but also the protein composition of the blend was almost similar to the control sample. The
blends. coarsest texture was obtained with the bread made from
In general, the RVA results indicate that cereal flours wheat/millet blend, while the other breads had a firm-
and whole grain meals have a wide range of pasting ness that was similar to the control sample. The sensory
properties, and RVA could be used to help formulate test showed that substitution of wheat flour with 15% of
cereal blends with certain pasting properties. When barley, rye, millet or sorghum whole grain meal did not
starch and protein peak viscosities of individual flours, have significant adverse effects on overall acceptability
whole grain meals and blends (12 samples) were sub- of pita bread (Fig. 8). The overall acceptability was
jected to statistical analysis, a significant correlation categorized as ‘‘like very much’’ for barley and rye
(r = 0.8342) was found between the two peak viscosities and ‘‘like moderately’’ for millet and sorghum. Similar

3000

2500
Protein peak viscosity (cp)

2000

r=0.8342
1500

1000

500

500 1000 1500 2000 2500 3000

Starch peak viscosity (cp)

Fig. 4. Relationship between starch peak viscosity and protein peak viscosity of wheat flours, cereal whole grains and blends.
16 S. Ragaee, El-Sayed M. Abdel-Aal / Food Chemistry 95 (2006) 9–18

sensory results for wheat/sorghum and wheat/millet non-wheat-containing cakes (Fig. 8). In our previous
breads were obtained by Munck (1994) and Dendy study, the whole grain meals were found to have higher
(1992) and for wheat/rye bread by Heinio, Liukkonen, levels of dietary fibre, minerals and antioxidants than
Katina, Myllymaki, and Poutanen (2003) Ragaee, had wheat flours (Ragaee et al., 2005). This would help
Campbell, Scoles, McLeod, and Tyler (2001). improve nutritional quality of such baked products,
Substitution of wheat flour with 30% of barley, rye, resulting in higher dietary intake of fibre and health-
millet or sorghum whole grain meal had no significant ef- enhancing components.
fects on the quality (i.e. cookie height and diameter) of A blend of barley, millet, sorghum and rye whole
cookie products (Fig. 6). The height and diameter of grain meal plus wheat flour and food additives was for-
cookies were almost similar in whole grain and control mulated and processed into a healthy snack product.
samples. The acceptability test of cookies showed no sig- The acceptability of the developed cereal-based snack-
nificant differences between cereal whole grain-contain- like food product was assessed by measuring degree of
ing cookies and 100% wheat flour cookies (Fig. 8). liking on a hedonic scale (Fig. 8). The snack food prod-
In the case of cakes, specific volume of control sam- uct was categorized as ‘‘like very much’’, based on over-
ples was slightly higher than those of whole grain- all acceptability. Studies on the nutritional quality and
containing cakes (Fig. 7). Additionally, the sensory test nutrient bioavailability in the developed multigrain
showed no significant differences between control and snack product are underway.

Specific volume
8 Loaf height (cm)
Specific volume/Loaf height (cm)

0
Wheat control + Barley + Millet + Rye + Sorghum

Fig. 5. Specific volume and loaf height of pita breads baked from control flour and cereal whole grain blends.

Cookie height (cm)

6 Cookie diameter (cm)
Cookie height or diameter (cm)

0
Wheat control + Barley + Millet + Rye + Sorghum

Fig. 6. Height and diameter of cookies made from control flour and cereal whole grain blends.
 S. Ragaee, El-Sayed M. Abdel-Aal / Food Chemistry 95 (2006) 9–18 17

3.0

2.5

2.0

Specific volume
1.5

1.0

0.5

0.0
Wheat control + Barley + Millet + Rye + Sorghum

Fig. 7. Specific volume of cakes made from control flour and cereal whole grain blends.

Wheat
10
+ Barley
+ Millet
Overall acceptability (9-point scale)

+ Rye
8 + Sorghum

0
Bread Cookie Cake Multigrain snack

Fig. 8. Overall acceptability of pita bread, cookie, cake and snack food products made from control flour and cereal whole grain blends on a 9-point
hedonic scale by a sensory test.

4. Conclusions Acknowledgements

The high contents of dietary fibre and antioxidants in Financial support from the Research Affairs at the
whole grain products provide a fundamental basis for UAE University (contract number 17-7-11/02) is greatly
incorporation of such grains into foods as health- appreciated. The authors are also thankful for the
enhancing ingredients. Surprisingly, the whole grain- excellent technical assistance provided by Mr. I. Abdel-
containing bakery products (pita bread, cake and Haliem and Mrs. I. Rabalski.
cookie) were comparable with the control products
(100% wheat flour) in terms of physical properties and
acceptability. This could encourage consumption of
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