Use of coconut flour as a source of protein and dietary fibre in wheat bread

Abstract

Bread made with wheat flour is an important part in the diet of many Sri Lankan. A substantial
amount of refined wheat flour imported from Europe is being used by bakeries. However, refined
wheat flour is not a good source of dietary fibre and protein. An attempt was made to utilize
coconut flour, a byproduct of the Virgin Coconut Oil (VCO) industry for the partial substitution of
wheat flour. Chemical analysis of coconut flour revealed that it contains 21.65% protein, 10.45
fibre, 59.77% carbohydrates and 8.42% fat. The fibre fraction contains 38.3% neutral detergent
fibre, 24.4% acid detergent fibre, 14.1% hemicelluloses, 10.3% celluloses and 38.0% dietary fibre.
Wheat-coconut flour blends were prepared by incorporating 10%, 20% and 30% coconut flour in all
purpose wheat flour. Blends were evaluated for bread making qualities. Mixing behaviour (water
absorption, arrival, dough development time and stability) of the blends was determined by
Farinograph. Water absorption decreased with the increase in substitution, whereas dough
development time, arrival time and stability were increased up to 20% substitution level. However,
at 30% level, an unstable Farinogram was observed. Breads were evaluated for sensory properties
(general appearance, crust colour, crumb grain, texture and taste). Coconut flour addition up to 10%
was ranked ‘good’ and 20% ranked ‘satisfactory’, whereas 30% substitution negatively affected
appearance, texture and overall acceptability of the product, ranked ‘poor’ in sensory evaluation.
This study revealed that up to 20% substitution is possible to produce bread with acceptable
qualities.

Full text

As. J. Food Ag-Ind. 2009, 2(03), 386-395
Asian Journal of
Food and Agro-Industry
ISSN 1906-3040
Available online at www.ajofai.info
Research Article
Use of coconut flour as a source of protein and dietary fibre in wheat
bread
K.D.P.P. Gunathilake*, C. Yalegama and A.A.N. Kumara
Coconut Processing Research Division, Coconut Research Institute, Bandirippuwa Estate, Lunuwila,
Sri Lanka.
*Author to whom correspondence should be addressed, email: kdppgunathilake@yahoo.com
Abstract
Bread made with wheat flour is an important part in the diet of many Sri Lankan. A substantial
amount of refined wheat flour imported from Europe is being used by bakeries. However, refined
wheat flour is not a good source of dietary fibre and protein. An attempt was made to utilize
coconut flour, a byproduct of the Virgin Coconut Oil (VCO) industry for the partial substitution of
wheat flour. Chemical analysis of coconut flour revealed that it contains 21.65% protein, 10.45
fibre, 59.77% carbohydrates and 8.42% fat. The fibre fraction contains 38.3% neutral detergent
fibre, 24.4% acid detergent fibre, 14.1% hemicelluloses, 10.3% celluloses and 38.0% dietary fibre.
Wheat-coconut flour blends were prepared by incorporating 10%, 20% and 30% coconut flour in all
purpose wheat flour. Blends were evaluated for bread making qualities. Mixing behaviour (water
absorption, arrival, dough development time and stability) of the blends was determined by
Farinograph. Water absorption decreased with the increase in substitution, whereas dough
development time, arrival time and stability were increased up to 20% substitution level. However,
at 30% level, an unstable Farinogram was observed. Breads were evaluated for sensory properties
(general appearance, crust colour, crumb grain, texture and taste). Coconut flour addition up to 10%
was ranked ‘good’ and 20% ranked ‘satisfactory’, whereas 30% substitution negatively affected
appearance, texture and overall acceptability of the product, ranked ‘poor’ in sensory evaluation.
This study revealed that up to 20% substitution is possible to produce bread with acceptable
qualities.

As. J. Food Ag-Ind. 2009, 2(03), 386-395 387
Introduction
Coconut plays an important role in the diet of the people in Sri Lanka supplying about 22% of the
total calories, second only to rice. Coconut production in Sri Lanka in 2008 was estimated as 2,776
million nuts [1], of which over two thirds were consumed domestically. Sri Lanka offers a wide
variety of kernel-based food products to the international market. Research and development on
coconut-based food products has taken place over a long period of time and new knowledge and
technologies have contributed to the diversification of products and byproducts which have in turn
opened up new industries in Sri Lanka. Virgin coconut oil (VCO) is a recently emerging high
demand product in the world and various types of cold presses are used for extraction of VCO from
the coconut kernel at low temperature. The whitish residue remained after extracting VCO from
cold press can be milled to flour [2]. Trinidad et al [3], reported that coconut flour can provide not
only value added income to the industry, but also a nutritious and healthy source of dietary fibre.
Coconut flour may play a role in controlling cholesterol and sugar levels in blood and prevention of
colon cancer. Studies revealed that consumption of high fibre coconut flour increases fecal bulk [4].
Bread made with wheat flour is an important part of the diet of many Sri Lankans. A substantial
amount of wheat flour imported from Europe is used in bakeries. However, refined wheat flour is
not a good source of dietary fibre. Therefore, partial substitution of wheat by other locally available
raw materials in the bakery can be undertaken in order to improve the nutritional value of bread.
Reduction of dependence on wheat imports will also lead to savings in foreign currency. Rodgers
[5], has described the necessity of having efficient, environmentally friendly research for the
conversion of industrial by-products into functional ingredients, including coconut flour made from
coconut residue. It is thus apparent that coconut flour can be incorporated with wheat flour in order
to improve the health benefits of bread. Similarly, many studies have been conducted to assess the
possibilities of adding natural ingredients to improve the nutritive value of wheat bread [6, 7, 8, 9,
10]. Masoodi [11], has studied the possibilities of incorporating apple pomace as a source of dietary
fibre in wheat bread. Researchers also have recommended the addition of wheat bran, wheat whole
grain and mixtures of different seeds, grain of other cereals (oat, rye and barley), dry fruit or
probiotic bacteria to improve the nutritional status of various wheat food products [10].
This present study was thus undertaken with the objective of utilizing coconut flour for human
consumption as a source of dietary fibre and protein. This paper reports on the effects of coconut
flour on some baking properties of wheat flour bread.
Materials and Methods
Preparation of flour
Different mixtures of all purpose wheat flour and coconut flour were used in this study. The
coconut flour was made from coconut residue after extracting VCO and was ground into fine
particles using a grinder (model HL 3294/C Phillips) and was then sieved using US mesh 100 to
obtain the coconut flour. This coconut flour was mixed with all purpose wheat flour at the levels of
10%, 20% and 30%. One hundred percent all purpose wheat flour used as the control. All purpose
wheat flour was purchased from a local super market in Colombo (Sri Lanka) under the brand name
of “Prima”.

As. J. Food Ag-Ind. 2009, 2(03), 386-395 388
Farinograph properties
Three hundred grams of different blends of wheat flour and coconut flour were mixed with the
required amount of distilled water. Water absorption, dough development time, arrival time and
stability were determined using the Farinograms of the Brabender OHG Duisburg (West Germany)
instrument.
Baking
Breads were prepared by dry mixing of wheat flour with different levels (0%, 10%, 20% and 30%)
of coconut flour. The blends were then again passed through a 30 mesh sieve for their uniform
mixing. Yeast breads were prepared from all blends and straight dough development procedure [12]
was used with slight modification for baking studies. The ingredients for two loaves are given
below:
Flour/blend: 500g
Compressed yeast: 5g
Sucrose: 10g
Shortening (vegetable fat):10g
Salt: 7g
Water: 300ml
Fermentation was conducted at 300C. Total fermentation period of dough was 150 min with first
punching after 90 min and second after an additional 35 min. Baking was done at 2300C for 25 min.
Figure 1 shows the flow chart of bread making process.
Weighing of ingredients Standard Mixing Fermentation
Rounder Divider Fermentation Punch back on standard mixer
Short recovery period Moulding Panning Final Proof
Baking
Figure 1.Flow chart of bread making process.
Chemical analysis
Moisture content (Oven dry method), fat content (Soxhlet extraction), crude fibre content and ash
(Gravimetric) content were determined according to methods proscribed by AOAC [13]. Protein
content was determined by the method described by Pearson [14]. Carbohydrate content was

As. J. Food Ag-Ind. 2009, 2(03), 386-395 389
determined by difference. Coconut flour was analyzed for different fibre fractions. Dietary fibre,
neutral detergent fibre, acid detergent fibre, hemicellulose and cellulose [15].
Sensory Evaluation
A sensory evaluation was undertaken to assess the bread quality using 50 consumer panelists with
the following score card (Table 1). Samples were coded with three digit random numbers and
served in random order for the panelists. Panelists were asked to rank each quality parameter of the
bread.
Table 1. Sensory scoring.
Sensory Attributes Scores
General appearance
Crust colour
Crumb grain
Texture
Taste and odour
Total
25
10
20
20
25
100
Acceptability of the breads was determined according to the following grading (Table 2).
Table 2. Acceptability ratings.
Grading score Acceptability
rating
91-100
81-90
66-80
51-65
50-less
Excellent
Good
Satisfactory
Fair
Poor
Statistical analysis
The data were analyzed and means and standard deviation were determined. Mean comparison was
done using ANOVA and Independent sample t-test using SPSS 10 statistical package.

As. J. Food Ag-Ind. 2009, 2(03), 386-395 390
Results and Discussion
Table 3 shows the proximate composition of coconut flour and all purpose commercial wheat flour
while Table 4 shows the various fibre fractions.
Table 3. Nutrient composition of coconut flour and all purpose wheat flour.
Component All purpose wheat
flour
Coco flour from
cold press
Moisture
Ash
Fat
Protein
Crude fiber
carbohydrates
9.76± 0.12
0.51±0.10
0.87±0.13
9.90±0.21
0.50±0.10
78.46±0.15
4.20±0.23
5.96 ±1.19
8.42 ±0.87
21.65±0.06
10.45± 2.50
59.77 ±3.32
Table 4. Different fibre fractions present in coconut flour.
Fibre fraction Percentage
Neutral detergent fibre
Acid detergent fibre
Hemi cellulose
Cellulose
Dietary fibre
38.3± 0.4
24.2±0.5
14.1±0.8
10.3±0.5
38.0±0.8
Different research using different methods has come up with different figures for coconut flour
composition [16]. Composition of coconut flour depends on the retention of components after the
extraction of coconut milk or oil from scraped/desiccated coconut. Therefore, composition of
coconut residue also will change proportionately. Hagenmaier [17], reported that coconut flour
contains 7.6% protein, 14% oil, approximately 17% crude fibre and 5% moisture. According to
Arancon [2], nutrient composition of coconut flour is mentioned as; protein 13.41%, moisture
2.80%, crude fat 10.23% and crude fibre 19.3%. Trinidad, et.al [18], showed that the dietary fibre
content of coconut flour was 60.0 +/- 1.0g/100g sample, 56% insoluble and 4% soluble. Further,
they described that the total dietary fibre content of coconut flour was greater than other dietary
fibre sources such as oat bran (8.3g/100g) and flaxseed (28.0g/100g). Ash, fat, moisture and protein
content of wheat flour used in this experiment were 0.51%, 0.87% and 9.76% and 9.9%,
respectively, on dry weight basis.
Neutral detergent fibre and acid detergent fibre obtained from the Vansoest method was 38.3% and
24.2% respectively. The coconut flour contained 14.1% hemicelluloses, which consist mostly of
acid soluble carbohydrates. Cellulose, the most insoluble fibre, is 10.3% in coconut flour. These
results indicated that coconut flour is rich in different types of edible fibres.

As. J. Food Ag-Ind. 2009, 2(03), 386-395 391
The use of a substitute for wheat flour affects the nutritive value of the product. The protein content
of the wheat flour for bread making generally ranges from 10-14%. The protein content of coconut
flour is about 21%. Thus the partial substitution of wheat flour by non-wheat flours, such as
coconut, slightly increases the protein content. According to Bressani, et al [19], cereal protein,
including wheat, is limited in lysine content and they also recommended that the biological value of
wheat flour can be significantly improved by the addition of lysine. Boceta, as cited by Barrett et.al
[20], stated that coconut flour when incorporated into wheat flour increases the amino acid content,
especially lysine. Therefore, incorporation of coconut flour into wheat flour improves the protein
content of composite flour and thus improves the nutritional status of food items such as bakery
products made from that composite flour.
(A) 100% Wheat Flour (B) 10% Coco Flour,
90% Wheat Flour

As. J. Food Ag-Ind. 2009, 2(03), 386-395 392
(C) 20% Coco Flour (D) 30% Coco Flour
80% Wheat Flour 70% Wheat Flour
Figure 2. Farinograms of different substitution levels of wheat flour and coco flour blends.
Table 5. Mixing behaviour of blends of wheat flour and coco flour.
Level of
substitution
Water
absorption
Dough
development
time (min)
Arrival time
(min)
Stability
0%
10%
20%
30%
61.0%
61.0%
60.5%
58.0%
5.5
6.0
6.5
>10
4.0
5.0
5.0
>10
18
>19
>18
ND
ND- Not determined
The Farinograph provides information on wheat quality, water absorption and mixing behaviour
(dough development time, arrival time and the stability). Farinogram curves are shown in Figure 2.
The amount of water absorption decreases as the level of substitution increases in order to get the
Farinograms to 500 brabender units for the evaluation of flour. Studies done by Mashayekh, et al
[21], revealed that oil seed flour added to wheat flour increased the Farinograph water absorption.
However, addition of coconut flour reduced the water absorption, even though coconut is
considered as an oil crop, coconut flour contains a considerably low amount of fat as it is produced
from defatted coconut residue and also there may be some interference of high fibre in coconut
flour in the dough development process. Dough development time and arrival time increased when
the level of substitution increased, suggesting that more time is required to compare with 100%

As. J. Food Ag-Ind. 2009, 2(03), 386-395 393
wheat flour with dough mixing for the preparation of bread. However, flour with 30% coconut flour
showed a much deviated form of Farinogram compared to 10% and 20% coconut flour blends and
100% wheat flour. Ten percent and twenty percent substituted blends showed much more stable
dough, compared with 100% wheat flour, and this may be due to the stabilization of gluten structure
of the dough by coconut protein present in coco flour. However, as shown in Figure 2(D), an
unstable Farinogram curve can be observed at 30% substitution level, probably due to variation in
dough development characteristics upon addition of more than 20% coconut flour, which may have
contributed to over dilution of gluten forming protein resulting in weakening of the dough. Similar
studies have been done for the determination of supplementation of wheat flour with cowpea flour
by Sharma, et al [22] and they described that the changes in hydrating properties of two proteins
may be another reason for differences in dough characteristics.
Table 6. Effect of coconut flour on sensory quality of bread.
Coco flour
level
General
appearance
Crust
colour
Crumb
grain
Texture
Odour
and taste
Total
score
0%-Control
10%
20%
30%
P value
21.8
21.5±0.3
14.5±0.3
9.5±0.3
<0.001
8.8
8.5±0.2
8.6±0.3
7.5±0.3
<0.001
18.0
17.0±0.3
14.1±0.3
8.4±0.3
<0.001
17.6
16.9±0.7
15.7±0.3
10.7±0.3
<0.001
19.8
19.5±0.3
17.4±0.3
10.1±0.3
<0.001
86.0
83.4
70.3
46.2
Table 6 shows the sensory evaluation scores of bread samples at different levels of coconut flour. It
is evident from the results that the scores for each sensory parameter decreased significantly with
the increase in coconut flour concentration. According to the results of sensory evaluation, at 10%
substitution level breads were graded as “good”, at 20% coconut flour level, breads were rated as
“satisfactory” and at 30% substitution level, the breads were rated as “poor”. Thus, these results
show that up to 20% substitution is possible to produce bread with acceptable qualities. Similar
results have been observed by Gunathilake, et al [23] for the incorporation of coconut flour into
wheat flour noodles and it was also shown that the addition of up to 20% coconut flour is feasible to
produce organoleptically acceptable noodles.
Conclusion
The present study confirmed that the blending of wheat flour with coconut flour at different levels
altered the organoleptic and rheological properties of different blends, even though it is acceptable
up to 20% fortification level. It is therefore concluded that adding up to 20% coconut flour actually
gives organoleptically acceptable bread. Fortification with coconut flour is advantageous due to the
increased nutritional value, as coconut flour is rich in protein and dietary fibre.

As. J. Food Ag-Ind. 2009, 2(03), 386-395 394
Acknowledgements
The authors acknowledge the assistance provided by Mrs. Damitha Rajapaksha, Industrial
Technology Institute, Sri Lanka, for the Farinograph study and staff of the Coconut Processing
Research Division, Coconut Research Institute, Sri Lanka for their assistance.
References
1. Coconut Research Institute, Sri Lanka (2008). http://www.cri.lk/yield.html
2. Bawalan, D.D. (2000). The economics of production, utilization and marketing of coconut
flour from coconut milk residue. CORD, XVI(1), 1–13.
3. Trinidad, P.T., Divinagracia, H.V., Aida, C.M., Faaridah, C.A., Angelica, S.M., Modesto,
T.C., Askali, C.A., Loyola, A.S. and Masa, D.B. (2001). Coconut flour from residue: A
good source of dietary fibre. Indian Coconut Journal, XXXII(6), 9–13.
4. Arancon, R.N. (1999). Coconut flour. Cocoinfo International, 6(1), 1–8.
5. Rodgers, S. (2004). Value adding with functional meals. In: Food Service Technology,
Blackwell Publishing Company, (4) pp149-158.
6. Becker, R. (1989). Preparation, composition, and nutritional implications of amaranth seed
oil. Cereal Foods World, 34, 950–953.
7. Welch, R.W. (1991). Hafer für die menshliche Ernährung im vereingten Königsreich. Getr.
Mehl Brot. 45, 89–92 in German.
8. Giami, S.Y., Mepba, H.D., Kiin-kabari, D.B. and Achinewhu, S.C. (2003). Evaluation of the
nutritional quality of breads prepared from wheat-fluted pumpkin (Telfairia occidentalis
Hook) seed flour blends. Plant Foods for Human Nutrition, 58, 1–8.
9. Klava, D. (2004). Improvement of nutritive value of wheat bread. Doctoral Dissertation,
Faculty of Food Technology, University of Agriculture, Jelgava, Latvia.
10. Bodroza-Solarov, M., Bojana Filipcev, Zarko Kevresan, Anamarija Mandic and Olivera
Simurina (2008). Quality of bread supplemented with popped Amaranthus Cruentus grain.
Journal of Food Process Engineering, 31 (5); 602-618.
11. Masoodi, F.A. and Chauhan, G.S. (1998). Use of apple pomace as a source of dietary fiber
in wheat bread. Journal of Food Processing and Preservation, 22 (1998), 255-263
12. AACC (1969). Approved Methods of AACC, 8th Edition. American Association of Cereal
Chemists, St. Paul, MN, USA pp 1-10.

As. J. Food Ag-Ind. 2009, 2(03), 386-395 395
13. AOAC (1999). AOAC Official Methods of Analysis, 14th Ed., Vol. 1, Association of
Official Analytical Chemists, Washington, DC, USA.
14. Pearson, D. (1973). Laboratory Techniques in Food Analysis, Butterworth & Co. Ltd,
London, England.
15. Van Soest, P.J. (1963). Use of detergents in analysis of fibrous feeds. A rapid method for
determination of fiber and lignin. Journal of Association of Official Analytical Chemists’,
46:829-835.
16. Marquez, P.O. (1979). Nutritional advantages of Philippine coconut flour. Coconut
Farmers Bulletin, 4, 1–7.
17. Hagenmaier, R. (1983). Dried coconut milk and other new foods from wet process.
Coconuts Today, 1(1), 17–24.
18. Trinidad, P.T., Mallillin, A.C., Valdez, D.H., Loyola, A.S., Askali-Mercado, F.C., Castillo,
J.C., Encabo, R.R., Masa, D.B., Maglaya, A.S. and Chua, M.T. (2006), Dietary fiber from
coconut flour: A functional food. Innovative Food Science and Emerging Technologies,
7: 309-317.
19. Bressani, R., Wilson D.L., Behar, M. and Scrimshaw, N.S. (1960). Supplementation of
cereal protein with amino acids, 111.Effect of amino acid supplementation of wheat flour.
Journal of Nutrition, American Society of Nutrition, 70(2):176-186.
20. Barrett, D.M., Somogyi, L.P. and Ramaswamy, H.S. (2004). Processing Fruits: Science and
Technology, 2nd Edition, CRC Press.
21. Mashayekh, M., Mahmoodi, M.R. and Entezari. M.H. (2008). Effect of fortification of
defatted soy-flour on sensory and rheological properties of wheat bread. International
Journal of Food Science and Technology, 43, 1693-1698.
22. Sharma, S., Bajwa, U. and Nagi, H.P.S. (1999). Rheological and baking properties of
cowpea and wheat flour blends. Journal of the Science of Food and Agriculture, 79:657-
662.
23. Gunathilake, K.D.P.P, Abeyrathne, Y,M.R.K. (2008). Incorporation of coconut flour into
wheat flour noodles and evaluation of its rheological, nutritional and sensory characteristics,
Journal of Food Processing and Preservation, 32.133-142.