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Jayakody et al. /Journal of Tropical Forestry and Environment Vol. 9, No. 02 (2019) 93-100
93
Composition analysis of selected Sri Lankan seaweeds
M.M Jayakody1, M.P.G Vanniarachchy1*, I. Wijesekara1
1Department of Food Science & Technology, Faculty of Applied Sciences, University of Sri
Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka
Date Received: 12-11-2018 Date Accepted: 20-12-2019
Abstract
Seaweeds are a rich source of health beneficial bioactive nutraceuticals and currently they are
under-utilized in Sri Lanka. In the present study, proximate analysis of seaweed varieties Chnoospora
minima and Porphyra sp. obtained from Mirissa, Matara, Sri Lanka and Ulva fasciata was taken from
Point Dondra Matara, Sri Lanka on June, 2018 were investigated. The moisture content, total fat content,
protein content and ash content were determined according to the Official methods of Analysis by
Association of Official Analytical Chemists after drying for 8h at 600 C. The results revealed that the
moisture contents (%) of Chnoospora minima, Porphyra sp. and Ulva fasciata were 13.24 ± 0.20, 14.30 ±
0.14 and 18.11 ± 0.01 respectively. Total fat contents (%) of Chnoospora minima, Porphyra sp. and Ulva
fasciata were 0.21 ± 0.11, 0.19 ± 0.03 and 0.28 ± 0.05 respectively. Protein contents (%) of Chnoospora
minima, Porphyra sp. and Ulva fasciata were 13.70 ± 0.2, 21.14 ± 0.04 and 11.84 ± 0.1. Total ash
contents (%) of Chnoospora minima, Porphyra sp. and Ulva fasciata were 17.20 ± 0.24, 5.40 ± 0.7 and
18.05 ± 0.21 respectively. Total carbohydrate content (%) was analyzed according to the Dubois method.
Chnoospora minima, Porphyra sp. and Ulva fasciata showed total carbohydrate content (%) as 3.87 +
0.66, 20.59 ± 0.24 and 7.68 ± 1.16 respectively. Moreover, the sulphate content was analyzed according
to the precipitate method. Chnoospora minima, Porphyra sp. and Ulva fasciata showed 1.45 ± 0.35, 2.75
± 0.07 and 4.54 ± 0.06, sulfate contents (%) respectively. In conclusion, highest ash content which
indicates a good mineral content was observed in Ulva fasciata and Chnoospora minima. Fibre, protein
and carbohydrate contents are significantly different among the 3 samples. Highest fibre content was
observed in Chnoospora minima. Highest protein and carbohydrate contents were observed in Porphyra
sp. But there is no significant difference in fat contents among the three samples.
Keywords: Chnoospora minima; Porphyra sp.; Ulva fasciata; proximate analysis; sulphur
1. Introduction
At present people are seeking more benefits from foods other than satisfying their hunger. Thus
the role of food in human health is gaining more attention over the last few years (Gupta and Abu-
Ghannam, 2011). In that case, since seaweeds are an underutilized abundant food resource in Sri Lanka
seaweed based products can be introduced as a good choice for consumption. The beneficial effects of
food can be attributed to different compounds present in foods such as phenolic compounds, sulphated
polysaccharides and organic acids which possess antioxidants, antimicrobial, antiviral and anticancer
activity (Gupta and Abu-Ghannam, 2011). Though the chemical composition of seaweeds is not well
known as the terrestrial plants but it is known to be rich in carbohydrates, protein and minerals as well as
bioactive compounds such as polyphenols, terpenoids, carotenoids and tocopherols. Seaweeds have been
also reported to produce a great variety of metabolic compounds which are not produced by terrestrial
plants. Bioactive compounds which have been isolated and identified from seaweeds include sulphated
polysaccharides (laminarins and fucoidans), polyphenols such as phlorotannins carotenoid pigments such
*Correspondence: mihiripg@sjp.ac.lk,
ISSN 2235-9370 Print / ISSN 2235-9362 Online ©University of Sri Jayewardenepura
94
as fucoxanthin and astaxanthin, sterols and mycosporine-like amino acids. (Gupta and Abu-Ghannam,
2011).
Generally seaweeds can be classifies in to 3 main groups according to their pigmentation as brown
(Phaeophyta), red (Rhodophyta), and green (Chlorophyta) seaweeds (Chan, Ho and Phang, 2006).
Seaweed is a food source which contains protein, lipids, vitamins and minerals. It is stated that this
nutrient content varies depending on the type of species, the time of collection, geographic habitat, and
ambient conditions such as water temperature and light intensity as well as nutrient concentration in water
(Marsham, Scott and Tobin, 2007).
Studies have been revealed that seaweeds are rich with polysaccharides. These seaweed
polysaccharides cannot be entirely digested by human intestinal enzymes. Hence they are regarded as
fibre rich food ingredients. Together with their low lipid content, seaweeds only provide a very low
amount of energy. Consumption of seaweeds can increase the intake of dietary fiber and lower the
occurrence of some chronic diseases (diabetes, obesity, heart diseases, cancers), which are associated with
low fiber diets (Wong and Cheung, 2000). The protein in algae contains all the essential amino acids.
(Dawczynski, Schubert and Jahreis, 2007). Matanjun et al., 2008 has also stated that, seaweeds contain all
the essential amino acids in different proportions, except for tryptophan, which was destroyed during
hydrolysis. Thus the present study has done to get a general idea about the nutritional composition of
Chnoospora minima, Porphyra sp. and Ulva fasciata available in southern cost of Sri Lanka.
2. Methodology
2.1. Sample collection
The seaweed samples of Porphyra sp. and Chnoospora minima seaweed varieties were manually
collected during June, 2018 from Mirissa, Matara district, Sri Lanka (5°56'53.74" (5.9482oN))and
80°28'17.71" (80.4715 oE)) and Ulva fasciata from Point Dondra, Matara district, Sri Lanka (5° 55' 7.9"
(5.9189°N) and 80° 35' 24.8" (80.5902°E)) All the algal samples were harvested manually from the
respective locations and then transported to the laboratory in polythene bags. They were thoroughly
cleaned to remove epiphytes and detritus attached to the fronds and kept in a freezer till further use.
Finally algal samples were dried at 600C, in a drying cabinet for 8 hours. Then they were pulverized into
small particles, sieved through the 355micron (Number 42) sieve. Then they were stored in room
temperature, sealed in polypropylene bags till further used in analysis.
2.2. Determination of moisture content
Moisture content was determined by the infrared moisture analyzer (Shimadzu, Max 60g, d=0.001g)
expressed as percentage by weight of sample.
2.3. Determination of total ash (Gravimetric method)
Total ash Content was determined according to the AOAC official method 923.03. Approximately 5g of
the samples were weighed into previously cleaned, dried and weighed porcelain crucibles. Subsequently
the samples were ignited slowly over a Bunsen flame until no more fumes evolved. The dishes were then
transferred in to the muffle furnace (Wise therm) set at 550 0C and incinerated until it was free of black
carbon particles and turns to white or grey in colour. The incinerated crucibles were cooled in the
desiccator and the weight was recorded. Ashing, cooling and weighing procedures were repeated until the
difference between two successive weights was less than 1 mg. Experiment was duplicated. Finally the
total ash percentage was determined by the following equation;
Jayakody et al. /Journal of Tropical Forestry and Environment Vol. 9, No. 02 (2019) 93-100
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Ash % = Weight of ash
Ash % = m3 - m1
m2 - m1
m1 = Weight of the empty crucible
m2 = Weight of the crucible + sample before drying
m3 = Weight of the crucible + sample after drying
2.4. Determination of protein content
Protein content was determined by Micro Kjeldhal Method (AOAC method 978.04) with following 3
main steps. Those were acid digestion of samples, Distillation of the samples followed by titration.
During acid digestion 50mg of the sample were measured on to a tissue paper and folded such that
samples do not come out. Then the samples were digested separately at 420 0C for 3 hours in Kjeldhal
digestion flasks with 2.5 ml of Conc. H2SO4 and a Kjeldhal tablet. After digestion the contents in the
digesting tubes were transferred to the tube in the distillation unit one by one while supplying 32% NaOH
and distilled water to the distillation unit. During the distillation, the emitted gas was collected to 5ml of
4% boric acid solution with few drops of Kjeldhal indicator in the medium. The gas trapped by 4% boric
acid was titrated with 0.02 M Standardized HCl and recorded the end point. Protein content of the
seaweed samples were calculated by the following equation. The experiment was triplicated.
Nitrogen (%) = (Sample titre – Blank titre ) x Molarity of HCl x 14 x 100
Weight of the sample taken x 1000
Protein = Nitrogen (%) x Factor
2.5. Determination of lipid content (Soxhelt extraction method)
Lipid content was determined by the soxhelt extraction method. Approximately 10g of finely ground
sample was weighed to the nearest 0.1g into the motor and pestle and twice the weight of anhydrous
sodium sulphate was added. The content was ground until a free flowing powder was obtained after which
it was transferred in to the extraction thimble and covered with a cotton wool. The extraction thimble with
the sample was placed in the soxhlet apparatus. A cleaned, dried and previously weighed round bottom
flask (250 ml) containing 200 ml of petroleum ether with pumice chips and a condenser was connected to
the soxhlet apparatus and refluxed for 5 hours keeping the heating rate low enough to prevent solvent
escaping from the top of the condenser during the refluxing. After the refluxing was over, the solvent was
distilled off and cooled the content with the flask and weighed. The process was repeated until a constant
X 100
X 100
Weight of the sample
96
weight was obtained. Experiment was duplicated. The crude fat percentage of the sample was determined
by the following equation,
Percentage of crude fat content of the sample = W1 - F X 100
W2
W1 = Weight of the flask with fat and chips.
F = Weight of the flask and the chips.
W2 = Weight of the sample
2.6. Determination of total carbohydrate content (Dubois method)
The sugar content was determined by using modified method of (Dubois et al., 1956). Approximately
0.1g of pulverized sample which was measured by the analytical balance (AGN220C max 220g, d=
0.0001g) was hydrolyzed at 100 0C in a water bath for 2 hours with 50ml of 2M HCl after which
neutralized by 50ml of 2 M NaOH. The neutralized solution was filtered through Whatman No. 41 paper.
500 µl of filtrate and 500 µl of 20% phenol solution was added into a test tube followed by 2.5 ml
concentrated sulfuric acid (Analytical grade reagent). Mixture was incubated for 10 min in room
temperature. After incubation mixture was vortex vigorously for 10 seconds. Then solution was again
incubated in room temperature for 15 min, followed by 37 0C incubator for 30 minutes. Absorbance was
measured at a wavelength of 490 nm using UV mini-1240 Spectrophotometer. Blank solution was
prepared following the same procedure as above replacing the sample with distilled water. The standard
curve was drawn for D- Glucose from regression analysis using the software MINITAB R 17 by
measuring the absorbance values corresponding to D-Glucose concentration. Experiment was triplicated
for all the samples and standards.
2.7. Determination of total fibre content
Total fibre content was calculated by the following equation;
Percentage of fibre content (m/m) = 100 - (A+ B +C+D+E)
A = Percentage moisture content of the sample
B = Percentage total fat content of the sample
C = Percentage crude protein content of the sample
D = Percentage total carbohydrate content of the sample
E = Percentage total ash content of the sample
2.8. Determination of sulphate content
Sulphate was determined using modified AOAC Gravimetric method (AOAC,1995) with minor
modifications. Dry seaweed sample of 0.5g was transferred into a beaker with 10ml of concentrated
HN03. The beaker was placed in hot plate and it was heated at 123 0C in a fume hood for 30 min to have
the final volume of digest as 2-3 ml. After cooling the sample in fume hood 2- 3 drops of 40% HCHO
solution were added to reduce the excess HNO3. The mixture was filtered into 250ml conical flask and 0.5
ml concentrated HCl was added followed by distilled water to bring the volume to 200ml. The solution
was heat to boiling and 10ml of 0.25 M BaCl2 was added drop wise with constant stirring for 5 min and
kept aside for 5h in a warm place, The BaSO4 solution was filtered with ash less Whatman filter paper
Jayakody et al. /Journal of Tropical Forestry and Environment Vol. 9, No. 02 (2019) 93-100
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and precipitate was ashed in crucibles in muffle furnace at 560 0C for 24h. The crucibles were transferred
to desiccator for cooling and weighed to determine the weight of BaSO4. The percentage sulphate was
calculated from the following equation;
Sulphate (%DB) = (0.4116 x A)
B
A = Weight of BaSO4
B = Weight of the sample
2.8. Statistical analysis
Analysis was performed in duplicates except for the crude protein content. Mean values of moisture, fat,
protein, carbohydrate, ash and fibre were analyzed by one-way ANOVA and Tukey comparison at p <
0.05 by MINITAB 17 to detect significant differences among groups.
3. Results
Table 1: Moisture, fat, and protein contents of Chnoospora minima, Porphyra sp., and Ulva fasciata
Seaweed variety
Moisture (%)
Fat (%)
Protein (%)
Chnoospora minima
13.24 + 0.20 c
0.21 + 0.11a
13.70 + 0.2b
Porphyra sp.
14.30 + 0.14b
0.19 + 0.03a
21.14 + 0.04a
Ulva fasciata
18.11 + 0.01a
0.28 + 0.05a
11.84 + 0.1c
Values are means ± SD of two determinations. Different letters a, b and c in the same column indicate
significant difference (p<0.05)
Table 2 : Carbohydrate, ash and fibre contents of Chnoospora minima, Porphyra sp., and Ulva fasciata
Seaweed variety
Carbohydrate (%)
ash (%)
Fibre (%)
Chnoospora minima
3.87 + 0.66c
17.20 + 0.24a
51.77 + 1.03a
Porphyra sp.
20.59 + 0.24a
5.4 + 0.7b
38.24 + 1.08c
Ulva fasciata
7.68 + 1.16b
18.05 + 0.21a
44.04 + 0.77b
Values are means ± SD of two determinations. Different letters a, b and c in the same column indicate
significant difference (p<0.05)
Table 3 : Sulphate content of Chnoospora minima, Porphyra sp. and Ulva fasciata
Seaweed variety
Sulphate content (%)
X 100
98
Chnoospora minima
1.45 + 0.35c
Porphyra sp.
2.75 + 0.07b
Ulva fasciata
4.54 + 0.06a
Values are means ± SD of two determinations. Different letters a, b and c in the same column indicate
significant difference (p<0.05)
4. Discussion
The results revealed that the highest composition of analyzed seaweed varieties is comprised of
fibre. The fibre content of the analyzed seaweed varieties are significantly different (p < 0.05) from each
other. Chnoospora minima has the highest fibre content among all the 3 varieties. Dietary fibre is defined
as an indigestible fraction which contains oligosaccharides and resistant starches, resistant proteins, and
associated compounds such as polyphenols (Jiménez-Escrig and Sánchez-Muniz, 2000). Generally fibre is
not digested by the digestive enzymes. But this undigested portion will supply many health benefits to the
body. Fibre adds bulk to the diet, fibre will also attracts water and turns to gel during digestion there by
traps carbohydrates and slows absorption of glucose hence it lowers variance in blood sugar levels, it also
lowers total and LDL cholesterol etc. (Dhingra et al., 2011). Thus consumption of fibre rich food will
enable the consumers to lead a healthy life.
The results of the analysis revealed that the crude protein content of the samples significantly
different among each other (p < 0.05). Highest protein content was recorded in the red algae variety
porphyra sp. (21.14 + 0.04). while lowest in the green algae U. fasciata (11.84 + 0.1) The results obtained
from the analysis agree with Fleurence, Morançais and Dumay, (2018) which states that the protein
content of marine algae differs according to the species and low for brown seaweeds (3 ± 15% of dry
weight), moderate for green algae (9 ± 26% of dry weight) and protein content is high for red seaweeds
(maximum 47% of dry weight) (Fleurence, Morançais and Dumay, 2018).
The fat content of the all the analyzed seaweed varieties were not significantly different (p > 0.05).
The data of fat content (%) remained in the range (<4% on DW) as reported earlier for various macro
algal species. (Kumari et al., 2010).
The carbohydrate content (%) of Chnoospora minima, Porphyra sp. and Ulva fasciata is
represented in Table 2. According to the results Carbohydrate contents of the 3 seaweed varieties are
significantly different (p < 0.05) recording the highest carbohydrate content 20.59 + 0.24 in Porphyra sp.
The phenol–sulfuric acid method is used to determine the Carbohydrate content of the samples. It is a
simple and rapid colorimetric method to determine total carbohydrates in a sample. This method
determines virtually all classes of carbohydrates, including monosaccharides, disaccharides,
oligosaccharides, and polysaccharides. Although the method detects almost all carbohydrates, the
absorptivity of the different carbohydrates varies. Thus, unless a sample is known to contain only one
carbohydrate, the results must be expressed arbitrarily in terms of one carbohydrate. In this method, the
concentrated sulfuric acid breaks down any polysaccharides, oligosaccharides, and disaccharides to
monosaccharide. Pentoses (5-carbon compounds) are then dehydrated to furfural, and hexoses (6-carbon
compounds) to hydroxymethyl furfural. These compounds then react with phenol to produce a yellow-
gold color. For products that are high in hexose sugars, glucose is commonly used to create the standard
Jayakody et al. /Journal of Tropical Forestry and Environment Vol. 9, No. 02 (2019) 93-100
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curve, and the absorption is measured at 490 nm. The color for this reaction is stable for several hours, it
is said that the accuracy of the method is within ±2% under proper conditions. (Nielsen, 2009).
The Table 3 represents the sulphate content of the 3 seaweed varieties. The sulphate contents of
the 3 seaweed varieties are significantly different (p < 0.05) and the highest sulphate content has been
recorded in U. fasciata as 4.54 + 0.06
According to certain research articles Sulphates and chlorides are the main anions found in
seaweeds. These are important constituents of charged polysaccharides in marine algae which related to
high salt concentration in the environment. (Gómez-Ordóñez, Alonso and Rupérez, 2010). Research
report by Rupérez and Saura-Calixto, (2001) has reported that physicochemical properties of dietary fibre
in edible seaweeds are related to the hydrophilic nature of the charged polysaccharides. Sulphated
polysaccharides from edible marine algae are not toxic for humans and, especially fucans and alginic acid
derivatives, are known to exhibit different biological properties, such as anticoagulant, anti-
inflammatory, antiviral, or anti- tumoral activities. (Rupérez, Ahrazem and Leal, 2002). Also, sulphated
polysaccharides from brown and red seaweeds have been reported to exhibit antioxidant capacity in vitro
and potentially could be used as natural antioxidants by the food industry (Rupérez, Ahrazem and Leal,
2002).
5. Conclusion
All the 3 seaweed varieties, Chnoospora minima, Porphyra sp. and Ulva fasciata are very good sources of
dietary fibre while all the 3 seaweed varieties are poor in fat. The three varieties are also moderately good
sources of carbohydrates, protein and minerals with a highest carbohydrate and protein content in
Porphyra sp. among the three.
Acknowledgment
The authors wish to thank department of Food Science and Technology of University of Sri
Jayewardenepura for supplying necessary equipment and chemicals for the research.
References
Chan, C., Ho, C. and Phang, S., 2006. Trends in seaweed research. Trends in Plant Science, 11:165-166.
Dawczynski, C., Schubert, R. and Jahreis, G., 2007. Amino acids, fatty acids, and dietary fibre in edible
seaweed products. Food Chemistry, 103:891-899.
Dhingra, D., Michael, M., Rajput, H. and Patil, R., 2011. Dietary fibre in foods: a review. Journal of Food
Science and Technology, 49:255-266.
DuBois, M., Gilles, K., Hamilton, J., Rebers, P. and Smith, F., 1956. Colorimetric Method for
Determination of Sugars and Related Substances. Analytical Chemistry, 28:350-356.
Fleurence, J., Morançais, M. and Dumay, J., 2018. Seaweed proteins. Proteins in Food Processing,
pp.245-262.
Gómez-Ordóñez, E., Alonso, E. and Rupérez, P., 2010. A simple ion chromatography method for
inorganic anion analysis in edible seaweeds. Talanta, 82:1313-1317.
100
Gupta, S. and Abu-Ghannam, N., 2011. Recent developments in the application of seaweeds or seaweed
extracts as a means for enhancing the safety and quality attributes of foods. Innovative Food Science &
Emerging Technologies, 12:600-609.
Jiménez-Escrig, A. and Sánchez-Muniz, F., 2000. Dietary fibre from edible seaweeds: Chemical structure,
physicochemical properties and effects on cholesterol metabolism. Nutrition Research, 20:585-598.
Kumari, P., Kumar, M., Gupta, V., Reddy, C. and Jha, B., 2010. Tropical marine macroalgae as potential
sources of nutritionally important PUFAs. Food Chemistry, 120:749-757.
Marsham, S., Scott, G. and Tobin, M., 2007. Comparison of nutritive chemistry of a range of temperate
seaweeds. Food Chemistry, 100:1331-1336.
Matanjun, P., Mohamed, S., Mustapha, N. and Muhammad, K., 2008. Nutrient content of tropical edible
seaweeds, Eucheuma cottonii, Caulerpa lentillifera and Sargassum polycystum. Journal of Applied
Phycology, 21:75-80.
Nielsen, S., 2009. Phenol-Sulfuric Acid Method for Total Carbohydrates. Food Analysis Laboratory
Manual, pp.47-53.
Rupérez, P., Ahrazem, O. and Leal, J., 2002. Potential Antioxidant Capacity of Sulfated Polysaccharides
from the Edible Marine Brown SeaweedFucus vesiculosus. Journal of Agricultural and Food Chemistry,
50:840-845.
Rupérez, P. and Saura-Calixto, F., 2001. Dietary fibre and physicochemical properties of edible Spanish
seaweeds. European Food Research and Technology, 212:349-354.
Wong, K. and Cheung, P., 2000. Nutritional evaluation of some subtropical red and green seaweeds. Food
Chemistry, 71:475-482.
