Nutritional Evaluation of Tropical Green Seaweeds Caulerpa lentillifera and Ulva reticulata

Abstract

Studies were conducted to evaluate nutritional qualities of two edible green seaweeds, Caulerpa lentillifera and Ulva reticulata, with a view to their utilization in human nutrition. The proximate composition, mineral and vitamin contents, free fatty acid, and amino acid profiles were investigated. Protein and ash contents were the two most abundant components in these seaweeds. Caulerpa lentillifera and Ulva reticulata contained 12.49%, 21.06% protein and 24.21%, 17.58% ash based on dry weight, respectively. Both seaweeds contained high amounts of minerals and balanced amino acid profiles. Regarding the Dietary Reference Intake, both kinds of seaweeds were notably rich in iodine. Caulerpa lentillifera was also rich in phosphorus, calcium, magnesium and copper, while Ulva reticulata was rich in potassium, manganese and ferrous. Comparisons to corresponding nutrient values in other seaweeds and some commonly consumed local vegetables, both seaweeds showed their potential of being health food for human diets or as source of ingredients with high nutritional values.

Full text

Kasetsart J. (Nat. Sci.) 40 (Suppl.) : 75 - 83 (2006)
Nutritional Evaluation of Tropical Green Seaweeds
Caulerpa lentillifera and Ulva reticulata
Pattama Ratana-arporn1* and Anong Chirapart2
ABSTRACT
Studies were conducted to evaluate nutritional qualities of two edible green seaweeds, Caulerpa
lentillifera and Ulva reticulata, with a view to their utilization in human nutrition. The proximate
composition, mineral and vitamin contents, free fatty acid, and amino acid profiles were investigated.
Protein and ash contents were the two most abundant components in these seaweeds. Caulerpa lentillifera
and Ulva reticulata contained 12.49%, 21.06% protein and 24.21%, 17.58% ash based on dry weight,
respectively. Both seaweeds contained high amounts of minerals and balanced amino acid profiles.
Regarding the Dietary Reference Intake, both kinds of seaweeds were notably rich in iodine. Caulerpa
lentillifera was also rich in phosphorus, calcium, magnesium and copper, while Ulva reticulata was rich
in potassium, manganese and ferrous. Comparisons to corresponding nutrient values in other seaweeds
and some commonly consumed local vegetables, both seaweeds showed their potential of being health
food for human diets or as source of ingredients with high nutritional values.
Key words: Caulerpa lentillifera,Ulva reticulata, seaweed, nutritional value, protein
1Department of Fishery Products, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand.
2Department of Fishery Biology, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand.
* Corresponding author, e-mail: ffispmr@ku.ac.th
INTRODUCTION
Seaweeds are major coastal resources
which are valuable to human consumption and
environment in many countries. Edible seaweeds
were widely consumed, especially in Asian
countries as fresh, dried, or ingredients in prepared
foods. Compared to land plants, the chemical
composition of seaweeds has been poorly
investigated and most of the available information
only deals with traditional Japanese seaweeds
(Fujiwara-Arasaki et al., 1984; Nisizawa et al.,
1987). The chemical composition of seaweeds
varies with species, habitat, maturity and
environmental conditions (Ito and Hori, 1989). In
general, seaweeds are rich in non-starch
polysaccharides, minerals and vitamins (Darcy-
Vrillon, 1993; Mabeau and Fleurence, 1993). As
seaweed polysaccharides cannot be entirely
digested by human, they are regarded as a new
source of dietary fiber and food ingredient.
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 occurence of some
chronic diseases (Southgate, 1990).
Although the seaweed floras in Thailand
are extensively found, they are relatively under-
utilized. Most of them are mainly used as animal
feeds and fertilizers by the coastal villagers. The
genus Caulerpa is common seaweed in tropical
and subtropical water. Within this genus, Caulerpa
Received date : 02/07/06 Accepted date : 26/09/06

76 Kasetsart J. (Nat. Sci.) 40 (Suppl.)
lentillifera is one of the favored species due to its
grass-green in color, soft, and succulent texture
and usually consumed in the form of fresh
vegetable or salad. It can be cultivated in ponds
and open lagoon in the Philippines. In Thailand,
many shrimp farms cultivate Caulerpa lentillifera
in the pond for the purpose of water treatment.
Ulva reticulata is also one type of green seaweed
which is under-utilized. It is widely spread in the
southern part of Thailand, especially in Pattani bay
and the coastal villagers use it as animal feeds.
Both types of green seaweeds are rarely promoted
for the increase use for food. One major limitation
is the lack of nutritive value of these types of algae.
To our knowledge, the nutritional data of both
green algae is not yet available. Thus, the aims of
this work were to determine the nutritionl
compositions of Caulerpa lentillifera and Ulva
reticulata.
This paper presented data on the
nutritional and chemical composition of Caulerpa
lentillifera and Ulva reticulata; i.e. proximate
composition, mineral, vitamin, fatty acid, and
amino acid contents. This work also reported a
comparative evaluation of nutritive values of these
seaweeds with those of some other seaweeds and
some locally consumed vegetables. The potential
of both seaweeds as sources of food nutrients was
discussed.
MATERIALS AND METHOD
2.1 Collection and preparation of samples
The Caulerpa lentillifera seaweed was
collected from culture ponds of coastal aquaculture
station in Amphor BanLam, Petchburi province,
in March. The Ulva reticulata seaweed was
collected from coastal area of Pattani Bay, Pattani
province, in May. The samples taken were washed
in running water and divided into three portions.
For vitamin analysis, fresh sample were taken
immediately by covering with black sheet and the
analysing steps were carried out with minimum
delay. For fatty acid composition, the freeze dried
samples were used. For the rest of the analyses,
dry samples were used. The dry samples were
prepared by drying the fresh seaweeds in the hot-
air oven at 60 rC until dry and kept in air-tight
plastic bag in desiccators at room temperature (25
rC) for further analysis.
2.2 Analytical methods
2.2.1 Proximate analysis
Total nitrogen, fiber, and ash contents
were determined by standard AOAC (1990)
methods. Fat content was determined according
to Bligh and Dyer method (Bligh and Dyer, 1959).
Total protein content was calculated by
multiplying Kjeldahl nitrogen by 6.25. Ash content
was conducted by ashing the ground dried samples
overnight in muffle furnace at 525rC. Crude fiber
analysis was determined by filtering with a Fiber-
Tec system.
2.2.2 Mineral contents
For the determination of mineral
elements (phosphorus, potassium, calcium,
magnesium, zinc, manganese, ferrous, copper and
iodine), triplicate determinations of each element
were carried out. The methods of analysis were as
followed:
P by Vanadomolybdophosphoric
yellow method
K Ca Mg by Atomic Absorption with
wet digestion (H2SO4-Se)
Zn Mn Fe Cu by Atomic Absorption
with wet digestion (H2ClO4-HNO3 3:5)
I by Spectrophotometric Kinetic
Assay Method
2.2.3 Vitamin contents
Vitamin determinations were conducted
by the Nutrition Division, Department of Health,
Ministry of Public Health. Methods of Analysis
were as followed (Nutrition Division, 2001):
Vitamin A/Carotene by HPLC method
Thiamin by Thiochrome method
Riboflavin by Spectrofluorometric method

77
Kasetsart J. (Nat. Sci.) 40 (Suppl.)
Niacin by Microbiology method
Ascorbic acid (Total Vit C) by 2,4 dinitro-
phenylhydrazine method
Vitamin E (Alpha-tocopherol) by HPLC method
2.2.4 Fatty acid compositions
Fatty acids were determined by gas
chromatographic quantification of their metyl
esters (FAMES), which were prepared by
extraction and transmethylation (modified Bligh
and Dyer method, 1959). FAMES samples were
analysed using capillary gas chromatography (GC-
17A, Shimadzu/ Japan) equipped with a DB-
WAX;J&W capillary column (30m ¥0.25mm,
film thickness 0.25 mm) and an FID Detector. The
injection and detection temperature were 250rC
and 270 rC with split ratio of 1:100 using helium
as carrier gas. The running method was through a
temperature gradient from 150 rC up to 250 rC
with an increase rate of 8.0 rC/min. Identification
of fatty acids in the samples were performed by
comparing their retention times with those of a
standard mixture (C14-C24 fatty acids) and peak
areas were calculated from the total identified fatty
acids area and the average values of two injections
of each duplicate extracts.
2.2.5 Amino acid compositions
Amino acid analysis was perfomed using
the Waters Associates AccQ-TAG method (Liu et
al.,1995). This technique comprises of three steps
(i) hydrolysis by 6NHCl at 110rC for 22 hours
(ii) pre-column derivatization of samples with
AccQ-fluor reagent and (iii) analysis by (reverse
phase) HPLC. The chromatographic separation
was performed using WATERS Alliance 2695 with
heater, WATERS 2475 Multi lfluorescence
detector (EX:250, EM:395 nm) and ACCQ-TAG
column (3.9¥150 mm, particle size 4 mm). The
solvent system consisted of two eluents: (A) AccQ-
TAG Eluent A and (B) Acetonitrile in water. A set
of amino acid standards (Sigma chemicals) was
analysed with each set of experimental samples.
The experiment was performed in duplicate.
Identification of the amino acid in the sample was
carried out by comparison with retention times of
the standards.
RESULT AND DISCUSSION
Proximate analysis
The proximate composition based on dry
weight of Caulerpa lentillifera and Ulva reticulata
were shown in Table 1. It was found that the protein
content of both seaweeds differed according to
species. The protein contents of both samples
(12.49-21.06%) were within the range of 10-47%
for green seaweeds reported by Fleurence (1999).
The protein content in Ulva reticulata was almost
twice of that found in Caulerpa lentillifera and
was notably higher than that of Ulva lactuca.
Variation in protein content of seaweeds can be
due to different species, seasonal period and
geographic area.
Compare to those reported in other
seaweeds, the protein content of Caulerpa
lentillifera (12.49%) was comparable to the red
algae Palmaria sp. (13.87%), notably higher than
Table 1 Proximate composition (g/100g sample dry basis) of Caulerpa lentillifera and Ulva reticulata.
Composition Caulerpa lentillifera Ulva reticulata
Crude protein (N factor = 6.25) 12.49±0.3 21.06±0.42
Crude lipid 0.86±0.10 0.75±0.05
Crude fiber 3.17±0.21 4.84±0.33
Ash 24.21±1.7 17.58±2.0
Carbohydratea59.27 55.77
Moisture 25.31±1.15 22.51±0.97
aCalculated by difference (= 100–crude protein-crude lipid -ash-crude fiber)

78 Kasetsart J. (Nat. Sci.) 40 (Suppl.)
some green algae Ulva lactuca (7.06%) (Wong and
Cheung, 2000),some brown algae (e.g.
Himanthalia elongata (7.49%) and Laminaria
ochroleuca (7.49%)), but was about half of that
reported in Porphyra sp. (24.11%) (Sanchez-
Machado et al., 2004). For Ulva reticulata, the
protein was three times higher than that contained
in the same genus Ulva lactuca but slightly lower
than that of Porphyra sp. (Sanchez-Machado et
al., 2004). However, it should be noted that the
protein content of seaweeds varied not only
between species but also between seasons
(Fleurence, 1999).
Ash contents of both seaweeds found in
the level of 17-24% were considerably high. High
level of ash was associated with the amount of
mineral elements. Ash content in Caulerpa
lentillifera (24.21%) was higher than that found
in Ulva reticulata (17.58%). The amount found
were comparable to those reported in other species
i.e., Himanthalia elongata (26.78%), Laminaria
ochroleuca (29.47%) and Porphyra sp. (19.07%)
(Sanchez-Machado et al., 2004). Generally, the ash
content of seaweeds are much higher than those
of terrestrial vegetables other than spinach
(Sanchez-Machado et al., 2004).
The total lipid contents in both samples
(0.75-0.86%) were found relatively low which
were in accordance with 0.7-1.05% as reported in
red and brown algae mentioned above (Sanchez-
Machado et al., 2004). Typically, seaweeds are not
considered to be good source of lipid.
Mineral contents
The mineral contents of both seaweeds
as well as the values reported in local vegetables
and selected edible seaweeds were shown in Table
2. The Dietary Recommended Intake (DRI) for
Thai male and female of age 19-50 years
recommended by Nutrition Division (2003) were
also presented in Table 2. It was clearly shown
that both seaweeds contained considerably high
amount of minerals. Regarding the DRI, both kinds
of seaweeds were notably rich in iodine. Apart
from iodine, Caulerpa lentillifera was also rich in
phosphorus, calcium, magnesium and copper
while Ulva reticulata was rich in potassium,
manganese and ferrous. Similar to other edible
seaweed, Gracilaria changgi was reported to
contain high level of calcium (651), zinc (13.8),
Table 2 Mineral contents (mg/100 g dry basis except Cu and I in mg/100g) of Caulerpa lentillifera,
Ulva reticulata and Gracilaria changgiacompared to Dietary Reference Intake (mg/day except
Cu and I in mg/day).
Minerals Caulerpa Ulva GracilariaaDRIbDRIb
lentillifera reticulata Changgi male female
P 1030 180 nr 700 700
K 970 1540 nr nr nr
Ca 780 140 651 800 800
Mg 630 140 nr 310-320 250-260
Zn 2.6 3.3 13.8 13 7
Mn 7.9 48.1 nr 2.3 1.8
Fe 9.3 174.8 95.6 10.4 24.7
Cu (mg) 2200 600 800 900 900
I (mg) 1424 1124 nr 150 150
aNorziah and Ching, 2000
bDietary Reference Intake : the amount recommended for consume daily for Thai adult of age19-50 years (Nutrition Division,
2003)
nr not reported

79
Kasetsart J. (Nat. Sci.) 40 (Suppl.)
ferrous (95.6) and copper (0.8) (Norziah and
Ching, 2000). Based on the result, these seaweeds
may serve as food supplements to help meet the
recommended daily adult intakes of some
minerals.
Vitamins
Quantitative analysis of vitamins was
calculated on the basis of 100g fresh edible portion
and was presented in Table 3. Comparison study
was made on the amount found in the green
seaweed samples to those presented in various
locally available vegetables. The vitamin A
content, presented as total Retinol Equivalent
(RE), found in both seaweeds at moderate amount,
i.e. about 7 times lower than the vitamin A-rich
vegetable such as carrot, but more than twenty
times greater than that found in cabbages.
Caulerpa lentillifera was also considered to be rich
in vitamin E with moderate amount of vitamin B1,
vitamin B2and Niacin while Ulva reticulata was
lack of vitamins except vitamin A.
Fatty acid composition
As the total lipids content of seaweeds
was quite low so they were not a conventional
sources of energy. However, most of them were
reported to be rich in polyunsaturated fatty acid
regarding to their fatty acid composition (Darcy-
Vrillon, 1993). Variations in fatty acid contents are
due to both environment and genetic differences
mentioned above (Sanchez-Machado et al., 2004).
In this work, thirteen fatty acids were identified.
The fatty acid composition of Caulerpa lentillifera
and Ulva reticulata were shown in Table 4,
together with some other seaweeds reported. It was
found that the most abudant fatty acid in both
seaweeds was C16:0 (palmitic acid), which
accounted for 67.83% of all fatty acid for Caulerpa
lentillifera and 41.53% for Ulva recticulata.
However, they also contained the essential fatty
acids of C18:2(w-6) (linoleic acid), C18:3(w-3)
(alpha-linolenic acid), C20:5(w-3) (the eicosanoid
precursors), C20:4 (w-6) (arachidonic acid) and
C20:5 (w-3) (eicosapentaenoic acid) in rather
small amounts. The fatty acid pattern of Caulerpa
lentillifera was similar to that of Porphyra sp.
(Table 4) but higher in saturated fatty acid (palmitic
and stearic acid) and lower in unsaturated fatty
acid except linoleic and linolenic acids. The
amount of eicosapentaenoic acid and
docosahexaenoic acid in Caulerpa lentillifera was
Table 3 Vitamin contents (mg/100 g edible portion except vitamin A) of Caulerpa lentillifera,Ulva
reticulata and some other vegetablesacompared to Dietary Reference Intakeb(mg/day except
vitamin A in mg/day).
Vitamins Caulerpa Ulva Cabbage Carrot Lettuce DRI DRI
Ientillifera reticulata male female
Total 170 167 7 1116 393 700 600
Vitamin Ac
Vitamin E 2.22 0 nd nd nd 15 15
Vitamin C 1.00 0 23 3 24 90 75
Thiamin 0.05 0.01 0.04 0.04 0.06 1.2 1.1
Riboflavin 0.02 0.13 0.22 0.05 0.18 1.3 1.1
Niacin 1.09 0 2.8 0.8 0.6 16 14
afrom Nutritive values of Thai foods (Nutrition Division, 2001)
bDietary Reference Intake :- the amount recommended for consume daily for adult of age 19-50 years (Nutrition Division,
2003)
cRE (Retinol Equivalent) = 1 microgram (mg) retinol or 6 microgram beta carotene
nd not determined

80 Kasetsart J. (Nat. Sci.) 40 (Suppl.)
Table 4 Fatty acid contents (mg/g sample) and profiles (g/100g fatty acids) of Caulerpa lentilifera,
Ulva reticulata and some edible seaweeds.
Fatty acids mg/g sample g/100 g fatty acids
Caulerpa Ulva Caulerpa Ulva PorphyraaPalmariaaGracillariab
lentillifera reticulata lentillifera reticulata sp. sp. changgi
C 16:0
Palmitic acid 8.92 1.43 67.83 41.53 63.19 45.44 22.0
C 16:1
Palmitoleic acid 0.80 0.32 6.08 9.29 6.22 5.26 nr
C 18:0
Stearic acid 1.46 0.92 11.1 26.72 1.23 1.28 nr
C 18:1 (w9)
Oleic acid 0.03 0.13 0.23 3.77 6.7 3.13 21.9
C 18:2 (w6)
Linoleic acid 0.56 0.14 4.26 4.07 1.17 0.69 nr
C 18:3 (w3)
Linolenic acid 0.36 0.19 2.73 5.52 0.23 0.59 nr
C 20:0
Arachidate 0.19 0.11 1.48 3.19 nr nr nr
C 20:1
Eicosanoate 0.18 0.06 1.36 1.74 4.7 0.20 nr
C 20:4 (w6)
Arachidonic acid 0.11 0.04 0.84 1.16 6.8 1.45 nr
C 20:5 (w3)
Eicosapentaenoic acid 0.03 0.03 0.83 0.87 6.03 24.05 33.1
C 22:0
Behanate 0.30 0.03 2.28 0.87 nr nr nr
C 22:1
Erucate 0.10 0.003 0.76 0.087 nr nr nr
C 22:6 (w3)
Docosahexaenoic acid 0.11 0.04 0.83 1.16 nr nr 12.9
nr not reported
a Sanchez-Machado et al,,2004
b Norziah and Ching, 2000
notably lower than those reported in Palmaria sp.
and Gracilaria changgi.
Amino acid composition
Table 5 showed the amino acid profiles
of both seaweeds. Fifteen amino acids were
detected and the separation of the amino acids in
the samples were reasonably resolved. Data on
tryptophan, methionine and cysteine were not
included in this work since the amino acids are
destroyed during acid hydrolysis. Apart from the
excluded amino acids, both seaweed samples
contained all the essential amino acids in different
proportions. Since cysteine and tyrosine can
replace methionine and phenylalanine,
respectively, through metabolic processes, two
amino acids are combined, i.e. methionine with
cysteine and phenylalanine with tyrosine for

81
Kasetsart J. (Nat. Sci.) 40 (Suppl.)
Table 5 Amino acid compositions (g/100 g sample dry basis) and profiles (g/100 g amino acids) of
Caulerpa lentillifera and Ulva reticulata.
Amino acids Caulerpa lentillifera Ulva reticulata EggaSoyaa
g/100 g g/100 g g/100 g g/100 g g/100 g g/100 g
sample amino sample amino amino amino
acids acids acids acids
Essential
amino acids
Threonine 0.79 6.38 1.15 5.41 4.7 4.1
Valine 0.87 7.03 1.34 6.30 6.6 5.2
Lysine 0.82 6.63 1.28 6.02 7.0 6.1
Isoleucine 0.62 5.01 0.90 4.23 5.4 5.1
Leucine 0.99 8.00 1.68 7.90 8.6 7.6
Phenylalanine 0.61 4.93 1.12 5.26 9.3 (+Tyr) 8.4(+Tyr)
Total
essential 4.7 37.99 7.47 35.12 41.6 36.5
amino acids
Nonessential
amino acids
Aspartic acid 1.43 11.56 2.66 12.50
Serine 0.76 6.14 1.36 6.39
Glutamic acid 1.78 14.39 2.76 12.98
Glycine 0.85 6.87 1.38 6.49
Arginine 0.87 7.03 1.84 8.65
Histidine 0.08 0.65 0.23 1.08
Alanine 0.85 6.87 1.72 8.09
Tyrosine 0.48 3.88 0.77 3.62
Proline 0.57 4.61 1.08 5.08
Total
nonessential 7.67 62.0 13.8 64.88
amino acids
Total amino 12.37 21.27
acids
aValerie et al., 1999
nutritional evaluation. The total amino acids
(tryptophan, methionine and cysteine not included)
were 12.37 g/100g sample (dry weight) in
Caulerpa lentillifera and 21.27 g/100g sample in
Ulva reticulata. From these total, 4.7 and 7.09g
amino acid/100 g sample corresponding to 37.99
and 35.12% respectively were made up of essential
amino acids. If the three excluded amino acids
were detected, the proportions would be higher.
The amino acid contents found in this study were
in consistent to those reported in literatures. In
Gracilaria changgi, the amino acid pattern was

82 Kasetsart J. (Nat. Sci.) 40 (Suppl.)
reported to comparable to that of hen’s eggs and
the ratio of essential to total amino acids was 0.4
(Norziah and Ching, 2000). Wong and Cheung
(2000) reported that Hypnea japonica, Hypnea
charoides and Ulva lactuca contained all essential
amino acids which accounted for 42.1- 48.4% of
total amino acid contents.
In this study, the total amino acid content
of each seaweed sample was comparable to its
corresponding crude protein content. Both
seaweed samples exhibited similar non-essential
amino acid patterns, in which aspartic and glutamic
acids constituted a substantial amount of the total
amino acids (about 25% of total amino acids).
Aspartic and glutamic acids were responsible for
the special flavor and taste of the seaweeds (Wong
and Cheung, 2000).
The result indicated that Caulerpa
lentillifera and Ulva reticulata proteins were of
high quality because the essential amino acids
represented almost 40% of total amino acids and
the essential amino acids profile were closed to
those of egg and soya protein (Valerie et al., 1999),
except for relative lack of data on tryptophan,
methionine and cysteine.
CONCLUSION
The edible green seaweeds, Caulerpa
lentillifera and Ulva reticulata, were analyzed for
their nutritional compositions and were then
compared to those in several other seaweeds and
local vegetables. It was found that the two
seaweeds studied appeared to be interesting
potential sources of plant food proteins owing to
their high protein levels and balanced amino acid
profiles. In addition, they also showed the potential
of being good sources of mineral supplements. The
results of the present study concluded that these
seaweeds can provide dietary alternatives due to
their nutritional values. Their commercial values
can be enhanced by promoting the use in foods
and expanding the range of seaweed-based
products. Further study needs to be done on the
utilization and sensory perceptions of these
seaweeds.
ACKNOWLEDGEMENTS
This project was funded by Kasetsart
University Research and Development Institute.
The authors wish to thank Assistant Professor
Chatcharee Kaewsuralikhit for supplying samples
of Ulva reticulata.
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