Carbohydrate-Electrolyte Characteristics of Coconut Water from Different Varieties and Its Potential as Natural Isotonic Drink

Abstract

Coconut water is known as a nutritious natural drink. It is not only considered functional, but also nutraceutical. Coconut water is widely used as isotonic drink or oral rehydration fluid, since it showed excellent rehydration index and blood glucose response in previous researches. The quality of isotonic drink is determined by its sugar content (as the source of carbohydrate) and electrolyte content. Moreover, its organoleptic properties should be able to stimulate the urge to spontaniously drink more. However, the processing of coconut water into isotonic drink usually applies ultra high or very low temperature which might deteriorate its nutrition value and organoleptic properties, causing the needs to use a considerable amount of food additives. There are plenty varieties of coconut in Indonesia, each produces different characteristics of coconut water. The objectives of this research are to compare the carbohydrate-electrolyte characteristics of coconut water, and also other essential characteristics from several varieties and to determine which variety is closest to the quality standard of isotonic drink. Therefore, isotonic drink can be developed with only minimum food additives. We compared Dalam Pangandaran, Genjah Salak and Hybrid PB121. The characteristics observed were total sugar, sucrose, glucose, fructose, potassium, sodium, magnesium, vitamin B1, vitamin B6 and vitamin C content, as well as pH, total soluble solids, clarity and colour. Coconut water obatined from Genjah (Dwarf) variety showed the more suitable characteristics for the development of isotonic drink. Thus the product can be developed by cold sterilitation process with minimum food additives.

Full text

Vol.5
(201
5
) No.
3
ISSN: 2088
-
5334
Carbohydrate-Electrolyte Characteristics of Coconut Water from
Different Varieties and Its Potential as Natural Isotonic Drink
Sari Intan Kailaku#*1, Andi Nur Alam Syah*, Risfaheri*, Budi Setiawan#2 and Ahmad Sulaeman#3
# Department of Public Nutrition, Bogor Agricultural University, Bogor 16680, Indonesia
E-mail: 1sari.kaylaku@gmail.com, 2bsetiawan.ipb@gmail.com, 3asulaeman06@gmail.com
*Indonesian Agency of Agricultural Research and Development, Indonesian Ministry of Agriculture, Bogor 16114, Indonesia
E-mail: 4ganesh.alam@gmail.com, 5risfaheribbpascapanen@yahoo.com
Abstract— Coconut water is known as a nutritious natural drink. It is not only considered functional, but also nutraceutical. Coconut
water is widely used as isotonic drink or oral rehydration fluid, since it showed excellent rehydration index and blood glucose
response in previous researches. The quality of isotonic drink is determined by its sugar content (as the source of carbohydrate) and
electrolyte content. Moreover, its organoleptic properties should be able to stimulate the urge to spontaniously drink more. However,
the processing of coconut water into isotonic drink usually applies ultra high or very low temperature which might deteriorate its
nutrition value and organoleptic properties, causing the needs to use a considerable amount of food additives. There are plenty
varieties of coconut in Indonesia, each produces different characteristics of coconut water. The objectives of this research are to
compare the carbohydrate-electrolyte characteristics of coconut water, and also other essential characteristics from several varieties
and to determine which variety is closest to the quality standard of isotonic drink. Therefore, isotonic drink can be developed with
only minimum food additives. We compared Dalam Pangandaran, Genjah Salak and Hybrid PB121. The characteristics observed
were total sugar, sucrose, glucose, fructose, potassium, sodium, magnesium, vitamin B1, vitamin B6 and vitamin C content, as well as
pH, total soluble solids, clarity and colour. Coconut water obatined from Genjah (Dwarf) variety showed the more suitable
characteristics for the development of isotonic drink. Thus the product can be developed by cold sterilitation process with minimum
food additives.
Keywords— coconut water; isotonic drink; carbohydrate-electrolyte; coconut varieties
I. INTRODUCTION
Coconut water is rich with macronutrient and
micronutrient content, i.e. carbohydrate, potassium, sodium,
magnesium and chloride [1]. It is widely used as isotonic
drink or oral rehydration fluid, because of its excellent
rehydration index [2] and blood glucose response [3],
therefore beneficial as after-exercise drink. Reference [4]
showed that coconut water is beneficial for rehydration and
physical performance recovery equal with that of
carbohydrate-electrolyte sports drink, in exercised male
subjects. Isotonic drink is carbonated or non carbonated
beverage product used for fitness improvement, containing
sugar, citric acid and minerals [5]. Not only as thirst
quencher, it is also known as sports drink for athletes
consumption, to maintain their hydration status, electrolyte
and energy while exercising.
The increasing interest for natural products leads to the
exploration of coconut water potential utilization in isotonic
drink product development. The obstacle in developing
coconut water-based product is its easily altered properties.
Once a coconut is opened and the water is extracted from it,
degradation will occur due to air contact, and the water will
lose almost all of its organoleptic characteristics and some of
its nutrient content, and starts to ferment. Thus, in only few
hours after its extraction, coconut water will be cloudy, pale-
yellowish, sour and unappetizing tasteless, due to the
activities of oxidase enzymes and microbial contamination
[6]-[7].
The shelf-life of coconut water isotonic drink can be
improved by ensuring the elimination of the causes of its
quality degradation. There are several methods commonly
used to preserve coconut water. Most commercial
productions use high temperature which might cause the lost
of nutrient content and its unique aroma and flavour [8].
Coconut water processing without using high temperature
was introduced by FAO [9], i.e. microfiltration. This cold
sterilisation process then was developed by [10] where the
microfiultration membrane was replaced with ultrafiltration
membrane. Unfortunately, the coconut water used in the
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research was from overly mature coconut and without
varieties selection, thus its characteristics were unsuitable for
the development of isotonic drink. The product development
involved a considerably amount of the addition of sucrose,
minerals and citric acids to obtain the standardized quality
requirement. In order to increase the benefit and superiority
of cold sterilisation process, the minimization of food
additives can be done by using coconut water from a
selected variety and nut age, with the closest characteristics
to isotonic drink quality requirement.
Indonesia has the highest coconut diversity with the
largest coconut plantation in the world [11]. Two large
varieties of coconut are Dalam (Tall) and Genjah (Dwarf).
Breeding activities has also produced Hybrid coconut from
Tall and Dwarf varieties [12]. The characteristics are
different among each varieties, and also among different nut
age. The objective of this study are: (1) to characterise
coconut water from Tall, Dwarf and Hybrid variety, and (2)
to determine the suitable variety for product development of
isotonic drink with cold sterilisation process.
II. METHODS
Analyzes were conducted at Food Analysis Laboratory,
Indonesian Centre of Agricultural Postharvest Research and
Development, Bogor, West Java. Coconut water was
obtained from coconut varieties planted at Experimental
Plantation, Indonesian Industrial Crops Research Institute ,
Sukabumi, West Java. Coconut age was pre-selected, i.e. 8-9
months, for the closest characteristics to isotonic drink
quality requirement [13].
The characteristics being observed were total sugar,
sucrose, glucose, fructose, potassium, sodium, magnesium,
vitamin B1, vitamin B6 and vitamin C content, as well as
total soluble solids (TSS), clarity and colour. Total sugar
determination as in [14]. Sucrose, glucose, fructose, vitamin
C, vitamin B1 and vitamin B6 were analyzed using High
Performance Liquid Chromatography [15]-[16]. Potassium,
sodium and magnesium content were determined using
Atomic Absorption Spectroscopy [17].
The characteristics of coconut water from all varieties
were described. The difference between each variety were
tested using One Way Anova with confidence level of 95%.
Sampling was done in three replications.
III. RESULTS AND DISCUSSION
The varieties being used in the study were Dalam
Pangandaran (Tall), Genjah Salak (Dwarf) and Hibrida
PB121 (Hybrid). The study used mature coconut water (8-9
months of age) for its more suitable characterisitics for the
development of isotonic drink. Reference [13] compared the
composition and physicochemical properties of different
aged coconut water. They reported that the total sugar
content tended to decrease during nut aging. Reference [12]
reported that potassium content decreased during aging,
while sodium content increased.
A. Carbohydrate-Electrolyte Characteristics
The results of sugar and mineral analyzes of coconut
water from different varieties compared with the Indonesian
National Standard (SNI) are presented in Table 1. Coconut
water from Dwarf variety had the significantly highest total
sugar, fructose and glucose content compared to Tall and
Hybrid variety (p<0.05). This is an important characteristic
for Dwarf as isotonic drink raw material. Beverages
containing 6-8% carbohydrate can maintain atheletes’ blood
glucose level and help them to achieve a good recovery rate
[18]. This sufficient total sugar content will allow isotonic
drink product development without additional sugar.
TABLE I
CARBOHYDRATE-ELECTROLYTE CONTENT OF COCONUT WATER
Components
Variety p SNI*
Dwarf Tall Hybrid
Total sugar
(%) 6.01+0.06c 5.57+0.02b 5.04+0.13a 0.003 > 5
Sucrose (%) 0.63+0.01b 0.50+0.00a 0.85+0.42c 0.001
Fructose (%) 2.67+0.04b 2.56+0.04b 2.07+0.05a 0.001
Glucose (%) 2.71+0.01c 2.51+0.01b 2.12+0.04a 0.000
Potassium
(mg/kg) 1497.40+
43.73 1567.96+
351.77 1504.00+
128.76 0.939 <
125-
175
Sodium
(mg/kg) 30.30+
6.18 37.33+
6.18 23.82+
6.18 1.000 <
800-
1000
Magnesium
(mg/kg) 95.40+
3.88 217.73+
119.42 24.30+
4.42 0.142 -
*Isotonic Drink Quality Requirement based on Indonesian National
Standard (SNI) 01-4452-1998
Carbohydrate content in isotonic drink is needed for an
immediate energy recharge [18] and glycogen replenishment,
which had been spent when one is doing a strenuous
physical activity [19].
Moreover, the existence of sufficient carbohydrate in
isotonic drink will produce a palatable taste and stimulates
the urge to drink spontaneously [20]. This is important to
ensure an athlete to voluntarily drink an adequate amount of
fluid. Coconut water has its own superiority compared to
other isotonic drink because of its natural sweet taste due to
the sugar content, along with the unique aroma and flavour,
making it a favorite beverage for most people.
Strenous physical activity or exercise escalates
electrolytes needs and can lead to dehydration. Therefore,
rehydration fluid should be taken adequately to rehabilitate
hydration status and should contain electrolytes to accelerate
the rehydration process [19].
Mineral composition is an important factor that makes
coconut water a natural rehydration fluid. High potassium
content is effective in replenishing intracellular fluid, while
high sodium content replenishes extracellular fluid [21].
The mineral contents of coconut water (K, Na, Mg) were
not significantly different in the three varieties (Table 1).
The lower content of sodium compared to SNI can be a
consideration in choosing a food additive to prolong shelf-
life. Choosing a material containing sodium, eg. sodium
benzoate, to act both as preservative agent and fortifier, is
more reasonable than other material eg. potassium sorbate
which unnecessarily increases potassium content.
24

B. Vitamins Content
Coconut water contains vitamins i.e. vitamin C, B1, B2,
B3, B5, B6, folic acid, and B7 [22]. Vitamins contents are
significantly different among the three varieties observed in
this study (p<0.05). Dwarf variety had the highest vitamin
B1, Tall variety contained highest vitamin B6, while Hybrid
coconut had the highest vitamin C content (Table 2).
Although product quality standard for isotonic drink does
not include vitamin content, the existence of vitamins in
coconut water is nevertheless an advantage and is important
in its role as isotonic drink. Beside its benefit as rehydration
and energy fluid, isotonic drink should have free radical
inhibition property. Oxidative stress can occur in
overworked muscle tissues during exercise, hence it is
beneficial for an athlete to consume rehydration fluid that
contains antioxidants [20].
TABLE II
VITAMINS CONTENT OF COCONUT WATER
Components
Variety p
Dwarf Tall Hybrid
Vitamin B1 11.97+0.13c 9.31+0.05b 6.65+0.18a 0.000
Vitamin B6 0.03+0.00a 0.47+0.01b 0.04+0.00a 0.000
Vitamin C 15.70+0.01b 14.45+0.08a 16.65+0.08c 0.000
C. Physicochemical Properties
Physicochemical properties are good indicators in
estimating the suitability of coconut varieties for the
production of coconut water as a beverage [23]. Dwarf
coconut produced more water compared to Hybrid, but less
than Tall coconut (Table 3). The water volume of Tall and
Dwarf were considerably sufficient for a convenient mass
production activity.
TSS and clarity level of the three varieties were
significantly different (p<0.05), but pH value was not (Table
3). Coconut water from Dwarf variety had the highest TSS
and clarity level. TSS generally represents the sweetness of
coconut water [13]. Clarity of coconut water is one of its
most important appearance attributes [24]. Consumers rate
clear beverages as the most thirst-quenching and opaque
beverages as the least [25].
TABLE III
PHYSICOCHEMICAL PROPERTIES OF COCONUT WATER
Properties
Variety p
Dwarf Tall Hybrid
Water volume
per nut (ml) 485+7.07b 632.5+10/.61c 330+28.28a 0.001`
pH 6.02+0.13 5.96+0.01 5.83+0.08 0.218
Total soluble
solids (oBrix) 5.95+0.08b 5.30+0.01a 5.50+0.00a 0.012
Clarity (% to
water) 98.40+0.01c
97.80+0.01b 97.05+0.08a 0.009
Colour
L 101.77+0.04
c
101.07+0.04
b
100.74+0.05
a
0.000
a -0.27+0.08b -0.21+0.08
b
-0.61+0.13
a
0.000
b 0.03+0.05
b
-0.07+0.03
a
1.19+0.08
c
0.000
L value (lightness) of coconut water decreases during
storage despite microfiltration and addition of acid in
product development [26]. L value of all the varieties in the
study were above 100 due to its high clarity (not white)
before storage. The high level of lightness and clarity of
Dwarf coconut water was an advantage for its general
appearance for future storage. Negative a values indicated a
spectrum of greenish in all samples. Positive b values
showed that the samples had yellowish spectrum, except in
Tall coconut water which showed bluish spectrum.
The characterization of coconut water samples from three
different varieties showed that Dwarf variety may be
recommended as raw material for isotonic drink product
development for its closest characteristics to the quality
standard. This result was resemblant with the conclusion in
[23], where the synthesis of biochemical data showed that
Dwarf coconut varieties, with their small nuts, high volume
of water, high sugar contents and good organoleptic scores,
were the most suitable cultivars to obtain sweet and tasty
product.
D. Processing Recommendation
Cold sterilisation process are becoming more commonly
used to extend the shelf-life of food and beverages product.
Membrane technology is widely used in various area, i.e.
biotechnology, pharmacy, food and beverages and gas
isolation. Ultrafiltration is a filtration process using
membrane, working in the pressure difference principal.
Ultrafiltration process and pasteurization were proven
equally effective in reducing enzyme activities in coconut
water [27].
The advantages of using membrane technology are: (1)
lower capital cost compared to convensional
separation/filtration technology, (2) lower operational cost
compared to centrifugation process, (3) easily scaled up and
faster installation, (4) clean and causes less degradation in
the products [28]. The improvement of coconut water shelf-
life can be done by microbial and enzyme filtration (not
deactivation) [29].
The utilization of coconut water from a suitable variety,
followed by cold sterilisation process that minimize the
degradation of organoleptic properties and nutritional
composition, may produce an isotonic drink product that
needs, if any, the minimum amount of food additives.
IV. CONCLUSIONS
The characterization of three varieties of coconut showed
that Dwarf coconut water may be recommended as isotonic
drink natural raw material that was the closest to the quality
standard of isotonic drink, for future processing with cold
sterilisation technology such as ultrafiltration.
ACKNOWLEDGMENT
The authors are grateful for the cooperation and assistance
of the plantation managers and technicians of Experimental
Plantation, Indonesian Industrial Crops Research Institute ,
Sukabumi, West Java, in exploring the varieties of coconut
and collecting the coconuts for the study.
25

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