Nutritional assessment of a jackfruit (Artocarpus heterophyllus) meal

Abstract

The mature jackfruit (Artocarpus heterophyllus) is consumed in Sri Lanka either as a main meal or a meal accompaniment. However, there is no scientific data on the nutrient compositions of cooked jackfruit meals. Thus, the objective of the study was to carry out a nutritional assessment of a composite jackfruit breakfast meal comprising seeds and flesh.
A jackfruit meal comprising of flesh (80% available carbohydrate) and seeds (20% available carbohydrate) was included in the study. The study was carried out in a random cross over design. Setting University of Sri Jayewardenepura. Study participants Healthy individuals (n=10, age: 20-30 yrs).
The macronutrient contents, rapidly and slowly available glucose (SAG) contents, water solubility index of the jackfruit meal were determined according to standard methods. The GI of the meal was calculated according to FAO/WHO guidelines.
The moisture content of the boiled jackfruit flesh was high (82% FW). Jack seeds contained 4.7% protein (FW), 11.1% total dietary fibre (FW) and 8% resistant starch (FW). Jackfruit meal elicited a GI of 75. The Glycaemic Load (GL) of the normal serving size of the meal is medium. The slowly available glucose (SAG) percentage of jackfruit meal (30%) was twice that of the standard. The boiled jackfruit flesh contained disintegrated starch granules while seeds contained intact swollen and disintegrated granules.
The jackfruit seeds are a good source of starch (22%) and dietary fibre. The meal is categorized as a low GI meal. The low GI could be dueto the collective contributions from dietary fibre, slowly available glucose and un-gelatinised (intact) starch granules in the seeds.

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Abstract
Objectives The mature jackfruit (Artocarpus
heterophyllus) is consumed in Sri Lanka either as a main
meal or a meal accompaniment. However, there is no
scientific data on the nutrient compositions of cooked
jackfruit meals. Thus, the objective of the study was to
carry out a nutritional assessment of a composite
jackfruit breakfast meal comprising seeds and flesh.
Design A jackfruit meal comprising of flesh (80%
available carbohydrate) and seeds (20% available
carbohydrate) was included in the study. The study was
carried out in a random cross over design.
Setting University of Sri Jayewardenepura.
Study participants Healthy individuals (n=10, age: 20-30
yrs).
Measurements The macronutrient contents, rapidly and
slowly available glucose (SAG) contents, water solubility
index of the jackfruit meal were determined according to
standard methods. The GI of the meal was calculated
according to FAO/WHO guidelines.
Results The moisture content of the boiled jackfruit flesh
was high (82% FW). Jack seeds contained 4.7% protein
(FW ), 11.1% total dietary fibre (FW ) and 8% resistant
starch (FW ). Jackfruit meal elicited a GI of 75. The
Nutritional assessment of a jackfruit (Artocarpus heterophyllus) meal
U P K Hettiaratchi
1
, S Ekanayake
1
, J Welihinda
2
(Index words: Artocarpus heterophyllus, jackfruit, glycaemic index, nutritional properties)
1
Department of Biochemistry, Faculty of Medical Sciences, University of Sri Jayewardenepura, and
2
Department
of Biochemistry and Molecular Biology, Faculty of Medicine, University of Colombo, Sri Lanka
Correspondence: SE, e-mail <sagarikae@hotmail.com>. Received 8 July and revised version accepted 25
November 2010. Competing interests: none declared.
Glycaemic Load (GL) of the normal serving size of the
meal is medium. The slowly available glucose (SAG)
percentage of jackfruit meal (30%) was twice that of the
standard. The boiled jackfruit flesh contained
disintegrated starch granules while seeds contained
intact swollen and disintegrated granules.
Conclusions The jackfruit seeds are a good source of
starch (22%) and dietary fibre. The meal is categorized
as a low GI meal. The low GI could be due to the collective
contributions from dietary fibre, slowly available glucose
and un-gelatinised (intact) starch granules in the seeds.
Ceylon Medical Journal 2011; 56: 54-58
Introduction
Jackfruit (Artocarpus heterophyllus) is reported to
have originated in India and Malaysia [1]. The jackfruit is
a species of the mulberry family (Moraceae) [1]. In Sri
Lanka it is known as "Kos" (Sinhala) and "Pala" (Tamil).
The fruit contains fleshy bulbs and starchy seeds
both of which are used as foods in Sri Lanka. The mature
jackfruit is consumed either as a main meal or a meal
accompaniment with rice and the ripe flesh as a fruit.
Jackfruit is reported to possess many medicinal properties.
The phenolic compounds isolated from jackfruit are

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reported to exhibit anti-inflammatory effect [1]. The
prenylflavones present in jackfruit had shown strong
antioxidant properties and is expected to act against lipid
peroxidation of biological membranes [2]. The hot water
extract of mature leaves are utilised in Ayurvedic treatment
for hyperglycaemia and diabetes [1]. The flavanoids
present in the extract have been identified to be
responsible for the non-toxic hypoglycaemic action [3].
Lectins present in the seeds have shown antifungal
properties while the crude methanolic extracts from root
bark and stems have shown broad spectrum antibacterial
activity [4].
Raw jackfruit flesh is regarded as a good source of
carbohydrate (25%), vitamin A and a fair source of protein
(1.6%) [6]. The postprandial glycaemic response to raw
and ripe jackfruit elicits low glycaemic index (GI) [7].
However, research has not focused on studying the
nutritional parameters of cooked jackfruit meals. This could
be due to the low consumption of cooked jackfruit meals
in other countries except in Sri Lanka and Bangladesh [1].
Although jackfruit is widely available and is liked by most,
many Sri Lankans do not consider it to be a suitable meal
or an accompaniment to rice in the diabetic food regime
due to the belief that it is high in digestible carbohydrate
and yields high energy. However, data is not available to
confirm this belief. Therefore the objective of this study
was to carry out a nutritional assessment on a jackfruit
breakfast meal.
Methods
Jackfruit meal
Jackfruit meal served for determination of GI
comprised of boiled jackfruit flesh (400g), jackfruit seeds
(~50g), coconut scrapings (25g) and an onion sambol (10g).
The flesh (800g) was boiled with water (100ml) under high
heat for 10 minutes and under low heat till all the water
was removed. Seeds (200g) were boiled with water (200ml)
till soft.
Determination of Glycaemic Index
GI was estimated with healthy individuals (n=10, age
– 20-30 years, BMI – 24±3 kgm
2
) according to the
guidelines given by FAO/WHO [8]. White sliced bread
(mass production) bought from retail outlets were used as
the standard food and given twice to the volunteers.
Informed, written consent was obtained from study
participants prior to the start of the study. Approval for
the study was obtained from the Ethics Committee, Faculty
of Medical Sciences, University of Sri Jayewardenepura.
Determination of chemical composition
The insoluble and soluble dietary fibre [9], protein
[10], fat [11], rapidly and slowly available glucose contents
[12], and water solubility indices (WSI) [13] of the jackfruit
meal were determined. The degree of gelatinisation of the
starch granules of raw and processed jackfruit flesh and
seed flour were examined under light microscope (1010)
by staining with KI/I2 solution [13].
Statistical analysis
The GI and Incremental Area Under Curve (IAUC)
values are presented as mean [standard error of mean
(SEM)]. The results were analysed using Microsoft Excel
(2003).
Results
The nutritional parameters of the jackfruit flesh, seeds
and the meal are presented in Table 1. The moisture
content of boiled jackfruit flesh and seeds were 82% and
53% [fresh weight (FW)] respectively and significantly
different (p<0.005). The available digestible carbohydrate
contents of the flesh and the seeds were 10% and 22%
(FW) respectively. The protein content of the meal was
6.8% with a higher contribution from the seeds while the
fat content of the meal was 11.5% (FW). Jack seeds
contained high total dietary fibre (TDF) (11.1% FW)
compared to flesh (2.6% FW). Jackfruit seeds also
contained 8% (FW) resistant starch (undigestible starch).
The average postprandial glycaemic response of the
jackfruit meal is presented in Figure 1. The jackfruit meal
maintained the satiety levels even at 2 hours from ingestion
unlike with the standard. The 50g available carbohydrate
portion of jackfruit meal contained 40g available
carbohydrate from jackfruit flesh (400g) and 10g from seeds
(~ 50g). The proportions of flesh and seeds were selected
according to palatability tests conducted by varying the
ratios. Due to the high moisture content of jackfruit flesh
the total meal portion given for determination of GI was
rather large (450g). According to the participants (80%)
the portion was difficult to consume and the normal
serving size (NSS) would be two thirds of the meal served
in determining GI.
The GI, IAUC and GL of the meal are presented in
Table 1. Jackfruit meal elicited a GI of 75 and can be
categorised as a low GI food. When analysing individual
glycaemic responses to the meal, 80% of individuals
elicited low glycaemic responses (low GI) while other two,
medium GI values.
The slowly available glucose percentage of jackfruit
meal was 30%. Jackfruit flesh elicited a water solubility
index of 28.7. Boiled jack flesh contained disintegrated
starch granules while seeds contained intact swollen and
disintegrated granules (Figure 2). Jackfruit meal contained
two sources of carbohydrates from jackfruit flesh and
seeds (vegetable and seeds).

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Table 1. Nutritional parameters of jackfruit flesh, seed, meal and the standard
Parameter
1
Jackfruit flesh
1
Jackfruit seeds
2
Jackfruit meal
2
Standard
Carbohydrate (SD) 10.0 (0.3) 21.9 (0.8) 50 g 50 g
IDF (SD) 1.5 (0.1) 7.9 (0.5) 13.5 0.8
SDF (SD) 1.1 (0.1) 3.2 (0.3) 6.5 2.4
TDF 2.6 11.1 20.0 3.2
Protein 0.9 4.7 6.8 8.2
Fat (SD) 0.8 (0.1) 1.3 (0.3) 11.5 3.2
Resistant starch 0.3 8.0 5.2 0.7
SAG% 17% 33% 30% 16%
Amylose 29 54 31 15
GI (SEM) ND ND 75 (11) 100
IAUC (SEM) ND ND 132 (19) 181 (18)
GL (NSS) ND ND 13 20
1
Values are given as g/100g fresh weight;
2
Values are given in the 50g available carbohydrate portion; SD – Standard Error: SEM – Standard
Error of Mean; IDF – Insoluble Dietary Fibre; SDF – Soluble Dietary Fibre; TDF – Total Dietary Fibre; SAG – Slowly Available Glucose; GI
– Glycaemic Index; IAUC – Incremental Area Under Curve; GL – Glycaemic Load; GL=[(GI /1.4)*available carbohydrate content in NSS]/
100; NSS – Normal Serving Size.
Figure 1. Glycaemic response to jackfruit meal and the standard.
Each point represents an average of 10 values.

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Discussion
The moisture and protein content of boiled jackfruit
(Table 1) are similar to reported raw values [6]. The total
energy contribution of the meal is 1370 kj. Jackfruit meal
provides 20% of daily energy requirement of a moderately
active individual. Jack seeds contained high amount of
resistant starch (undigestible starch). RS is categorised
into four types (RS1-RS4) [14] and jackfruit seeds may
contain RS1 type. The undigestible starch escapes
digestion in the small intestine, passes into the colon and
is reported to act like dietary fibre [14]. The postprandial
glycaemic response (Figure 1) and GI of the jackfruit meal
were determined. Jackfruit meal elicited a low GI (Table 1).
This is the first reported data on GI of a jackfruit meal in
spite of having 2487 data on GI of different foods in the
recent "International Tables of Glycaemic Indices and
Glycaemic Load Values" [15].
Jackfruit meal elicited a low inter individual variation.
This is a positive aspect of this commonly available food
item as inter individual variation to the same food is
reported to vary widely [16] making it difficult to
recommend foods that are even low GI to individuals who
Figure 2. Starch granules of raw and boiled jackfruit flesh and seeds (10x10)
(a) Jackfruit flesh (raw)
(b) Jackfruit flesh (boiled)
(c) Jackfruit seeds (raw) (d) Jackfruit seeds (boiled)
need to control postprandial blood sugar levels. The GI of
the jackfruit meal is significantly lower (p<0.05) than the
other Sri Lankan meals tested previously in the same
laboratory except for the rice mixed meal containing red
rice, lentil curry, boiled egg, 'gotukola' sambol (Centella
asiatica), 'kiri hodi' [17], and legumes [18]. Thus, the low
GI of the jackfruit meal confirms its suitability as a main
meal or an accompaniment with rice.
Protein, fat and dietary fibre contents of foods have
been reported to elicit significant negative relationships
with GI (p<0.05) [16]. However, during our previous
studies, only the dietary fibre content of Sri Lankan meals
elicited a significant negative relationship with GI [17].
Thus, the high fibre content of the jackfruit meal (20 g)
could be contributing to a lower GI of the meal. Influence
of dietary fibre on GI will be more applicable and beneficial
for the Sri Lankan population as the commonly eaten Sri
Lankan meals comprise of many vegetables and green
leaves which are natural sources of fibre.
High SAG content of jackfruit meal (30%) when
compared with most of the Sri Lankan foods (3-51% –
unpublished data) could also have contributed in part to

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the low GI. Most Sri Lankan foods have a high
gelatinisation point with correspondingly low SAG
[unpublished data]. This confirms the suitability of jackfruit
as a meal for individuals controlling the postprandial
glycaemic response.
The amount of soluble substances leached out
following processing is reflected by water solubility index
(WSI). Jackfruit flesh contained high WSI values (28.7)
indicating hydrolysis and leaching of more soluble
substances (proteins, amylose etc.) during cooking. The
low GI of the meal indicates that leached out substances
could be molecules other than amylose and amylopectin.
Boiled jackfruit flesh contained disintegrated starch
granules while seeds contained intact swollen and
disintegrated granules indicating the effect of wet
processing on granules (Figure 2).
Sources of carbohydrates available in a meal also
influence plasma glucose and insulin responses [16].
Jackfruit meal contained two sources of carbohydrates
(eg: vegetable and seeds). The inclusion of 10%
carbohydrate from seeds or presence of other compounds
in the seeds such as -D-Galactose specific lectin which
have the capacity to bind mono- and oligosaccharides as
reported for another species of Moraceae family,
Artocarpus integra (also called as jackfruit) might also be
responsible for low GI of this meal [20]. The presence of
compounds of this nature that can bind glucose would
either reduce the absorption of glucose or slow the process
of digestion thereby yielding a low glycaemic response.
Conclusion
Jackfruit has beneficial nutritional parameters and a
low GI. This could be due to the collective contributions
of dietary fibre, slowly available glucose, intact starch
granules in seeds and influence of different sources of
carbohydrates.
Acknowledgements
The financial assistance by NSF RG/2005/AG/10 and
IPICS Sri 07 is acknowledged.
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