Characterization and Heavy Metal Determination of Starch Obtained

from Rambutan (Nephelium lappaceum) Seed

Lia Laila

, Bayu Eko Prasetyo

1,2

, Mariadi

1,2

Faculty of Pharmacy, Universitas Sumatera Utara, Medan, Indonesia, 20155

Nanomedicine Center of Innovation, Universitas Sumatera Utara, Medan, Indonesia 20155

Keywords: Rambutan, seed, starch, heavy metal, characterization

Abstract: The needs of excipients in pharmaceutical industry and raw materials in food industry such as starch, elevate

the local plants to be utilized as an alternative source. Rambutan seed has the potentiality to be used as the

one of the starch sources. The aim of the study was to produce starch and do the characterization included the

heavy metal determination of starch obtained from rambutan seed. The starch was obtained by grinding the

rambutan seed with water in ratio of 1:5. The characterization parameters were the organoleptic and

microscopic features; yield value; moisture content; viscosity; and FT-IR spectra. The heavy metals measured

were lead (Pb), copper (Cu) and zinc (Zn) by using Atomic Absorption Spectrophotometer instrument. The

results showed that the rambutan seed starch had granular shape and gave 23.5% of yield value, 4.24 ± 0.78%

of water content, 270.83 ± 7.22 cP of viscosity (in 5% solution), acceptable concentration of the existed heavy

metal. It can be concluded that the rambutan seed can be suggested to be utilized as an alternative source for

the industry to produce standardized starch.

1 INTRODUCTION

Starch either as pharmaceutical excipient or raw

material is mostly required in pharmaceutical and

food industries (Mohammed, 2017). However, the

availability of the commercial starch in the market is

not enough to fulfil the requirement. The starch

producing industries is very limited compared to the

industries that need starch as raw material. Cassava,

potato, and corn are the most common sources to

produce starch. Starch is the most abundant

carbohydrate reserve in plants and it is found in

leaves, flowers, fruits, seeds, different types of stems

and roots (Smith, 2001). Indonesia is well-known to

have abundant natural sources which have not been

utilized properly. Therefore, it is needed to explore

and manage the natural sources to overcome the

nation problem. The utilization of plants, especially

fruits that rich in carbohydrate is one of the ways that

can be implemented.

Rambutan (Nephelium lappaceum L.) is a tropical

fruit belonging to the Sapindaceae family. The fruits

are ovoid, with a red or yellow pericarp covered with

soft hairs that vary in colour from green, yellow and

red (Suganthi and Josephine, 2016). Rambutan fruit

contains fat 35%, ash 2% and vitamin C 4%. The

seeds were abundant in fats (38.9%), protein (12.4%)

and carbohydrates (48%). The seeds have traces of an

alkaloid, sugar, starch and ash (Harahap et al., 2012).

Knowing the high amount of carbohydrate in

rambutan seed, it is a potent source to make the seed

as the alternative starch source since the usage of the

seed is not very much applied. However, it is needed

to confirm that the starch obtained from rambutan

seed is fulfil the requirement as pharmaceutical

excipient. Therefore, the purpose of this research was

to characterize the starch and determine the heavy

metal content of the starch obtained from the

rambutan seed.

2 MATERIALS AND METHODS

2.1 Materials

The materials used were rambutan seed obtained from

rambutan fruit available from the local market in

Binjai - North Sumatera (Indonesia), distilled water,

65% nitric acid (Smart Lab, Jakarta-Indonesia),

demineralized water (Bratachem, Medan-Indonesia).

Laila, L., Prasetyo, B. and Mariadi, .

Characterization and Heavy Metal Determination of Starch Obtained from Rambutan (Nephelium lappaceum) Seed.

DOI: 10.5220/0010095508610864

In Proceedings of the International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches (ICOSTEERR 2018) - Research in Industry 4.0, pages

861-864

ISBN: 978-989-758-449-7

861

2.2 Methods

The methods conducted in this study were rambutan

seed preparation, starch preparation, characterization

of the rambutan seed starch included organoleptic and

identification; yield value; moisture content;

viscosity; FT-IR spectra and heavy metal

determination.

2.2.1 Rambutan Seed Preparation

The skin of rambutan fruits were peeled off and the

fleshes were removed to obtain rambutan seed. The

seeds were washed, dried and put in the refrigerator

(LG) for further experiment.

2.2.2 Starch Preparation

The rambutan seed were ground with the addition of

distilled water in the ratio of 1:5. The mixture was

filter to obtain starch suspension. The suspension

were left until the starch was sedimented at the

bottom of the container. The water part was removed

and the starch was dried in the oven (Dynamica) and

ground, then filtered using shieve no. 80. The yield

value was calculated based on the obtained starch (b)

with the amount of the rambutan seed (a) as stated in

the equation (1).

𝑦𝑖𝑒𝑙𝑑 𝑣𝑎𝑙𝑢𝑒 





𝑥 100% (1)

2.2.3 Organoleptic and Identification

The organoleptic parameters evaluated were colour,

taste and odour. The identification of starch was

included the color test with lugol solution, the

mucilage formation and the

microscopic

characterization (The United State of Pharmacopoeia,

2005). The microscopic characterization was

conducted using distilled water as the mounting agent

(Selvam, 2013). The starch was evaluated using

microscope (Boeico, Germany) with 40x

magnification.

2.2.4 Moisture Content Determination

Moisture content determination was done by using

gravimetry methods. Some amount of sample was

weighed and dried in the oven at 105

C for 3 hours

and weighted until constant weight was obtained

(Ningsih et al, 2010). The moisture content was

determined in triplicate. The moisture content was

calculated by comparing the initial weight of the

starch (w1) with the constant weight of the starch

obtained after dried in the oven (w2) as stated in the

equation (2).

𝑚𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑐𝑜𝑛𝑡𝑒𝑛𝑡 





𝑥 100% (2)

2.2.5 Viscosity Determination

The rambutan seed starch was made into 5%

suspension in water, and then heated until boiled. The

viscosity at this state was measured, and then

continued left the mucilage to be cool (approximately

C) for the next measurement.The viscosity of

rambutan seed starch was determined by Brookfield

Viscometer. The determination of the viscosity was

performed in triplicate for each state of temperature.

2.2.6 FT-IR Analysis

The starch of rambutan seed was analysed for the

functional groups using Fourier Transform Infra Red

Spectrophotometer (Prestige 21, Shimadzu, Japan).

Each spectra was recorded at a resolution of 4 cm

-1

a range of 500-4000 cm

-1

. The obtained spectra was

compared with the potato starch as the official starch

in United State of Pharmacopoeia.

2.2.7 Heavy Metal Determination

The starch of rambutan seed was analysed for the

presence of the Pb, Cu and Zn.The heavy metals were

determined using atomic absorption

spectrophotometer (Hitachi Z-2000) with wavelength

of 283.3 nm for Pb, 324.8 nm for Cu and 213.9 nm

for Zn. Samples were analyzed in triplicate.

3 RESULTS AND DISCUSSION

3.1 Yield Value of Starch

Based on the starch preparation, it was obtained

23.5% of yield value . The result indicated that

rambutan seed could produce 23.5% starch from the

amount of the seed.This amount is high enough as the

seed of rambutan contains 48% of carbohydrate

which means approximately 48.96% of the

carbohydrate was isolated as starch.

ICOSTEERR 2018 - International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches

862

3.2 Organoleptic and Identification

Results

The organoleptic results showed that rambutan seed

starch had yellowish white colour, bitter taste, and

distinctive odour of rambutan. The identification of

starch using lugol solution gave dark purple colour. It

was fulfilled the required identification as stated in

USP which starch will give orange-red to dark blue

color (The United State of Pharmacopoeia, 2005).

The microscopic feature showed that the starch of

rambutan seed had circular shape with hilum as seen

in the Figure 1.

Figure 1: The microscopic characterizationof rambutan

seed starch with 40 x magnification, most of the

granules had concentric hilum (cross mark in the

middle of granules)

This shape has similarity with the starch in

common. It was confirmed that the sample produced

was starch. The presence of starch is different

according to the types of plant and the composition of

starch for each part of the plant is not similar either.

Starch can be found in the roots, rhizomes, tubers,

stems, leaves, flowers, pollens, fruits and seeds as

store of energy. Each part can has transitory or

storage type of starch. The granule type of starch can

be simple, compound or semi-compound (Selvam,

2013). From Figure 1, it can be seen that the rambutan

seed starch had simple and compound granule type

with concentric hilum position. Concentric hilum

means that hilum located near to the middle of the

granule.

3.3 Moisture Content and Viscosity

Results

The moisture content of the starch was 4.24 ±

0.78%.The moisture content of the starch is one of the

very important parameter that influences the quality

of the starch. High moisture content will cause the

stability of the starch become decrease due to the

possibility of the growth of microorganisms. The

starch granules usually have moisture content below

than 10% (Copeland et al., 2009).

The viscosity value of the rambutan seed starch

was 270.83 ± 7.22 cP. The temperature of a solution

or suspension will influence the viscosity value

(Haase et al., 1995). The increase of viscosity value

of the starch is due to the gelatinization process

(Sulaiman, 2011).

3.4 FT-IR Characterization

The FT-IR analysis of starch rambutan seed can be

seen from the Figure 2. The spectra showed some

functional groups. These functional groups included

–C-H stretch, –O-H group and C-O-C asymmetric at

2924.09 cm-1, 3340.71 cm-1 and 1149.57 cm-1; -C-

OH bending vibrations at 856.39 cm-1 and 570.93

cm-1 . These results were in accordance with the

earlier reports of starch [Amini et al., 2014;

Tongdeesontorn et al., 2011). FTIR is used to perform

preliminary testing, especially to compare the

functional group of a compound with another

compound. A functional group of potato starch and

rambutan seed starch as seen on the FTIR spectrum

was appeared almost identical. It means that the

rambutan seed starch had similar functional group

with the potato starch.



Figure 2: The spectra of starch obtained from the

rambutan seed compared with potato startch



3.5 Heavy Metal Analysis Result

The heavy metal analysis of starch obtained from

rambutan seed was conducted using Atomic

Absorption spectrophotometer. The result can be seen

in the Table 1.

Characterization and Heavy Metal Determination of Starch Obtained from Rambutan (Nephelium lappaceum) Seed

863

Table 1: The heavy metal analysis of starch obtained from

rambutan seed

Heav

metal Concentration (ppm)

Pb not detecte

Cu 0.6228±0.37

Zn 0.6171±0.91

Normally, Pb is found in the sample that

contaminated with pollution such as place which

near to the factory or street. Lead in the starch of

rambutan seed was not detected. This result might be

due to the position of the seed is in the inner part of

the fruit which not directly exposed to the

environment. In the other hand, copper and zinc

were detected in the starch obtained from the

rambutan seed. The presence of the metals might be

due the soil environment factor and the hyper

accumulator characteristic of the plant. This hyper

accumulator character could accumulate specific

metals in the certain tissue of the plant (Irawanto et

al., 2015; Knox et al., 2000).

4 CONCLUSION

It can be concluded that rambutan seed have big

potency to become one of the alternative source of

starch, however further development needed to

increase the utility of the starch.

ACKNOWLEDGEMENT

This research was funded by Universitas Sumatera

Utara according to the TALENTA Research Contract

of Universitas Sumatera Utara year 2018 number

2590/UN5.1.R/PPM/2018 dated March 16, 2018.

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