Quality Improvement of Liquid Smoke of Coconut Shell

by Tar Scrubber

Reka M. Sari

, Saharman Gea

, Basuki Wirjosentono

and Sunit Hendrana

Postgraduate Chemistry Study Program, Faculty of Mathematics and Natural Sciences, Universitas Sumatera Utara,

Jl. Bioteknologi No. 1 Kampus USU, Medan, Indonesia

Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Sumatera Utara, Jl. Bioteknologi

No. 1, Medan 20155, Indonesia

Research Centre for Chemistry, Indonesian Institute of Sciences, Kawasan Puspiptek, Gedung 452, Tangerang Selatan,

Banten 15314, Indonesia

malikabdul4329@gmail.com, rachmadfauzi8888@gmail.com

Keywords: Coconut Shell, Liquid Smoke, Quality of Liquid Smoke, Tar Scrubber.

Abstract: One of the most challenging issues concerning to the pyrolysis of liquid smoke coconut shell is the presence

of tar. The acidity, water content, density and content analysis of liquid smoke using coconut shell which

produced at 500

C using pyrolysis reactor equipped with a tar scrubber were compared to liquid smoke

produced conventionally. Characterization of acidity of the liquid was measured by pH meter by adhering to

ASTM E70, water content by using volumetric Karl Fischer titration method following ASTM E203 and

ASTM D1744 method, the density by AOC 1995, and dichloromethane extracts content by gas

chromatography-mass spectrometry (GC-MS). The results showed that the pH range of liquid smoke was

pH 2.4 to 2.6 with the water content of 89.970 to 94.593%, and the density of 1.0118 to 1.0036 g/mL. The

carbonyl and phenol content were 5.05 to 6.473% and 85.057 to 90.024% respectively. From the results can

be concluded that the quality of liquid smoke produced by tar scrubber is better than the quality of liquid

produced by conventional method.

1 INTRODUCTION

Coconut shell liquid smoke is a result of pyrolysis of

coconut shell or condensation of steam distillation.

The constituents of the liquid smoke are obtained

from thermal degradation reactions of cellulose,

hemicellulose, and lignin. Hemicellulose owned the

highest CO

, lignin generated the highest CH

and

cellulose produced the highest CO characterized by

the largest HHV (Zhao, Jiang and Chen, 2017).

In the process of pyrolysis also produced liquid

smoke, tar and non-condensable gases. Liquid

smoke which is a by-product of the charcoal

industry has high economic value when compared to

being discharged into the atmosphere. Liquid smoke

is obtained from dew condensation resulting from

decomposition of organic compounds during the

pyrolysis process. The content of liquid smoke from

pyrolysis is phenol compound of 90.75%, carbonyl

3.71% and alcohol 1,81%, the compound is

antimicrobial which can preserve food (Hadanu and

Apituley, 2016). The application of liquid smoke is

mainly associated with the functional properties of

liquid smoke, including as an antioxidant,

antibacterial, antifungal, and its potential in forming

the product.

Antimicrobial properties can inhibit the activity

of spoilage and spoilage microbes in food so that it

can extend the shelf life of food products (Olatunde

and Benjakul, 2018). In addition, liquid smoke can

also have an effect on distinctive taste, color, and

aroma. Some types of agricultural waste such as

corn cobs, rice husks, peanut shells, coconut shells,

coconut fiber, mangrove wood, pine and others

contain phenols and antibacterial properties that can

preserve and give flavor to food products (Dungani

et al., 2016).

Liquid smoke produced from coconut shell needs

further processing because it contains higher levels

of benzopyridene containing toxic thus liquid smoke

from coconut shell is not yet suitable for use

(Budaraga et al., 2016). The major proportion of

262

M. Sar i, R., Gea, S., Wirjosentono, B. and Hendrana, S.

Quality Improvement of Liquid Smoke of Coconut Shell by Tar Scr ubber.

DOI: 10.5220/0008920802620265

In Proceedings of the 1st International Conference on Chemical Science and Technology Innovation (ICOCSTI 2019), pages 262-265

ISBN: 978-989-758-415-2

commercial full-strength liquid smoke to be

composed of water (11–92%), tar (1–17%), acids

(2.8–9.5%), carbonyl containing compounds (2.6–

4.6%) and phenol derivatives (0.2–2.9%) (Baltes et

al., 1981). Further treatment is needed to reduce

levels of toxic compounds, eliminate tar, increase

liquid smoke yield and its quality.

The general method used in removing tar from

liquid smoke is redestilation. Redestilation is the

process of purifying liquid smoke based on

differences in the boiling point of liquid smoke.

There have been many studies doing liquid smoke

redestilation (Darmadji, 2002; Budaraga et al., 2016;

Ketut Budaraga et al., 2016). At present, the method

offered in removing tar is wet scrubber because it is

simple, economical and high efficiency. Some

studies use this method for removing tar in syngas.

The objective of this study was to determine

important chemical characteristics of a full-strength

liquid smoke from tar scrubber. The chemical

volatile and semi-volatile constituents of these

product were identified using gas chromatography-

mass spectrometry (GC-MS) analysis. pH, acidity,

density were also determined.

2 MATERIALS AND METHODS

2.1 Materials

Raw material used in this study was coconut shell

from coconut shell charcoal industry, Johor, Medan,

Indonesia.

2.2 Equipment

In this study, the equipment used were a set of

pyrolysis tar scrubber reactor, pH meter,

pycnometer, analytical balance, Karl Fischer

coulometric titrator and GC-MS.

2.3 Liquid Smoke Production

Production of liquid smoke was done by pyrolysis.

The pyrolysis reactor was equipped with a tar

scrubber which could be charged with as much as

500 kg of material. The reactor cover was connected

by a pipeline to the cooling tubes used to condense

the fumes and generate the liquid smoke. After all

materials were inserted into the furnace, it was

closed, the condenser was set, and the cooling tube

was streamed with cold water. Pyrolysis was carried

out at a temperature 500°C for 8 hours.

2.4 Characterization

Acidity of liquid smoke was characterized by pH

meter, water content by using volumetric Karl

Fischer titration, the density by AOC 1995, and

dichloromethane extracts content by gas

chromatography-mass spectrometry (GC-MS).

3 RESULTS AND DISCUSSION

3.1 Liquid Smoke Chemical

Components

Liquid smoke compositions are obtained from

pyrolysis of coconut shell. The traditional liquid

smoke manufacturing saw dust pyrolyzed in

temperature ranges of 350-600

C and under

atmospheric pressure conditions. In this research, the

liquid smoke was obtained from thermal

degradation reactions of cellulose, hemicellulose,

and lignin. From a proximate components

standpoint, the three major components of coconut

shell are cellulose, hemicellulose, and lignin . The

pyrolysis of lignin was reported at around 310-500

C and yielded the major source of phenols

(Martinez et al., 2007). In the other research, the

hemicellulose yielded furan, furan derivatives, and a

series of aliphatic carboxylic acids (Siskos et al.,

2007).

The quality of liquid smoke is very dependent on

the composition of chemical compounds contained

in liquid smoke. The compounds contained in liquid

smoke are strongly influenced by the conditions of

pyrolysis and types of raw materials (Budaraga et

al., 2016). This is due to the large levels of cellulose

and hemicellulose from each ingredient. Cellulose

pyrolysis takes place in two stages, namely the first

stage is an acid hydrolysis reaction followed by

dehydration to produce glucose, while the second

stage is the formation of acetic acid and homologous

together with water and a small amount of furan and

phenol (Collard and Blin, 2014).

Identification of phenol and carbonyl were detected

gas chromatography-mass spectrometer in

dichloromethane fractions. Results were shown on

Table 1 in which phenol ranged from 85.057 –

90.024% while carbonyl from 5.05 – 6.473%. This

shown that there were an increase in the chemical

components produced by pyrolysis tar scrubber.

Quality Improvement of Liquid Smoke of Coconut Shell by Tar Scrubber

263

Table 1: Chemical Compenents of Liquid Smoke.

Method

Chemical

Components

(%) Area

Tar Scrubber

Phenol

90.024

Carbonyl

6.473

Conventional

Phenol

85.057

Carbonyl

5.05

3.2 Density

Specific gravity is the relative ratio between the

density of a substance and the density of pure water.

The Table 1 below shows the effect of the results of

pyrolysis by conventional methods and tar scrubbers

on the specific gravity of liquid smoke.

From the Table 2 it can be seen that the specific

gravity of liquid smoke from the tar scrubber at a

temperature of 500⁰C has a higher value than the

value of the specific gravity of liquid smoke in the

conventional method.

Table 2: Density of Liquid Smoke.

Method

Density (g/mL)

Tar Scrubber

1.0118

Conventional

1.0036

3.3 Acidity

Acetic acid compounds are classified as acid

compounds that affect the pH of liquid smoke and

taste and aging of smoke products. In addition,

phenol levels also affect the pH of liquid smoke

because phenol has acidic properties which are the

influence of aromatic rings. The pH value is one of

the quality parameters of liquid smoke produced.

The pH measurement was carried out on the liquid

smoke from the pyrolysis results and the distillation

results from each material with the results obtained

as shown in Table 3.

Table 3: Acidity of Liquid Smoke.

Method

Acidity (pH)

Tar scrubbe

2.4

Conventional

2.6

The tendency to decrease the pH of liquid smoke

is because the content of Acetic acid and phenol

compounds increases after distillation. The higher

the total phenol level in liquid smoke, the lower the

pH value or more acidic.

3.4 Water Content

From the Table 4. below it can be concluded that the

higher the pyrolysis temperature, the lower the water

content contained in liquid smoke. At the

conventional method was lower temperature than tar

scrubber method. The water content contained in

liquid smoke was quite large because this

temperature was evaporated and condensed.

Whereas at temperatures of 500⁰C there is a

decomposition of components of organic matter

contained in wood to produce liquid smoke with a

more concentrated color and water content which

tends to decrease.

Table 4: Water Content of Liquid Smoke.

Method

Water Content (%)

Tar Scrubber

89.970

Conventional

94.593

4 CONCLUSIONS

Optimum condition obtained through hydrogel

Generally, the manufacture of liquid smoke by the

pyrolysis tar scrubber method can improve liquid

smoke quality. In addition, the most phenol and

carbonyl contents were produced in tar scrubber

method.

ACKNOWLEDGEMENTS

The authors would like to thanks to the Ministry of

Research, Technology and Higher Education for

funding support by scheme of PMDSU 2017.

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