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IC-FSSAT 2021 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 807 (2021) 022053 doi:10.1088/1755-1315/807/2/022053

The effect of soaking time on mucilage removal from the

coffee bean using pectinase enzyme

Fitri1, A B Tawali2 and A Laga2

1
Agricultural Science Study Program, Graduate School, Hasanuddin University,
Jl. Perintis Kemerdekaan Km 10, Tamalanrea, Makassar 90245
2
Food Science and Technology Study Program, Department of Agricultural
Technology, Faculty of Agriculture, Hasanuddin University, Jl. Perintis Kemerdekaan
Km.10, Tamalanrea, Makassar 90245

E-mail: fitrihamzah@outlook.com

Abstract. The perfect coffee fermentation process is characterized by the release of mucilage
that covers the coffee beans. The mucilage that doesn't come off entirely from the coffee beans
can affect the taste of the coffee. The mucilage, which is composed of pectin, can be removed
using the pectinase enzyme. This study aims to determine the optimal soaking time required to
remove the mucilage from the coffee beans. Coffee beans are soaked in a liquid containing the
pectinase enzyme for 1, 2, 3, and 4 hours. The results showed that soaking coffee beans for 4
hours in the pectinase enzyme was the best contact time in releasing the coffee bean mucilage.
Soaking coffee beans for 4 hours in the pectinase enzyme produced a pectin yield of 0.25%,
total dissolved solids 1.05oBrix, pH 6.55, and total sugar 15.67%.

1. Introduction
Coffee is one type of plantation crop that is widely cultivated in Indonesia and throughout the world.
That plant becomes one of the crops that has a high selling value in international trade [1,2]. Quality
greatly affects the selling value of a coffee bean, where the quality of aroma and taste are the most
important factors that affect consumer acceptance of a coffee bean [2].
The post-harvest processing of coffee is an important factor affecting the quality of taste and aroma
of coffee beans. Generally, there are three post-harvest processing methods for coffee beans: dry-
processed, wet-processed, and semi-dry (pulped natural) processing [3]. In the dry process, cherry
coffee is dried directly under the sun until it reaches a moisture content of about 10% -12% [4]. In the
wet process, the pulp from the cherry coffee is removed mechanically. After that, the coffee beans are
soaked in water for a few days and then dried. Most of the Arabica coffee is processed using a wet
process [3,5]. And in the semi-dry process, the skin is exfoliated mechanically, and the coffee beans
are dried directly without going through a soaking process [3,4].
During the wet process, the coffee beans undergo fermentation. Fermentation is a chemical process
that causes changes in the molecules contained in coffee beans. Fermentation of coffee is essential to
the removal of mucilage from parchment coffee. The perfect fermentation process is characterized by
the release of mucilage from the coffee beans. The mucilage still attached to the parchment can
prolong the drying time of the coffee beans. Besides, mucilage that is not removed properly can cause
mould growth during the storage process, which will reduce the quality of the coffee beans [6].
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution
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IC-FSSAT 2021 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 807 (2021) 022053 doi:10.1088/1755-1315/807/2/022053

Coffee mucilage is a thin layer that sticks to the coffee beans' walls composed of polysaccharides.
In the fermentation process, mucilage is broken down in coffee pulping stations and coffee plants in
the field by microorganisms that occur naturally. Bacteria, yeast, and fungi break down sugars and
pectins within the mucilage, producing acids and alcohol [7]. Besides, through the fermentation
process, the mucilage in the coffee beans can also be removed by adding enzymes that can degrade the
polysaccharides that compose mucilage, for example, the pectinase enzyme. Several factors can affect
the enzyme's work in degrading the substrate, one of which is the contact time between the enzyme
and the substrate. Therefore, this study was conducted to see the effect of the soaking time of coffee
beans on the pectinase enzyme on the release of coffee beans mucilage.

2. Material and methods

2.1. Material
The sample used in this study was coffee beans that came from the Arabica type. The pectinase
enzyme used is a commercial pectinase enzyme.

2.2. Methods
2.2.1. Preparation of pectinase enzyme solution. The commercial pectinase enzyme was weighed as
much as 0.083 grams and dissolved in a citrate buffer pH 4.5 to obtain a pectinase enzyme solution
with 50 units/gram activity.

2.2.2. Determination of pectin yield. Each coffee bean is weighed as much as 40 g, then put into a
round bottom flask, 1000 mL of 0.01 M HCl solution was put into a round bottom flask, and the
extraction process was carried out at 60 OC. After that, the extraction process results are filtered using
filter paper to separate the extracted filtrate from the residue. The resulting extracted filtrate is added
with 96% alcohol solution (1:1) and left to stand for one night. The resulting precipitate is then filtered
with filter paper and washed with 96% alcohol. The acid-free sediment is then placed in a porcelain
dish and dried in an oven at 60 – 62OC for ± 3 hours. The dried pectin was then weighed using an
analytical balance to determine the dry pectin weight.

2.2.3. Analysis of total dissolved solids. Total dissolved solids were measured with a hand
refractometer.

2.2.4. Total sugar analysis using the luff schoorl method [8]. The sample of coffee beans was weighed
3 grams and added 100 ml of 3% HCl. The samples were heated for 3 hours. Transfer to Erlenmeyer
or beaker glass. Add 30% NaOH dropwise while stirring, then measure the pH to 5.5. Transfer it to a
250 ml measuring flask with the volume of distilled water, then homogenize it. Filter the filtrate. Save
the filtrate into the bottle. Add 10 ml of Luff Schrool solution and 25 ml of distilled water and heated
for 15 minutes. After cold. Add 10 ml of 20% KI solution and 15 ml of 25% H 2SO4 slowly. Then drop
as soon as possible 0.1 N thio solution with 0.5% starch as much as 5 ml as an indicator. The titration
reacts when the new colour changes to a milky white colour. Make a blank test (35ml distilled water +
10 ml of Luff Schrool solution + a few grains of stones dipped in Erlenmeyer). Simmer for 10 minutes
using an upright cooler. Bring to a boil quickly, then add 10 ml of 20% KI solution and 15 ml 25%
H2SO4, titrate with 0.1 N Tio (use starch indicator)

2.2.5. Analysis of pH. Ground coffee beans and put in a 10 ml beaker. The pH of the coffee beans is
then measured using a calibrated pH meter

2
IC-FSSAT 2021 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 807 (2021) 022053 doi:10.1088/1755-1315/807/2/022053

3. Results and discussion

3.1. Pectin yield

Chemically, coffee mucilage is composed of water, pectin, sugar, and organic acids. Where the total
pectic substances contained in coffee mucilage reach 39% [9]. The yield of pectin in coffee beans after
soaking in the pectinase enzyme solution can be seen in figure 1.

Figure 1. Pectin yield of the coffee bean after soaking on pectinase.

Based on the results, it can be seen that soaking coffee beans in the pectinase enzyme can degrade
the pectin content, which is a constituent of coffee bean mucilage. The lowest pectin yield was
obtained in soaking coffee beans for 4 hours (0.25%). The yield of pectin in coffee beans decreased
with increasing soaking time.
Pectin is a complex polysaccharide that generally forms plant cell walls. In coffee plants, these
molecules are present in the mucilage layer attached to the surface of the coffee bean and become the
main constituent of the mucilage. Soaking coffee beans in the pectinase enzyme solution causes the
pectin molecules to degrade so that the coffee mucilage breaks down and can be removed from the
coffee beans. This is due to the ability of the pectinase enzyme to break down the α-1,4-glycoside
bonds in pectin. This is in accordance with [10], which states that the pectinase enzyme is an enzyme
capable of hydrolyzing the α-1,4-glycoside linkage in pectin and producing D-galacturonic
compounds.

3.2. Total dissolved solids and total sugar

Total dissolved solids are the amount of all organic and inorganic in a solution [11]. Total dissolved
solids are closely related to total sugar content. The total dissolved solids can show all the amounts of
sugar that are solids in a solution. The total dissolved solids and the total sugar of coffee beans soaked
in the pectinase enzyme solution can be seen in figure 2 and figure 3.

Figure 2. Total dissolved solid of the coffee bean after soaking on pectinase.

3
IC-FSSAT 2021 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 807 (2021) 022053 doi:10.1088/1755-1315/807/2/022053

Figure 3. Total sugar of coffee bean after soaking on pectinase.

Based on figure 2 and figure 3, it can be seen that the total solids and total sugar content in coffee
beans tend to increase with increasing soaking time in the pectinase enzyme. Total dissolved solids
(1.05oBrix) and the highest sugar content (15.67%) were obtained from soaking coffee beans for 4
hours. When the coffee beans are soaked in the pectinase enzyme, this enzyme will hydrolyze the
coffee mucilage's pectin compound. Apart from containing galacturonic acid, it also contains neutral
sugars such as galactose, arabinose, and xylose. So that the hydrolysis of pectin compounds can
increase total sugar levels and total dissolved solids in coffee beans. This is in accordance with [10],
which states that some pectins are composed of repeated disaccharides that carry the branch chains of
neutral sugars galactose, arabinose, and xylose.

3.3. pH
pH is the degree of acidity used to express the level of acidity and alkalinity of a solution. The pH
level of coffee beans soaked in the pectinase enzyme can be seen in figure 4.

Figure 4. pH of the coffee bean after soaking on pectinase.

Based on the results, it can be seen that there is no significant change in the pH of coffee beans
soaked in the pectinase solution. The mucilage removal process does not cause a change in the acidity
of the coffee beans. Changes in acidity usually occur in fermented coffee beans. This is in accordance
with [12], which states that during the fermentation process, the microflora will break down the
molecules in the coffee beans and produce alcohol and organic acids, increasing the acidity of the
coffee beans.

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IC-FSSAT 2021 IOP Publishing
IOP Conf. Series: Earth and Environmental Science 807 (2021) 022053 doi:10.1088/1755-1315/807/2/022053

4. Conclusions
The addition of the pectinase enzyme to the coffee beans can help remove the mucilage from the
surface of the coffee beans. The longer the soaking time, the more mucilage that can be broken down.
The process of removing the coffee bean mucilage can also affect the total sugar and the total
dissolved solids of the coffee beans.

References
[1] Privat I, Foucrier S, Prins A, Epalle T, Eychenne M, Kandalaft L, Caillet V, Lin C, Tanksley S,
Foyer C, and Mccarthy J 2008 Differential regulation of grain sucrose accumulation and
metabolism in coffea arabica (arabica) and coffea canephora (robusta) revealed through gene
expression and enzyme activity analysis New Phytologist 178(4) 781-797.
DOI: 10.1111/j.1469-8137.2008.02425.x
[2] Sunarharum W B, Williams D J, and Smyth H E 2014 Complexity of coffee flavor: a
compositional and sensory perspective Food Research International 62 315–325.
https://doi.org/10.1016/j.foodres.2014.02.030
[3] Brando C H H 2004 Harvesting and green coffee processing coffee: growing, processing,
sustainable production ed Wintgenz J N (Weinheim: WILEY-VCH Verlag GmbH & Co.
KGaA) p: 204-757
[4] Karim M A, Wijayanti F, and Sudaryanto A 2019 Comparative studies of coffee processing
methods for decision making in appropriate technology implementation AIP Conference
Proceedings 2114 020015 https://doi.org/10.1063/1.5112399
[5] Pandey A, Soccol C R, Nigam, P, Brand D, Mohan R, Roussos S 2000 Biotechnological
potential of coffee pulp and coffee husk for bioprocesses Biochemical Engineering Journal
6(2) 153–162. https://doi.org/10.1016/S1369-703X(00)00084-X
[6] Haile M, Kang W H 2019 The role of microbes in coffee fermentation and their impact on coffee
quality Journal of Food Quality 2019 1-6. https://doi.org/10.1155/2019/4836709
[7] Klingel T, Kremer J I, Gottstein V, and de Rezende T R 2020 A review of coffee by-products
including leaf, flower, cherry, husk, silver skin, and spent grounds as novel foods within the
european union Foods 9(5) 665 https://doi.org/10.3390/foods9050665
[8] Sudarmadji S, Haryono B, and Suhardi 1997 Prosedur analisa untuk bahan makanan dan
pertanian (Yogyakarta: Liberty) (In Indonesian)
[9] Elias L G 1979 Chemical composition of coffee-berry by-products Coffee Pulp: Composition,
Technology, and Utilization ed Braham J E, Bressani R (Ottawa: International Development
Research Centre) p: 11-16
[10] Pedrolli D B, Monteiro A C, Gomes E, and Carmona E C 2009 Pectin and pectinases: production,
characterization and industrial application of microbial pectinolytic enzymes The Open
Biotechnology Journal 3(1) 9–18. https://doi.org/10.2174/1874070700903010009
[11] Rinawati, Hidayat D, Suprianto R, and Dewi P S 2016 Penentuan kandungan zat padat (total
dissolve solid dan total suspended solid) di perairan teluk lampung Analit: Analytical and
Environmental Chemistry 1(1) 36–46 (In Indonesian)
[12] Hatiningsih S, Antara N S, and Gunam I B W 2018 Microbiological and physicochemical
changes of green coffee (coffea arabica) fermentation in kintamani, bangli, bali Media Ilmiah
Teknologi Pangan 5(2) 123–138