banana peels

APEC Youth Scientist Journal Vol. 4 / No.1

62

BANANA PEELS: AN ECONOMICAL REFINING AGENT

FOR CARCINOGENIC SUBSTANCE IN WASTE COOKING OIL

∗ Rifqi Taqiuddin1, Nabila Yahdiani Aliah1

1Al Irsyad Satya Islamic School

Parahyangan Street KM 2.7 Kota Baru Parahyangan Padalarang-West Bandung, West Java Indonesia

ABSTRACT

There are so many consumers and small scale traders of fried food in this world,

including Indonesia. Unfortunately, some of the traders usually do not have enough capital to

create a good healthy standard for the food they produced and therefore they use their

cooking oil (usually called waste cooking oil) repeatedly more than 8-10 times. Obviously the

oil is not a good healthy standard for producing food. Useless materials in the waste oil

especially peroxide will increase risks of some diseases, such as cancer. This research

conducted to test the effectiveness of banana peel as readily available, low cost, environment

friendly bio-material. The banana peel could adsorb peroxide and increase the brightness of

waste cooking oil. Several 100 ml samples of waste cooking oil were treated at room

temperature using combinations of 2 grams of dehydrated banana peel, activated carbon

banana peel, carbon banana peel, and/or shallot, and compared to commercial activated

carbon as absorbent. After 24 hours, the concentration of peroxide (peroxide number) was

calculated using a thiosulphate titration method. Clarity, thus purity of each samples were

also compared by analysing the absorbance using a spectrophotometer. The result shows that

dehydrated banana peel is the best material applied to remove peroxide in waste cooking oil

compared to activated carbon banana peel, carbon banana peel, shallot, and commercial

activated carbon. Whereas shallot is the material that results in the brightest waste cooking

oil compared to other material used.

Key words: banana peel, absorbent, waste cooking oil, cancer, peroxide numbe

∗ Correspondence to : Rifqi T ([email protected])

Yayuk P ([email protected])


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1. INTRODUCTION

There are many consumers of fried food in this world, including Indonesia. There are

many small scale fried food traders who sell varieties of fried food, for example fried banana.

Unfortunately, some of the traders usually do not have enough capital to create a good

healthy standard for the food they produce. For example, they will use their cooking oil

(usually called waste cooking oil) repeatedly more than around 8-10 times that obviously not

a good healthy standard for producing food. The reason is the high cost of the cooking oil

itself, so if the producers use the oil repeatedly, they do not have to spend much money on

buying fresh cooking oil and they can minimize the cost production.

The use of waste oil for frying can decrease the nutrient content of food and increase

the health risk for the food consumers. People that consume food that fried use waste cooking

oil will have high probability to suffer from so many diseases such as cholesterol,

hypertension, blockage of bloodstream, and also cancer.

One of the serious diseases that can cause by consuming waste cooking oil is cancer.

This disease is thought to be caused by a polar compound contained in waste cooking oil

called peroxide.

1.1. Waste Cooking Oil

Oil is a triglyceride composed by three fatty acid units, and could form liquid at a room

temperature (25oC). Oil that can be made from plants or animals contains lots of unsaturated

fatty acid, which make the oil can be oxidized easily. Cooking oil that made from palm oil

will damage easily by oxidation (Rosita et al., 2011) especially during deep frying process.

This oil that has been oxidized in high temperature is usually called waste cooking oil

(Rahayu, et. al., 2007).

Oxidation at a high temperature cause the breakdown of double bonds that turn into a

single bonds between two C atoms, then release the free radical called peroxide (Sartika,

2009). In normal conditions and in a short period of time, this free radical can be neutralised

by defence systems in the human body, but in high doses and long exposure times, it can

damage the human body or even cause necrosis of cells (Rahayu, et al, 2007).


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Figure 1. Oxidation of fatty acid into hydro peroxide

Oxidation in oil occurs at the C atom near the double bond position and the

hydroperoxide is released shown in Figure 1 above. A high amount of peroxide indicates the

low quality of cooking oil. The peroxide number of a sample can be calculated by titration

analysis using thiosulphate solution and amylum as indicator (Wildan, 2002)

Nowadays, waste cooking oil are still commonly in use. If the use of this waste cannot

be controlled, it will cause a serious problem and give risks to human. To decrease the risks

of diseases such as cancer, fried food producers could refine the waste cooking oil by using

an absorbent that will absorb the useless materials inside it.

1.2. Banana Peels

Banana peels are agricultural waste that discarded all over the world as useless material.

They cause waste management problems although they have some compost and cosmetics

potentiality (Hossain, et al., 2012). Banana peels also contain high potassium and phosphorus,

which prove to be helpful in the compost. The substance could be used for medicine as well

as personal care and known for anti-fungal and antibiotic properties, loaded with lot of

vitamins, minerals and fibber that benefit for skin care and for healing the wound (Sakaltar,

2011).

Besides that, banana peels have absorbent potentiality (Hossain, et al., 2012). It is very

useful for purification and refining processes. Banana peel has absorption capabilities for

some elements and ions in liquid or solution. Banana peel has absorption capacities to

remove chromium from wastewater (Memon, et al., 2008), copper (Hossain, et al., 2012) and

also some dyes (Velmurugan, et al., 2011). Unfortunatelly, the benefit of banana peels are not

popular as many people still do not realise about.


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Banana peels are readily available, low cost, and environment friendly bio-material.

This agricultural waste is also inexhaustible, cheap and non-hazardous, and are specifically

selective for heavy metals and can be easily disposed by incineration (Das et al., 2011).

Considering those criteria, banana peels are selected to be prepared as a bio-absorbent.

Banana peels contain high organic carbon (41.37%) and have been subjected to

biomethanation and biogas production. Because of this, they also could be used as material

for charcoal and activated charcoal as common absorbent (Mopoung, 2008).

Organic matter in banana peels may be converted by controlling thermal decomposition

into carbon. The mechanisms involved in the conversion of organic matter to carbon are: (1)

desorption of absorbed water up to 150oC, (2) splitting of matter structure water between

150oC and 260oC, (3) chain scissions, or depolymerization, and breaking of CO and C-C

bonds within ring units evolving water, CO and CO2 between 260oC and 400oC, (4)

aromatization forming graphitic layers above 400oC, and (5) above 800oC, the thermal

induced decomposition and the rearrangement reaction are almost terminated leaving a

carbon template structure. The major components of organic matter break down in a stepwise

manner at 200-800oC (hemicellulose), 260-350oC (cellulose) and 280- 500oC (lignin).

Between 260oC and 400oC almost 80% of the total weight loss that occur which may vary

between 40% (lignin) to about 80% (cellulose) due to evolution of H2O, CO2, and volatile

hydrocarbon species from fragmentation reactions of the polyaromatic constituents

(Mopoung, 2008).

Chemical activation of carbons is very common method for obtaining activated carbons

including for banana peel carbon with very high surface areas. KOH is one of the most

effective activating agents employed for organic materials. KOH might be more selective in

the activation process, causing a more localized reaction with the carbon precursor and is

more effective for the highly ordered materials (Mapoung, 2008). Beside KOH, NaCl could

also be used for carbon activation. An experiment result shows that activated carbon is through

immersion NaCl 30% combined with physics activation resulting the best characteristics for

absorbent (Mujizah, 2010). Charcoal that immersed in NaCl solution as dehydrating agent will

absorb the salt. Increasing salt concentration caused increasing of minerals absorbed and enlarges

the carbon porous (Kusuma and Utomo, 1970 in Mujizah, 2010).

1.3. Biosorption

Biosorption is a property of certain types of inactive, dead, microbial biomass to bind

and concentrate heavy metals from even very dilute aqueous solutions. Biomass exhibits this


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property, acting just as a chemical substance, as an ion exchange of biological origin (McGill,

2011). The biosorption process involves a solid phase absorbent and a liquid phase (solvent,

normally water, oil) containing a dissolved species to be absorbed (sorbate, metal ions). Due

to higher affinity of the absorbent for the sorbate, the latter is attracted and removed by

different mechanisms. This process will continue until equilibrium is established between the

amount of solid-bound sorbate and its portion remaining in the solution (Khoo&Ting., 2011;

Knorr, 2011).

The degree of sorbent affinity for the sorbate determines its distribution between the

solid and liquid phases. The advantages of biosorption over conventional treatment methods

include low cost, high efficiency, minimization of chemical and biological sludge, and

regeneration of biosorbent and possibility of metal recovery (Khoo&Ting, 2011; Knorr,

2011).

The biosorption mechanisms by non- living cells for example using biomaterial peels

occur in two stages: passive uptake which takes place immediately, and active uptake which

takes place slowly. The first stage thought to be physical adsorption or ion exchange at the

cell surface, reaching the adsorption equilibrium within 30-40 min (Khoo&Ting, 2011; Knorr,

2011).

The use non-living biomaterials or dead cells are mental binding compound that have

been gaining advantage because toxic ions do not affect them. In addition, dead cells require

less care and maintenance, and cheaper (Mofa, 2011). Furthermore, dead biomass could be

easily regenerated and reused (Das et al., 2011).

The major factors that affect the biosorption processes are initial metal ion

concentration, temperature, pH and biomass concentration in solution. Temperature does not

influence the biosorption processes in the range of 25o- 35oC. However, pH seems to be the

most important parameter in the biosorption processes (Aksu et al., 2011).

The important things to solve the gaining of waste cooking oil by recycling it in

harmless way is find out the suitable adsorbent to refining this waste in cheaper and easy way.

This research conducted to learn how to refining waste cooking oil using waste material

produced by the producers itself, which is the banana peels. The experiment in this research

conducted to test the effectiveness of banana peel to adsorb peroxide in waste cooking oil and

increasing brightness waste cooking oil by comparing the use of dehydrated banana peel,

activated carbon banana peel, carbon banana peel, shallot, and commercial activated carbon

as absorbent.


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2. EXPERIMENTAL INVESTIGATION

This experiment conducted in three steps: preparation, treatment and chemical analysis.

2.1.Preparation

Before the treatment was conducted, the adsorbent and the sample should be prepared.

There are six (6) kinds of absorbent that was used in this experiment: dehydrated banana peel,

banana peel carbon, banana peel activated carbon, combination of banana peel carbon and

shallot, shallot and commercial activated carbon. Commercial activated carbon was used in

order to compare its ability to a cheaper more environmentally-friendly option.

Banana peel was sliced into 0.5 cm x 0.5 cm and dried using oven until the weight was

constant. Figure 2 shows the dehydrated banana peels. The other sliced and dried banana

peels, then burnt turn into carbon. Some carbon banana peels then immersed in 30% NaCl

solution and dried again to get banana activated carbon.

Figure 2. Dehydrated banana peel

Shallot is the other biomaterial that usually used by people to clean the waste cooking

oil. Before it was used, shallot was sliced into small pieces and then immersed into the waste

cooking oil for six (6) hours. Beside shallot, commercial activated carbon that bought from

chemical shop was also be used in this experiment.

Waste cooking oil was collected from fried food producers after it was used repeatedly

around 8-10 times for deep frying. Waste cooking oil then filtered using fabric in order to

clean the oil from the food residual and other solid waste. After that, waste cooking oil was

measured and put on the cup 100 ml each as shown on Figure 3.

Figure 3. Waste cooking oil


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2.2.Treatment

Each absorbent was immersed in waste cooking with a ratio of 100 ml waste cooking

oil and 2 grams of adsorbent. All samples were put in a room temperature for 24 hours and

stirred periodically. After this treatment, all samples except the one that using shallots as

absorbent were filtered to clean the waste cooking oil, and then they were prepared to be

analysed the chemical content and the brightness. Waste cooking oil that had been treated by

using shallot was heated first until 50-60oC for 5 minutes before analysing, following the

common procedure that used by traders. As the control, fresh cooking oil and non-treated

waste cooking oil were also used in the experiments.

Figure 4. Waste cooking oil after treatment

2.3.Analysis

All samples of waste cooking oil then were analysed and measured the number of

peroxide using thiosulphate titration method and using amylum as the indicator (Wildan,

2002).

Five grams of sample of waste cooking oil was weighed and put in the Erlenmeyer flask and

covered. The next step, 30 ml mixture of acetic solution, alcohol and chloroform (20:20:20)

were added and mixed until dissolve completely. 1 ml of saturated KI and 50 ml distillate

water were also added to the flask, then put in the dark place for 30 minutes. This mixture

was quickly titrated using a 0.02 N thiosulphate solutions until the colour turned light yellow.

0.5 ml of the indicator, amylum, was then added and the titration continued until the blue

black colour disappear. This method was repeated for all samples.

Peroxide number of samples waste cooking oil count follow the formula below.

Peroxide number =

Peroxide number : concentration of peroxide in ppm (part per million)

ml thiosulphate : volume of thiosulphate (samples-blank samples) in ml

N : normality of thiosulphate solution

gram sample : weight of samples in gram


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The physical appearance of waste cooking oil was observed by measuring the

brightness. This was analysed by measuring the absorbance using a spectrophotometer at 378

nm wavelength. Low absorbance indicates low suspended material inside it and indicates the

high brightness of the sample.

3. RESULT AND DISCUSSION

3.1. Peroxide number

The peroxide number contained in oil is indicates the destruction of chemical

bonding in oil molecule caused by oxidation. This oxidation could be caused by atmosphere

exposure and/or high temperature. A high peroxide number indicates a high destruction of the

oil and the cause of rancidity of the oil (Wildan, 2002). This high rancidity will influence the

taste and the smell of the oil and also shorten the length of storage time (Panagan, 2010).

High amount of peroxide can poison the living cell of organism and cause the cells

death called necrosis. Single electron in outer shells of peroxide will attack and damage the

cells and cause pathological death of cells. This was caused by the decreasing of energy

supply for the cells. Consequently, these cells will shrink and turn into darker colour, and for

a long time exposure it will cause cancer (Rahayu et al., 2007).

Figure 5 shows the peroxide number in every sample of waste cooking oil. The

investigations showed that waste cooking oil that was treated by using shallot has the highest

peroxide number because it got through the heating in process in the treatment which makes

the oil oxidized and peroxide increased. Waste cooking oil that was treated using shallot

contains 71.47 ppm peroxide, while waste cooking oil that was treated using combination of

shallot and carbon banana peel contains 73.60 ppm peroxide. Even, the concentrations of

peroxide in these samples are higher than waste cooking oil (65.60 ppm). According to the

method used by traders, after the waste cooking oil treated using shallots then it have to be

heated. Unfortunately, this heating process makes the oil oxidized and breakdown more

double bonds between C atoms in oil. As the result, more peroxides released and the

concentration of peroxide (peroxide number) increased. Panagan (2010) state that shallot has

a natural antioxidant which could prevent oxidation and prevent cooking oil destruction.

Some people in the community also use shallot to purify the waste cooking oil. But, this

experiments showed that the use of shallot for refining waste cooking oil was not suitable,

because shallot only act as antioxidant to prevent oxidation not to adsorb or fix the

destruct/oxidised waste cooking oil. Shallot might be used as antioxidant and can be added to


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fresh cooking oil to prevent oxidation during deep frying process not to purify the oxidised

waste cooking oil.

Figure 5. Peroxide number of samples waste cooking oil (in ppm)

Waste cooking oil that was treated by using dehydrated banana peel indicated the

lowest peroxide number compared to the waste cooking oil which was treated by using other

banana peel and almost the same with waste cooking oil that was treated by using

commercial activated carbon. The result of this experiment show, the peroxide number of

waste cooking oil that was treated by using dehydrated banana peel is 59.20 ppm, while the

peroxide number of waste cooking oil that was treated by using commercial activated carbon

is 57.60 ppm. It is lower than other waste cooking oil that was treated using other banana peel

which are 62.40 ppm for waste cooking oil was treated using carbon banana peel and 61.87

ppm for waste cooking oil that was treated using activated carbon banana peel. It indicated

that original structure of banana peel can absorb peroxide more effectively than decomposed

banana peel into carbon. The original structure of the banana peels consists of organic matter

e.g cellulose that absorb the peroxide molecules better than the structure of carbon banana

peel. Pores that are formed during the dehydration process might be more suitable to the size

of peroxide molecules. These small pores in dehydrated banana peels were produced due to

the release of volatiles compound (Mopoung, 2008). Larger pores are formed during

carbonization and activation process (Mujizah, 2010).

3.2. Brightness

The brightness of oil indicated by the value of absorbance showed the total amount of


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suspended solid material contain inside the waste cooking oil. Figure 6 shows the absorbance

value of the absorbance.

Figure 6. Absorbance value of samples waste cooking oil

Waste cooking oil that was treated by using shallot had the brightest colour (lowest

absorbance), which indicates a lack of suspended materials. It may be caused the higher

surface area of sliced shallot compare to banana peel pieces. The absorbance of this sample is

2.230, is lower than waste cooking oil (2.500) and other treated waste cooking oil. This sliced

shallot act like net that can trap the large size suspended material, but cannot act as good

absorbent to absorb very small molecules such us peroxide. However, waste cooking oil was

treated by using banana peel carbon and commercial activated carbon has darker colour

(higher absorbance) because flakes absorbent material that suspended inside it needed to be

filtered completely.

4. CONCLUSION

The present results showed that banana peel can decrease the amount of peroxide in

waste cooking oil. Compare among the all absorbents that have been used, dehydrated banana

peel is the best, most economical and environmental material to remove peroxide in waste

cooking oil compared to activated carbon banana peel, carbon banana peel, shallot, and


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commercial activated carbon. Whereas, shallot is the material that gave results in the

brightest waste cooking oil compared to other material used.

5. ACKNOWLEDGEMENTS

We would like to acknowledge Ms. Yayuk Purwandari as our mentor in Al Irsyad Satya

Islamic School and for her invaluable guidance. We would also like to extend our gratitude to

Mr. Dendi Ruswandi as our teacher for his assistance and support.

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Rifqi Taqiuddin Nabila Yahdiani Aliah1

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