Citric Acid In Citrus Fruits In Removing Stains Biology Research Paper

Cognition about natural bleaches to take discoloration may be utile in our day-to-day life. Natural bleaches can be found in assorted types of fruits juice and many more. This green “ bleaches ” are more friendly to environment and cheaper than commercial merchandise.Citric acid is one of decoloring agent that can be found in the citrous fruit fruits such as lemon. This paper will discourse on the procedure of taking discolorations by citric acid in different type of fruit juices. The probe was focused on “ How does the type of citrous fruit fruits used affect the rate of reaction of discoloration removable? ” Since discolorations have different types, the effectivity of citric acid on two types of discolorations ( man-made and vegetable based discoloration ) had been discussed more in this probe.

MATERIALS AND METHODS: The experiment was conducted with different type of fruits ; lemon, calcium hydroxide, navel orange and Ananas comosus. The clip taken for the different type of discoloration to be removed by different type of fruits had been recorded and be analyzed to place the most best used as natural bleaches.

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Consequence: Even though the lemon juice is more popularly known as natural bleach but based on the experiment, the best used citrous fruit fruit as bleaching agent is lime and the citric acid is most effectual used to take veggie based discoloration.


Bleachs used worldwide in family to take or bleach discolorations which whiten or lighten the colour of apparels. Chemically, bleaches will interrupt the discoloration molecules into smaller molecule that easy be removed. D.Noemia Souza ( 2008 ) stated that bleaches are chemical that capable to whitening the cloths and taking discolorations by destructing coloring affair ” . There are two types of reaction that involve in bleaching. Normally decoloring procedure involves in oxidization procedures such as H peroxide and some involve the decrease processes such as Na chlorite. However in decoloring procedures, the oxidization and decrease besides can happen at the same time.

Bleaching procedure for discolorations most effectual when both an oxidative and a reductive bleaching stairss worked together and this referred as  full ” bleaching ” ( J.M. Cardamone & A ; W.N. Marker, 1995 ) There are assorted types of bleaches, and each type of bleach is specifically used for certain type of cloths. The cloths are really specific and if used with incorrect bleach, the cloth will have on out. Concentration, pH, clip and temperature are the assorted conditions which are affect the action of bleach on cloths.

Chemistry of bleach

Hydrogen peroxide is the most outstanding bleach and normally used in commercial bleaches. However, harmonizing to D.Noemia Souza ( 2008 ) , the strongest bleach is sodium hypochlorite while the weakest is sodium chlorate and the H peroxide is milder.

Normally, the Na hypochlorite will incorporate 15-18 % of Cl ( D.Noemia Souza, 2008 ) . Under certain status, the solution will break up into Na chlorite ( eq1 ) which so reacts with hypochlorite and bring forth the Na chlorate ( eq2 ) . The Na hypochlorite will undergoes farther reaction to let go of O ( eq3 ) . Thus it is classified as “chlorine bleach ”

Hydrogen peroxide bleaching will disassociate into H+ and per hydroxyl ions HOO- ( eq1 ) .The per hydroxyl ions is the active bleaching agent. Under alkalic conditions it will let go of O ( eq2 ) .Cotton would damage under this conditions as the bleaching consequence is slow and the bleaching rate is fast. The activator and stabilizers are added to command this status ( J.M. Cardamone & A ; W.N. Marker, 1995 ) .

Mechanism of decoloring

  • Based on Procter & A ; Gamble ( 2005 ) the procedure of bleaching is divided into two, which are ;
  • Interrupting up the discoloration
  • The stain consist of molecule ironss covering the cloths
  • The bleach molecule will interrupt the discolorations into smaller pieces
  • After that procedure, bleach molecule will vanish
  • The discoloration is now broken into smaller pieces which can be easy removed by the wetting agent
  • Bleaching the discolorations
  • The discolorations colour has its beginning in the double-bond connexions
  • Then, the bleach will interrupt up the bond and change over it into individual bond, extinguishing its ability to absorb seeable visible radiation.

Citric Acid as Natural Bleach

Citric acid is weak organic acid and one of the acids found in citrous fruit fruits such as calcium hydroxide and lemon. It popularly used in nutrient industrial as perservative. It besides can move as natural bleaching agent and an antioxidant. So it is utile in our day-to-day life to take discoloration or soil from cloth and decolor the topographic point. Citric acerb exist in many type of veggies and fruits but more concentrated in calcium hydroxide and juice where the dry weight of citric acid in fruit comprimise every bit much as 8 per centum ( ) .The concentration of cotric acid in fruits range from 0.005 mol/L for oranges to 0.30 mol/L in lemons and calcium hydroxides ( Wiki.Org )

Rationale of the Study

Nowadays, most of people prefer to utilize biodegradable merchandise or “ green ” merchandise. Particularly in current downswing economic system, many people change to less expensive merchandises. Using citrus fruits as an alternate ways to take discoloration is the good pick. The inquiry that arises here is what the significance of cognizing which of the citrous fruit fruits is best used in taking discolorations?

Significance of the Study

Sodium hypochlorite ( chlorine bleach ) and hydrogen peroxide ( oxygen bleach ) are highly popular in the market to whiten the cloths and in discoloration removable. However, there are some disadvantages utilizing O and Cl bleaches. Most of them are risky if ingested or inhaled and should be used with attention. Lindsay Evans ( 2009 ) besides explained the Cl can do negative wellness effects. Besides, they are dearly-won and give a bad impact to our environment particularly rivers and lakes ecosystem. Chlorine that fluxing into rivers or lakes will unite with other chemical to organize a stable compound where it will stay unchanged in groundwater for many old ages ( Wisconsin, 2010 ) . On the other manus, citric acid best utilizations as natural bleaches because it does less harm to ecology of rivers and lake.

Restriction of the survey

All of the experiment will carry on in the Mara College Seremban ‘s research lab. Most of the stuff such as citrous fruit fruits ; lemon, calcium hydroxide, navel oranges and Ananas comosus and table salt are obtained from Carrefour Cheras in Cheras, Selangor, Malaysia. So, all of the fruits are non in the same degree of freshness due to different status during storage that may impact the freshness of the fruits. Besides that, the fruits might non come from same tree and this will impact the concentration of acid in the fruits.

Research Question

The focal point of survey is to look into the ability of citrous fruit fruits as natural bleach to take discoloration from cloth. The chief aim of this survey is to place which of the citrous fruit fruits ; calcium hydroxide, lemon, Ananas comosus, and navel oranges is best used as bleaching agent.

So the research inquiry of the survey is “ How does the different type of citrous fruit fruit used ; lime, lemon, pineapple, and navel oranges affect the rate of reaction of discoloration removable? ”

The survey uses 4 different types of citrous fruit fruits which are lime, lemon, pineapple, and navel oranges that will pull out into juice and add with table salt ( sodium chloride ) .


The research inquiry of the survey is “ How does the type of citrous fruit fruits used affect the rate of reaction of discoloration removable? ” The rate of reaction of discoloration removable is the highest at the most acidic solution. So the hypothesis is the most acidic fruit in this instance is lime or lemon as both contains high concentration of citric acid.


Independent Variable

There are two independent variables in this experiment as the experiment is divided into several parts. The first independent variable is the different types of citrous fruit fruit juices ; lemon, navel orange, calcium hydroxide and Ananas comosus. While the 2nd independent variable is the different type of discolorations where man-made discoloration ( sirup ) and vegetable discoloration ( tomatoes ) are used throughout the experiment.

Dependent Variable

Rate of reaction to take the discoloration from cloth will be the dependent variable. The clip taken will be record by stop watch for the discoloration to bleach. Then by utilizing the graph the gradient is determine which represent the rate of reaction.

Fixed Variable

The fixed variables are type of fabric ( cotton ) , volume of juice ( 5oml ) , temperature ( 100Esc ) and volume ( 100ml ) of H2O bath and measure of Na hydrated oxide ( 3 teaspoon ) . All of this stuff will be use in same measure throughout of the experiment.

Procedure and Analysis

Before proving the concentration of citric acid, the standard Na hydroxide solution demands to be prepared. In order to fix 0.1 M of NaOH, 9.0 cm3 of 1.0M Na hydrated oxide solution was diluted with 100.00cm3 of distilled H2O. Then the Na hydroxide solution was standardising to find its concentration by titrated it with KHP. This acerb base reaction is shown in Equation 1 ( M.L.Gillette, 1999 ) ;

Two part of 0.5g of dried K H phthalate ( KHP ) was weighed and dissolved with 50ml distilled H2O in conelike flask. The Phenolphthalein solution was added for 2-3 beads into KHP solution to bespeak the terminal point of titration. Phenolphthalein was used because the pH scope of merchandise is 8-10.The Na hydrated oxide was titrated with KHP solution until pale pink colour was produced. The volume of NaOH solution added was recorded.

Datas Analysis

The intent to standardise Na hydroxide solution against K H phthalate is to find the exact value of Na hydrated oxide concentration. By titrate the 0.1M of Na hydroxide solution against KHP solution the consequences collected are more accurate. The concentration of Na hydrated oxide was found to be 0.1002M

Calculation for finding the concentration of the Na hydrated oxide ;

KHP ( aq ) + NaOH ( aq ) NaKP ( aq ) + H2O

To cipher the figure of mole of KHP

Number of mole= mass/molar mass = 0.5g KHP/ 204.2 = 2.449A-10-3mol KHP

To cipher the figure of mole of NaOH required to neutralised KHP solution

No. of moles of NaOH = No. of moles of KHP = 2.449A-10-3mol NaOH

To cipher molar concentration of NaOH solution

Concentration of NaOH = ( figure of moles/ volume of NaOH ) A-1000 = ( 2.449A-10-3/ 24.45 ) A-1000 = 0.1002M

Percentage uncertainness of the concentration of the 0.1M of Na hydrated oxide % Uncertainty of Concentration of 0.1M NaOH = Volume ( H2O ) + Volume ( NaOH ) + Concentration of NaOH ( 1.0M ) % Uncertainty of VH2o = 0.04/100.00 A- 100 = 0.040 % Uncertainty of VNaOH = 0.05/9 A- 100 = 0.600 % Uncertainty of CNaOH = 0.040+ 0.600 =0.64 %

The lemon was cut into little pieces and blend with liquidizer. The juice released was putted into the beaker and labeled with A. First measure was repeated once more until half of the beaker filled. Then, the extracted juice was filtered through muslin fabric. The whole process were used once more with another type of fruits, calcium hydroxide, navel orange and Ananas comosus and labeled with ;

Citric acid Determination

The ground of citric acerb finding is because to cognize the exact value of citric acid in juices for informations analysis. This procedure is carried out by adding NaOH into the fruit juices. The about 10 milliliters of lime juice was prepared by utilizing pipette and transferred into a conelike flask. Then, the calcium hydroxide juice was diluted with 20ml of distilled H2O and three beads of phenolphthalein was added into solution.

The solution with 0.1M Na hydrated oxide ( NaOH ) was added from burette to the juice sample while twirling the mixture until the reaction mixture turned into swoon pink colour. The terminal point was reached when the pink colour persists for 30 seconds. The volume of NaOH added was recorded. The procedures were repeated once more to increase the truth. Then, the process was repeated with different type of juice ; lemon, orange and Ananas comosus. By utilizing the expression, the molar concentration of citric acid in the fruit juice was calculated.

Procedure for procedure of discoloration removable

The white cloth cotton was cut into3cmA-3cm size for 20 pieces and each pieces of fabrics were stained with syrup solution. Then the stained apparels were dried for approximately 1 hr. 20 cm3 of lime juice was prepared and the initial pH of juice was recorded by utilizing pH metre. For the first test, a stained fabric was held under the running H2O and was soaked in the lime solution for more than 30 proceedingss. After that, the stained fabric was put into100Esc hot H2O bath and the clip taken for the stained decolorize was recorded. However, the stained took longer clip to bleach where the norm of clip taken can non be recorded.

So I used another method by adding 3 teaspoon of table salt ( sodium chloride ) into lime juice. The pH value of juice was recorded. The stained fabric was rubbed with salt before soaked into the solution for an hr. Then, the stained fabric was putted into 100°C hot H2O bath and the clip taken for the stained decolorized was recorded. In order to place the best fruit best usage to take the discoloration, the whole measure was repeated once more with another type of fruits ; lemon, navel orange, and Ananas comosus. The consequences from different type of fruits were compared.

Besides that, I besides used the different type of discoloration to prove which 1 is more effectual been bleached by citric acid. In this experiment I used veggie based discoloration which is tomato discoloration. The first method is used ; without adding the tabular array salt ( sodium chloride ) and the consequence was recorded and be compared with man-made discoloration ( sirup ) .

Qualitative informations

For man-made discoloration:

  • The pink ‘s coloring material of discoloration bends into colourless.
  • Fabrics become white
  • Fabric fabrics smell fruity.
  • The juices become more slippy when added with sodium chloride.
  • For organic discoloration
  • The ruddy coloring material of tomatoes bleach
  • The fabric coloring material bend into redish
  • The cloth turns white after held under running H2O.

Datas Analysis

Harmonizing to the informations collected, the different type of fruits and different type of discoloration will impact the clip taken for the discoloration to bleach. For the sirup discoloration, there must be influenced by Na chloride ( cooking salt ) as it is difficult to take by citric acid entirely. Adding the cookery salt involved the osmosis construct where the solution will go more concentrated, the H2O will traveling from the fabric to the salt and taking the discoloration together ( T. Lister & A ; J. Renshaw, 2000 ) .

When the cookery salt is added into the juice, the pH of juices bead and go more acidic. However, chemically the cookery salt does non impact the sourness of citric acid. The bead in pH value may be due the presence of H2O in the juices which react with the salt and let go of the H ions which might do this to be happened. The ground seting stained cloth into the hot H2O is to increase the reaction by addition the motion of atom and cut down the clip taken to take the discoloration ( Kenneth M.S, 1942 ) .

The highest rate of reaction ( Table 4.9 ) calculated is lime juice and the lowest rate of reaction is pineapple juice. The reaction for both juices can be related with its pH and concentration. In term of concentration of citric acid, the higher the concentration of citric acid will increase the sourness of juice and the clip taken for discoloration removable will go faster. However, this might non be true for lemon juices. Even though, it has highest citric acid concentration but the clip taken for discoloration removable is non the fastest. This likely because of mistake and restriction occurred and will be discussed more in other subdivision.

Meanwhile, graph 4.4 shows the rate of reaction of discoloration removable for both type of discoloration by utilizing Microsoft Excel. It is show that the rate of reaction for removable discoloration in tomatoes stain is 0.154, higher than syrup discoloration. This is might be because the sirup discoloration is more thick and syrupy. While the vegetable based stained ( tomatoes ) is easier to take because it is organic in nature and more soluble in lemon juice.

Decision and Evaluation


The experiments showed that the type of citrous fruit fruits used does impact the mean clip taken to take the discoloration. The hypothesis that rate of reaction would be highest in the most acidic fruit ( calcium hydroxide ) which consist high concentration of citric acid, is besides supported based on the information collected. The pH of calcium hydroxide is 2.2 ; most acidic among the others citrus fruits. The chief aim of this essay is to place which of the type of citrous fruit fruits ; calcium hydroxide, lemon, Ananas comosus, and navel oranges are best used as bleaching agent. As reference above, the type of citrous fruit fruit does impact the rate of reaction to take the discoloration. However, it besides depends on the type of discoloration.

Trial on cloth with man-made discoloration without adding Na chloride ( salt ) required a long clip where the mean clip taken can non be collected. Meanwhile, citrous fruit fruits are best used on cloth with vegetable based discoloration as there in no influence with Na chloride. It can be said that the Na chloride act as accelerator and doing the removable of discoloration easier. In add-on, the clip taken to take the discoloration for vegetable based discoloration is fastest comparison than man-made discoloration. The hot temperature was used in the experiment to rush up the reaction. Thus it can be concluded that, the calcium hydroxide is the best used as bleaching agent but with certain status ; type of discoloration and temperature.


Some mistake and restriction happening during the experiment which causes the consequence collected imprecise. The restriction and mistakes in these experiments can be divided into several parts. For the first portion is job in process A. Initially, the Na hydrated oxide prepared had been assumed precisely 1.00M. However, to prove the truth of the concentration, the Na hydrated oxide had been standardized utilizing KHP solution. After ciphering the concentration of the Na hydrated oxide, the concentration of Na hydrated oxide is about 0.1M with 0.2 % of per centum mistake.

There is a restriction occur when ciphering the concentration of citric acid by titrate it with Na hydrated oxide solution. One job is the citrous fruit fruits incorporate several type of acid. So, in the experiment the citric acid had been assumed as exclusive acid in citrous fruit fruits and be supported by Dr. Ewa & A ; Thomas. As a consequence, the sums of citric acerb concentrations calculated are inaccurate and larger than theoretical value. The citric acid should been standardized to cognize the exact concentration, where it cut down the uncertainnesss. Besides that, some common error occurred in the experiment such as improper place of burette and parallax mistake in taking the measuring.

To get the better of this, there is no other solution except cut down the parallax mistake by positioning the eyes straight to the graduated table reading needed and place the setup used at the smooth surface. Furthermore, it was difficult to find that the coloring material of the solution turned to conk tap coloring material because if the titration of NaOH was titrated without attention the solution will go excessively ruddy. So the consequence of the first swoon tap color come out should be observed and detected decently so it needs a peculiar spouse in making that occupation.

Based on informations collected, there is mistake between the concentration of citric acid and pH value for lemon juices where purportedly the pH of lemon juice should be most acidic as it has highest citric acid concentration. The job may originate in finding the citric acid concentration where the value of citric acid calculated in lemon juice was wrong. Because of the lemon used are in different freshness ( as reference earlier in restriction of survey ) , it might impact the consequence. So, the same lemon must be usage throughout the experiment.

In the last portion ( procedure D ) , one of the mistake occurs is during taking the mean clip taken to take the discoloration from cloth. When the stained cloth is place into hot H2O, it is hard to place whether the fabric decolorize or non because it is possible for cloth to turn into white without be rub. To better this, the experiment must be repeated for several times to increase the truth. There is besides a restriction where the removable of discoloration can non be seen clearly when trial conducted with java at first.

So, to get the better of this job, the discoloration was changed into sirup which the ruddy coloring material can be seen clearly. However the job had comes when there is alteration in pH value of fruit juice after adding with NaCl due to presence f H2O. This might be because restriction that occurred during extraction of juice. So, it is necessary to guarantee all the equipment to rinse and dry first before carry oning any experiment.

Recommendation for farther research

More work could be done on the usage of Na chloride ( cooking salt ) in taking discoloration ; is it effectual used and how it will increase the effectivity of citric acid in taking discoloration? The other usage of citric acid beside remove discoloration should be investigated as if citric has potential in other cleansing procedure. Besides that, while the experiment was done by utilizing citrus fruits as natural bleaching agent other natural decoloring agent should be considered. Probe on the effectivity of citric acid by comparing it with the commercial bleaches and colour safer bleaches has applications in our day-to-day life.

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Citric Acid In Citrus Fruits In Removing Stains Biology Research Paper. (2017, Jul 08). Retrieved from