All living beings are made in a big percentage by water. To determine the percentage of content in water of the olives we will continue the following steps: We take 2 olives, we weight them, we cut (for it evaporate faster) and we put them in a container to dry them later.
Fresh weight: 8.8 gr.
We put the container with the
2 olives on a stove and we leave during a week to that dries off well: Photo:After weight:4.4 gr
Difference of weigh will correspond:4.4gr
Calculate now the percentage of water that possess the olives:
8.8 ----- 100% X= (100*4.4)/8.8 = 50% 4.4 ----- X
Practice 2: Determination of reductors glucids
The glucids are the main substances of the plants from were they take the energy to do their vital functions. Among the glucids there are sweets and polysaccharides.
In this practice we are going to guess through chemical methods of sugus present in the olive pulp.
1- We take one olive, we get out the pulp.
2- We cut the pulp in small pieces and we put it in a recipient.
3- We crush it with a mortero.
4- Then we put water to make it in more fluid.
5- We put the paste in a glass tube.
6- With one pipette we put two cm3 of Fehling A in a glass tube.
7- In these glass tube we put 2 cm3 of Fehling B, and we obtain a blue mixture.
8- These solution is put in a glass tube with the olive and we mix it.
9- Then we heat the mixture with a gas lighter.
10- If the mixture become red is by the presence of the reductors glucids (glucose).
Practice 3: determination of starch.
Beside the sugar in the plants there are polisacarid glucids as the starch, the substance that we're going to extract from the flesh. This substance is the reserve of many plants.
1.- To get a sample to compare we get a potato, that is very rich in starch. After cut it in a half and make incisions, we throw some drops of lugol. This colouring turns lilac the starch.
2.-We get now an olive, we take the pulp off and we crush it.
3.-Once the flesh of the olive is crushed, we throw some drops of lugol on it.
Practice 4: Determination of protein.
To determine the presence of two proteins perform this experiments:
Reaction xantoproteic
1-Extracting oil from seeds of several bones.
2-Let them dry for a week
3-Take the dry seeds of olives and crushed them in a container.
4- Once crushed the cast in a test tube, add 1cm3 of concentrated nitric acid.
5-Heat the test tube with a cigarette lighter. If there are proteins, they react with nitric acid and the sample will turn yellow
6-Write your result: becomes yellow because it has protein
Biuret reaction:
The name of the reaction is that because of the proteins and how them come into contact with soda forming a substance called biuret.
1- Take various seeds and dried crushed olives in a bowl.
2- Once crushed the cast in a test tube, add 1 cm3 of 20% sodium hydroxide. Biuret will be formed only if there are proteins.
3- Then add a few drops of cupric sulfate diluted to 1%
4- If the sample turns purple color that must be reacted with the biuret to cupric sulfate, demonstrating that protein.
5-Write your result: Turns color purple
Practice 5: determination of lipids
We do some proves:
Insolubility in water:
1. We take several olives and we cut into pieces the flesh in very small pieces.
2. We begin the flesh in a pipe of test and we add more or less 5cm3 of water (up to enrasate the pipe of test).
3. We wave the pipe to mix and we stop to rest.
4. Already quiet the mix we can observe how they have been formed a small yellow bubbles owed than the lipids are insoluble in the water and by minor desity they are on the water.
Solubility in Solvents organics:
1. We take the flesh of a olive and we cut it.
2. We begin the flesh in a pipe of test and we add more 2cm3 of ether.
3. We stop to rest the mix (ether with lipids) and we add in a sump of porcelain or glass.
4. We evaporate the liquid to the fire and we obtain a bubbles of oil.
Practice 6: Oil extraction
In this practice we compare with the process of an industrial oil mill in the oil extraction, but in the laboratory.
1-Crushing:
We take 100 olives and we remove the stone to them. We grind the pulp of the olives with a beater (in the industrial oil mill the olives crush with mills or metallic crushing machines).
2-Beaten:
We put a little cold water to them. Slowly, We remove it with a dessertspoon the paste, while we heat it. With that form the extraction of the oil will be easier.
Photo:
3-Pressed:
We put a strainer on a precipitated glass. We spill carefully the paste on the strainer to separate the liquid of “orujo” (solid part). In the industrial oil mill the liquid of “orujo” separate with a system of presses or by centrifugation.
4-Decanation:
We leave in a place during one week so that separates by movement. The process have three different phases: first it is the oil, second is “alpechín” and third he is” orujo “remaining, all good differentiated at first.
5-Separation of the oil:
With a pipette, we extract carefully the oil and we putl it in a bottle or test tubes.
6-Centrifugation:
Finally, we have to centrifuge this oil to finish of separating it of some remainders and that appeared clean.
Practice 7: saponifcation's reaction
The saponification is a chemical reaction between a lipid and a base. The greasy acids of the lipids are difficult to hidrolice but they can be broken very easy if the lipid is in a basic enviroment.
Grease+soda→Glycerin + soap
1.- The original recipe for make soap recommends to use 6 l of oil and grease, 5 ½ l of water and 1kg of caustic soda(NaOH).
2.- However, as we have got few oil, we are going to remake the calculations to make soap with only 2 ml of oil.
To do it, start calculating the quantity of water that we're going to need in the relation with the oil:
Calculate now the quantity of soda in the relation with the water:
3.-Realise in a test tube the solution of soda and water with the calculated quantities. We remove it until the complete solution of soda.
Photo:
4.- Later we add 2 ml of oil and we continue moving slowly until the soap is formed.
Photo:
5.-We extract the soap of the tube and we put it in a Petri's plate and we model it like a bar and we wait until it finish solidifying . Photo:
6.-After extracting the soap we add water in the tube an we shake it. The abundance of lather indicates us that there is a bit of soap.
Photos:
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