All living beings are made in a big percentage by water. To determine the percentage of content in water of the olives we will do the following steps:
We take 2 olives, we weight them, we cut them( to evaporate water faster) and we put them in a container to dry them later.
Fresh weight: 9.270gr
We put the container with the 2 olives on a stove and we leave them there during a week and we wait that they dry off well.
Weight: 4.8gr
Difference of weight will correspond to water content: 4.47gr
The percentage of water that have the olives is 48'22%
Practice 2: Reductors glucids determination
The glucids are the main substances that the plants use to take the energy to do their vital functions. Among the glucids there are sugars and polysaccharides(like the starch that is the reserve substance of the plants)
In this practice we are going to guess through chemical methods the sugar present in the olive pulp.
1.- We take an olive, we get out the pulp and we separate the bone.
2.-We cut the pulp in small pieces and we put it in a recipient.
3.-We crush it.
4.-Then we put water to make it more fluid.
5.-We put the paste in a test tube.
6.-With one pipette we put two cm3 of Fehling A in a test tube.
7.-In these test tube we add 2 cm3 of Fehling B, and we obtain a blue mixture.
8.-We put this solution in the test tube with the olive and we mix it.
9.-Then we heat the mixture with a gas lighter.
10.-If the mixture becomes red the presence of the reductors glucids(glucose) is shown.
Results: It has glucose because the mixture is red.
Practice 3: determination of starch.
Among the sugars in the plants there are polysacharide 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 comparewe get a potato, that is very rich in starch.After cutting it in a half and making some incisions, we throw some drops of lugol.It colours the starch to purple.
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.
4.-Conclusions: It has starch because it turns purple.
Practice 4: Determination of protein.
To determine the presence of two proteins perform this experiments:
Xantoproteic reaction
1.-Extracting oil from seeds of several bones.
2.-Let them dry for a week.
3.-Take the dried seeds of olives and crushed them in a container.
4.-Once crushed the cast in a test tube, add 1 cm3 of concentrated nitric acid(HNO3)
5.- Heat the test tube with a gas lighter. If there are proteins, they react with nitric acid and the sample will turn yellow.
6.-Results: it has proteins because it turns yellow.
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 tthere 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 biuret to cupric sulfate, demostrating that protein.
5.-Results: it has proteins because it turns purple.
Practice 5: determination of lipids
We do some experiments:
Insolubility in water:
1.-We take several olives and we cut the flesh in very small pieces.
2.-We throw the flesh in a test tube and we add more or less 5 cm3 of water(up to enrasate the test tube).
3.-We shake the tube to mix and we stop to rest.
4.-After it we can observe how these appear small yellow bubbles due to the insolubility of the fat oil in the water and due to the minor density it floats over the water.
Solubility in solvents organics:
1.- We take the flesh of a olive and we cut it.
2.-We put the flesh in a test tube and we add 2cm3 of ether.
3.-We stop to rest the mix(ether with oil) and we put it in a sump of porcelain or glass.
4.-We evaporate the liquid with fire and we obtain some bubbles of oil.
Practice 6: oil extraction
In these 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 are crushed with mills or metallic crushing machines).
2.-Beaten:
We put a little cold water to them. Slowly, we remove the paste with a spoon , while we heat it. Doing this the extraction of the oil will be easier.
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 "orujo" is separated with a system of presses or by centrifugation.
4.-Decantation:
We leave in a place during one week so that separate by movement. The process have three different phases: first it is the oil, second is "alpechín" and third it is "orujo" remaining, all good differentiated at first.
5.-Separation of the oil:
With a pipette, we extract carefully the oil to finish separating it of some remainders and that appeared clean.
Practice 7: saponificaton's reaction
The saponification is a chemical reaction between a lipid and a base. The oily acids of the lipids are difficult to hidrolice but they can be broken very easy if the lipid is in a basic enviroment.
Oil+soda=Glycerin+soap
1.- The original recipe for make soap recommends to use 6 l of oil,
2.- However 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
6000ml-5500ml
2ml-x ml
x=1'8ml
Calculate now the quantity of soda in the relation with the water:
5500ml-1000gr
1'8ml-x gr
x=0'33 gr
3.-Realice in a test tube the solution of soda and water with the calculated quantities. We remove it until the complete solution of soda.
4.-Later we add 2 ml of oil and we continue moving slowly until the soap is formed.
5.-We extract the soap of the tube and we put it in a Petri's plate and we model it like a bar. We wait until it finish solidifying.
6.-After extracting the soap we add water in the tube and we shake it. The abundance of lather indicates us that there is a bit of soap.
