ANALISA DATA IDENTIFIKASI AIR SUSU

1. PerbandinganUkuranButirLemakThis experiment aims to compare the time / see the grain size of fat in milk, using a microscope. Here praktikan conduct the experiment with ways to shed a drop of milk on a glass object, then closed with a de glass. Then observed with a microscope before it is set up to focus.From the observation that telahdilakukan data showed that after observed with a microscope looks fat droplets are very small and tight. And granules of fat are not appropriate. This is because the milk had been diluted. From the experiments it can be concluded that the grain size of the fat is ready to drink milk is uniform (homogeneous).

2. Film formationThis experiment aims to find out what happens if the milk is heated. In the first heating milk to a boil turned out to form a white membrane, then the membrane was taken and Millon tests. After the drops Millon reagent, the membrane becomes colored kuning.setelah silenced, gradually became reddish brown.The milk is heated was allowed to cool, then heated back up to three times the warming. In the second heating was formed after the membrane and tested with Millon tests, the membrane becomes reddish brown, but more faded than the first film. In the third heating was also formed membrane. But the film is formed on heating a third less than the First Instance and the second heating.At this time filming experiment performed three times.Membrane is formed is a mixture of casein and calcium salts. Breast milk contains proteins, one of which is casein. Milk solution isoelectric point of 4.6.But the normal pH of water solution of milk is 6.0 to 6.6. Casein from the milk is there as a soluble salt of calcium carbonate and can not be coagulated by the boiling. However, forming a thin layer on the surface of the solution. This solution will not be formed if there is warming.In this event, hydrolyzed casein into soluble casein at Ca2 + and the crystal clear liquid called "whey" which still contains albumin and globulin and soluble salts. From the description it can be concluded that the membrane formed is mixed with salt casein calcium in the first heating.

3. Protein test TerhadapSusuThe purpose of this experiment is to detect the presence of protein in milk.Reagents used were reagent Millon and biuret reagent. This experiment is done by taking 3 ml of water and milk in a test tube and then into it in add 3-5 drops of Millon reagent, the water turns the milk to form clumps of yellow turbid.After it heats the reaction tube and the milk becomes reddish brown and form two layers with the lower layer nodes. Changes that occurred proved that breast milk contains proteins that are amino acids such as tyrosine phenol group gengan. The precipitate formed will change when heated to red brick.reaction:

Experiments with biuret reagent made by adding 2-3 drops of biuret reagent in 1 ml of milk. Apparently after the biuret reagent drops, water, milk a murkypurple. Biuret reagent is a reagent that is used to detect the presence ofpeptide bonds, consisting of a mixture solution

of CuSO4 in alkaline conditions(a mixture of CuSO4 and NaOH). The existence of a purple color indicates the presence of protein in the form of milk that has peptide bond with the amino group and an amino acid with the carboxyl group of amino acid liquid.reaction:

4. PenentuanTitikBeku's MilkThe experiment was done in order to determine the freezing point of milk. The experiment begins by entering the 5 ml of distilled water into a test tube.Furthermore insert ice cubes into the container (water bath) as high as 2/3 andadd 5 tablespoons of salt, stirring rate. Test tubes filled with distilled waterwhich had been was then put in a water bath containing ice cubes, until all ofdistilled water to freeze. Once frozen, the tube removed from the water bathand measure the temperature of each interval of 30 seconds until melteddistilled water / melt all. Furthermore do the same experiment but replacingdistilled water with milk.Obtained from experimental data as follows:

Aquades

Waktu

(detik)

Suhu

(oC)

Waktu

(detik)

Suhu

(oC)

30

60

90

120

150

180

210

240

3

2

10

10

10

11

10

10

270

300

330

360

390

420

450

480

11

8

9

7

7

7,5

7

7,5

· Air Susu

Waktu ( detik ) Suhu (oC)

30

60

90

-4

-3

-2,5

120

150

180

210

240

-2

-1,5

-1,5

-1

-1

Berikut ini merupakan grafik hubungan temperature dengan waktu :

From the above data, it is known that the milk will melt / melt faster thandistilled water. While the freezing point of water and the milk can be determined as follows:· aquadesBerdasarkangrafik, Suhukonstan = TOF = 10 ° CTitikbekuaquades = 10 ° C· Water MilkBerdasarkangrafik, suhukonstan = ΔTf =-1oCTfsusu = TOF - ΔTf = 10 - (-1) = 11oCJadititikbekususu = 11oCFrom the experimental results show that the freezing point of distilled water is lower than the freezing point of milk. These results are inconsistent with the theory, because it is based on the theory of the freezing point of distilled wateris higher than the freezing point of milk. This can be caused by adnya peptidebond in the breast milk, this peptide bond is stronger than hydrogen bonding indistilled water so as to decide this peptide bond more difficult, thus becoming more difficult to freeze.

5. Determination of pH of milkThe experiment was conducted to determine the pH of milk. The milk pH was determined by two ways ie, with milk dripping on universal pH paper and litmus paper. Based on the results of testing with universal pH paper, pH 6 milk isshown in yellow. Thus the milk is sour. While based on the litmus paper test,showed similar results that the milk is sour bengan marked color change bluelitmus paper red to purple after spilled milk. Thus, according to two tests conducted can be concluded that the milk is acidic with a pH of 6.

CONCLUSIONA. Grain formation of fat in milk is homogenized.2. In the formation of a yellowish film coating, after treated with Millon reagent.Film and dark yellow to dark brown over time. On heating the second and thirdfilm layers are formed. The film layer is mixed with salt casein calcium in thefirst heating.3. Breast milk contains a protein tyrosine and peptide bond through a testprotein with Millon reagent and biuret reagent.4. Breast milk has a lower freezing point than the freezing point of distilled water due to the

milk peptide bond is stronger than hydrogen bonds in milk.5. Based on the pH test using a universal pH paper and litmus milk showedthat the water is acidic with a pH of 6.

VIII. DAFTAR PUSTAKA

Aisyiah Birinda. 1993. Biokimia I. Jakarta : Gramedia.

Ana Poedjiati. 1999. Dasar-dasar Biokimia. Jakarta : UI Press.

Sri Retno D.A. 2011. Petunjuk Praktikum Biokimia I. Surakarta : Lab. KIMIA FKIP UNS.

Winarno. 2002. Kimia Pangan dan Gizi. Jakarta : Erlangga.

ISOLASI KASEIN

This experiment aims to isolate casein from milk. In these experiments usedpowdered milk. Isolation of casein can be done by acidification. In experimentscarried out the isolation of casein by acidification by adding glacial aceticacid. Milk is a colloidal system of dispersed and pendispersinya system isliquid (emulsion). The system is not very stable, but the milk, colloidal systemsare stabilized by the presence of casein as emulsifier. The first step is to heat the milk of 100 ml up to a temperature of 40 ° C, heating only up to a temperature of 40 ° C, in order not to damage the water content of the milk ofanother tritofan, serine and treonina, after reaching 40 ° C, the milk was appointed and added dropwise glacial acetic acid as much as 1 ml, stirring constantly and over time the white precipitate formed. This is a caseinprecipitate, the precipitate is then separated from the filtrate by filtering it.Deposition of solids / powder white, while the filtrate a saturated liquid slightly yellow in color. The filtrate was then kept for experimental identification ofcasein The next step is to dissolve the precipitate in 50 ml 95% alcohol, thenmendekantasinya, then repeat this step using 50 ml of ethanol: ether = 1:1.Then added another 50 ml ether; alcohol and filtered, and washed with 50 mlether. The series aims to purify the casein derived from milk componentsother. Once filtered, dried casein obtained after dry and weighed. Casein mass obtained is 6.0912 mg. so that the levels of casein in 100ml of milk isLevels of casein === 6.0912 mg / ml

conclusionA. The purpose of the experiment is to isolate casein from milk

2. Casein can be isolated by chemical hydrolysis, either by acidification, the addition of alkali or enzyme completely3. By acid hydrolysis of casein is performed at high temperatures, only doneup to a temperature of 40 ° C only breast milk for the other components are notdamaged4. White casein obtained by mass 6.0912 g5. Casein content of milk in 100 ml of water is 6.0912 mg / ml6. Addition of 95% alcohol function is to purify the casein from the othercomponents of milk

Daftar Pustaka

Anna, Pudjianti. 1999. Dasar-Dasar Biokimia. Jakarta : UI Press

Ahmad, Dwi S dan Subarno. 1999. Petunjuk Praktikum Biokimia. Surakarta: F.MIPA UNS

Tim Dosen Praktikum Biokimia. 2011. Petunjuk Praktikum Biokimia. P.MIPA : UNS Press

Aisyah, G. 1993. Biokimia I. Jakarta : Gramedia

Sujadi. 1996. Petunjuk Praktikum Biokimia. Surakarta:UNS Press

http://elfafajri.blogspot.com/2011/06/air-susu.html

http://elfafajri.blogspot.com/2011/06/isolasi-kasein-dari-susu.html

http://en.wikipedia.org/wiki/Milk

http://en.wikipedia.org/wiki/Casein