Etiket Arşivleri: experiment

Acid-Base Titrations

Titration is an analytical method used to determine the exact amount of a substance by reacting that substance with a known amount of another substance. The completed reaction of a titration is usually indicated by a color change or an electrical measurement. An acid/base neutralization reaction will yield salt and water. In an acid-base titration, the neutralization reaction between the acid and base can be measured with either a color indicator or a pH meter.

Acid + Base  Salt + Water

In this experiment, a phenolphthalein color indicator will be used. Phenolphthalein is colorless in acidic solutions and pink in basic solutions. Phenolphthalein is also used in forensic crime scene analysis to detect the presence of blood, Kastle-Meyer test. In the Kastle-Meyer test, hemoglobin catalyzes the oxidation of the colorless form of phenolphthalein to its bright pink form. Four lab periods assigned for this experiment. In part I you will prepare an acid (HCl) solution and a base (NaOH) solution. These solutions will be used for all four periods so it is important to keep these solutions. These solutions will be titrated against each other to obtain a base/acid ratio. In part II you will find the normality of the base solution by titrating it against a solid acid standard. The normality of the acid can be calculated from the normality of the base and the base/acid ratio from part I. In part III the base will be titrated against an unknown acid to find the equivalent weight of the acid. In part IV the equivalent weight of an unknown base will be determined by reacting the unknown base with an excess of HCl and “back-titrating” the left-over acid with NaOH.

Equipment and Reagents (Part I)

6 NHCl 1 Liter plastic bottle 2 beakers (50 mL)
6N NaOH 2 burets 250 mL Erlenmeyer Flask
500 mL Florence Flask Iron stand wash bottle
Distilled water buret clamp phenolphthalein indicator
Stopper(or parafilm) 2 x 50 mL graduated cylinder

Procedure (Part I)

1. Rinse a clean 500 mL Florence flask with a small portion of DI water. Place about 16-17 mL of 6 M or 6 N HCl into the flask and dilute to 500 mL with distilled water. The 500 mL is approximated by bringing the level of the solution up to the point of constriction of the neck of the flask. Stopper the flask and shake to mix. The solution should be approximately 0.2 N HCl. Label the flask with tape.

2. Rinse a clean 1 L plastic bottle with distilled water. Place about 32-34 mL of 6 M or 6 N NaOH into the bottle and dilute to 1 liter with distilled water. Place the cap on the bottle and shake to mix. The solution should be approximately 0.2 N NaOH. Label the bottle with tape.

3. Obtain 2 burets from the stockroom and clamp them onto the ring stand using the buret clamp. Label the buret as acid or base. Label the 50 mL beakers as acid or base. These beakers will be used to transfer the solutions into the burets. Rinse each buret with about 5 mL of DI water and with about 3 x 5 mL of the solution to be used. Fill each buret with the correct solution and flush all of the air bubbles out of the buret tip.

4. Read the initial level of each buret to the nearest 0.02 mL and record this in your notebook. The proper reading is taken from the bottom of the meniscus (see Figure 1 below). If the initial reading is at exactly at zero, then report 0.00 mL.

5. Allow about 25 mL of the acid to run into an Erlenmeyer flask from the acid buret. Record the initial and final readings of this transfer. Calculate the volume of acid transferred by subtracting the final volume reading by the initial volume reading. Your final answer should be to the hundredth place.

6. Add about 20 mL of distilled water into the flask and add 2-3 drops of phenolphthalein indicator. The flask should remain colorless at this point.

7. Record the initial volume of base. Slowly add NaOH from the base buret into the flask with constant swirling. Continue adding base until a very faint color remains. If the color is too bright, add a few drops of acid so that the solution becomes colorless. Add base again to reach the faint end-point. Repeat this process until a faint pink end-point is reached. Record the final volume of base and the initial and final volume of extra acid added to this flask

8. Calculate the total final volume of acid and final volume of base added.

9. From these values, calculate the base to acid ratio:

Source: https://lahc.edu/classes/chemistry/arias/Exp%207%20-%20AcidBaseF11.pdf

Membrane Filtration of Water

Membrane Filtration of Water

Theory:

Experiment No: 5 Membrane Filtration Method in “Basic methods for the Microbiological Analysis of Foods” by Prof. Dr. Osman ERKMEN. Nobel Yayınevi. Ankara 2007.

Sample:

1- Dirty river water (100, 150, 200 ml)

2- Drinking water (100, 150, 200 ml)

Materials:

1- Membrane Filtration Apparatus and Vacuum pump.

2- Plate Count Agar.

3- Sterile filter paper (0.45 mm)

4- Forceps

Procedure:

1- First Sterilize the Filtration apparatus and forceps by passing through flame.

2- Place the coarse filter between flask and funnel and close the lid. Make sure the tap of funnel is closed.

3- Take 50ml of water sample and pour into funnel without filter paper to make a trial run to wet the surface of coarse filter. Run the vacuum pump and open the tap of funnel.

4- All of the sample should be passed through coarse filter.

5- Release the funnel lock and take a sterile filter paper.

6- Open the package of filter paper at aseptic conditions and take it by using sterile forceps.

7- Place the filter paper on the coarse (green side upper) filter let it get wet and remove the green upper cover by using forceps. Filter paper should be stick on the surface of coarse filter.

8- Then place the funnel close the lock. Close the tap of funnel.

9- Add 100 ml of sample in the funnel at aseptic conditions and run the vacuum pump. Open the tap of funnel to pass the entire sample through the filter paper.

10- After all of the sample was passed, remove the funnel and remove the filter paper from the surface of coarse filter.

11- Place the filter paper on PCA at aseptic conditions. And close the lid of petri dish.

12- Repeat the procedure for 150, 200 ml of sample amounts.

13- Incubate the petri dishes in the 37°C Incubator.

14- Count formed colonies on the filter paper. Calculate number of microorganisms per ml of water sample.

Source: http://ibs.gantep.edu.tr/duyuru/files/articles/membrane-filtration-method-procedure5004.pdf

Experiment: Determination of Fat

Name of Experiment            : DETERMINATION OF FAT

QUESTIONS

  • What is the principle of soxhelet extraction apparatus?

The principle of soxhelet extraction apparatus is to occur an intermittent extraction with excess of fresh condensed solvent in a special sample tube with a siphon attachment. The sample is held in a porous filter container such as thimble, and extracted fat returns with the solvent when siphoned, but does not redistill with the solvent and condense back to the sample.

  • What is the function of lipids on human body?

  1. They are source of energy.

  2. They need for vitamins that melted in fat.

  3. They need for Linoleic acid, Linolenic acid and Arachidonic acid because of certain of them cannot be made by the body. Essential fatty acids in lipids form part of the structure of all cell membranes.

  4. They preserve to body from out effects.

  • Define extractable fat and total fat.

  1. The extractable fat: The extractable fat is crude fat. It can be extracted by les polar solvents. Also, its amount is too much than other matters in food.

  2. The total fat: The total fat content consists of the additional ‘bound’ lipids which require more polar solvents (alcohols) for their extraction.

  • What is the function of acid added to the sample prior to the extraction?

The function of acid added to sample prior to the extraction is dissolved to proteins in lipids.

Gravimetric Determination of Sulfate In an Unknown Solution

GRAVIMETRIC DETERMINATION OF SULFATE IN AN UNKNOWN SOLUTION

AIM

The main objective of this experiment is to determine the concentration of sulfate ion in an unknown solution by using gravimetry.

INTRODUCTION

Gravimetric analysis is based on the measurement of the mass of a substance of known composition that is chemically related to the analyte. Gravimetric analysis includes precipitation, volatilization and electrodeposition methods.
In precipitation gravimetry of the analyte is carried out by the use of inorganic or organic precipitating agents. The two common inorganic precipitating agents are silver nitrate, which is used to precipitate halide ions such as chloride, and barium chloride for precipitating sulfate ion.
Additionally, potassium, ammonium, rubidium, and cesium ions can be precipitated by sodium tetraphenylborate. Sulfate is quite common in nature and may be present in natural water in concentrations ranging from a few to several thousand milligrams/liter. Sulfates are of considerable concern because they are indirectly responsible for two serious problems associated with the handling and treatment of wastewater. Odor and sewer corrosion problems result from the reduction of sulfates to hydrogen sulfide under anaerobic conditions.


Source: http://users.metu.edu.tr/chem223/Sulfate.pdf

Experiment: Soap Making ( Saponification )

EXPERIMENT : SOAP MAKING (SAPONIFICATION)

In this experiment we prepare soap from animal fat (lard) or vegetable oil. Animal fats and vegetable oils are esters of carboxylic acids; they have a high molecular weight and contain the alcohol, glycerol. Chemically, these fats and oils are called triglycerides (See chapter 27.3 of Bruice). The principal acids in animal fats and vegetable oils can be prepared from the natural triglycerides by alkaline hydrolysis (saponification). You may also choose to add a scent to your soap by adding an essential oil. You can purchase the scent you want to add or isolate it from the natural source using a process of steam distillation (see ‘Natural Product Isolation’ procedure at the end of this lab)

The natural acids are rarely of a single type in any given fat or oil. In fact, a single triglyceride molecule in a fat may contain three different acid residues (R1COOH, R2COOH, R3COOH), and not every triglyceride in the substance will be identical. Each fat or oil, however, has a characteristic statistical distribution of the various types of acids possible—See chapter 26.3, pg 1121 of Bruice for some examples. The fats and oils that are most common in soap preparations are lard and tallow from animal sources, and coconut, palm, and olive oils from vegetable sources. The length of hydrocarbon chain and the number of double bonds in the carboxylic acid portion of the fat or oil determine the properties of the resulting soap. For example, a salt of a saturated long-chain acid makes a harder, more insoluble soap. Chain length also affects solubility. Tallow is the principal fatty material used in making soap. The solid fats of cattle are melted with steam, and the tallow layer formed at the top is removed. Soapmakers usually blend tallow with coconut oil and saponify this mixture. The resulting soap contains mainly the salts of
palmitic, stearic, and oleic acids from the tallow, and the salts of lauric and myristic acids from the coconut oil. The coconut oil is added to produce a softer, more soluble soap. Lard (from hogs) differs from tallow (from cattle or sheep) in that lard contains more oleic acid.

Pure coconut oil yields a soap that is very soluble in water. The soap contains essentially the salt of lauric acid with some myristic acid. It is so soft (soluble) that it will lather even in seawater. Palm oil contains mainly two acids, palmitic acid and oleic acid, in about equal amounts. Saponification of this oil yields a soap that is an important constituent of toilet soaps. Olive oil contains mainly oleic acid. It is used to prepare Castile soap, named after the region in Spain in which it was first made. Toilet soaps generally have been carefully washed free of any alkali remaining from the saponification. As much glycerol as possible is usually left in the soap, and perfumes and medicinal agents are sometimes added. Floating soaps are produced by blowing air into the soap
as it solidifies. Soft soaps are made by using potassium hydroxide, yielding potassium salts rather than the sodium salts of the acids. They are used in shaving cream and liquid soaps. Scouring soaps have abrasives added, such as fine sand or pumice.


Source: http://facweb.northseattle.edu/jpatterson/pdf/chem252p/252Preparation%20of%20%20Soap10.pdf

Yogurt Analysis ( Hakan MAVİŞ )

FE 421 FOOD MICROBIOLOGY LABORATORY

Name of student       : M. Hakan MAVİŞ

Group                            : B – 2

Name of experiment : Milk and Milk products, Yogurt Analysis

Purpose:

The purpose pf this experiment was to analyze microbiological properties of yogurt and to investigate the number of lactic acid bacteria and formation of mold and yeast.

Theory:

The effect of yogurt as a dietary supplement was investigated with regard to the gut ecosystem and lipid metabolism of 12 healthy, elderly people (78.3 +/- 9.8 years, body mass index 23.6 +/- 5.3 kg m -2, and mean +/- SD). Commercial yogurt with homogenized fruit was prepared by fermenting milk with yogurt specific cultures Lactobacillus delbrueckii ssp. bulgaricus (strain AY/CSL) and Streptococcus thermophilus (strain 9Y/CSL). The subjects consumed their usual diet (equal to 6279-6698 kJ d -1) over a 2-week baseline period (baseline start to end) and then were supplemented for 4 weeks with 250 g d -1 of fruit yogurt. The yogurt was administered in 125 g portions twice per day: at breakfast in substitution of milk and in the afternoon in substitution of tea with milk (test). At the end of the 4-week period the volunteers returned to their usual diet for a further 4 weeks (follow-up). At the end of each trial period no changes were observed in faecal water content, pH, bile acid concentration or cytolytic activity of the faecal water. Throughout the study there was significant variation neither in dietary intake of macro- and micronutrients, nor in the plasma lipids and, during the experimental period, in the counts of the total anaerobic microorganisms, bifidobacteria, lactobacilli, coliforms or enterococci. The only significant difference was observed in the clostridia counts, which decreased (P < 0.05) after the consumption of yogurt. Moreover, this effect was still evident at the end of the follow-up period. Since this last result can be considered a positive modification of the colon ecosystem, as clostridia are involved in the production of putrefactive compounds, it is possible that a yogurt-supplemented diet can maintain and/or improve the intestinal microbiota of elderly subjects.

Procedure:

  1. a) Total Count:

Firstly; from yogurt dilutions were prepared from 10-1 to 10-6 dilutions. For this, 25 g yogurt sample was weighed and added above 225 ml peptone water thus 10-1 yogurt dilution was prepared then; from 10-1 dilution 1ml was taken and it was added to 9 ml water thus 10-2 dilution was prepared. In the same manner, 10-3, 10-4, 10-5 and 10-6 dilutions were prepared. Finally; from each tube 0, 2 ml was taken with pipette and sample dilutions were put on the plate count agar (PCA) and then spread out with spread plate method and incubated at 30 oC for 1 to 3 days. After incubation number of microorganisms in gram was calculated in yogurt.

  1. b) Lactic Acid Bacteria:

At previous experiment prepared dilutions were used for this experiment. Again sample dilutions were taken 0, 2 ml and put on the mean rogosa sharp agar (MRS). Then; plates were incubated at 35 oC for 24 to 48 hours. Finally; number of lactic acid bacteria was calculated in gram.

  1. c) Mold and Yeast Count:

Again, at first experiment, preparaed dilutions were used for this analysis. In here; 0, 2 ml sample dilution was taken and was put on potato dextrose agar (PDA) and spread out with spread plate method. Then PDA was incubated at 25 oC for 2 to 5 days. Finally; number of microorganisms was calculated in gram.

MATERIALS:

  • Yogurt

  • Plate count agar

  • Mean rogosa sharp agar

  • Potato dextrose agar

  • Peptone water pipette

  • Spreader

  • Bunsen burner

  • Etuv

  • Test tube rack

  • Alcohol

RESULT and CALCULATIONS:

PCA

Total count

10-1

10-2

10-3

10-4

10-5

10-6

Open yogurt

25

5

1

0

2

0

Pasteurized yogurt

46

13

11

4

3

1

Open yogurt

19

4

1

0

4

7

PDA

Mold & Yeast

10-1

10-2

10-3

10-4

10-5

10-6

Open yogurt

TNTC

TNTC

TNTC

198

21

6

Pasteurized yogurt

1

0

0

0

0

0

Open yogurt

TNTC

TNTC

TNTC

189

16

8

 

MRS

LAB

10-1

10-2

10-3

10-4

10-5

10-6

Open yogurt

TNTC

TNTC

TNTC

TNTC

2

2

Pasteurized yogurt

TNTC

TNTC

TNTC

152

4

1

Open yogurt

TNTC

TNTC

TNTC

207

4

8

For PCA

Number of microorganisms = (46 * 101) / 0, 2 ml = 2300

For PDA

Number of microorganisms = (198 * 104) / 0, 2 ml = 9, 9*106

Number of microorganisms = (189 * 104) / 0, 2 ml = 9, 45*106

Average number of m / o’s = (9, 9*106 + 9, 45*106) / 2 = 9, 675106

For MRS

Number of microorganisms = (152 * 104) / 0, 2 ml = 7, 6*106 (pasteurized)

Number of microorganisms = (207 * 104) / 0, 2 ml = 1, 035*107 (raw)

Discussion:

In this experiment, we examined properties of microorganisms and calculated the number of microorganisms in yogurt. For this, we made three analyses. For the number of microorganisms on plate count agar, for lactic acid bacteria on mean rogosa sharp agar and for mold and yeast on potato dextrose agar were used for yogurt microbiologic analyses. In here; MRS was used to determine total number of lactic acid bacteria. PDA was used to determine the number of mold and yeast. When we diluted the yogurt sample, we used the peptone water has a great protective effect. For this, 1g peptone was dissolved in 1L of distilled water and pH was adjusted to 7, 0 and it dispenses in sufficient quantity to allow for loss during sterilization.

The end of experiment, at pasteurized yogurt 2300 microorganisms was calculated on PCA. Actually; in open yogurt more microorganisms should have been observed. On the other hand; also in here, these microorganisms were useful microorganisms like Lactobacillus bulgaricus and Streptococcus thermophilus.

On MRS, lactic acid bacteria were calculated as 7, 6*106 for pasteurized yogurt and 1, 035*107 for open yogurt.

Experiments In General Chemistry 2 ( Dr. Ayşe Elif BÖYÜKBAYRAM )

Experiments

11. Çözeltilerin Hazırlanması

12. Çözünürlük ve Çözünürlüğü Etkileyen Faktörler

13. Donma Noktası Alçalmasından Molekül Kütlesi Tayini

14. Kinetic Study of the Reaction Between Ferric and Iodine Ions

15. Le Chatelier Kuralı

16. Asit Baz Titrasyonu

17. pH ve İndikatörler

18. Oxidation-Reduction Electron Transfer Reactions

19. The Solubility Product Constant of Calcium lodate, Ca(IO3)2

20. Sabun

References


Kaynak: http://fen.karabuk.edu.tr/kimya/lab%20foyleri/genel%20kimya/genel%20kimya%202.pdf

Methylene Blue Reduction Test and Direct Microscopic Count Method

FE 421 FOOD MICROBIOLOGY LABORATORY

Name of student : M. Hakan MAVİŞ

Group : B – 2

Name of experiment : Methylene Blue Reduction Test and Direct Microscopic Count Method

PURPOSE:

The purpose of this experiment was to investigate the coliform in milk and learn methylene blue reduction test and direct microscopic count method for milk.

THEORY:

The Standard Plate Count (SPC) procedure is used to determine the number of bacteria in a sample. In most cases the initial day SPC represents those bacteria that survive pasteurization (thermoduric), although gross contamination after pasteurization can cause high counts. The regulatory standard of < 20,000/ml is generally easily achieved. Most initial day bacteria counts are <500/ml while counts higher than 1000/ml suggest a potential contamination problem, either in the raw milk supply or within the processing equipment.

The ideal milk shows no increase in bacteria counts during refrigerated storage. When milk is held under refrigeration, only bacteria capable of growth under these conditions will grow. While most bacteria prefer warmer temperatures for growth, some bacteria, referred to as psychrotrophs (“cold-loving”), are capable of growth at 45oF or less. The most common types of psychrotrophic bacteria that rapidly spoil milk do not survive pasteurization; thus their presence in milk is the result of post-pasteurization contaminants due to less than adequate sanitation practices. The initial day SPC of fresh pasteurized milk is not a good indicator of the numbers of psychrotrophs present since most bacteria that survive pasteurization are not psychrotrophic (a few types of thermoduric bacteria will grow slowly under refrigeration conditions). A significant increase in the SPC after 7-10 days of refrigeration storage is evidence of psychrotrophic growth and suggests that post-pasteurization contamination has occurred and that shelf-life will be shortened. Generally, when the SPC exceeds 1 – 100 million, the product will become unacceptable due to flavor defects related to bacterial growth. The key to preventing spoilage and extending the shelf-life of a product is to prevent post-pasteurization contamination through a well-designed quality assurance program. It only takes one psychrotrophic bacteria per container of milk to cause spoilage.

The coliform bacteria (coli) count is used as an index of sanitation during the handling and processing of milk products. Coliforms are killed by pasteurization, thus when present in milk, they are regarded as post-pasteurization contaminants resulting from poor sanitation.  Though the standard is “not to exceed 10/ml,” detection of any coliform bacteria suggests that there is some point in processing that has been neglected in regard to effective cleaning and sanitation procedures. As a rule, the detection of coliforms in milk will indicate the potential for a shortened shelf-life due to concurrent contamination with psychrotrophic bacteria. Milks with coliform counts exceeding 10/ml are not tasted on subsequent days in this program.

MATERIALS:

  • Tcyptone glucose yeast agar

  • Milk

  • Methylene blue solution

  • Tubes

  • Pipette

  • Spreader

  • Bunsen burner

  • Test tube rack

  • Etuv

  • Ethyle alcohol

PROCEDURE 1:

1 – Total Count:

Firstly; milk was diluted from non dilution milk to 10-5 dilution in the test tube. In order to make 1 ml non-dilution milk was taken and it was added to 9 ml distilled water and thus 10-1 milk dilution was occurred and this process was continued to 10-5 dilution. After that; 0, 2 ml dilution was taken with pipette from each dilution (non-dilution, 10-1, 10-2, 10-3, 10-4, 10-5) these were inoculated to tcyptone glucose yeast agar with spread plate method. Then; these were incubated at 37 oC for 24 hours. After incubation, between 300 – 30 being microorganisms were counted and in ml numbers of microorganisms were calculated.

2 – Methylene Blue Reduction Test:

Secondly; raw milk and pasteurized milk were studied separately. 10 ml milk was put in the test tube and 3 – 4 drops methylene blue solution was added to milk. Then; milk and methylene blue solution were mixed vigorously, then; these tubes were incubated at 37 oC for 30 minutes. Milk was examined and observed whether decolorization was occurred or not.

RESULTS 1:

Total Count:

non

10-1

10-2

10-3

10-4

10-5

A – raw milk

TNTC

359

284

65

38

9

B – paste. Milk

TNTC

47

2

0

0

0

C – raw milk

TNTC

TNTC

TNTC

198

33

7

Group A)        For 10-2 dilution: (284*102) / 0, 2 ml = 142000

For 10-3 dilution: (65*103) / 0, 2 ml   = 325000

For 10-4 dilution: (38*104) / 0, 2 ml   = 1900000

(142000+325000+1900000) / 3 = 789000

Group B)        For 10-1 dilution: (47*101) / 0, 2 ml   = 2350

Group C)        For 10-3 dilution: (198*103) / 0, 2 ml = 990000

                        For 10-4 dilution: (33*104) / 0, 2 ml   =1650000

(990000+1650000) / 2 = 1320000

Methylene Blue Reduction à this method depends on the ability of microorganisms to change oxidation-reduction potential of medium. Bacteria consume dissolved oxygen in medium and produce some enzyme. These enzymes oxidize substrate and hydrogen removed from substrate and hydrogen was held with methylene blue solution and light blue of milk converted to white or colorless.

PROCEDURE 2:

3 – Coliform Test:

Firstly; milk was diluted from non-dilution to 10-5 dilution, then 0, 2 ml diluted and milks were spread out on violet red bile agar with spread plate method then plates were incubated at 37 oC for 48 hours. After 48 hours number of colonies was counted and in ml number of microorganisms was calculated.

4 – Direct Microscopic Count Method:

In here; firstly; slide was taken and on slide 1 cm2 area was determined and one loopful raw milk was put on this area and raw milk was spread out with distilled water in this area. Then; on slide milk was waited to get dry in air. After that; one loopful xylol was added on each square and waited for 1 min then slide was washed with water. Afterwards; 1 – 2 drops methylene blue was added onto each square and waited for 2 min and again slide was washed with water. Next; slide was got dry in air. Finally; on each square, one drop iol immersion was added and milk was examined under 100X objective.

RESULT 2:

Coliform Test:

non

10-1

10-2

10-3

10-4

10-5

A – raw milk

TNTC

TNTC

TNTC

165

16

2

B – raw Milk

TNTC

TNTC

TNTC

TNTC

10

3

C – raw milk

TNTC

TNTC

TNTC

50

15

2

Group A)        For 10-3 dilution: (165*103) / 0, 2 ml = 825000

Group C)        For 10-3 dilution: (50*103) / 0, 2 ml = 250000

Direct Microscopic Count Method:

1st region

2nd region

3rd region

4th region

5th region

1st half slide

3

6

8

14

21

2nd half slide

2

4

5

10

15

1st half slide à 3+6+8+14+21 = 52

2nd half slide à 2+4+5+10+15 = 36

Average number of microorganisms = (52+36) / 10 = 8, 8

Average number of m/o’s = 8, 8 * 15700 * 100 = 14130000

In here 100 is 0, 01 ml milk.

DISCUSSION:

In this experiment; we examined microbiological properties of milk. In milk number of microorganisms was calculated with total count method and coliform bacteria were investigated with coliform test. Also; methylene blue test was applied the milk. In this test one drop methylene blue solution was dropped into milk and colour of milk was slightly blue. After 30 minute slight blue colour of milk converted to white, this transformation was related with number of microorganisms in milk. Microorganisms were used the dissolved oxygen and microorganisms produced certain enzymes. These enzymes oxidize the substrate, thus hydrogen was removed from substrate. Hydrogen was held with methylene blue solution and color of milk was colourless this process was called decolourization. In addition; while raw milk decolorized for 30 minutes pasteurized milk decolorized for 4 – 5 hours. This showed that; in raw milk, number of microorganisms was more than in pasteurized milk.

Secondly; number of microorganisms was determined with total count method. In each milk dilution, number of microorganisms was calculated with accordance to between 30 – 300 microorganisms and as a result; we observed that raw milk was to contain more number of microorganisms than pasteurized milk.

Next; coliform test was applied the milk and in here number of microorganisms was calculated. Finally; in milk microorganisms was examined with microcopy and dark blue microorganisms were observed and at five regions average number of microorganisms were calculated, and these were determined at the result and calculation.