Preparation of casein

I. The purpose and requirements

1. Master to use the centrifuge;

2. Master prepared from milk casein in the principles and methods. II. The experimental principle

Casein is protein phosphorus, but also the heterogeneous mixture, rich in Tyr, Met, Gys, (Gys) 2, pI equal to 4.7 to 4.8, insoluble in ethanol. The experimental use when in the isoelectric point of the principle of minimum solubility, the milk's pH to 4.7, the casein will precipitate out. Sediment washed with ethanol to remove lipid impurities, you get pure casein

III. Equipment and reagents

1. Equipment

a. Centrifuges

b. Filtration system(Buchner funnel);

c. Constant temperature heating device

2. Reagent

a. pH4.7 acetic acid - sodium acetate buffer (0.2mol/L) 30ml

b. Milk 30ml

c.95% ethanol

IV. Methods of operation

1. The 30ml milk heated to 40℃, stirring slowly add heated to 40 ℃, pH4.7 acetic acid - sodium acetate buffer, 30ml (with a precision pH meter or pH paper and adjusted to pH 4.7).

To have mixed suspension cooled to room temperature, centrifuge (4000 rpm / min) centrifugation for 5 minutes, remove the supernatant, the crude products obtained casein.

2. The precipitate washed once with water, centrifugation for 5 min (4000 r / min), discard the supernatant.

3. Add 30ml of ethanol in the precipitation, stirring a moment, put all the suspension transferred to Buchner funnel filtration.

4. The precipitate on the surface of the dish open, to get pure casein.

5. Accurately weighed to calculate concentration and yield.

V. The experimental results and analysis

1. The experimental results

Data of the measurement is shown in the following table.

The amount

Casein(g)

of milk(mL)

30 2.0 values(g/L) 66.7 value(g/L) 35 190.5 Measured The theoretical Yield（%） End of the experiment to be casein yield was 190.5%, far greater than 100%, which is derived from the experimental proof of casein in the more impurities. Impurities which may be: water, ethanol and milk in some of the impurities.

2. The experimental analysis

a. Washed precipitate, when washed only once, did not completely wash out the impurities, so that the product is still more residual impurities, the results of this error is caused by one of the reasons.

b. After the filtration, did not use ethanol - ether mixture washed precipitate, not in the final precipitate washed with ether, resulting in the final product contains fat-soluble substances, alcohol, water and other impurities, which is the result of errors caused by one of the reasons.

c. No air-dried, during the experiment, water and ethanol in the product is not completely evaporated.

d. Buchner funnel in the transfer of sediment from the pan to the surface when a small amount of sediment left in the Buchner funnel and filter paper, and a small amount of precipitation is lost, leading to the result of error.

 

第二篇：实验报告英文

TEST REPORT

The TOSI Test provides an indication of cleaning performance. The red material on the TOSI Test stainless steel strip simulates the blood (protein) that is to be broken down and removed. This is an indication of the product performance for breaking down protein bioburden.

The Test Strip on the Left shows the results using the four Enzyme RUHOF Endozime AW Triple Plus.

The Test Strip on the Right shows the results using the all-in-ONE four Enzyme Detergent Surgical Instrument Lubricant Cleaner.

Both strips were exposed to the same time and temperature following their exposure to the diluted product. The products were diluted as per the product Directions for Use (DFU).

NOTE: the TOSI test only tests for protein ((blood)) removal. The TOSI Test does not test for the removal of fats, carbohydrates, and starches and is therefore one indication of the potential performance derived from using an enzyme cleaner, but is NOT comprehensive. It has been shown that the most challenging bioburden to be removed includes an emulsion of fats, proteins, and starches. That requires a cleaning agent that will remove all forms of bioburden.

WHAT ARE THE DIFFERENCE BETWEEN THE RUHOF PRODUCT AND THE ALL-IN-ONE PRODUCT  ????

BOTH PRODUCT HAVE THE FOUR ENZYMES

BOTH PRODUCT DELIVER DETERGENT AND SURFACE CONDITIONERS

THE ALL-IN-ONE DELIVERS:

a higher concentration of the 4 enzymes,

a higher concentration for surfactant detergents.

The INGREDIENTS of the all-in-ONE chemical complex is superior to ingredient of the RUFOH product.

ergo-Logistics

Technical Support: John Temple