PROCEDURES (Protein tests)
UDY HOME
WELCOME TO UDY
BEGINNING SET-UP AND TESTING
PRINCIPLE OF PROTEIN MEASURMENT
SAMPLE PREPARATION
CYCLONE SAMPLE MILL
BLENDER
BALANCES
DISPENSING
REAGENTS
REAGENTS (continued)
UDY COLORIMETER SET UP
STORAGE AND USE OF DYE SOLUTIONS USING PREPARED SOLUTIONS
REACT-R-MILL AND
REACT-R-SHAKER
MEASUREMENT
(UDY Colorimeter)
UDY COLORIMETER
TROUBLESHOOTING
PROTEIN MEASURMENT -- SOURCES OF ERROR
PROCEDURES
(Protein tests)
CRUDE PROTEINS IN SOLID MATERIALS
PROTEIN IN MEAT PRODUCTS
PROTEIN IN DAIRY PRODUCTS
PROTEIN IN
RAW / HOMOGENIZED MILK
PROTEIN IN WHEY AND WHEY PRODUCTS
CASEIN OR DENATURED WHEY IN LIQUID AND POWDERED MILK
TRUE PROTEIN IN WHEY
 

Procedures

General

This section gives specific information regarding Protein tests. The individual procedures do not give general information regarding use of the various pieces of equipment used. Equipment setup and general information is given in preceding sections (Sample Preparation, Weighing, Dispensing, and Measurement). To facilitate understanding of the procedures, condensed descriptions using drawings are included for: Milk protein; Meat and Dairy products protein measurement; and Solid commodity protein measurement. Principles used for Protein are in the introductory section.

Before attempting to perform tests, go through all appropriate manual sections. Some items are not used in all tests. See your individual packing lists for items included and specific procedure sheets for items required for each method.

A general rule which must be followed to consistently achieve accurate results is to keep instruments and all operations clean and orderly. Consistency must be used in the operations of dispensors and performance of the steps within a procedure. Running replicate tests, especially of the first test of a day, is advisable.

Table I

Protein Regression Line and Procedural Values for Solid Commodities

  General Procedure
1. Weigh the specified amount of finely ground and representative sample.
2. Dispense 40.0 ml (40.37 g " 0.08 g) of UDY Reagent Dye Solution into React-R-Tube.
3. Transfer weighed sample and about 1/4 g Filter Aid into the React-R-Tube.
4. Shake React-R-Tube until equilibrium is reached.
5. Measure the temperature of reaction mixture and set UDY Colorimeter.
6. Filter from React-R-Tube or Sample Bottle and note first steady reading. (Approximately 25-30 drops).
7. Apply temperature correction if not 25oC.
   


Protein System
%P = A(CI -C)		 A CI Sample
Weight
(mg)		 Reaction
Time*
(min) 		PO
1. Alfalfa 32.3 1.130 500 1.5 15.2
2. Alfalfa haylage 40.5 1.110 500 1.5 18.2
3. Barley 26.7 1.064 800 1.0 10.8
4. Beans 50.0 1.110 320 1.0 22.5
5. Bermuda Grass 32.3 1.130 500 1.5 15.2
6. Casein Powder 119.8 1.320 100 1/2 79.1
7. Chickpeas 33.9 1.210 320 1.0 18.6
8. Corn (Maize) 18.4 1.100 1000 2.0 8.1
9. Corn Silage 25.3 1.050 800 2.0 9.9
10. Cottonseedmeal 67.7 1.320 140 2.0 44.7
11. Cowpeas 41.7 1.150 320 1.0 20.4
12. Fishmeal 88.5 1.320 120 2.0 58.4
13. Gainesburger 34.1 1.320 320 1.0 22.5
14. Gram 36.4 1.190 320 1.0 19.3
15. Grass Peas 41.5 1.320 240 1.0 27.4
16. Lentils 46.7 1.150 280 1.0 22.9
17. Lindseedmeal 50.5 1.150 280 1.0 24.7
18. Malted Barley 31.3 1.060 800 1.0 12.5
19. Milk Powder 47.9 1.320 250 1/2 31.6
20. Mungbeans 36.1 1.200 320 1.0 19.5
21. Mustardmeal 52.6 1.320 200 1.0 34.7
22. Mustard Seed 52.1 1.210 240 1.0 28.7
23. Oats 21.6 1.156 720 1.0 10.7
24. Oat Groats 29.1 1.230 480 1.0 16.6
25. Peanutmeal 65.4 1.320 160 3.0 43.2
26. Peas 37.0 1.260 280 1.0 22.2
27. Pigeon Peas 30.0 1.320 320 1.0 19.8

 

Table I (contd)

  Protein System
%P = A(CI - C)		 A CI Sample
Weight
(mg)		 Reaction
Time*
(min)		 PO
28. Rapemeal 38.5 1.200 340 1.0 20.8
29. Rice 15.3 1.220 800 1.0 8.6
30. RomanMeal Bread 29.4 1.032 800 1.0 10.9
31. Rye 33.3 1.020 720 1.0 12.0
32. Safflower Meal 54.1 1.190 240 1.0 28.7
33. Sesamemeal 61.9 1.320 160 1.0 40.9
34. Sorghum (Milo) 26.7 1.050 1000 2.0 10.4
35. Soybeans 50.0 1.320 200 1.0 33.0
36. Soybean Hulls 14.1 1.320 800 1.0 9.3
37. Soybeanmeal 61.5 1.320 160 1.0 40.6
38. Sunflowermeal 48.6 1.320 250 1.0 32.1
39. Teneru Glycine 27.8 1.050 700 2.0 10.8
40. Triticale 22.6 1.070 800 1.0 9.3
41. Urd Beans 35.7 1.220 320 1.0 20.0
42. Wheat 27.4 1.052 800 1.0 10.7
43. Wheat-Flour 25.9 1.070 1000 1/2 10.6
44. Wheat-Gluten 98.2 1.320 200 1.0 64.8
45. Whey Powder 19.2 1.320 720 1/2 12.7
46. Whey Protein Conc. 52.7 1.320 230 1/2 34.8
47. Yeast (Torula) 67.1 1.320 200 1.0 44.3

*Reaction times are for the React-R-Tube used in the high speed (3450 rpm) Reactor-R-Mill and for samples prepared with a 1.0 m screen in the Cyclone Sample Mill. When using the React-R-Shaker with samples bottles in the Shaker Trays, the reaction time will vary by product and the fineness of the sample. Time of shaking must be experimentally determined.

Table II

UDY Colorimeter Settings and Protein Equation Values

for Several Dairy Products

 

  Protein System
%P = A(CI - C)		 ml
Sample		 grams
Sample		 A CI PO
1. Milk: Whole,Skim,Half & Half
Egg Nog,Buttermilk, etc.		 2.00 2.06 6.10 1.257 3.64
2. Fresh Vat Whey 6.00 6.18 2.23 1.148 1.09
3. Cultured Cream, Yogurt,
Condensed products Dilute 2-fold with H20 		2.00 2.06 12.20 1.257 7.28
4. Soft Cheese: Creamed, Cottage, Spreads, etc.Dilute 10-fold with 0.2% NaOH 4.00 4.12 32.20 1.200 17.3
5. Firm Cheese: Cheddar, Swiss,Jack, Processed, etc. React-R-Tube 30 sec. -- 0.300 39.9 1.320 26.3
6. Cream 4.00 4.12 3.20 1.200 1.73
7. Dairy Desserts   2.06 6.47 1.257 3.86
8. Powdered*: Buttermilk, Whole Milk, NFDMS, etc. React-R-Tube 15 sec. -- 0.250 47.9 1.320 31.6
  if reconstituted 10-fold 2.00 2.06 61.0 1.257 36.4
9. Powdered Fresh Whey   0.720 19.2 1.320 12.7
  If reconstituted 10-fold 6.00 6.18 25.8 1.148 12.6
10. Powdered WPC -- 0.230 52.7 1.320 34.8
  If reconstituted 10-fold 2.00 2.06 61.8 1.257 36.9
11. Powdered Caseinates -- 0.100 119.9 1.320 9.1
  If reconstituted 20-fold 1.75 1.80 136.0 1.292 86.0
             

ADDITIONAL PRODUCTS

SAMPLE Type % Protein Range ml Grams Sample A CI PO
Permeate 0.00 - 0.30 20 20.6 .0872 0.880 0.19
Fresh Whey 0.45 - 1.00 8 8.24 1.74 1.100 0.77
Fresh Whey 0.70 - 1.30 6 6.18 2.23 1.148 1.09
Concentrate 4.5 - 9.6 8 8.24 17.4 1.100 7.66
Concentrate 7 - 13 6 6.18 22.3 1.148 10.9
Concentrate 11 - 21 4 4.12 32.0 1.200 17.3
Concentrate 25 - 43 2 2.06 61.0 1.257 36.4

*Powdered products can also be reconstituted by blending 10 to 15 g with nine times this weight of water to give a 10-fold dilution. Blend 3 to 4 minutes.

The A value includes dilution factors where appropriate.

Table III

Temperature Correction

Within a limited range of 15o to 35oC, an approximate Percent Protein or dye concentration correction can be made if the temperature deviates from the recommended 25C.

Approximate corrections are summarized in the Table below. To calculate the correction factors, multiply the slope value A in Table I or II by 0.003 and by the number of degrees different from 25C. Add the correction above 25C. Subtract the correction below 25C.

 

Temperature Correction   Percent Protein Correction
(oC) (oF) (dye concn) (small grains) (fluid milk) (soybeans)
35 97 -0.030 +1.0 +0.20 +1.9
34 95 -0.027 +0.9 +0.18 +1.7
33 93 -0.024 +0.8 +0.16 +1.5
32 91 -0.021 +0.7 +0.14 +1.3
31 89 -0.018 +0.6 +0.12 +1.1
30 87 -0.015 +0.5 +0.10 +0.9
29 85 -0.012 +0.4 +0.08 +0.7
28 83 -0.009 +0.3 +0.06 +0.6
27 81 -0.006 +0.2 +0.04 +0.4
26 79 -0.003 +0.1 +0.02 +0.2
25 77 0 0 0 0
24 75 +0.003 -0.1 -0.02 -0.2
23 73 +0.006 -0.2 -0.04 -0.4
22 71 +0.009 -0.3 -0.06 -0.6
21 69 +0.012 -0.4 -0.08 -0.7
20 67 +0.015 -0.5 -0.10 -0.9
19 65 +0.018 -0.6 -0.12 -1.1
18 63 +0.021 -0.7 -0.14 -1.3
17 61 +0.024 -0.8 -0.16 -1.5
16 59 +0.020 -0.9 -0.18 -1.7
15 57 +0.030 -1.0 -0.20 -1.9
           

Examples:

(1) Soybean Meal, A, 61.5; correction = 61.5 x 0.003 = 0.18%
Protein per degree centigrade difference from 25C
(2) Milk, A = 6.10; correction = 6.10 c 0.003 = 0.018 % Protein
per degree centigrade difference from 25C.