How to quickly identify the quality of corn gluten meal powder ?

As a kind of protein material, Corn gluten powder has been widely used in feed
industry.

High quality corn gluten meal corn gluten powder
The corn gluten meal is the by-products of corn starch , powder, golden. It contains rich amino acids, can encourage disease-resistant ability of the livestock.Specification:

1)Protein: 60%MIN
2)Moisture: 10% Max
3)Ash: 5% Max
4)Fat: 3% Max

Product parameter

It is a high protein content, beautiful color, and has been favored by the feed
industry.

However, there is a serious adulteration of protein materials, and the
adulteration of corn gluten powder is more common, which should arouse people’s
attention. The adulteration identification of corn gluten powder can be started
from many aspects. First of all, look at the appearance of smell and through
microscopic examination to determine its adulteration. Second, the detection of
conventional indicators.

It includes water, ash, crude protein and so on. Third, targeted adulteration
identification. Including the identification of urea and ammonium salts. The
most scientific determination is to carry out amino acid analysis, but only a
small number of enterprises have the conditions, and most enterprises are
through the national testing agencies to complete, which from the time and
economic constraints on the universality of amino acid detection. The author
developed a method to identify the adulteration of corn gluten powder by rapid
protein determination. 1 The experimental principle of this method when the urea
is carefully heated to 150~160℃, it can take off 1 ammonia molecules and produce
double urea. Double-urea and alkali and a small amount of copper sulfate
solution to produce a purple-red complex, because protein molecule contains
peptide tendon, and double urea structure similar, so also can present this
reaction and produce magenta complex, under certain condition its color depth
and protein content is proportional, thus, can use absorbance method to
determine protein content. The maximum absorption wavelength of the complex is
560nm.

At present, the adulterated ingredient of corn protein powder is mainly “protein
essence”.

The experiment proves that this method is not interfered by the content of
“protein essence”, so the method is feasible.

2 reagent

2.1 Preparation of alkaline sulfuric acid solution There are 2 ways to prepare
this solution:

(1) with potassium sodium tartrate as stabilizer, the 10ml10mol/l potassium
hydroxide and 20ml25% sodium tartrate solution were added to 930ml distilled
water, and the 40ml4% copper sulfate solution was added slowly by stirring
(otherwise the hydrogen oxide deposition would be formed).

(2) Glycerol as a stabilizer, the 10ml10mol/l of potassium hydroxide and 3.0ml
glycerin added to 937ml distilled water, stir violently (otherwise will produce
copper hydroxide precipitation) and slowly add 50ml4% copper sulfate solution.

2.2 Carbon tetrachloride need not be formulated, direct use.

3 Instrument spectrophotometer, centrifuge (4000rpm), Kjeldahl digestion
furnace, automatic nitrogen determination instrument.

4 Sample preparation To select a representative sample of 200g, after smashing
all through 40 mesh screen, installed in sealed containers to prevent changes in
the composition of the sample.

5 Analysis steps 5.1 Standard curve is prepared to use Kjeldahl nitrogen method
to determine the protein content and confirm that the authentic corn protein
powder samples to do the standard sample. According to the protein content of
the sample, respectively, the standard protein-like 40mg, 50mg, 60mg, 70mg,
80mg, 90mg, 100mg, 110mg, 8 50ml, and then each added 1ml carbon tetrachloride,
and then diluted with alkaline copper sulfate solution to 50ml. , shaking 10min,
static 1h, take the upper supernatant centrifugal 10min. After centrifugation,
the transparent liquid in the dish, at 560nm wavelength, with distilled water as
the reference liquid, adjust the instrument 0 points and the determination of
the absorbance a of each solution. With the content of protein as the horizontal
axis, absorbance A is the ordinate drawing standard curve.

or by calculation, the content of the tested sample is obtained. 5.2 samples
were measured accurately (make the protein content between 40~110mg) in 50ml na
colorimetric tube, add 1ml carbon tetrachloride, after the operation step color,
in the same condition to measure its absorbance a. Using the measured a value,
the protein MG number is found on the standard curve, then the protein content
is obtained, or the crude protein content is obtained by substituting the
standard equation, and the true or false is determined.

In practice, the crude protein of the sample can be measured by GB, and then the
data measured by the two methods are compared, if they are similar, the sample
does not contain “protein essence”. 5.3 Results were calculated for the protein
mass fraction (%) of =1/1000xc/mx100% protein (mg/100g) =cx100/m C for the
standard curve of the quality of proteins identified mg;m for the sample. 5.4
Precautions (1) The samples used for standard curve drawing should be the
authentic corn gluten powder; (2) The standard curve does not need to do the
curve every time after doing well, this method can be used for adulteration
identification of beans, oilseeds, Oryzenin protein raw materials. 6 conclusion
The use of this method to identify the adulteration of corn gluten powder,
compared to the detection of amino acids save time and money. For the addition
of “protein essence” of the plant protein raw material detection effect more
accurate.
This method is simple and rapid, and it can show its superiority in large
quantity sample detection.