The raw material for making soy sauce is generally soybean meal or bean cake. The cycle is long, so that protein is fully hydrolyzed and sugar is fully generated, and there is enough time to generate various complex aroma components and flavor substances. The produced soy sauce naturally has outstanding sauce flavor, delicious taste, mellow taste and elegant color.
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The main physical and chemical indexes of soy sauce are amino acid nitrogen and total
Nitrogen and salt content, salt-free solids, etc. Among these indicators,
Amino acid nitrogen is the most important. Quality index detection standard
Whether it is true or not, on the one hand, directly affects the rights and interests of consumers, on the other hand
On the one hand, it also affects the reputation and benefits of enterprises. So, for example,
How to improve the accuracy of detection and make the detection results as much as possible?
Close to the true value to prevent unqualified products from entering the market, which
Very important.
Amino acid is one of the important ingredients in soy sauce, which is made of
Protein in the raw material is hydrolyzed, and there is also ammonia.
Bases and carboxyl groups. Soy sauce is dark, and we
Formaldehyde and acid meter are generally used, that is, formaldehyde is added to make it
The basicity of the amino group is masked to show carboxylic acid, and then hydrogen and oxygen are used.
Sodium titration, its principle is this:
Soy sauce contains a variety of amino acids, as well as various amino acids.
Equivalence points are different, so there is a certain error, but this is the most.
Simple and direct method, so it is still produced with soy sauce.
For enterprise use. Try to make the test results accurate, mainly including
The following points:
! Blank problem
General soy sauce production enterprises should be aminated every day.
Acid nitrogen detection, so there is no need to vent every day.
White test, but when distilled water or formaldehyde solution is replaced by bottle,
It is necessary to retest the blank, and it is found in practice that every
A batch of distilled water, different formaldehyde bottles, blank sometimes vary greatly.
Big, if you have been using unchanging blank data, test it.
There must be a big error in the result.
"Instrument positioning problem.
The acidity meter we use will be used for some time.
Relocation, especially when the room temperature is very different.
The selected standard # $ buffer solution should be ready just now.
Standard buffer solution, which shall be accurately prepared according to regulations.
If the washing liquid is stored for too long, its # $ value will also change.
Directly affect the titration end point and eventually lead to the test results.
Not accurate.
%&&() sodium hydroxide solution
Because the general enterprise has to test every day, so prepare.
A large bottle &; & () sodium hydroxide solution, after accurate calibration.
It has been used ever since. In the long-term work, it was found that hydrogen oxidation
The concentration of sodium will change slightly with time,
Especially in summer, the concentration of sodium hydroxide gradually weakens, and we
High test results often lead to some unqualified products.
Products are put on the market under the mistaken belief that they are qualified, so they are widely used.
Sodium hydroxide solution is still seldom prepared, frequently prepared, frequently calibrated and in summer.
This is especially true in the season, which needs to be recalibrated once a month.
Although there is no color ratio and red index of soy sauce in the national standard
There are clear data indicators, but in the sales of soy sauce, it is generally
Consumers are most concerned about the coloring rate and red index.
In recent years, people pay more and more attention to color.
A well-known brand of soy sauce wins the market by color.
Therefore, the same brand of soy sauce should have its stable color, which
Only by accurately detecting the color rate and red index can we
So as to ensure its stability.
The color ratio and red index of soy sauce are both *+soy sauce.
Diluents are read in * and-cuvettes respectively (*&; . -,and
/* & amp； . -wavelength absorbance value, using the formula, the color rate is 0.
1/* &2
! & amp& amp& amp
& AMP3/,red index 0 *&; 45
1。
1/* & calculation, to
There are several points to keep the accuracy of these two test results.
Very important.
(Preheating of the instrument
The instruments we use for testing are generally 3! *-type spectroscopy
Photometer This instrument usually needs to be warmed up for half an hour to stabilize.
Before testing, the zero point and * & should be adjusted repeatedly; & walk back and forth several times
Provided that there is no deviation every time. Furthermore, in the spectrophotometer,
The desiccant was also replaced in Qin Ying to keep the inside of the instrument dry.
Maintain the stability of the instrument.
/Selection and cleaning of cuvettes
Just take two *-test tubes.
Well, it's very careless. Used cuvettes are usually just
It is impossible to clean the fine substances adsorbed on it with tap water.
It's been cleaned. Two light transmission conditions should be selected before testing.
They are all the same cuvettes. The specific method is to compare two cuvettes.
Put distilled water into the dishes respectively, and measure the absorbance value of one dish.
Adjust to zero, and then pull the other one to see if it is also zero.
If it is not zero, the cuvette must be re-selected.
After a period of use, the cuvette can be cleaned with potassium dichromate.
At the same time, it can generally meet the requirements after cleaning.
3 data reading
When reading the absorbance value, eyes must be placed on the pointer.
Straight ahead, there can be no deviation, especially in the red index measurement.
When measuring. For example, if there is a soy sauce, the test results are as follows.
1/* &0 & amp*(， 1(* & amp； 0&'%(,its red index is 0.
* & amp45
1(* &
1/* &
0 * & amp45
& amp6%(
& amp6*(
0%633, but if the number read
There is a slight deviation in time, which is pronounced as1/*&; 0 & amp'*%(,
1(*&0&6% (,its red index is 0 *&; 45
& amp6%((
& amp6*%(
%673, the error is very large. Therefore, accurate reading of data.
It is also crucial.
There are many reasons that affect the accuracy of test results.
Discussion on improving the detection accuracy of amino acid nitrogen and chromaticity in soy sauce by% test technology
Wanfang Data
These are just a few aspects that are not paid much attention to.
It is hoped that the test data can not only serve consumers, but also serve enterprises.
Production provides guidance and plays its due role.