Method for simply and conveniently measuring content of non-protein nitrogenous substance in milk product

A technology for protein content and nitrogen-containing substances, applied in color/spectral characteristic measurement, chemical analysis by titration, material analysis by observing the impact on chemical indicators, etc., can solve the problem of backward and passive detection methods and errors in measurement methods , unable to deduct and other issues

Inactive Publication Date: 2014-02-12
JIANGNAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when the non-protein nitrogen-containing compound contained in an unnatural substance is not clear, it cannot be deducted, and the measurement method will cause errors
Especially when urea, melamine and other nitrogen-containing substances are illegally added to the product, they can all be digested and measured, and cannot be deducted. Even though the method of measuring urea and melamine has been studied, it cannot be ruled out that criminals use other

Method used

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  • Method for simply and conveniently measuring content of non-protein nitrogenous substance in milk product
  • Method for simply and conveniently measuring content of non-protein nitrogenous substance in milk product
  • Method for simply and conveniently measuring content of non-protein nitrogenous substance in milk product

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] 1. Take casein as a standard substance, measure it simultaneously with the Kjeldahl method and the Coomassie brilliant blue method, and compare the results. Coomassie brilliant blue value / Kjeldahl nitrogen method = 1.11, so the correction factor for converting Coomassie brilliant blue method into Kjeldahl nitrogen method is 0.901.

[0018] 2. Five samples of commercially available milk were used to determine the total nitrogen content (calculated based on protein content) by the Kjeldahl method, as A, and the results are as follows:

[0019]

[0020] 3. Take 1 mL each of the above 5 types of milk, put them into 100 mL volumetric flasks No. 1 to No. 5, and dilute to the scale line. Take 1ml of diluted milk from each volumetric flask and put it into the corresponding 25mL colorimetric tube, then add 5mlL of prepared Coomassie Brilliant Blue, set the volume to the 10mL mark, and shake well. Absorbance was measured at 595 nm with a UV spectrophotometer. Draw a good sta...

Embodiment 2

[0026] 1. Take 1 part of commercially available milk sample, and use the Kjeldahl method to measure the total nitrogen content (calculated based on protein content), which is 3.112%. Nitrogen-containing substances such as urea and melamine were added respectively at 1.0% (No. 1), 1.5% (No. 2), and 2.0% (No. 3) (calculated by protein content).

[0027] 2. with the same Kjeldahl method as in embodiment one, measure the total nitrogen content (calculate in protein content), as A, the results are as follows:

[0028]

[0029] 3. measure the total nitrogen content (calculated in terms of protein content) with the same Coomassie brilliant blue method as in Example 1, and × 0.901, calculate the conversion value, as B. The result is as follows:

[0030]

[0031] 4. The content of non-protein nitrogenous substances (calculated by protein content) = A-B, and calculate the recovery rate, the results are as follows:

[0032]

[0033] The recovery rate is good, indicating that t...

Embodiment 3

[0035] 1. Five samples of commercially available colored dairy products were used to measure the total nitrogen content (calculated based on protein content) by the Kjeldahl method, as A, and the results are as follows:

[0036]

[0037] 2. Dilute the above dairy products 10 times, add an appropriate amount of activated carbon to decolorize.

[0038] 3. After filtering, dilute 10 times. Measured with the Coomassie brilliant blue method identical with embodiment one, the results are as follows:

[0039]

[0040] 4. The content of non-protein nitrogenous substances (calculated based on protein content) = A-B, the results are as follows:

[0041]

[0042] It shows that none of the above 5 kinds of dairy products contain non-protein nitrogen-containing substances, and negative numbers are normal measurement errors. It also states that the method is applicable to colored dairy products.

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Abstract

The invention discloses a method for simply and conveniently measuring the content of a non-protein nitrogenous substance in a milk product. According to the method, casein serves as a standard substance; a kjeldahl method and a colorimetric method are used for measuring simultaneously; a correction coefficient is calculated; a calculated result of the colorimetric method can be converted into total nitrogen of the kjeldahl method. When a sample is measured, the two methods are used for measuring simultaneously, and the result of the colorimetric method is converted into a result of the kjeldahl method, and deducted from total nitrogen of the kjeldahl method, so that the content of the non-protein nitrogenous substance in the milk product can be obtained. A colored sample is decolorized and then measured by the method, and milk powder can be diluted and then measured by the method.

Description

technical field [0001] The total nitrogen in dairy products can be determined by the Kjeldahl method, and the total protein content can be determined by the colorimetric method, and the data of the Kjeldahl method can be corrected. After deducting the two, the non-protein content in dairy products can be obtained. Nitrogen content makes it better used in the fields of food, medicine and health care products. Background technique [0002] China's dairy industry started late, with a low starting point, but developed rapidly. Especially since the reform and opening up, milk production has increased rapidly with double-digit annual growth rate, far higher than the world average level of 1% in the same period. The output and total output value of China's dairy products have increased by more than 10 times in the last 10 years, which has gradually attracted the attention of the world. But at the same time, there is still a huge gap between China's per capita milk consumption com...

Claims

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Application Information

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IPC IPC(8): G01N21/33G01N21/78G01N31/16
Inventor 宋健赵泳
Owner JIANGNAN UNIV
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