Method for determining content of beta-lactoglobulin in milk powder

Abstract

The invention discloses a method for determining the content of beta-lactoglobulin in milk powder. The method comprises the following steps: (1) selecting TK-11 as a specific peptide fragment and conducting beta-lactoglobulin quantification; (2) synthesizing the peptide fragment, and conducting isotope labeling on the peptide fragment; (3) accurately quantifying the synthesized standard peptide fragment by adopting an isotope dilution mass spectrography; (4) conducting sample treatment and enzyme digestion; (5) hygroplasm analysis, namely filtering the solution after enzyme digestion through a filter film, and then carrying out selective ion scanning analysis on the filtrate by adopting mass spectrography; and (6) calculating according to a formula, so as to complete the determination on the content of beta-lactoglobulin in milk powder. By adopting the method, determination results are accurate and reasonable.

Description

technical field [0001] The invention relates to a method for measuring protein content, in particular to a method for measuring β-lactoglobulin content in milk powder. Background technique [0002] β-lactoglobulin (β-lactoglobulin) is a kind of protein in fresh milk, accounting for about 7-12% of fresh milk protein. The β-lactoglobulin monomer consists of 162 amino acid residues. The protein has a stable molecular structure and is not easy to be digested and hydrolyzed by pepsin. Therefore, it is very easy to join the human blood circulation through the gastrointestinal tract, and it is easy to stimulate the immune system to produce hypersensitivity reactions. It is the main allergen for infants , It is easy to cause allergies in babies (the baby's digestive system is not yet fully developed, β-lactoglobulin is easier to be absorbed "whole", and it is judged as a pathogen by the immune system). β-lactoglobulin has A, B, C3 different variants. Mainly A and B, pI between 5....

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Problems solved by technology

Among them, enzyme-linked immunosorbent assay (enzyme-linked immunosorbent assay, referred to as ELISA) uses ELISA to measure protein content, which has the characteristics of high sensitivity, low minimum detection limit, and no need for sample purification. However, this method is greatly affected by the environment and operators. The quantitative repeatability is poor; the detection range of the radioimmunodiffusion method is limited; the accuracy is not high and there is a certain radiation hazard; the ultraviolet spectrophotometry is fast and simple, but the error is large; and the gel chromatography is suitable for high-purity samples Determination; and carry out high-performance liquid chromatography determination method with cation-exchange chromatographic column, has improved the accuracy of quantification, but used a large amount of NaCl in the mobile phase of this method, is the most taboo for high-pressure liquid chromatograph, for The instrument is very damaged

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