Study On The Model For Rapid Detecting Foreign Proteinin Raw Milk

Based on the effect of the foreign protein addition on milk's physical and chemical parameters, the parameters that are substantially influenced by foreign protein are selected for establishing methods to detect foreign protein addition. The range of the main parameters in normal milk was obtained through experiments, and methods for detecting three different foreign proteins was studied. The results showed that:1) After the addition of hydrolyzed protein, the parameters that were significantly influenced are the protein content, the specific gravity, the acidity, oligopeptide content, the non-casein nitrogen content, the non-protein nitrogen content and the free amino nitrogen content. The principal component analysis method based on the above parameters was used to establish the following correlation: F=-0.361ZX₁+0.201ZX₂+0.269ZX₃-0.176ZX₄+0.376ZX₅+0.356ZX₆+0.337ZX₇If the addition of hydrolyzed protein to milk is above 1‰, the result from principal component analysis can show the difference between normal and adulterated milk (R=0.919,α<0.05), and can be used for detecting the hydrolyzed protein addition in combination with the sensory evaluation.2) After the addition of glycine, the parameters that were significantly influenced are the protein content, pH, the non-casein nitrogen content, the non-protein nitrogen content, the free amino nitrogen content and the freezing point. The principal component analysis method based on the above parameters was used to establish the following correlation: F=0.254ZX₁+0.132ZX₂+0.361ZX₃+0.364ZX₄+0.346ZX₅-0.401ZX₆If the addition of glycine to milk is above 1‰, the result from principal component analysis can show the difference between normal and adulterated milk (R=0.808,α<0.05), and can be used for detecting the addition of glycine in combination with the sensory evaluation.3) After the addition of whey protein, the parameters that were significantly influenced are the protein content, the lactose content, the dry substances content, not fat solid content,the specific gravity, the non-casein nitrogen content and the freezing point. The principal component analysis method based on the above parameters was used to establish the following correlation: F=0.384ZX₁+0.384ZX₂+0.380ZX₃+0.398ZX₄+0.381ZX₅-0.346ZX₆+0.357ZX₇ If the addition of whey protein to milk is above 1‰, the result from principal component analysis can show the difference between normal and adulterated milk (R=0.987,α<0.05), and can be used for detecting the addition of whey protein in combination with the sensory evaluation.