Detection Technology Of Thiocyanate And Hydroxyproline In Milk And Dairy Products

Nowadays, few studies have examined the illegal added inedible substances in dairy product. The determination method of thiocyanate, hydroxyproline, and its comprehensive evaluation were still in their infancy. Therefore, to speed up the detection technology, to confirm the methods and the standards for its limits, to use risk analysis technology, and to propose a suitable way to detection for inedible substances in China has become very urgent.In this study, a method was developed to determine the concentration of thiocyanate in milk and dairy products by ion chromatography, the influence about processing method and separation condition on the determination results was discussed. The Standard curve was linear(R2=0.9996) and the concentration range was from 0.1 to 2.0 mg/L. The average recovery rate was from 92.0% to 96.6% and RSD was from 1.18% to 2.28%. The LOQ was 1.0 mg/kg. This method is simple, rapid, reliable and suitable for measuring thiocyanate in milk and dairy products.We selected fresh milk as the research object, and screened the content of thiocyanate and analysed these data, determine the distribution of thiocyanate background value in fresh milk. The content of thiocyanate in fresh milk is generally below 8.0 mg/kg. When the value was in the range from 8.0 to 15.0 mg/kg, there is the possibility of artificially adding or the milk product quality decline as a result of poor production conditions. When the content of thiocyanate was more than 15 mg/kg, it can be identified by the existence of artificial added. In addition, we identified the source of the thiocyanate in milk, and find a solution to reduce this index.In this research, by using the ion exchange Chromatography with post column derivatization, we developed a method for determination of hydroxyproline in milk and dairy products. The Standard curve of Hyp was linear(R2=0.9987) and the concentration range was from 2.0 to 50 mg. The average recovery rate was from 92.8% to 96.8% and RSD was from 1.14% to 2.64%. The LOD was 42.5 mg/kg. Compared with the traditional spectrophotometry, this method was high sensitivity, strong selectivity, high automaticity, safety and green. According to the results, we confirmed the conversion coefficient between hydroxyproline and gelatin(F=7.437). This method is suitable for qualitative and quantitative determination of leather hydrolyzed protein(characteristic component – hydroxyproline) in dairy products.