Detection Of Adulteration In Goat Milk Containing Cow Milk Based On ?-carotene As Feature

The researches of new detection technology play an important role to ensure Chinese dairy industry development to be sustained,healthy and rapid.Adulteration of dairy products is always the problem that dairy quality safety focused on to solve,especially the adulteration of milk source is key to prevent.Goat milk as the characteristic resource of Shaanxi province and its nutrition and market advantages are more and more outstanding which has been paid extensive attention and energetically support.While motivated by profit the phenomenon of adulteration goat milk with cow milk is becoming more and more seriously,which restricted the healthy development of goat milk industry and has become a much more prominent issue.So a detection method aiming at this kind of adulteration needs to be established urgently to perfect the system construction of goat milk quality and safety.This research established a high-performance liquid chromatography(HPLC)method based on beta-carotene as feature using cow milk and milk in Shaanxi Yangling and the surrounding areas as raw material.The main conclusions were as follows:(1)The results of detection the beta-carotene in cow milk using national standard method(GB 5413.35-2010)and the optimized sample pretreatment method in this study were 8.62±0.16?g/100g and 8.59±0.14 ?g/100g,respectively;Sample processing time were 3 hours and 85 minutes respectively;Two methods do not have significant difference(P>0.05)while optimized sample pretreatment method has saved almost a half time that improved efficiency and had comparative advantage as well as popularize value.(2)Optimized chromatographic condition in this study:mobile phase:methanol-acetonitrile-trichloromethane ratio:820:60:120(v/v/v);wavelength:450nm;column temperature:room temperature;flow velocity:1.5 mL/min;sample amount:20 ?L.The detection limit is 0.31 ?g/100mL sample test solution;The repeatability of relative standard deviation(RSD)is 1.66%;the average sample recovery is 94.17%;(3)In April to September the main product season of goat milk,the beta-carotene variation range of cow and goat milk are 7.50?13.03 ?g/100g and 0.19?0.22?g/100g respectively.The content of beta-carotene in cow milk presents a gradually increasing trend along with the change of seasons and the enrich in species and amounts of green fodder.While the beta-carotene in goat milk does not have a significant variation with the change of seasons and fodder,it is always remained in a low and stable level about 0.20?g/100g;The significant difference(P<0.01)provided science basis to beta-carotene can be used as a feature to detect the adulteration of cow and goat milk;(4)In April to September the detection linear equation of cow and goat mixed milk were Y=7.2402X+0.0311,R2=0.9972);Y=8.5611X+0.0377,(R2=0.9988);Y=9.424X+0.1196,(R2=0.9959);Y=10.342X+0.1237,(R2=0.9984);Y=11.172X+0.1257,(R2=0.9967);Y=13.064X+0.0301,(R2=0.9958);The linear range is 0%?100%proportion of cow milk in mixed milk.Detect the blind samples according to the detection linear equation of cow and goat mixed milk and the results show that the relative error range of the proportion of cow milk in mixed milk which is calculated based on the linear regression equation and the actual proportion of cow milk in mixed milk is 2.20%?4.74%;The relative error is smaller and can be used to quantitatively detect the adulteration of goat milk with cow milk when the percentage of cow milk in goat milk is more than 5%.