Study On The Detection And Degradation Of Aflatoxin B₁ And Aflatoxin M₁ In Milk

Aflatoxins（AFs）belong to secondary metabolites,which generated by Aspergillus flavus and Aspergillus parasiticus,have potent teratogen,mutagen and carcinogen.Milk has high nutritional value,is easy to absorb and is susceptible to pollution by aflatoxin in the process of production,storage and circulation,then pose a threat to human health.Thus pursuing rapid detection and degradation means of aflatoxin in milk has practical significance.The research object of this paper were aflatoxin B₁ and aflatoxin M₁ in milk,immunoaffinity column-high performance liquid chromatography method and enzyme-linked immunosorbent assay were adopted to determine aflatoxin B₁ and M₁,detection limit,recovery and precision were compared.Meanwhile detoxification effects of aflatoxin B₁ and aflatoxin M₁ by microwave irradiation were considered with ELISA,and main nutrition indicators of processed milk were evaluated.1.The detection results of AFB₁ and AFM₁ by high-performance liquid chromatography with a fluorescence detector（HPLC-FLD）and enzyme linked immunosorbent assay（ELISA）showed that: in HPLC,detection limit of AFB₁ and AFM₁ were 0.02 μg/L and 0.01 μg/L;in ELISA,detection limit of AFB₁ and AFM₁ were 0.05 μg/L and 0.02 μg/L.AFB₁（0.003,0.006,0.012,0.024 μg/kg）and AFM₁（0.005,0.01,0.025,0.05 μg/kg）standard solutions were added into blank milk samples and the results of recovery experiments indicated that,in HPLC,the recovery of AFB₁ and AFM₁ were in range of 77.58%⁸2.81% and 77.51%⁸2.23%,with the RSD of 1.93% and 3.51%;in ELISA,the recovery of AFB₁ and AFM₁ were in range of 77.28%⁷9.11% and 75.40%⁷6.34%,with the RSD of 2.20% and 3.80%,and recovery about AFB₁ of the two methods had no significant difference（P>0.05）,recovery of HPLC when additive amount of AFM₁ were higher than 0.025 μg/kg had significant difference with ELISA（P<0.05）.2.The results of single factor and response surface experiment of microwave degradation of AFB₁ showed that: microwave irradiation time impacted greater than the microwave power,and the microwave power was greater than the initial content of AFB₁,the three factors affect significantly.Optimum degradation conditions parameters of AFB₁ were obtained according to Box-Behnken experimental design and response surface experiment result,when the microwave power was 694.11 W,the microwave irradiation time was 5.73 min,the initial concentration of AFB₁ was 7.78 μg/L,the degradation rate of AFB₁ was predictably 94.38%,the verified value was 93.72%.3.The single factor and response surface experiment of microwave degradation of AFM₁ results indicated that: microwave power impacted greater than microwave irradiation time,while the microwave power was greater than the initial content of AFM₁,microwave power and initial content of AFM₁ affect significantly.Optimum degradation conditions parameters of AFM₁ were obtained according to Box-Behnken experimental design and response surface experiment result,when the microwave power was 649.27 W,the microwave irradiation time was 5.48 min,the initial content of AFM₁ was 0.09 μg/L,the degradation rate of AFM₁ was predictably 94.78%,the verified value was 94.25%.4.Main nutritive index such as protein,fat content,lactose and vitamin C of processed milk were measured,the results showed that: with the increase of microwave power,the content of nutritive index decreased gradually,the content of protein,fat and vitamin C had extremely significant difference（P<0.01）,lactose content had no significant difference（P>0.05）,the content of vitamin C reduced significantly;With the increase of microwave irradiation time,the content of fat and vitamin C had extremely significant difference（P<0.01）,protein and lactose content had no significant difference（P>0.05）,vitamin C content had serious damage;The addition of AFB₁ had no effect on index content,the content of protein,fat and vitamin C had no significant difference（P>0.05）,while vitamin C had significant differenc（P<0.05）,the addition of AFM₁ had no effect on protein,fat,lactose and vitamin C,the content of all index had no significant difference（P>0.05）.In conclusion,the two methods are highly accurate,have high sensitivity and good repeatability,it showed that accuracy of HPLC was better than ELISA when AFM₁ concentration was higher.ELISA is more reliable to determine aflatoxins in batch samples rapidly in view of the sample preparation process,equipment and technical factors.Microwave irradiation can effectively degrade AFB₁ and AFM₁ in milk,and cannot affect main nutritional ingredient of milk markedly.