Fluorescence-based PCR Detection of Goat Milk Powder Mixed with Cow Milk

[Objectives]To amplify and identify the specific gene fragments of cattle and sheep by real-time fluorescence-based PCR,and quickly and accurately identify the adulteration problem of goat milk powder according to the differences of mitochondrial genes among different species.[Methods]The specificity,limit of detection and repeatability test were carried out by isolating somatic cells,extracting template DNA and determining the reaction conditions of real-time fluorescence-based PCR.[Results]The real-time fluorescence-based PCR method could be used to identify the bovine and ovine-derived materials of milk powder with high specificity,high sensitivity and good repeatability,and the limit of detection of milk components in goat milk powder could reach 0.01%.[Conclusions]The real-time fluorescence-based PCR method can be used to quickly and accurately detect the milk components in goat milk powder,and provide some technical support for the adulteration detection of dairy industry.

Inhibitory Effect of Lactic Acid Bacteria on Salmonella

[Objectives]To explore the inhibitory effect of lactic acid bacteria(LAB)on the growth of Salmonella.[Methods]The inhibitory effect of lactic acid bacteria on Salmonella was investigated by Oxford cup agar diffusion test from the aspects of lactic acid bacteria body,metabolites,pH,thermal stability and acid resistance.[Results]The growth of Salmonella was disturbed by the inhibition of lactic acid bacteria.The mechanism of inhibitory effect may be:simple low pH and lactic acid bacteria have no inhibitory effect on Salmonella;however,there are active substances in the metabolites of lactic acid bacteria,which have high thermal stability and a wide range of acid resistance,and are effective substances for inhibiting the growth of Salmonella.[Conclusions]This study is helpful for screening more natural preservative substances,reducing the contamination rate of Salmonella to food,and is expected to provide a theoretical basis for the preservation and preservation of food.

Evaluation on Uncertainty of Detection Results of Aerobic Plate Count

[Objectives]To determine the aerobic plate count(APC)in the milk samples,evaluate the uncertainty of the test results,and to provide a scientific basis for the quality control of the testing process.[Methods]In compliance with the national food safety standard Food Microbiological Examination:Aerobic Plate Count(GB 4789.2-2016),the aerobic plate count in the milk samples was detected.The source of the uncertainty of the test result was analyzed and a mathematical model was established in accordance with Evaluation and Expression of Uncertainty in Measurement(JJF 1059.1-2012).Then,the introduced uncertainty components were evaluated to determine the uncertainty of the final combined aerobic plate count.[Results]The expanded uncertainty of the test result of the aerobic plate count in the milk samples was 0.0434,and the logarithmic value interval of the results was(3.924,4.010),and the antilogarithm was taken to get the aerobic plate count in the sample to be 8395-10233 CFU/mL.[Conclusions]This method can effectively evaluate the uncertainty of the aerobic plate count,and ensure the accurate and scientific laboratory test data.