Study On The Rapid Analysis And Detection Of Nutrients And Harmful Substances In Different Roasted Flavored Coffee And Its Determination

[Objective]Coffee is more and more popular with its unique flavor and functional properties.Baking temperature and baking time determine the degree of coffee roasting,and have an important influence on the generation and change of coffee flavoring substances.The main roasting flavor substances of coffee are aroma components that are directly related to coffee flavor and have strong representativeness.This article analyzes roasting degree through comprehensive analysis.The relationship between the formation and changes of the main flavor substances of coffee,such as the detection of the components of chlorogenic acids,biogenic amines and amino acids in coffee at different baking temperatures,to understand and master the fine coffee roasting process Provide scientific reference.[Methods]First,optimize the HPLC conditions.Secondly,the sample pretreatment method was optimized.The specific procedure was:Accurately weighed 1.0 g of the coffee sample in a stoppered test tube,add 20 mL of pure aqueous solution first,and mix with a vortex shaker,ultrasonically extract for 15 min,then at the rate of 5000 r/min centrifuged for 10 min,the supernatant was taken in a 50 mL volumetric flask,and then 25 mL of pure aqueous solution was added to the stoppered tube.The above operation was repeated for the second time.Finally,the solution was brought to the mark with a pure aqueous solution.Two samples of 1 ml were accurately pipetted,and a 0.45 ?m aqueous microfiltration membrane was used for filtration and then the chlorogenic acid was detected by HPLC.Then another portion of the stoppered test tube was filled with 200 ?L of sodium bicarbonate solution(0.4 mol/L)and 400 pL of 4-dimethylaminophenylazobenzenesulfonyl chloride derivative(3.0 mmol/L).Mix with the vortex shaker and derivatize it in a water bath at 70 ? for 20 min,filter it through a 0.45 ?m microporous membrane and measured the biogenic amine by HPLC;re-weigh about 100 mg of the coffee powder sample into the digestive tract and add 6 mol/L hydrochloric acid.After the solution was vacuum-pumped,the tube was sealed and placed in an electric blast oven at 110? for 22 h.After the digestive tube was cooled to room temperature,the digestive solution was filtered to a 50 mL volumetric flask.The digestion tube was washed twice with distilled water and the filtrate was combined.The volume of distilled water was adjusted to 50 mL and the mixture was mixed.Pipette 1mL digestive filtrate was evaporated to dryness with a rotary evaporator at 50 ?,the 0.02 mol/l hydrochloric acid solution 2mL dissolved,and the 0.45?m filter membrane is used to detect the amino acid content,Finally,the coffee produced by the three varieties of Yunnan Pu'er was tested using the established method.[Results]This method completed the separation and analysis of six chlorogenic acids within one hour.The six kinds of chlorogenic acids had good linearity in the range of 0.10-100.0 mg/L,the correlation coefficient(r)? 0.999,the detection limit was 0.05-0.10 mg/kg,and the limit of quantitation was 0.18-0.29 mg/kg.The spiked recoveries of 2000,5000,and 10000 mg/kg were from 96.3%to 104.8%,and the relative standard deviation(RSD)was between 0.30%and 2.10%(n=6).The calibration standard has good linearity in the range of 10-250 pg/L.[Conclusion]In this study,six kinds of chlorogenic acids and five kinds of biogenic amines in the coffee were determined by high performance liquid chromatography(HPLC)and 18 kinds of amino acid ion exchange chromatography with ninhydrin post column derivatization amino acid automatic analyzer.The pretreatment conditions of the sample are optimized,the method is simple and the sensitivity is high.