Studies On Aging Evaluation System Of Hop And Hop Products

A method was developed for the determination ofα- andβ-acid in hop pellets by reversed-phase high performance liquid chromatography.Separation and quantification were achieved by an EC 250/4 Nuclesoil,100-5 C₁₈(4.0×250 nm,5μm) with Guard Cartridge CC 8/4 Nuclesoil 100-5 C18 and a gradient elution program,acetonitrile-methanol-tris buffer(20 mmol/L,pH 7.5 with 36%HCl) as mobile phase at a flow rate of 0.55 mL/min,temperature 40℃and detected with ultraviolet detector at 314 nm.The recoveries ofα- andβ-acids,were between 95.7%and 97.8%.Variation coefficient was 1.03 and 1.11%.The detection limits were 0.21 and 0.28 mg/L.This is a simple,accurate and convenient method.The influence of three main isomers ofα- andβ-acid during aging and force aging were researched by RP-HPLC.The content of adhumulone and lupulone is a little inα- andβ-acid, and few reduced during aging.A Hop Age Index(HAl) concept was put forward,compared with hop deteriorative degree and HSI value,it show that HAI value can evaluate aroma hop and more accurate and repeatability than hop deteriorative degree.A method was developed for the determination of four kinds of of isomerizedα-acids in hop, hop extracts and beer by the same column.The mobile phase is methanol methanol:H₂O:H₃PO₄(85%): EDTANa₂(0.2 mol/L)(750:240:10:1,respectively) with 1.0 mL/min flowing rate,temperature 35℃and detected with ultraviolet detector at 270 nm.The inject volumn is 10μL.The precision is between 1.09-1.86%.The recoveries of four kinds of of isomerizedα-acids were between 91.3 %and 98.0%.This is a simple,accurate and convenient method.The influence of beer bitter by different kinds of aroma hop and bitter hop was researched.Above 88%content of iso-α-acid is isocohumulone and isohumulone in beer which was brewed by aroma hop.About 55%content of iso-α-acid is isohumulone in beer which was brewed by bitter hop.A Calculation Bitter Unit(CBU) concept was put forward.It could calculate beer bitter unit by the content of three main isomers of iso-α-acid using HPLC. It can more accurate and repeatability than traditional method.