Study On Flavor Evolution Of Aroma Compounds Derived From Hops During Beer Brewing And Storage

Simcoe hops and Saaz hops,these two aroma hops,were selected for this aging test.The aging of hops was accelerated by the aging test,the changes of the concentration of aroma compounds derived from hops were detected by Gas Chromatography-Mass Spectrometry(GC-MS).The effects of aging hops on taste and flavor of beer were studied by sensory analysis.The results showed the concentration of aroma compounds from hops had a decrease except caryophyllene oxide,the concentration of caryophyllene oxide in fresh Simcoe and Saaz hops were 0.21 and 0.15 ?g/L,respectively.And increased to 4.25 and 1.56 ?g/L in aged 4 hops,respectively.It was found that the concentration of aroma compounds in moderately aged hops reached the highest level.Beer brewed with moderately aged hops has better taste and quality than beer brewed with over-aged hops and fresh hops.Beers brewed with fresh hops had a strong green flavor and moderate aroma of flowers and fruits,pure flavor,mellow body.Beer brewed with over-aged hops has thin floral and fruit aroma,poor flavor,but it was worthwhile to mention that this beer had a unique baking aroma,which was also favored by some consumers.Then the beers were brewed with Citra hops,the aging test was carried out to simulate the storage of beer at room temperature.The changes of aroma compounds derived from hops during beer storage were studied.The GC-MS results showed that only linalool and caryophyllene oxide increased during beer storage,the concentration of linalool in base beer was 1.78 ?g/L,and increased to 6.12?g/L after stored for 9 months,and then deceased to 5.56 ?g/L after stored for 12 months,which showed an overall upward trend.No caryphyllene oxide was detected in the base beer,but it's concentration rose to 5.25 ug/L after 12 months storage.The concentration of other aroma compounds decreased.Base beer and beers stored for 1~2months had higher aroma compounds concentration,pure flavor,mellow body and were most popular among consumers,beers stored for more than 2 months began to have a distinct aging taste,hoppy aroma and other aroma were fading away,the body and flavor were not good,they were not popular with consumers.