Research On Quality Characteristics Of Magnum Hops

Hops had a long history in beer brewing, which contained a variety ofpharmacological activities such as bitter substances, polyphenols and hop oil receivedextensive attention by researchers. Hops was an important economic crop in Xinjiang,but facing some problems for instance less varieties, single color, root aging and so on.In order to enrich the hops market, changing the single category in domestic beer, itwas important to introduce and breed new varieties of hops actively. Magnum hopsOriginated in German had received high praise by foreign brewers, because it was avariety with peracid, bitterness and odour. This paper, based on volatile components,bitter substances, flavonoids, polyphenols, and the changes of hop bitters duringstorage in Magnum hops introduced in Xinjiang, evaluated brewing performance andinhibited lipid oxidation comprehensively.Conductance was a common, rapid method to determine the content of α-acid,but it also had some problems in determining the conductance due to differences inthe freshness of hops in the analysis process. By comparative analysis of the differentvarieties in fresh and aged hops, it determined the dosages of dimethyl sulfoxideadded hops. The best technological conditions included toluene extract10mL,methanol40mL, dimethyl sulfoxide5mL, under which conditions the leadconductance value was most stable and accurate. As there was no clear definitionabout "aged hops", it was recommended that the analysis of lead conductance value inhops should be added dimethyl sulfoxide, in addition to during the harvest of hops.The analysis results indicated that the changes of flavonoids and β-acids weresmall during the whole flowering among the content of flavonoids, polyphenols,α-acids and β-acids. The remaining ingredients were positively correlated with growthtime. Hops components measured in different years showed that, with the hop plantsgradually matured, the contents of α-acid and β-acid increased, while the contents ofco-humulone and co-lupulone reduced year by year. The head space-solid phase microextraction-gas chromatography-massspectrometry (HS-SPME-GC-MS) was used to identify the composition and contentof volatile components in Magnum Hops, which compared with the traditional steamdistillation (SD).The chemical composition was qualitatively analyzed by massspectral library retrieval combined with Kovats retention indices (RI), which could getthe composition and content of volatile components.It showed that the methanol extract of Magnum, Marco polo and Tsing daoflower hops had antioxidation in the antioxidant experimental study. While, It was notnotable between the three kinds.It compared the gravimetric method with UV method to determine the hopsbitterness value via brewing experiments. The results indicated that there weresignificant differences between them via t-test. It determined the bitterness value byUV method, through optimizing the pretreatment conditions ultimately. With differenttemperatures accelerating Magnum hops oxidation, it indicated hop bitter substancesα-acids and β-acids declined at different rates, storage index (HSI) was graduallyincreased, the change of bitterness value was relatively slow, along with the storagetemperatures. While, Magnum hops had good storage property compered with theMarco Polo and Tsingdao flower reported in the literature under low temperaturestorage conditions.