Analysis Of Characteristic Aroma Substances For Malt And Its Appilication During Dark Beer Brewing

In this paper,key special malt aroma components for malt were qualitatively analyzed.Then 14 typical special malt aroma compounds were chosen and quantified in malt and dark beer.Firstly,the content of specialty aroma compounds among different malts were compared.Secondly,dark beers were detected to determine their differences in malt aroma characteristic.At last,changes of special malt aroma compounds during dark beer brewing were tracked.A brewing method was decided combining with content of malt aroma compounds and sensory evaluation.Using simultaneous distillation extraction(SDE)and solid phase micro-extraction(SPME)pre-teatment methods with GC-O-MS,special aroma flavour of pale malts,caramel malts and black malts was qualitatively analyzed.More than 150 compounds were found and identified by existing retention index and NIST database.Combined with peak intensity method and GC-O-MS,69 kinds of compounds were sniffing out among three types of malt.Flavor wheel showed difference between two extraction results was small.Aromatic extraction dilution analysis(AEDA)for liquid extracted by SDE determined up to 40 kinds of key aroma substance.Qualitative classification of all compounds shows that nitrogen-containing heterocyclic compounds only contribute to black malt aroma significantly and oxygen-containing heterocyclic contribute most to caramel malt and black malt aroma.Based on the qualitative work,14 special malt aroma compounds were selected to quantitatively analysis for malt and dark beer.Quantitative analysis of 14 kinds of special aroma compounds by HS-SPME-GC-MS method indicated significant differences among three types of malt.Most special aroma substances in pale malt are difficult to detect.Content of maltol,pineapple ketone in caramel malts is very high.Meanwhile,content of most nitrogen-containing heterocyclic compounds in black malts are higher than 100 ?g/kg.Principal component analysis revealed that content of aroma compound for domestic malt was significantly lower than the foreign specialty malts.Special aroma content of dark beer was established by HS-SPME-GC-MS.The result in dark beer demonstrated pineapple ketone and maltol had higher content.However,the content of such compounds in beer which tasted good is just at the medium level.Therefore,appropriate content of malt aroma substances is more contribute to equilibrium for dark beer flavor.In the single factor experiment,content of malt aroma compound and sensory evaluation were used to assess the quality of dark beer.Result showed that species and amount of caramel malts,black malts,hops,and yeast influence the content of aromatic substances and beer quality.In addition,sensory evaluation combined with orthogonal experiment was utilized to optimize the brewing process of dark beer.Dark beer brewing showed as followsin order: caramel malts > yeast > hopping regimes > black malts.The final brewing technology of dark beer was optimised with caramel malts J1,black malts H3, yeast C and whirlpool tank-hopping.The addition amount of dark beer during brewing process by response surface method of Box-Behnken.The final brewing technology of dark beer was optimised with 14.37% of caramel malts,2.59% of black malts,0.58‰ of hops and 1.24x107mL-1 of yeast.The physicochemical and sensory index of dark beer is in accordance with the national standard for quality of dark beer requirements.