Study On The Characteristic Flavor Of Jiaoxiang Malt And Its Changing Law During The Roasting Process

The roasting malt is a special malt with a "roasting flavor".Adding it to beer will improve the stability of the beer quality and also give the beer a roasting flavor.The source of the flavored flavor material is primarily believed to be the product of the Maillard reaction the oxidation of the unsaturated fatty acid,and the caramelization reaction.This study mainly uses the analysis and identification of volatile olfactory flavor compounds as the main technical means,determines the composition and characteristics of the flavor compounds of the roasting malt,and the key flavor substances of the roasting malt;explores the flavor of roasting malt under different wheat-making techniques.Changes in the compound.The main research results of the thesis are as follows:The composition of different kinds of roasting malt flavor was analyzed by headspace solid phase microextraction-gas chromatography and mass spectrometry.A total of 56 flavors of roasting malt were isolated and identified from six samples of roasting malt.There are 15 kinds of aldehyde compounds,11 kinds of pyrazine compounds,8 kinds of furan compounds,6 kinds of alcohol compounds,and 6 kinds of azole compounds.The difference of flavor substances between roasting malt and other special malt was analyzed,and the typical flavor substances mainly affecting roasting malt were 2-phenyl crotonaldehyde and 2.5-dimethyl-3-cthylpyrazine 5-piperidin-2-pyrrolidine,2-acetylpyrrole,2-acetylfuran,decyl alcohol,4-methyl-2-phenyl-2-pentenal,3-methylbutyric acid,2,5-dimethylpyrazine,3,5-diethyl-2-methylpyrazine,2,6-dimethylpyrazine.p-vinyl eucalyptol.2-methyl-6-ethylpyridinium Pyrazine,2-octene-l-ol,2-methylpyrazine,acetic acid,furfural,maltol,benzaldehyde,benzyl alcohol.This result indicates that roasting malt and other special malts can be distinguished on the flavor level..The content of 14 flavor substances in the roasting malt was determined by gas chromatography and external standard method.The feasibility of the method was verified.The detection limit of 14 flavor substances reached 0.50-1.52 ?g/mL.The precision of the extraction method is below 5%,and the recovery rate of various flavor substances is within 85%?120%,which can meet the requirements of testing.Comparing the content of 14 flavor substances in 9 kinds of special malt,the content of 14 flavor substances in roasting malt was less than chocolate malt,coffee malt,crystalline malt and black malt,but higher than barley malt and coke fragrant wheat bud.The difference in flavor is not obvious.A total of 10 key flavor substances of roasting malt were identified,which were 2,5-dimethylpyrazine,2,6-dimethylpyrazine,furfural,2-acetylfuran,benzaldehyde,5-methyl Furfural,1-mercaptopyrrole,n-acetic acid,maltol,2-methoxy-4-vinylphenol.The principal component analysis method was used to analyze the 14 flavor substances of 9 kinds of special malt,and the Y value formula of the roasting malt was obtained.Y=0.218Z1+0.344Z2+0.241Z3+0.458Z4+0.464Z5+0.432Z6+0.492Z7+0.308Z8+0.503Z9+0.486Z10+0.511Z11+0.394Z12+0.181Z13+0.408Z14.The standardization of the 14 flavor substances of the roasting malt is introduced into the formula,and the Y value of the roasting malt is obtained between-4.5 and-3.This mathematical model can be used for the identification and differentiation of roasting malt.3.Exploring the effects of different malting temperatures,times and raw materials on the quality of the malt.It was found that the moisture content of the prepared malt malt decreased significantly with the increase of temperature(P<0.05),and the chroma of the roasting malt increased with the increase of temperature.With the increase of the temperature of the wheat,the pyrazines showed an overall upward trend.The content of furfural,2-acetylfuran and 1-mercaptopyrrole increased gradually with increasing temperature of wheat.5-methylfurfural gradually decreased with increasing temperature of wheat.The temperature at which the overall flavor material is formed or accumulated ranges from 100? to 140?.Under different maiking time,the moisture content of the prepared roasting malt decreased with time,and the chromaticity of the roasting malt increased with time.At high temperatures(160?),the content of pyrazines,furan compounds,maltol and 2-methoxy-4-vinylphenol increases with time.In the process of making roasting malt from different raw materials,the moisture content of raw barley is much faster than other raw materials during the process of making wheat.Barley immersed in wheat for 2 d has higher chroma than other raw materials in the process of making roasting malt High moisture content of barley or green malt is beneficial to the production of pyrazines in the process of preparing roasting malt.The content of furan compounds in the process of preparing roasting malt was higher than that of other treatment groups.