Studies On The Melanoidins Of Beer Malt During Malting

When the steeped barley was germinated, enzymes were activated, which dissolved the polymer materials in barley. Melanoidins were brown substance originated by the Maillard reaction during the dry and roasting process by interactions between carbohydrates (typically reducing sugars) and compounds characterised by a free amino group, such as amino acids in the barley. Melanoidins were the major ingredient of the malt chroma and were the main source of evaluation the quality of malt and beer. As mixture of complex structure, melanoidins were necessary to establish the optimization of extraction condition of malt melanoidins.This paper studied on the optimization of extraction condition of melanoidins from malt, the assay was conducted by four factors and four levels completely randomized experient, including the ethanol concentration, solid-liquid ratio, stirring rate and the extraction time, and standard addition method. The influences of roast temperature and roasting time on the chroma and melanodins, At the same time correlativity between the melanoidins and reducing sugars and alpha amino nitrogen were studied. Some functional properties of melanoidins were studied. The results were as follows:1. Through the combination of four factors and four levels completely randomized experient and standard addition method, the optimization of extraction condition of melanoidins from malt were as follows:ethanol concentration was 80%, ratio of solid to liquid was 1:10, the stirring rate was 50 r/min and extraction time was 3 h, the recovery rate was 103%.2. Under the roast condition of 80?,85?,90?,95?,100?and 105?, concentrations of malt melanoidins and chroma had a good linear correlation, the coefficients of correlation were 0.7777,0.8939,0.9703,0.9739,0.9307 and 0.9374. In the process of roast of light color and brunet malt, malt quality could be determined by melanoidins.3. Through determining of the melanoidins and reducing sugar, alpha amino nitrogen, under the different roast condition, when melanoidins content rised, the reducing sugar and alpha amino nitrogen content were declining. The coefficients of correlation were greater than 0.7614 and 0.9451 respectively, the results showed that melanoidins had better correlation with alpha amino nitrogen.4. The study of melanoidins biological characteristics, showed that malt melanoidins had the good capacity for reducing and chelating, the regression equation was respectively:Y= 0.4383X+0.775, R2= 0.9624; Y= 2.1059X+92.342, R2= 0.9593. Melanoidins could improve the quality of beer, and provide the theoretical basis for the special beers.