Hellwig Michael, Henle Thomas
Chair of Food Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany.
J Agric Food Chem. 2020 Nov 18. doi: 10.1021/acs.jafc.0c06193.
Individual Maillard reaction products (MRPs), namely, free and protein-bound glycated amino acids as well as dicarbonyl compounds, were quantitated in various types of brewing malt using chromatographic means. Among the protein-bound glycated amino acids, which were analyzed following enzymatic hydrolysis, -ε-fructosyllysine was the dominating compound in light (EBC < 10) and dark (10 < EBC < 500) malts, accounting for up to 15.9% of lysine derivatization, followed by -ε-maltulosyllysine (light malts, up to 4.9% lysine derivatization) or pyrraline (dark malts, up to 10.4% lysine derivatization). Roasting of malt led to the degradation of most of the protein-bound glycated amino acids. The same trends were visible for free glycated amino acids. A novel MRP-derived Strecker aldehyde, namely, 5-(2'-formyl-5'-hydroxymethylpyrrol-1'-yl)-pentanal (pyrralinal), was detected in dark malt. The most abundant 1,2-dicarbonyl compound in malt samples was 3-deoxyglucosone (up to 9 mmol/kg), followed by 3-deoxymaltosone (up to 2 mmol/kg). Only few MRPs such as 5-hydroxymethylfurfural, furfural, the dicarbonyl compounds glyoxal, methylglyoxal, and diacetyl as well as protein-bound rhamnolysine and MG-H1 correlated with the malt color. A comparison of MRPs present in malt with corresponding amounts in beer points to neoformation of MRPs such as MG-H1 and 3-deoxygalactosone during the brewing process.
使用色谱方法对各种类型的酿造麦芽中的单个美拉德反应产物（MRP）进行了定量分析，这些产物包括游离和与蛋白质结合的糖化氨基酸以及二羰基化合物。在酶促水解后分析的与蛋白质结合的糖化氨基酸中，ε-果糖基赖氨酸是淡色麦芽（EBC<10）和深色麦芽（10<EBC<500）中的主要化合物，占赖氨酸衍生化的比例高达15.9%，其次是ε-麦芽酮糖基赖氨酸（淡色麦芽，赖氨酸衍生化比例高达4.9%）或吡咯赖氨酸（深色麦芽，赖氨酸衍生化比例高达10.4%）。麦芽烘焙导致大多数与蛋白质结合的糖化氨基酸降解。游离糖化氨基酸也呈现相同趋势。在深色麦芽中检测到一种新型的MRP衍生的斯特雷克醛，即5-(2'-甲酰基-5'-羟甲基吡咯-1'-基)-戊醛（吡咯醛）。麦芽样品中最丰富的1,2-二羰基化合物是3-脱氧葡萄糖酮（高达9 mmol/kg），其次是3-脱氧麦芽酮糖（高达2 mmol/kg）。只有少数MRP，如5-羟甲基糠醛、糠醛、二羰基化合物乙二醛、甲基乙二醛和双乙酰以及与蛋白质结合的鼠李糖赖氨酸和MG-H1与麦芽颜色相关。麦芽中存在的MRP与啤酒中相应含量的比较表明，在酿造过程中会新形成MRP，如MG-H1和3-脱氧半乳糖酮。
