23蒸汽喷射技术对麦汁煮沸期间挥发物质-牟宏师姐详解.ppt

The impacts of steam injection technology on volatile formation and stripping during wort boiling 蒸汽喷射技术对麦汁煮沸期间挥发物质 形成和去除的影响 斯蒂夫 浦里斯 诺丁汉大学 Wort Boiling – Process Objectives Wort boiling has a number of important process objectives, including: inactivation of mash enzymes. trub formation. wort sterilization. formation of flavour/colour compounds. Isomerisation of hop α-acids to iso-α-acids. Stripping of unwanted volatile compounds Young Scientists Symposium on Malting Brewing Distilling, Ghent, 2014 麦汁煮沸过程的目的 麦汁煮沸过程有很多目的，包括： 糖化过程中酶的钝化 不良挥发性化合物的去除 热凝固复合物的形成 麦汁灭菌 酒花中的α-酸异构化为异α-酸 风味/色素复合物的形成 Wort Volatiles During the boil and hot wort stand, wort volatiles can be generated, added (with hops), evaporated (stripped) or can bind to other wort components. Areas of relevance(相关领域): Some compounds will pass into beer at levels which are flavour active: e.g. kettle hop aroma compounds Some compounds need to be effectively stripped during the boil to remove undesirable characters, e.g. DMS Some of the compounds generated in thermal reactions are implicated in beer staling (e.g. staling aldehydes) or precursors of such compounds (furfural/ furfuryl ethyl ether) Some thermally formed compounds may be used as ‘heat load’ indicators – e.g. hydroxymethylfurfural (HMF) * 在麦汁煮沸以及高温保持阶段，麦汁中的挥发性物质会形成，会增加（加入酒花后），会蒸发（汽提）或者能与其他的麦汁成分结合。 麦汁中的挥发性物质 一些化合物，即某些风味活性成分（例如酒花中的香味成分）会进入到啤酒，形成一定的量。 一些化合物需要在煮沸阶段被有效的去除，从而除掉一些不良的性质，例如： 二甲基硫(DMS) 在热反应阶段会形成一些导致啤酒老化的化合物（例如：老化醛类）或者是这些化合物（糠醛或者糠基乙基醚）的前驱物质 一些加热形成的化合物可能会作为“热负荷”的指示剂，例如羟甲基糠醛（HMF） Henry’s Law determines volatile stripping rate Defines the concentration (or partial pressure, p) of volatile in air above an aqueous solution at equilibrium and constant temperature The equation applies to dilute ideal solutions (e.g. wort) Compounds with a high Henry’s law constant will partition (strip) to the gas phase more readily even in dynamic, non-equilibrium, conditions like wort boiling. pi = partial pressure exerted by component i