Analysis of the Enzymatic Decomposition of Barley Starch to Simple Carbohydrates

The decomposition of barley starch plays a fundamental role in the final quality of fermented beverages in the brewing industry. The process of mashing involves steeping milled barley in water to stimulate the enzymatic decomposition of starch into simple carbohydrates. The temperature of the water significantly impacts the activity of the enzymes and in turn the resulting concentrations of sugar products. A kinetic model accurately predicting the types and quantities of sugars formed as a function of mash temperature would serve as a tool to tailor sugar profiles and optimize mashing procedures for a desired product. Sixty minutes mashes were conducted over a series of temperatures ranging from 61 to 73 °C and samples analyzed using high performance liquid chromatography. The concentration profiles of fructose, dextrose, sucrose, maltose, maltotriose, and maltotetraose as a function of time were determined for each mash temperature. A reaction kinetics model was proposed and rate constants and reaction orders were extracted from the experimental data and used to simulate mashes at each temperature. The model was validated for the isothermal experiments and the model’s predictions were then compared to mash samples taken from a local microbrewery. The model was found to accurately capture the behavior of each sugar and the resulting sugar concentrations in the brewery. The model was then adjusted to gain insight into the profiles of several different mashing procedures.