Impact of Gaseous Carbon Dioxide and Boiling Power on Dimethyl Sulfide Stripping Behavior During Wort Boiling

The impact of carbon dioxide (CO2) supply flow rate on dimethyl sulfide (DMS) removal during wort boiling was studied when applying a 1 h hold between the end of preheating and the beginning of boiling. This was done during wort boiling by varying the boiling power (from 500 to 1,500 W), aiming to reduce energy consumption to reach the target of an end-of-boil DMS concentration of 100 ppb (w/v). When using the Mitani equation, which describes S-methyl methionine (SMM) conversion into DMS and DMS stripping, the preboiling step allowed a reaction rate coefficient of SMM conversion (k(1)) value of 0.0099 min(-1) to be obtained. The values of volatilization rate coefficient of DMS (k(2)) during the provision of CO2 at a flow rate between 5 and 11 L/min and boiling power between 500 and 1,500 W were between 0.02049 and 0.07882 min(-1). It was found that the coefficient k(2) increased with the increase of CO2 supply flow rate and the increase of boiling power. At a fixed boiling power of 1,500 W, the use of CO2 supply flow rate permitted the target of 100 ppb to be attained in an interval of 39.21 min for 11 L/min to 62.31 min for 5 L/min. The energy saved in the boiling process when applying CO2 supply flow rate between 5 and 11 L/min was 2.49-4.57 MJ.