Modeling of Dimethyl Sulfide Stripping Behavior When Applying Delayed Onset of Boiling during Wort Boiling

Abstract

The response surface methodology, using the central composite design as a tool for modeling, was used to study the impact of two parameters (power supply and boiling time) and their effect on dimethyl sulfide (DMS) removal during wort boiling, when applying delayed onset of boiling. It was observed that the two parameters were significantly impacting the DMS removal with a 21% contribution for power supply and a 58% contribution for the boiling time (P = 0.000 for both). The interaction of the two factors was also significant (P = 0.008) with a contribution of 7%. With the S-methyl methionine conversion to DMS following the pseudo first-order kinetics reaction, k₁ was computed as 0.0054 min⁻¹, and the values of k₂ were between 0.0151 and 0.407 min⁻¹. After several statistical analyses, we learned that the results coming from the theoretical equations for DMS removal at each studied power supply were not significantly different from the experimental value obtained in the laboratory, validated by the use of these equations. The time spent to reach the residual DMS target of 30, 50, and 100 ppb was 141–377, 94–295, and 60–197 min, respectively, and the energy used to reach the same target was 11.31–12.69, 8.46–8.85, and 5.40–5.91 MJ, respectively.

• Power supply
• Boiling time
• Dimethyl sulfide
• Wort boiling
• Central composite design (CCD)
• Response surface methodology (RSM)