%0 Journal Article
%T Kinetic Modeling of Hop Acids during Wort Boiling
%A Yarong Huang
%A Johannes Tippmann
%A Thomas Becker
%J International Journal of Bioscience, Biochemistry and Bioinformatics
%D 2013
%I IACSIT Press
%R 10.7763/ijbbb.2013.v3.161
%X The thermal degradation of iso-alpha-acids wasinvestigated at four pH levels between 4.5 and 6.5 at differentboiling temperatures (90-130 ˇăC) during the wort boiling time(0-360 min). The free energy of activation and the reaction rateconstant (k) of the degradation of iso-alpha-acids werecalculated. Raising pH value from 4.5 to 5.5 and from 5.5 to 6.5decreased the reaction energy about 20 kJ/mol. The relativeproportion of isocohumulone stays almost constant. Wedeveloped a kinetic model for the irreversible consecutivereation; iso-alpha-acids are isomerized form of alpha-acids bythe application of heat in solution and at the same timeiso-alpha-acids are degraded to humulinic acids and othercompounds. This kinetic model is useful to calculate time toadded hops into boiling kettle.
%K Activation energy
%K alpha-acids
%K degradation
%K iso-alpha-acids
%K kinetics
%K pH value.
%U http://www.ijbbb.org/papers/161-E005.pdf