ABSTRACTThe manufacturing of several sweet cherry products involves the use of calcium bisulfite brines and generates significant amounts of the brine for disposal. One of the primary concerns preventing the reclamation and reuse of these brines is the enzymatic softening of product caused by polygalacturonase enzymes that may be present in spent brine. The objective of this investigation was to evaluate the thermal stability of the polygalacturonase enzyme in cherry brine so that thermal inactivation processes can be designed.The first‐order rate constants to describe thermal inactivation of polygalacturonase in cherry brine were measured over a range of typical pasteurization temperatures (68°to72°C). The results were used to characterize thermal resistance of the enzyme in terms of Z‐value (8.4°C) and activation energy (271kJ/mole). The thermal stability of the enzyme was maximum between pH2.8and3.5and at sugar concentrations above12%. A pasteurization system for cherry brine should be designed with all of the thermal stability characteristics considered in order to assure maximum product q