The Use of an Extracellular Ferulic Acid Esterase from Lactobacillus acidophilus K1 for the Release of Phenolic Acids During Mashing

J. Inst. Brew. 117(3), 427-434, 2011 A purified extracellular ferulic acid esterase from Lactobacillus acidophilus K1 was successfully used during mashing for the release of free phenolic acids into sweet wort. The enzyme was produced in bioreactors and partially purified to obtain the monoenzyme preparation. Release of free ferulic and vanillic acid into the wort at 52 degrees C (with the use of 4.09-14.60 enzyme activity units/L of the mash) and ferulic acid at 62 degrees C (14.60 units/L) was observed. Free p-OH-benzoic and syringic acids were effectively released at 26 degrees C at each enzyme concentration used. Free p-OH-benzoic acid was also released by the enzyme (14.60 U/L) at 52 degrees C-74 degrees C. Free protocatechuic acid was effectively hydrolyzed by the enzyme preparation (8.75 U/L and 14.60 U/L) at 26 degrees C-52 degrees C. Free caffeic acid (effectively released at 26 degrees C-62 degrees C) originated from chlorogenic acid. No p-coumaric acid was released due to the action of bacterial esterase during mashing. Ferulic acid esterase from L. acidophilus K1 exhibited no ability to release free phenolic acids during mashing at 62 degrees C or at 74 degrees C due to its low thermostability. In conclusion, L. acidophilus K1 is an attractive source for the production of ferulic acid esterase, which can be useful for the release of antioxidant phenolic acids in the early stages of mashing.