The Chemical Properties of Doenjang Prepared by Monascus Koji

Abstract

Monascus koji have been used as a natural food colorant and preservative in Asia countries for centuries. This study was investigated to the chemical properties of Doenjang prepared with Monascus koji. Four kinds of Doenjang were fermented with Aspergillus koji only and Aspergillus koji plus 10%, 20% and 30% Monascus koji of its amount, respectively, and the changes of characteristics were investigated during fermentation. All the Monascus koji substituted Doenjang showed lower protease activities than Aspergillus koji Doenjang over all periods of fermentation. No differences of amino nitrogen and free amino acids were found after 30 days of fermentation and reducing sugars and peptides were found during over all periods of fermentation in each other. The Monascus koji gave higher a-, L- and C-values and lower h-values than Aspergillus koji. Sensory profiles of color, flavor, taste and overall quality on the final products which fermented during 60 days, indicated that there were no differences each other. From these results Monascus koji suggested as 30% substitutes for Aspergillus koji in Doenjang preparation.