Quality characteristics of ‘Kochujang’ made with pigmented rice flour ‘Nuruk’ by various fungal strains during aging

Abstract

In this study, pigmented rice flour 'Nuruk' was prepared using various fungal strains to improve the quality of Korean traditional 'Kochujang', and the quality characteristics during the aging of 'Kochujang' made with the 'Nuruk' were confirmed. The pH of 'Nuruk' was highest using Aspergillus oryzae pigmented rice flour 'Nuruk' (N2) at 5.83, and the highest acidity was Aspergillus niger pigmented rice flour 'Nuruk' (N3) at 2.69. The crude ash content was 1.10-1.14% from the 'Nuruk' made with pigmented rice flour, which was higher than the 0.42% from 'Nuruk' made with white rice flour. The pH of 'Kochujang' decreased gradually from 0 to 90 days as aging progressed. The titratable acidity was 2.76-3.71%, which increased with increasing aging period. During the aging of 'Kochujang', the water content increased by 2-3%. The reducing sugar content decreased from 0.33 to 3.25% after 60 days of aging and increased to 3.85 to 4.94% at the end of aging. Regarding the color values, the 'Kochujang' made with white rice flour 'Nuruk' showed higher overall L, a, and b values than the 'Kochujang' made with pigmented rice flour 'Nuruk'. A sensory evaluation of six kinds of 'Kochujang' revealed the 'Kochujang' made with N2 'Nuruk' to have the highest preference in all evaluation items.