Preperation of Sweet Potato Doenjang using Colored Sweet Potato

The effect of sweet potato on the quality of Doenjang was investigated during fermentation. Viable cells of yeast decreased gradually after 4 weeks of fermentation, but those of aerobic bacteria increased in the late stage. Amylase activity of Doenjang was higher in the late stage of fermentation, while neutral protease maintained high activity during fermentation. Hunter L and b values of Doenjang decreased gradually during fermentation, while a value was increased. The pH of Doenjang decreased gradually until 10 weeks of fermentation, and the titratable acidity was low in the sweet potato added groups. The acid value was low in the Shinyulmi sweet potato added Doenjang. Water activity and oxidation-reduction potential of Doenjang decreased during fermentation. Reducing sugar of Doenjang decreased in the middle stage of fermentation, and it was low in sweet potato added groups. The alcohol content of Doenjang decreased after 2 weeks of fermentation. Amino and ammonia-type nitrogen of Doenjang increased during fermentation and reached the maximum after 10 and 12 weeks of fermentation, respectively. After 12 weeks fermentation, 8% of Shinyulmi sweet potato added Doenjang was more favorable taste, flavor and overall acceptability (p<0.05) than the control or the Yeonwhangmi sweet potato added groups.

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Quality characteristics of Doenjang prepared with sweet potato

Cha¹,

Park²,

Kim³

2017

Quality characteristics of low salted garlic Doenjang during fermentation

Cho¹,

Kang²,

Kim³

et al. 2014

We investigated the changes in the quality characteristics of Doenjang with low salt contents (6, 8, 10, and 12%) and 10% garlic. The Doenjang was analyzed at an interval of a week during its fermentation for six weeks, at room temperature. Its L color gradually decreased, but its a and b colors did not change significantly. Its salinity increased by about 1% after six weeks. In contrast, immediately after its preparation, its pH was gradually decreased and its acidity was increased for the fermentation. The reducing sugar was significantly increased from 1.34~1.88 g/100 g immediately after its preparation to 7.25~9.13 g/100 g after six weeks, which was higher as the salt concentration decreased. The amino-type nitrogen doubled from 100~130 mg% at 0 week to 210~290 mg% at six weeks, which were lower with the higher salt concentrations. The growth curve of the Bacillus fermentation strains of Doenjang increased to two weeks but gradually decreased since, and the growth of the Bacillus was favorable for up to two weeks in the Doenjang with 10% and 12% salt added. Otherwise, the yeast was reduced rapidly during the early fermentation of the Doenjang, and slightly changed after three weeks of fermentation. The results of this study showed that the reducing sugar and amino-type nitrogen contents of the low-salt garlic Doenjang were higher with the lower salt dose, and the physicochemical quality of the 6%-salt Doenjang was not significantly affected. Thus, we suggest that low-salt Doenjang can be manufactured with the addition of 6% salt and 10% garlic.

Changes in the physicochemical characteristics of low-salt Doenjang by addition of halophytes

Choi¹,

Gil²,

Mun³

et al. 2018

The aim of this study was to investigate changes in the physicochemical characteristics of Doenjang fermented with halophyte powder for 24 weeks. The pH of all Doenjang samples slightly decreased during the fermentation period, with a range of 5.3-6.1. The acidity peaked at 8 weeks and subsequently decreased. The content of amino-type nitrogen steadily increased during fermentation and peaked at 1,174.6±18.2 mg% in Doenjang without halophyte powder. On the other hand, in the same sample, the reducing sugar content decreased to 1.0±0.0 mg%. Total bacterial counts slightly decreased during fermentation, but there was no significant difference according to the addition of halophyte powder. In the analysis of taste components using a taste sensor, the richness value was higher in the halophyte Doenjang (4.01 to 7.52) compared with that in the commercial Doenjang, and the sourness (-3.65 to -1.33) and bitterness (-1.63 to -0.27) were lower than those of the commercial Doenjang. Several characteristics were different depending on whether halophyte powder was added, but halophyte powder did not appear to affect the microbial growth. Thus, Doenjang can be produced with superior properties and taste components and improved functionality and taste using halophytes.