Suaeda asparagoides(Miq.) is a salt marsh plant, which has long been prescribed in the traditional medicine for the treatment of hypertension and liver toxification in oriental countries. The S. asparagoides powder at the ratio of 0, 5, and 10% of grain-type Meju was added to manufacture Doenjang in brine according to the salt concentrations (8 and 12%). After 24 weeks of fermentation, the Doenjang samples were investigated the changes in the physicochemical and microbiological quality characteristics, anti-inflammatory effect, and taste evaluation by using taste sensing analysis.
There was no significant difference in moisture and salt contents of Doenjang added with S. asparagoides powder during the fermentation. The pH in all samples was decreased during the fermentation period, while the titratable acidity was increased until 8 weeks and then decreased, especially that of 8% NaCl non-powder adding Doenjang was the highest. The lightness value of Doenjang showed a tendency to decrease as the concentration of powder increased, lightness and yellowness value decreased during fermentation period. The 8% NaCl non-powder Doenjang was shown the highest amino-type nitrogen content, the higher the amount of S. asparagoides powder added, the lower the content of amino-type nitrogen. All samples increased until the 4 weeks. The reducing sugar content in all samples was increased until 4 weeks and then decreased, especially that of 12% NaCl Doenjang added at the concentration of 10 % S. asparagoides powder was the highest.
The change in total aerobic bacterial number of Doenjang did not differ by 6.9-8.1 logCFU/g and 12% NaCl Doenjang increased the concentration of S. asparagoides powder added, it tended to decrease cell number. The change in lactic acid bacterial number decreased during fermentation period.
To evaluate the anti-inflammatory effect of Doenjang added S. asparagoides powder extracted using 80% EtOH, we performed to study the inhibition of pro-inflammatory factors such as NF-κB(nuclar factor κB), NO(nitric oxide), TNF-α(tumor necrosis factor alpha), IL-6(nterleukin-6), iNOS(inducible nitric oxide synthase) and COX-2(cyclooxygenase-2) in lipopolysaccharide (LPS)-induced RAW 264.7 cell line. The cell viability was determined by MTT assay. The results showed that the Doenjang extracts reduced the production of NO, IL-6, COX-2 and iNOS increased in LPS-stimulated RAW cell without cytotoxicity. In the case of NF-κB and TNF-α there were no significant difference between control and samples.
By using taste sensing analyzer, the Doenjang samples added with S. asparagoides powder were shown the lower bitter taste than that of commercial soybean paste, and richness was significantly higher than that of commercial soybean paste.
In conclusion, these results suggest the Doenjang added with the S. asparagoides powder may be a developed the functional food related to anti-inflammation due to the significant effects on inflammatory factors. If the 12% NaCl concentration Doenjang added with powder carried out sensory evaluation it will be an excellent Doenjang in terms of its functionality.