This study explored the suitability of nurungji as a substitute for malt. Rice beers (R20, R40, R60) and nurungji beers (N20, N40, N60) were prepared by substituting 20%, 40%, and 60% malt with the rice and nurungji, respectively. All samples were fermented at 25oC for 5 days and stored at 2oC for 15 days to study quality characteristics. The pH value of wort solution was the highest at R60. The viable cell counts of all samples were not significantly different during fermentation and storage. As the amount of rice and nurungji increased, the L value in chromaticity increased, whereas the a and b values tended to decrease during fermentation and storage. The reducing sugar, soluble solid contents, and specific gravity of the wort solution were higher in nurungji beer than in rice beer. After fermentation and storage, the alcohol content of N40 was 5.83%, the highest among the prepared rice and nurungji beers. The total polyphenol, flavonoid contents, DPPH, and ABTS scavenging activity of beer decreased with increased rice and nurungji substitution ratios during fermentation and storage. Notably, nurungji beer showed higher antioxidant activity than rice beer during fermentation and storage.

This study was conducted to investigate the effect of manufacturing temperature on curcuminoid contents and the antioxidant activity of turmeric (Curcuma aromatica Salab.) powder-enhanced nurungji. Two different processes employed turmeric powder (2%): AR (added after rice cooked) and BR (added before rice cooked). AR and BR nurungji samples were prepared by heating cooked rice at 180oC, 200oC, and 220oC for 3 minutes. As a result of the HPLC analysis, the contents of curcumin, demethoxycurcumin, and bisdemethoxycurcumin decreased as the heating temperature increased. Moreover, AR samples showed higher curcuminoids than BR samples. The total polyphenol contents, DPPH, and ABTS radical scavenging ability proportionally increased with the increase of the manufacturing temperature. On the other hand, flavonoid contents were decreased with increasing temperature. These results suggest that the preparation of turmeric powder-enhanced nurungji by AR process at 200oC is preferable to preserving curcuminoid contents and antioxidative activity.

This study was performed to evaluate the quality characteristics and antioxidant activity of Nurungji by varying the purple sweet potato powder addition time (AR: added after rice cooking, BR: added before rice cooking) and powder ratio (0, 2, 4, 6, 8%) on the prepared rice during Nurungji’s manufacturing. In both AR and BR samples, water binding capacity, soluble solid content, reducing sugar, and hardness increased with an increasing proportion of purple sweet potato powder; however, the pH and moisture content decreased. The L value and b value decreased and increased with the influence of anthocyanin in purple sweet potato powder. The total polyphenol, flavonoid, anthocyanin contents, DPPH, and ABTS radical scavenging activity were highest in Nurungji with 8% of purple sweet potato powder. Moreover, AR samples showed higher antioxidant activity than BR samples. Based on the study results above, the preparation of Nurungji with 8% purple sweet potato powder by AR process was more favorable based on the content of antioxidants and antioxidant activity.