The Geomunoreum Lava Tube System, declared as a UNESCO World Heritage Site, has a unique natural ecosystem. The information available about this ecosystem, which contains lava caves with secondary carbonate speleothems, is sparse. Hence, extensive research is warranted for establishing a conservation standard. We commenced microbial research on the system and have been studying the microorganisms coating the lava tube wall to acquire fundamental information for understanding the lava cave ecology of Jeju Island. Samples were collected from yellow-colored walls in six caves that are part of the system―the Bengdwi, Utsanjeon, Bukoreum, Manjang, Gimnyeong, and Yongcheon caves. This study focused on yellow walls as it is the most easily distinguished color. According to previous studies, the color of cave walls is attributed to microorganisms or their components. To determine whether the yellow mats from the Jeju lava tube walls are caused by microorganisms, we examined samples at the microscopic scale, by staining mats and analyzing bacterial isolates from glitter particles. As a result, we found that the yellow walls of lava tubes are comprised of microbial mats.

The objective of this study was to determine the changes in content of polyphenolics, flavonoids, amino acids, especially γ-aminobutyric acid (GABA), and the antioxidant activities in the methanol extracts of four different pigmented rice seeds (white, black, red, and green color) at different germination stages, dry seeds (DS), imbibed seeds (IS), and germinated seeds for 1 (GS1), 2 (GS2) and 3 days (GS3). Total phenolics content at 1000 mg/kg extract was highest in black rice, ranging from 208.3 to 257.3 mg/kg, and followed by red rice 144.7 to 185.7 mg/kg, brown rice 151.3 to 194.2 mg/kg and green rice 125.7 to 160.7 mg/kg (lowest). Total flavonoid level had same tendency to total phenolics among colored rices with significant differences, showing highest amounts (45.2 to 56.8 mg/kg) in black rice and lowest (18.8 to 23.0 mg/kg) in green rice. Total phenolics and total flavonoids levels in black and brown seeds were highest when soaked, and in red rice when nonsoaked, and in green rice when germinated for 1 day. These results showed that content of physiologically- active substances were differ depending on seed coat color, soaking or germinating degree. Content in total amino acids during germination was ranged from 136.5 to 232.0 mg/kg in green rice (highest), and 98.9 to 176.0 mg/kg in red rice (lowest). Total content of amino acids and GABA level in all seed colors were high in order of GS3 > GS1 > IS > DS. The antioxidant activity of the methanol extracts from all the seed colors concentration-dependently increased. DPPH free radical scavenging activity at 2,000 mg/kg was highest in black rice by 83.0 to 87.7%, and lowest in green rice by 44.3 to 65.7%.

The results of testing general components, physical property and physical function after having made steamed rice cake by adding eggplant, which caters to consumers’ tastes are as follows. It showed that when eggplant powder content increased, the moisture content of steamed rice cake with eggplant was decreased. It also showed that the lightness value (L) of steamed rice cake with eggplant powder was the highest as 82.75 in the control group. When eggplant powder content increased, the redness (a) and yellowness (b) were increased. From the results of having measured the antioxidant potential over the steamed rice cake with freezing-drying eggplant powder by DPPH radical elimination, we figured out that it was the lowest as 48.30% in the control group. As more eggplant powder was added, its elimination increased accordingly. As per hardness of steamed rice cake with eggplant, the added group with 7% was revealed as the highest at 0.757. It showed that adhesiveness was the lowest as 30.233 in the control group, and springiness and cohesiveness were on the rise as freezing-drying eggplant powder was increased. Furthermore, softness and chewiness were shown to be high in the added group with eggplant powder of 3, 5%. The evaluation over the overall preference was the highest in 5% added group. Judging from this, adding 3~5% eggplant powder against non-glutinous rice powder is considered an optimal quantity in making steamed rice cake with eggplant.