Yuzu (Citrus junos) undergoes traditional processing to create preserved yuzu with a sugar content of 50%. This study aimed to produce low-sugar yuzu syrup using artificial or natural sweeteners instead of sugar. Among artificial sweeteners, maltitol showed minimal browning and lack of deposition at high temperatures. The addition of xanthan gum (0.2%) and carboxymethyl cellulose (0.2%) resolved the issue of layer separation and viscosity decrease of yuzu syrup. Alternatively, grain syrup, a natural sweetener, improved viscosity and homogeneity without the additives. Yuzu syrups were developed using yuzu juice and preserved yuzu, with maltitol (20~40%) or grain syrup (50~70%) as the sweetener. Yuzu syrups containing 35% maltitol (M35) or 55% grain syrup (G55) had less than 5% and 10% free sugar, respectively. These syrups exhibited taste patterns similar to commercial yuzu syrup in analysis using an electronic tongue. Furthermore, M35 and G55 contained yuzu flavonoids at concentrations of 19.82 mg/g and 24.09 mg/g, respectively. Antioxidant activity (DPPH, ABTS radical scavenging) of M35 and G55 was equivalent to 10.55, 17.59 mg/100 g of Vitamin C and 97.39, 33.92 mg/100 g of Vitamin C, respectively. Consequently, M35 and G55 offer promising alternatives to preserved yuzu, providing low-sugar yuzu syrups enriched with functional ingredients.

The content of bioactive substances and antioxidative activity in conventionally grown brown rice (CGBR) and organically grown brown rice (OGBR) were compared. Minerals (mg/100 g) such as magnesium (OGBR, 168.59±2.62; CGBR, 121.43±2.22), copper (OGBR, 0.50±0.06; CGBR, 0.41±0.05), and manganese (OGBR, 4.70±0.04; CGBR, 2.49±0.02) were higher in OGBR than in CGBR (p<0.05). In addition, levels of (μg/100 g) vitamins B2 (OGBR, 27.22±2.56; CGBR, 22.12±2.24) and B6 (OGBR, 46.32±2.66; CGBR, 39.91±3.32) were higher in OGBR than in CGBR (p<0.05). The contents (mg/100 g) of β-sitosterol (OGBR, 27.40±2.79; CGBR, 24.75±1.06), total phenolic (OGBR, 6.72±0.02; CGBR, 6.64±0.02), and ferulic acid (OGBR, 1.75±0.45; CGBR, 1.11±0.14) as well as the antioxidative activity (OGBR, 53.09±1.90%; CGBR, 48.29±3.38%) evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay were higher in OGBR than in CGBR, although no significant differences between samples were observed. In comparison to the control group, brown rice samples significantly inhibited cholesteryl ester hydroperoxide formation in rat plasma subjected to copper ion-induced lipid peroxidation. The inhibitory effect of OGBR was higher than that of CGBR. These results indicate that OGBR showed higher levels of bioactive substances and enhanced antioxidative activity than CGBR, although the differences were not statistically significant.

The antioxidant substance in black onion was identified. The assays that used 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazo line-6-sulphonic acid) (ABTS+) radicals showed that the ethyl acetate fraction of black onion methanol extract had a higher level of radical-scavenging activity than the other fractions. Two antioxidative compounds were purified and isolated from the ethyl acetate fraction via column chromatographies of silica gel and Sephadex LH-20 using the guided DPPH radical-scavenging assay. The isolated compounds were identified as 3,4-dihydroxybenzoic acid (1) and quercetin (2) based on mass spectrometry and nuclear magnetic resonance. The isolated compounds showed a high level of DPPH and ABTS+ radical-scavenging activity. Compound 2 had a higher level of radical-scavenging activity than 1.

The antioxidant activities of makgeolli and other alcoholic beverages were compared. Based on the same volume (70 μL eq.) of the alcoholic beverages, the 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid ammonium salt) (ABTS+) radical-scavenging activities were as follows: whisky > makgeolli crude extract (MCE) > rice wine (RW) > clarified makgeolli (CM) > soju. Based on the same alcohol concentration (6%) of the alcoholic beverages, however, makgeolli showed the highest activity. In addition, based on the same volume (70 μL eq.), the inhibition effects against the formation of cholesteryl ester hydroperoxide (CE-OOH) were as follows: soju > whisky > RW > MCE > CM. Based on the same alcohol concentration (6%), however, the inhibition effects against the formation of CE-OOH were as follows: RW > MCE > soju > whisky > CM. Therefore, it was suggested that makgeolli may contain radical-scavenging- and metal-ion-chelate-type antioxidants and may increase the antioxidant activity in the blood.