Hye-Yoon Yi, Jae-Wan Park, Seok-Kyu Yu, Dong-Shin Kim, and Ji-Yeon Chun. Journal of the Korean Society of Food Science and Nutrition 2022;51:845-54. https://doi.org/10.3746/jkfn.2022.51.8.845

Yellowball (Citrus hybrid cv. Yellowball ) is a new citrus hybrid between Haruka (C. tamurana × natsudaidai ) and Kiyomi (C. unshiu × sinensis) and is known to possess strong antioxidant activity. However, detailed information on the antioxidant components of its peel has not yet been reported. This study evaluated the antioxidant activity of the peel and identified the antioxidant components by fractionating a methanolic extract of Yellowball peels using liquid-liquid extraction with n-hexane, ethyl ether (ether), ethyl acetate (EA), butanol, and water. The phenolic contents and antioxidant activities of the n-hexane, ether, and EA fractions were higher than those of the other fractions, and these fractions were further separated by semi-preparative high-performance liquid chromatography (HPLC). Four antioxidant peaks, EA1, EA2, EA3, and He1, were isolated and analyzed using ultra-performance liquid chromatography–quadrupole-time- of-flight mass spectrometry (UPLC-Q-TOF MS). Sinapoyl glucoside and hesperidin were identified in EA2 and EA3, respectively, and a polymethoxylated flavone (PMF) complex (5-hydroxy-3,6,7,8,3’,4’-hexamethoxyflavone, natsudaidain, tetrameth- oxyflavone, and tangeretin) was identified in He1. A compound in EA1 with m/z 223.0246 [M-H] could not be identified and was named unknown2. The antioxidant activity of unknown2 (IC50=69.17 μg/mL) was similar to that of Trolox, which was noted as a major antioxidant in Yellowball peel. Further studies on the antioxidant capacity of Yellowball peel are required; however, these results provide a foundation for using Yellowball peel as an antioxidant.

This study aimed to evaluate the effects of controlled atmosphere (CA) treatment on the postharvest quality of strawberries harvested at different 50% and 80% maturity under export shipping conditions. The strawberries were subjected to CA and refrigerated container (Reefer) environments at 10 °C, and their quality attributes were then analyzed. Metabolomic profiling revealed significant variations in primary and secondary metabolites and volatile organic compounds (VOCs). A pathway analysis revealed that CA conditions altered metabolic pathways related to sugar, amino acid, and energy metabolism during storage. CA treatment effectively delayed the accumulation of anthocyanins and enhanced the levels of specific amino acids and VOCs essential for the flavor and aroma of strawberries. Bioluminescence imaging revealed that CA treatment effectively reduced lipid peroxidation. A correlation analysis showed that certain VOCs and secondary metabolites significantly correlated with lipid peroxidation, indicating their role in enhancing antioxidant activity and reducing oxidative stress. These results suggest that CA conditions are associated with significantly reduced weight loss, the maintenance of firmness, and lower respiration rates in strawberries, particularly in those harvested at 80% maturity, extending the shelf life and improving the sensory quality of strawberries. Therefore, CA treatment is an effective method for long-term export.

This study investigated the effects of storage on the quality characteristics and metabolite profiles of onion (Allium cepa L.) bulbs from different cultivars and cultivation regions. Physiological traits such as respiration rate, weight loss, and firmness showed a general decline during storage, with only slight but statistically significant differences observed among cultivars and regions. Metabolomic analysis using UPLC-Q-TOF MS combined with multivariate statistics revealed that sugars, organic acids, amino acids, and organosulfur compounds were significantly altered over the storage period. In particular, sucrose and maltopentose increased by up to 3.09- and 4.65-fold, respectively, while glutamyl-S-allylcysteine and glutathione glycylmethyl ester showed increases of 7.22- and 8.12-fold, respectively, especially in the ‘Terius’ cultivar. These compounds are involved in structural degradation, antioxidant defense, and flavor development, reflecting cultivar- and region-specific metabolic regulation. The findings provide insights into the biochemical mechanisms underlying storage-related changes and may inform strategies for improved postharvest management and quality preservation of onions.

The cultivated area of large-sized Ziziphus jujuba Mill., commonly known as wang jujube in South Korea, is undergoing an expansion due to the increasing recognition of its value as a fresh fruit. This study aimed to analyze differences in metabolites and antioxidant activities between the dried fruits of Korean 'Bokjo' landrace and three cultivars of large-sized jujube as part of an effort to evaluate the potential use of wang jujube as a medicinal material and food ingredient. The sugar content was highest in the Cheonhwang, Daeneung, Hwangsil, and Bokjo cultivars, in descending order, while the organic acid content was highest in Daeneung, followed by Cheonhwang, Bokjo, and Hwangsil. The levels of minerals, amino acids, and fatty acids were most abundant in Bokjo, followed by Hwangsil, Daeneung, and Cheonhwang. Phenolic compounds were most abundant in Bokjo, Daeneung, Hwangsil, and Cheonhwang, with rutin and quercetin being predominant in Bokjo, Cheonhwang, and Hwangsil, while Daeneung mainly contained rutin and gallic acid. A principal component analysis revealed that the three large-sized jujube cultivars were compositionally distinct from the traditional Bokjo variety, forming two separate groups: the 'Bokjo-Hwangsil' group and the 'Cheonhwang-Daeneung' group. The overall DPPH antioxidant activity ranged from 66.5 to 70.7%, showing minimal differences across cultivars. The ABTS antioxidant activity ranged from 68.3 to 69.2%, showing no significant variation. Positive correlations were observed