• Food Science and Preservation
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• v.18 no.3
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• pp.310-318
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• 2011

The main objective of this study was to manufacture black onions using different methods, and to analyze the color and physiological and antioxidant activities of their water extracts. Black onions were produced via high-temperature aging (70, 80, and $90^{\circ}C$). At $90^{\circ}C$, onions with different weights (large, 90-L; medium, 90-M; and small, 90-S) and small onions with different appearances (whole, 90-S-W; cut, 90-S-C; and peeled, 90-S-P) were also produced. The colorimetry measurements showed that the extract from the 90-S-C black onion had the highest ${\Delta}E$ value among all the extracts from all the black onion groups. The extract from the 90-S-C black onion had a 3.3 times higher total phenol content than that from the $70^{\circ}C$ black onion extract (11.62 and 3.51 mg/g, respectively). The DPPH radical scavenging activities of the extracts from 90-S-W, 90-S-C, and 90-S-P were higher than those of the other black onion extracts, and the 90-S-C black onion extract had the highest level of 48.3% (at the concentration of 10 mg/ml). The 90-S-C black onion extract also had the highest level of antioxidant activities (ABTS radical scavenging activity, 0.84 mg AA eq/100 g, and nitrite scavenging ability, 49.8%). These results clearly demonstrated that 90-S-C was the best among the conditions used and that the water extract of the 90-S-C black onions had a significantly higher level of antioxidant activities than the extracts from the other black onions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.5
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• pp.648-654
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• 2010

This study investigated the antioxidant activities and antimicrobial effects of MeOH extracts from some spices. The total flavonoid contents of MeOH extracts from ginger, garlic, onion, Chinese pepper (Zanthoxylum schinifolium) and black pepper (Piper nigrum) were 20.3%, 10.0%, 4.3%, 6.6% and 12.8%, while the total phenol contents were 19.3%, 1.0%, 0.5%, 3.4% and 7.9%, respectively. The order of the nitrite-scavenging abilities of spice extracts were ginger> black pepper> Chinese pepper> garlic> onion (p<0.05). MeOH extract from ginger showed antimicrobial activity to Bacillus cereus, and garlic extract showed strong antimicrobial activity to Salmonella enteritidis. However, onion extract did not show any antimicrobial activity. The electron donating ability of MeOH extract from ginger was markedly higher than those of garlic, Chinese pepper, black pepper and onion extracts. Antioxidative activities in linoleic acid substrates were in order of BHT> ginger> Chinese pepper> black pepper> garlic> $\alpha$-tocopherol> onion. Antioxidative activities in linoleic acid emulsion substrates were in order of BHT> $\alpha$-tocopherol> ginger> black pepper> Chinese pepper> garlic> onion.

• Journal of Life Science
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• v.21 no.12
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• pp.1740-1745
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• 2011

Volatile flavor compounds of 3 commercial products of black onion extract (produced in Changnyeong, Muan and Jeungpyeong) purchased in the online/offline markets were analyzed. A total of 51 compounds were detected in samples by solid phase microextraction (SPME)/GC/MSD, consisting mainly of carbonyl compounds (15), sulfur-containing compounds (8), aromatic compounds (6), furans (6), nitrogen-containing compounds (3), alcohols (2), acids (2) and miscellaneous compounds (10). Among carbonyls, 4 compounds including 2-methylbutanal, 3-methylbutanal, nonanal and benzaldehyde were detected in all samples, while two sulfur containing compounds, dimethyl disulfide and dimethyl trisulfide, were detected in high amounts and considered to be key flavors in black onion extracts. Particularly, thiophenes and 3 sulfur containing compounds (methylpropyl disulfide, methyl-(Z)-propenyl disulfide and methyl-(E)-propenyl disulfide) were detected only in two products. With acetic acid, furfural and pyrazines that formed through Maillard reaction during black onion aging were detected in high amounts in all samples. This also contributed to characteristic flavors such as roasted, sweet, and sour, in the flavor of black onion extracts.

• Food Science and Preservation
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• v.18 no.6
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• pp.954-960
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• 2011

The antioxidant activities of the ethanol, methanol, and water extracts of black onion were investigated. The highest extraction yield (28.56%) and total polyphenol content (13.5 mg/g) were found in the water extract. The water extract also showed the highest protective effect on the RAW 264.7 cell anti-inflammatory activity, and the water and ethanol extracts showed the highest reducing power. The water extract showed higher DPPH and ABTS radical scavenging activities (65.98 and 89.69%, respectively) than the other solvent extracts (ethanol, 47.77%; methanol, 66.12%). Hence, black onion can be used as a potent natural antioxidative source.

• Journal of Nutrition and Health
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• v.41 no.6
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• pp.493-501
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• 2008

The objectives of this study were to investigate the antihyperglycemic and hypolipidmic effects of sea oak(Eisenia bicyclis, EB) in the diabetic state and to examine the appropriateness of formulated EB pill for the effects. The various test materials obtained from EB were included in the experimental diets with 15% fat/0.5% cholesterol and fed to streptozotocin-induced diabetic mice weighing $35.0{\pm}0.7$ g for three weeks but not in the control diet having the same composition. The test materials were EB dry powder, water and ethanol extracts, viscozyme-treated EB water extract(EB enzyme-TR) and formulated pill containing dry powders of the EB, two kinds of seaweed, black soybean, sesame, onion and garlic. BG was measured during feeding period and serum insulin, lipids and thiobarbituric acid reactive substances(TBARS) and intestinal disaccharidase activities were measured at the end of the three weeks of the feeding. BG increase was lower in the EB enzyme-TR group after 10 days of the experimental diet but lower in EB pill group after 15 days compared with the control group. Serum insulin levels were higher in the EB enzyme-TR and EB pill groups. Intestinal maltase but not sucrase activity was higher in EB enzyme-TR fed group than the control group. Serum levels of total cholesterol and triglyceride were reduced by the EB enzyme-TR and EB pill compared with the control diet. HDL-/total cholesterol was increased by all EB test materials. Serum TBARS levels were lower in the EB ethanol extract and EB pill groups than in the control group and tended to be lower in the other EB groups. It is concluded that the EB enzyme-TR is the best among the EB preparations to be utilized as a functional component for improving blood glucose and lipid profile in diabetic subjects in the future. However, the pill containing low level of the EB powder is also regarded as effective and readily usable when formulated with the several other ingredients of the proper composition.(Supported by the RIC Program of MOCIE, Korea).