• 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 Life Science
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• v.21 no.3
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• pp.464-467
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• 2011

Quercetin is a major flavonoid present in onions, which acts as an antioxidant. Quercetin exists both as a free compound and conjugated with carbohydrates, primarily as glucosides in onion. Aged black onion was made through a 30 day aging process in which the onions were kept in an environment of $60^{\circ}C$ and high humidity (90% RH). Quercetin and quercetin glucosides were assayed in onion bulbs before and after the aging process, using high performance liquid chromatography-electrospray ion trap mass spectrometry (HPLC-ESI/MS/MS). Quercetin mono- and diglucosides were identified in fresh onion bulbs, whereas quercetin aglycone was the only form present in aged black onion bulbs. These findings indicate that the quercetin mono- and di-glucosides present in fresh onions undergo complete deglycosylation during the aging process. Such profiling will provide a rapid method that can be used to assess changes in the two major quercetin glycosides during the aging process of onion bulbs.

• 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.

• Preventive Nutrition and Food Science
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• v.18 no.3
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• pp.169-174
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• 2013

The acute and subacute hypoglycemic and antihyperglycemic effects of drinkable ripe onion juice (Commercial product name is "Black Onion Extract") were investigated in normal and streptozotocin-induced diabetic rats. For tests of acute and subacute hypoglycemic effects, ripe onion juice (5 and 15 mL/kg b.w.) was administered by oral gavage to normal Sprague Dawley rats and measurements of fasting glucose levels and oral glucose tolerance tests were performed. Tolbutamide was used as a reference drug at a single oral dose of 250 mg/kg b.w. To test anti-hyperglycemic activity, the ripe onion juice was administered to streptozotocin-induced diabetic rats by oral gavage at single dose of 15 mL/kg b.w. per day for 7 consecutive days. Oral administration of the ripe onion juice at either dosed level of 5 or 15 mL/kg b.w. showed no remarkable acute hypoglycemic effect in normal rats. The two dosed levels caused a relatively small reduction, only 18% and 12% (5 and 15 mL/kg b.w., respectively) decrease in glucose levels at 2 h after glucose loading in normal rats. However, at 3 h after glucose loading, blood glucose levels in the ripe onion juice-dosed rats were decreased to the corresponding blood glucose level in tolbutamide-dosed rats. Although showing weak hypoglycemic potential compared to that of tolbutamide, oral administration of ripe onion juice (15 mL/kg b.w.) for a short period (8 days) resulted in a slight reduction in the blood glucose levels that had elevated in Streptozotocin-induced diabetic rats. In conclusion, these results suggest that the commercial product "Black Onion Extract" may possess antihyperglycemic potential in diabetes.

• 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.

• Food Science and Preservation
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• v.19 no.2
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• pp.229-234
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• 2012

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.

• 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.

• Korean journal of food and cookery science
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• v.15 no.6
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• pp.595-602
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• 1999

This study was intended to develop traditional Korean soup recipe which can be used for food service and meet consumers' taste with a focus on clear soup such as clear radish soup, sea mustard soup, dried pollack soup, croaker soup, and backbone soup. The developed sample(S1) showed the highest level of overall preference among consumers. There were significant differences in sensory characteristics of the samples especially between S1 and others. The sensory characteristics of each soup showed a slight difference depending on the kind of soup, however, all items had an effect on overall preference. One of the standardized recipe to make broth was presented as follows: The ingredients for broth consists of the shank or brisket of beef(100 g), water(10 cup), spring onion(20 g), onion(30 g), garlic(10 g), salt(1 teaspoonful), and black pepper power(1/10 teaspoonful). 1) The meat part of shank or brisket is prepared. 2) The unfrozen meat is immersed in cold water for 20 min, whereby blood is extracted from the meat. 3) 10 cups of water are poured into the pan and boiled enough. 4) After water has boiled enough, the lump of meat with blood extracted is cut into 2 or 3 pieces and is boiled in the boiling water by high-intensity heat with the pan lid uncovered, and dirty foam is scooped out while boiling. 5) If the broth begins to be extracted, the intensity of heat is lowered for boiling for one hour or so, and then again boiled for 30 min with spring onion, garlic, onion and the like. If the broth is extracted enough, spring onion, garlic, onion, and others are removed from the pan. the broth is seasoned with salt and black pepper powder, and foam is removed by using fine mesh sieve or gauze. Then, 6 cups of clear broth is obtained finally.

• Food Science and Preservation
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• v.21 no.1
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• pp.46-54
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• 2014

Yellow and black soybean Cheonggukjangs (YBSC) prepared with an addition of onion (Allium cepa L.) in different contents (0, 5, 10, 20, and 30%, w/w) were manufactured, and the sensory evaluation was carried out. The optimum addition ratio of onion was determined to be 20%. Total phenolic and flavonoid contents of YBSC prepared with an addition of onion were higher than those of the YBSC prepared without an onion. In addition, YBSC prepared with an addition of onion showed higher 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activities than those prepared without an onion. Furthermore, rat blood plasma 1 hour after oral administration of YBSC prepared with an onion was more effective in suppressing the accumulation of cholesteryl ester hydroperoxide than those prepared without onion and control. These results indicated that the consumption of the YBSC prepared with onion may contribute to the antioxidant defense in vivo.

• Microbiology and Biotechnology Letters
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• v.8 no.3
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• pp.155-166
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• 1980

Studies have teen undertaken to investigate the degree of microbial contamination in the subsidiary materials which have been known as an important source of microorganisms associated with spoilage of fish sausage and fish paste products. Twenty hinds of food ingredients including starch, spices and condiments, 59 samples in total collected from commercial fish sausage processing plants and supermarket in the period of July to October 1979, were examined for standard plate count, coliform and fecal coliform, mold and yeast, thermoduric microorganisms, aerobic sporeformers (mesophilic and thermophilic), anaerobic sporeformers (mesophilic and thermophilic) and sulfide spoilage anaerobes. The results obtained are summarized as follows. 1. Among the food ingredients examined, corn starch, black pepper, hot pepper, onion, garlic, ginger, beef extract and frank marked high bacterial contamination with general and sporeforming microorganisms. And bacterial content of marked samples were generally higher than that of the samples from plants. 2. The high standard plate count caused by high content of these bacteria like thermoduric, mesophilic or thermophilic sporeforming aerobes. 3. Bacterial content of food ingredients such as black pepper and beef extract being used in plants, and black pepper, hot pepper, onion and garlic from the market were exceeded the bacterial standards being enforced in Japan and U. S. A. 4. Average standard plate count was in the range of 10$^4$to 10$^{5}$ /g for black pepper, wheat flour, onion and garlic collected from plants, and 10$^{5}$ to 10$^{7}$ /g for black pepper, hot pepper, onion and garlic from market. No plate count was observed in pepper essence and coloring material. 5. Coliform organism was detected in starch, black pepper, hot pepper, onion, garlic, ginger and gluten that showed high standard plate but no fecal coliform in the samples except black pepper and hot pepper. 6. Average mold and yeast count was 140 to 460/g for corn starch, wheat flour and black pepper from plants, and 10$^3$/g for black pepper and hot pepper from market. No count was observed in the other ingredients. 7. Sulfide spoilage sporeforming anaerobes boiled for 5 min. at 10$0^{\circ}C$ and incubated at 55$^{\circ}C$ was not detected in all the samples examined.