• Journal of Microbiology and Biotechnology
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• v.34 no.6
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• pp.1206-1213
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• 2024

Citrus fruits offer a range of health benefits due to their rich nutritional profile, including vitamin C, flavonoids, carotenoids, and fiber. It is known that unripe citrus has higher levels of vitamin C, dietary fiber, polyphenols, and flavonoids compared to mature fruits. In this study, we assessed the nutritional components of unripe citrus peel and pressed juices, as well as their anti-obesity potential through the modulation of adipocyte differentiation and the expression of adipogenesis-related genes, specifically PPARγ and C/EBPα, in 3T3-L1 preadipocytes. Our analysis revealed that unripe citrus peel exhibited elevated levels of fiber and protein compared to pressed juice, with markedly low levels of free sugar, particularly sucrose. The content of hesperidin, a representative flavonoid in citrus fruits, was 3,157.6 mg/kg in unripe citrus peel and 455.5 mg/kg in pressed juice, indicating that it was approximately seven times higher in unripe citrus peel compared to pressed juice. Moreover, we observed that the peel had a dose-dependently inhibitory effect on adipocyte differentiation, which was linked to a significant downregulation of adipogenesis-related gene expression. Thus, our findings suggest that unripe citrus possesses anti-obesity effects by impeding adipogenesis and adipocyte differentiation, with the peel demonstrating a more pronounced effect compared to pressed juice.

• Korean journal of food and cookery science
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• v.21 no.2 s.86
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• pp.243-249
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• 2005

Citrus juice, a concentrate manufactured by the Jeju Provincial Corporation, was converted into vinegar orderly by alcohol and acetate fermentation. The juice with a 6-fold dilution by distilled water was used as the sole nutrient source throughout the experiments. The diluted juice contained 12.96Brix of total sugar, $0.632\%$ of total acid and $20.23{\mu}g/ml$ of hesperidin. Naringin was not detected from the juice. Citrus wine having $5.6\~6.3\%$ alcohol was produced from the diluted juice after 3 days of fermentation at $28^{\circ}C$. A kind of citrus-malomelo-yeast CMY-28 was used for the wine fermentation. The wine was successfully fermented for 8 days at $30^{\circ}C$ after inoculation of seed vinegar which contained active cells of acid producing bacteria CV1. The inoculum size of the seed vinegar was controlled to $10\%$(v/v) of the citrus wine. The wine was converted into vinegar by the fermentation process. Citrus vinegar, the final fermentation product, was colored with very thin, radish-yellow and was transparent. It's acidity ranged between $5.8\~6.2\%$ of that of acetic acid. The vinegar attained the best score by sensory test among several natural fruit vinegars. It was clear from the results that high quality citrus vinegar could be produced from concentrated citrus juice. However, the fermentation conditions should be improved to reduce the amount of reducing alcohol.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.750-755
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• 1996

Citrus juice was treated with supercritical carbon dioxide $(SC-CO_{2})$ and the effect of temperature and pressure on quality of citrus juice was determined. Pectinesterase (PE) was inactivated by $(SC-CO_{2})$ below temperatures necessary for thermal inactivation. There was no significant change in the pH, Brix and total acidity of citrus juice before and after $(SC-CO_{2})$ treatment, but brightness was improved. More ascorbic acid was retained during $(SC-CO_{2})$ treatment of citrus juice than thermal treatment $(93^{\circ}C/0.66\;min)$.During storage of supercritically treated citrus juice at $4^{\circ}C$, activity of PE was reversible. Sensory evaluation showed that color, flavor, taste and overall acceptance of $(SC-CO_{2})$ treated juice were not significantly different from untreated juice. This method offers potentially beneficial processing avenues for citrus juice and other juices, especially in the area of minimally processed products.

• Culinary science and hospitality research
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• v.15 no.4
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• pp.18-27
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• 2009

In oder to investigate the cooking potentiality for Japanese dishes using domestic Citrus sudachi cultivated in Jeju, sauce making, grilling, steaming, pot-boiling, frying, and sushi/sashimi making were prepared and evaluated. The content of moisture, fat, protein, fiber, carbohydrate, and ash in the Citrus sudachi juice were 91.5%, 0.21%, 0.62%, 0.23%, 5.32%, 0.25%, receptively. The acidity, $^{\circ}Brix$ 7.4, pH of sudachi juice were 5.09%, $^{\circ}Brix$ 7.4, pH 3.02, receptively. In Japanese cuisine, it was possible for sudachi juice to replace vinegar in dressing for raw vegetables, and various sauce for fish dishes such as ponzu, wafu dressing, sushi vinegar and tentsuyu. Among thirteen kind of Japanese cuisine with sudachi juice, broiled mackerel, barbecue, tobinmusi showed high acceptability in the sensory evaluation. The most acceptable recipe of vinegar soy sauce was considered by the ratio of 4(soy sauce) : 3(sudachi juice). In addition, it is possible to use processed good made from the Citrus sudachi juice as all kind of Japanese cooking seasoning. Therefore, imported lemons or limes might be replaced with domestic citrus sudachi cultivated in Jeju.

• Food Science and Preservation
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• v.3 no.1
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• pp.23-32
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• 1996

Total carotenoid contents, color values and spectrum characterization in the range of UV of fruit juice and organic acid and free sugar contents determined by HPLC were investigated on 10 varieties of Cheju citrus fruits. Carotenoid contents of juice were 0.47-9.20$\mu\textrm{g}$/ml which showed higher with Dangyooja while showed lowest content with Meiwa Kumquat. Lightness (L) of juice was highest in Meiwa Kumquat, and in the order of Sankyool, Navel orange and Hungjin. Redness(a) and yellowness(b) were in the order of Dangyooja, Natsudaidai, Sambokam and Kinkoji. The maximum absorption wavelengths if citrus Juices were variable at 269.5-285.5nm according to varieties and it was observed that were changed by mixing with Juices of other varieties. Major organic acids of citrus juice were citric and malic acid, and citric acid was 64.4-95.1% of total organic acids. Ascorbic acid was high in Navel orange, Sudachi and Dangyooja, and low in Meiwa Kumquat and Hungjin. Major free sugars were sucrose, glucose and fructose. Sucrose was 49.2-75.2% of total free sugars, and high in Sankyool and Meiwa Kumquat. Glucose and fructose were high in Meiwa Kumquat and Navel Orange.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.5
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• pp.598-604
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• 2012

Four types of mixed citrus and carrot juice (CCJ) were prepared with citrus-pressed juice and cake, and carrot-pressed juice. Their physicochemical properties and antioxidative activities were investigated. The four types of juices were created using different ratios of citrus-pressed juice, carrot-pressed juice, citrus-pressed cake, and additives. The mixing ratios of the four CCJ were as follows (all ratios given in the order of citrus-pressed juice : carrot-pressed juice : citrus-pressed cake : additives; 70:30:0:0 for CCJ-1, 65:30:0:5 for CCJ-2, 65:30:5:0 for CCJ-3, and 60:30:10:0 for CCJ-4. Acidity was low in CCJ-3 and -4 at 0.82 and 0.80, respectively, compared with 0.95 in CCJ-1. The fructose, glucose, and sucrose content was 2.11~5.76 g/100 g, 1.20~2.75 g/100 g, and 3.00~4.21 g/100 g, respectively. Total phenolic content was 1.17 and 1.22 times high as 863 and 898 mg% in CCJ-3 and -4, respectively, compared with 735 mg% in CCJ-1. DPPH radical scavenging activities of methanol extracts of CCJ-3 and -4 were 3.05 and 3.29 times as high as 58.7% and 63.3%, respectively, compared with 19.2% in CCJ-1. Superoxide anion scavenging activities were also 1.67 and 1.80 times higher in CCJ-3 and -4 than that of CCJ-1. Inhibition of NO production in methanol extracts of CCJ-4 were 1.15 and 1.57 times as high as 20.9% and 28.5%, respectively, compared with 18.2% in CCJ-1. Based on the sensory evaluation, CCJ-3 was more preferable in terms of color, flavor, taste, and overall preference than CCJ-1, -2, and -4. It was concluded that CCJ-3 made with 65% citrus-pressed juice, 30% carrot-pressed juice, and 5% citrus-pressed cake were high in antioxidative activity and the inhibition of NO production, and more preferable in terms of sensory attributes.

• Korean journal of food and cookery science
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• v.21 no.2 s.86
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• pp.263-269
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• 2005

Citrus juice, a concentrate manufactured by the Jeju Provincial Corporation, was converted into vinegar orderly by alcohol and acetate fermentation. The juice with 6 folds dilution by distilled water was used as the sole nutrient source through out experiments. Diluted juice contained $12.96^{\circ}Brix$ of total sugar, $0.632\%$ of total acid and $20.23{\mu}g/m{\ell}$ of hesperidin. Naringin was not detected from the juice. Citrus wine having $5.6\~6.3\%$ alcohol was produced from diluted juice by 3 days of fermentation at $28^{\circ}C$. A kind of malomelo yeast CMY-28 was used for wine fermentation. The wine was succeedingly fermented for 8 days at $30^{\circ}C$ after inoculation of seed vinegar which contained active cells of acid producing bacteria CV1. Inoculum size of seed vinegar was controlled to $10\%$(v/v) of citrus wine. The wine converted into vinegar by the fermentation. Citrus vinegar, the final product of fermentation, was colored with very thin radish-yellow and transparent. It's acidity ranged between $5.8\~6.2\%$ as acetic acid. The vinegar got the best score by sensory test among several natural fruit vinegars. It was clear from the results that citrus vinegar in high quality could be produced from concentrated citrus juice, however fermentation conditions should be improved to reduce the amount of reducing alcohol.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1613-1618
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• 1999

Extracts of Citrus sudachi juice and peel were obtained by several organic solvents such as hexane, acetone, ethyl acetate and methanol. Their antimicrobial spectrum were determined against 14 strains of gram positive and 4 strains of gram negative bacteria by paper disk method and minimal inhibitory concentration (MIC) was also obtained. Antimicrobial activities of solvent extracts from Citrus sudachi juice showed stronger than those of solvent extracts from peel. Acetone extract from juice showed the strongest antimicrobial activity among extracts, but the hexane extract did not show antimicrobial activities on tested target strains. The MIC was differant among tested strains; i.e. 0.5% (v/v) to Bacillus subtilis, 1% to Pseudomonas fragi, 1.5% to Listeria monocytogenes and Escherichia coli O157:H7, 2% to Propionibacterium acnes and Salmonella typhimurium, and 2.5% to Staphylococcus aureus.

• Food Science and Preservation
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• v.4 no.2
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• pp.181-187
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• 1997

New HPLC method was developed for determination of some flavonoids such as naringin, hesperidin, neohesperidin, rutin, quercitrin, naringenin, hesperetin and apigenin and their contents in citrus juice and citrus peel from citrus varieties Brown in Cheju. Detection was at 280nm and reverse phase ${\mu}$-Bondapak C-18 column was used. Water/methanol/acetic acid as the mobile phase was better than water/acetonitrile/acetic acid. Flavonoids were more stable in 20% n,n-dimethylformamide in methanol(20% DMF) than methanol and pH 12 adjusted by 1N-sodium hydroxide solution. Standard flavonoid solutions were injected three times consecutively and the reproduciability was 0.236 to 3.550%, Correlation coefficient of the calibration curve was 0.9946 to 0.9999. The exiraction efficiency of hesperidin from citrus peel was evaluated with different extraction method such as reflux, ultra-sonicating method, using three solvents (aqueous solutions with pH12 adjusted by 1N-sodium hydroxide, methanol and 20% DMF), respectively. The reflux for 4 hour in 20% DMF was the most efficient of the tested methods and solvents, and recovery percentage were 78.0∼130.0%. Flavonoids were determined in citrus juice. Naringin was 68.2mg/100$m\ell$ in Natsudaidai, Hesperidin were 85.6mg/100$m\ell$ in Sankyool and Neohesperidin was 25.3mg/100$m\ell$ in Dangyooja. Flavonoids were determined in citrus peel. Naringin was 110mg/g in Dangyooja, Hesperidin was 242mg/g in Hungjin and Neohesperidin was 87.9mg/g in Dangyooja.

• Food Science and Preservation
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• v.8 no.4
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• pp.442-448
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• 2001

The citrus juice obtained from Jeju mandarines, Citru unshiu, was filtered to remove 20% of its original volume through the hollow fiber ultrafiltration systems equipped with various pore sizes of membranes. As the results of ultrafiltration, the contents of total acids, ascorbic acid, ascorbic acid, free sugars and neohesperidin in retentate showed the tendencies of gradual decreases with the increase of membrane pore sizes from 10K to 100K daltons, but tendencies were inverted when the membrane with 500k was used. The changes of color, soluble solids, total nitrogen, amino-nitrogen, naringin and hesperidin were not consistent with the membrane pore size. Considering all the data obtained using various pen sizes of membranes, the filtration system with NMWC 500K daltons was the most effective to produce citrus juices with hither quality.