• Korean Journal of Food Science and Technology
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• v.9 no.4
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• pp.245-250
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• 1977

Experiment were conducted to find out the effective drying method of citrus peel produced in Korea by varying the temperature of hot air, surface area of peels, peels from several citrus varieties and physicochemical treatment of the peel. 1. About $3{\sim}6\;days$ were required to reduce the moisture level of the peel from 70%(wet basis) to 20% at room temperature without forced convection. 2. Drying was speeded up until the temperature of hot air reached $60^{\circ}C$. Beyond that no significant increase in drying rate was observed. About 50 minutes were needed to reduce the moisture level (dry basis) to below 10% at $60^{\circ}C$ by forced convection 3. When the peel surface area was increased twice by cutting the peel into 256 fractions, the overall drying time (the time required to reduce the moisture level to 10%, dry basis) was shortened to 15 minutes from 50 mintes of the original peel. 4. No significant difference in drying rate was observed among the peels from several citrus varieties except Shaddock jabon and Citrus ponki tanaka, which dried more slowly than others. 5. Treatment of $Ca(OH)_2$ and the pressing of the peel before drying were effective in drying only when the initial moisture content was substantially higher.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1178-1183
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• 1999

Essential oils were isolated from the peel of mandarin (Citrus unshiu Marc. Var. Okitsu) cultivated in Cheju Island. Among three different isolation methods investigated, simultaneous distillation gave higher yield 1.14%(w/w) than solvent extraction or cold pressing. The densities of essential oils were between 0.8409 and 0.8530, which showed no significant effect of the isolation methods. Some variations in the number of constituents detected and the content of d-limonene in the peel oils were observed depending upon the isolation methods. The citrus fruit was collected seasonally from the field and used as a sample for analysis. The peel thickness and the peel content of citrus fruit were around 2 mm and about 17% on wet weight basis, respectively, in harvest season. The maximum yield of essential oils was obtained in September from citrus peels just prior to ripeness and thereafter the yield had a tendency of decrease but remained over 1%(w/w). The relative content of d-limonene, the major constituent of citrus peel oils. increased gradually with ripening up to 68.69%(relative peak area, RPA). The other minor constituents were ${\gamma}-terpinene,\;{\beta}-elemene$, farnesene, hexadecanoic acid, ${\alpha}-pinene,\; {\beta}-myrcene$ and linalool in the decreasing order of their own contents of 7.75, 2.96, 2.29, 1.76, 1.63, 1.56 and 1.46%(RPA).

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1237-1242
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• 2009

Polymethoxylated flavones (PMFs) extracted from Citrus sinensis 'Jincheng' peel were characterized by chromatographic and spectroscopic techniques. Seven individual PMF were identified. 3, 3', 4', 5, 6, 7-hexamethoxyflavone (HEX), nobiletin (NOB), heptamethoxyflavone (HEP), 5-demethylnobiletin (DN), and tangeretin (TAN) were characterized through electrospray ionization mass spectrometry (ESI-MS) in positive mode of protonated molecular ions $[M+H]^+$, the diagnostic fragment ions, together with the UV-Vis spectra and high performance liquid chromatography (HPLC) elution order from literature data. Sinensetin (SIN) and tetramethyl-O-scutellarein (SCU) were isolated and identified through their MS, $^1H$ nuclear magnetic resonance (NMR) and UV-Vis spectral studies. The levels of PMFs in peels from different cultivars of citrus fruits grown in China were determined for the first time. The results showed that C. aurantium 'Bitter orange' peel was the most promising variety for HEP. C. sinensis peel was a good source for SIN and SCU.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.3
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• pp.331-337
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• 2015

Citrus and its peels, which are by-products from juice and/or jam processing, have long been used in Asian folk medicine. Citrus peels show an abundant variety of flavanones, and these flavanones have glycone and aglycone forms. Aglycones are more potent than glycones with a variety of physiological functions since aglycone absorption is more efficient than glycones. Bioconversion with cytolase converted narirutin and naringin into naringenin and hesperidin into hesperetin. Therefore, this study aimed to investigate the anti-oxidant and anti-inflammatory effects of bioconversion of Citrus unshiu (CU) peel extracts with cytolase (CU-C) in RAW264.7 cells. HPLC chromatograms showed that CU and CU-C had 23.42% and 29.39% total flavonoids, respectively. There was substantial bioconversion of narirutin to naringenin and of hesperidin to hesperetin. All citrus peel extracts showed DPPH scavenging activities in a dose-dependent manner, and CU-C was more potent than intact CU. RAW264.7 cells were pre-treated with $0{\sim}500{\mu}g/mL$ of citrus peel extracts for 4 h and then stimulated by $1{\mu}g/mL$ of lipopolysaccharide (LPS) for 8 h. All citrus peel extracts showed decreased mRNA levels and protein expression of LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner. Especially, CU-C markedly inhibited mRNA and protein expression of iNOS and COX-2 compared to intact citrus peel extracts. All citrus peel extracts showed decreased NO production by iNOS activity. This result suggests that bioconversion of citrus peel extracts with cytolase may provide potent functional food materials for prevention of chronic diseases attributable to oxidation and inflammation by boosting the anti-inflammatory effects of citrus peels.

• Food Science and Preservation
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• v.9 no.4
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• pp.411-417
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• 2002

Effect of temperature(room temperature and boiling) and content of citrus peel(0.1∼6.0%) on the extractable hesperidin and naringin in the vinegars(apple, brown rice and persimmons) and also, dietary effect in hyperpiesia rats on blood pressure, biochemical changes were investigated. Extractable amounts of hesperidin and naringin in persimmons and brown rice vinegar were higher than those of apple vinegar in the both extraction of room temperature and boiling. Hesperidin and naringin contents showed highest in the one day extraction at room temperature when citrus peel was below 1% but, 3∼5 days extraction was optimum when the peel was above 2%. Hesperidin and naringin contents showed maximum at 2 hours extraction in case of boiling. Neutral lipids, total cholesterol and LDL cholesterol in blood, and blood pressure(reduction of 10.7∼33.2 mmHg) of the hyperpiesia rats took in 0.5% apple vinegar with 0.2, 0.4 and 0.6% citrus peel powder for 4 weeks were lower or reduced than those of control groups. But HDL cholesterol was higher than that of control groups.

• Journal of Physiology & Pathology in Korean Medicine
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• v.38 no.1
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• pp.10-15
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• 2024

Previous studies have highlighted the pivotal role of the β-adrenergic receptor (β-AR) signaling pathway in stimulating cancer metastasis induced by chronic stress. According to the theory of traditional Korean medicine, chronic stress can induce Qi stagnation. Based on the traditional role of premature citrus unshiu peel in moving Qi, we hypothesized that an ethanol extract of premature citrus unshiu peel (EPCU) can attenuate chronic stress-induced cancer progression. In this study, we investigated the potential role of EPCU on modulating the adrenergic agonists-induced metastatic properties of liver cancer cells. Our findings revealed that adrenergic agonists, including norepinephrine (NE), epinephrine (E), and isoproterenol (ISO), augmented the migratory capacity of Hep3B human hepatocellular carcinoma cells, which was completely abrogated by EPCU treatment in a concentration-dependent manner. Consistently, EPCU inhibited the E-induced invasive property of Hep3B cells in a dose-dependent manner. These results suggest that EPCU efficiently attenuates adrenergic agonists-induced metastatic abilities of liver cancer cells. As a molecular mechanism, EPF suppressed the phosphorylation of major components of β-AR signaling pathway, including Src, signal transducer and activator of transcription 3 (STAT3) and ERK, induced by E treatment. Taken together, our results demonstrate that EPCU impedes the adrenergic agonists-driven metastatic potential of cancer cells by inhibiting β-AR signaling pathway. This study provides basic evidence supporting the probable use of premature citrus unshiu peel to prevent metastasis in liver cancer patients under chronic stress.

• Food Science and Biotechnology
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• v.16 no.2
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• pp.311-314
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• 2007

Citrus sunki Hort. ex Tanaka is one of several Jeju-native citrus fruits. A number of biological properties for citrus fruits have been suggested, however little is known about those of C. sunki. The present study tested whether fermented product of C. sunki peel (FSP) might affect the activities of enzymes regulating ethanol metabolism. Effects on body weight gain as well as on fatty liver formation were also investigated. The activities of alcohol dehydrogenase and aldehyde dehydrogenase were stimulated remarkably by FSP. Excessive ethanol-induced cytotoxicity was also prevented by FSP in HepG2 cells. FSP decreased the weight gain and fatty liver formation induced by a high-fat diet in mice. From these results, FSP might be a potent source of neutraceuticals useful for preventing ethanol-induced health problems.

• Journal of Environmental Science International
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• v.16 no.11
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• pp.1279-1285
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• 2007

The activated carbon was prepared from waste citrus peels using NaOH. With the increase of NaOH ratio, iodine adsorptivity and specific surface area of the activated carbon prepared were increased, but activation yield was decreased. The optimal condition of activation was at 300% NaOH and $700^{\circ}C$ for 1.5 hr. For the activated carbon produced under optimal condition, iodine adsorptivity was 1,006 mg/g, specific surface area was $1,356 m^2/g$, and average pore diameter was $20{\sim}25{\AA}$. From the adsorption experiment for benzene vapor in fixed bed reactor, it was found that the adsorption capacity of activated carbon prepared from waste citrus peel was higher than that of activated carbon purchased from Calgon company. This result implied that the activated carbon prepared from waste citrus peel could be used for gas phase adsorption.

• Journal of Life Science
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• v.19 no.8
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• pp.1081-1087
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• 2009

In this study, the effects of feeding citrus peel on the nutritional composition of chicken meat were investigated. The samples consisted of chicken meats provided with only feed for laying hens without citrus peel (CP-0), and chicken meats fed with 1.0%, 1.5% and 2.0% citrus peel during the starter (initial period feed; 1${\sim}$9th day), the grower (middle period feed; 10${\sim}$24th day), and the finisher (latter period feed; 25${\sim}$36th day), respectively. There was no significant difference between CP-0 and CP-1 regardless of feeding citrus peel in terms of chicken's moisture, protein, fat, ash or caloric content. The cholesterol content was significantly lower in the CP-1 chicken meats than in the CP-0 chicken meats (p<0.05). The K P and Ca contents were significantly higher in the CP-1 chicken meats than in the CP-0 chicken meats (p<0.05), but there were no significant differences between CP-0 and CP-1, regardless of feeding citrus peet in terms of chicken meat's Na and Mg. There were no significant differences between CP-o and CP-1 regardless of feeding citrus peet in terms of chicken meat's vitamin A, xanthophyll, ${\beta}$-carotene, hesperidin or naringin, but vitamins $B_1$ and $B_2$ were significantly higher in the CP-1 chicken meats than in the CP-0 chicken meats (p<0.05). There were no significant differences between CP-0 and CP-1 regardless of feeding citrus peet in terms of chicken meat's amino acid composition - most of free amino acids and fatty acid composition - but L-glutamic acid was significantly higher in the CP-0 chicken meats than in the CP-1 chicken meats, and the DL-${\beta}$-amino isobutyric acid was significantly higher in the CP-1 chicken meats than in the CP-0 chicken meats (p<0.05).

• Journal of Food Hygiene and Safety
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• v.26 no.4
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• pp.355-360
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• 2011

This study was performed to investigate the antioxidant effects of 4 citrus fruits including Hallabong, Cheonhyehyang, Cheonggyeon, and Jinjihyang. In this study the citrus fruits were separated in three parts of peel, pulp segment membrane (PSM), and pulp and extracted with methanol, then concentrated using a rotary vacuum evaporator. Total polyphenol contents ranged 23.497~42.341 mg/g in peel, 13.285~21.872 mg/g in PSM and 6.333~11.627 mg/g in pulp of the citrus fruits. The total polyphenol contents were highest in the peel and PSM of Jinjihyang and in the pulp of Cheonhyehyang. 1,1-diphenyl-2picryl hydrazyl (DPPH) radical scavenging activities were highest in the peel and PSM of Jinjihyang and in the pulp of Cheonhyehyang. 2,2'-Azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacities were also highest in the peel and PSM of Jinjihyang and in the pulp of Cheonhyehyang. Reducing powers were highest in the peel of Cheonggyeon, in the PSM of Jinjihyang, and in the pulp of Cheonhyehyang. There were significant correlations in between total polyphenol contents and the radical scavenging activities, and reducing power each other. These results indicate that the 4 citrus fruits (Hallabong, Cheonhyehyang, Cheonggyeon, and Jinjihyang) evidently have antioxidant capacities and their peel parts have the highest antioxidant activities.