• 한국응용곤충학회지
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• 제39권4호
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• pp.259-266
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• 2000

This study was carried out to investigate the status of spot damage by fruit piercing pests and the kinds of these pests on yuzu (Citrus junos) fruit in Koheung, the most chief producing district of yuzu fruit in Korea, from ’97 to ’99. The extent of spot damage by fruit piercing pests on yuzu was increasing in recent years. This damage of fruits was severe in the lower canopy than the high one from ground and intercropping groves between yuzu trees had a greater damage to compare with single cropping of yuzu. Spot damage of yuzu fruit was occurred mainly from late September to early November when yuzu fruit is enlarging and coloring yellow. The blackish concave spot on yuzu fruit surface was appeared in 3 days after introduction of Riptortus clavatus into a netted cage containing one yuzu fruit and the diameters of this spot was 8.3 mm. At 10 days after introduction, this spot changed into milky-white with 9.2 mm diameters. One concave spot has contained oil cells by 17.7 and its external appearances has unchanged until harvest. The kinds of piercing pests of yuzu fruit were investigated with 3 orders, 16 families and 37 species. These pests were classified by 11 species of bugs, 5 species of hoppers and 21 species of moths. Among them, dominant species were Physopelta gutta, Halyamorpha halys, Empoasca vitis, Aedia leucomelas, Agrotis tokionis, etc. Macroglossum bombylans and Acherontia s쇼x are newly confirmed species as the fruit piercing moths in Korea.

• 한국식품영양학회지
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• 제37권2호
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• pp.67-79
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• 2024

Yuzu (Citrus junos) undergoes traditional processing to create preserved yuzu with a sugar content of 50%. This study aimed to produce low-sugar yuzu syrup using artificial or natural sweeteners instead of sugar. Among artificial sweeteners, maltitol showed minimal browning and lack of deposition at high temperatures. The addition of xanthan gum (0.2%) and carboxymethyl cellulose (0.2%) resolved the issue of layer separation and viscosity decrease of yuzu syrup. Alternatively, grain syrup, a natural sweetener, improved viscosity and homogeneity without the additives. Yuzu syrups were developed using yuzu juice and preserved yuzu, with maltitol (20~40%) or grain syrup (50~70%) as the sweetener. Yuzu syrups containing 35% maltitol (M35) or 55% grain syrup (G55) had less than 5% and 10% free sugar, respectively. These syrups exhibited taste patterns similar to commercial yuzu syrup in analysis using an electronic tongue. Furthermore, M35 and G55 contained yuzu flavonoids at concentrations of 19.82 mg/g and 24.09 mg/g, respectively. Antioxidant activity (DPPH, ABTS radical scavenging) of M35 and G55 was equivalent to 10.55, 17.59 mg/100 g of Vitamin C and 97.39, 33.92 mg/100 g of Vitamin C, respectively. Consequently, M35 and G55 offer promising alternatives to preserved yuzu, providing low-sugar yuzu syrups enriched with functional ingredients.

• 한국토양비료학회지
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• 제51권1호
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• pp.28-34
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• 2018

Yuzu (Citrus junos) gummosis disease, caused by Phytophthora nicotianae, was first reported in 1997. As known in citrus, Phytophthora is the most fastidious soil-borne pathogen to control. In order to minimize its damage to Citrus spp., integrated pest management (IPM) approach, including fungicide chemicals and resistant cultivars, is necessary. Therefore, in this study we tried to evaluate tolerance of yuzu cultivars and its related species against yuzu Phytophthora. Trifoliate orange was evaluated as a susceptible host to yuzu Phytophthora by both mycelial growth onto extract media and immature fruit inoculation. However, in zoospores spray-inoculation on 2-year-old cuttings tree, trifoliate orange appeared to have a resistant property as showing less than 6% diseased leaf rate. Among yuzu cultivars only 'Namhae No. 1' appeared resistant property against both P. nicotianae and P. citrophthora. The 'Namhae No. 1' showed 5.7% and 10.6% diseased leaf ratio by P. nicotianae and P. citrophthora, respectively. Clearly, in order to reduce damages caused by two yuzu Phytophthora, we suggest that growers may utilize a trifoliate orange as a rootstock and 'Namhae No. 1' as a scion for fruit production.

• Biomolecules & Therapeutics
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• 제23권2호
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• pp.149-155
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• 2015

Our previous study demonstrated that yuzu has an anti-platelet effect in rat blood. In the present study, we examined whether the anti-platelet effect of yuzu can be extended to human blood by investigating its ability to inhibit aggregations induced by various agonists in human platelet rich plasma (PRP). This study also investigated the underlying mechanism of yuzu focusing on ADP granule secretion, $TXB_2$ formations, and $PLC{\gamma}$/Akt signaling. The results from this study showed that ethanolic yuzu extract (YE), and its components, hesperidin and naringin, inhibited human platelet aggregation in a concentration-dependent manner. YE, hesperidin and naringin also inhibited $TXB_2$ formation and ADP release. The phosphorylation of $PLC{\gamma}$ and Akt was significantly inhibited by YE, heperidin and naringin. Furthermore, we demonstrated that YE, heperidin and naringin has anti-platelet effects in rat ex vivo studies, and lower side effects in mice tail bleeding time studies. The results from this study suggest that YE, hesperidin and naringin can inhibit human platelet aggregation, at least partly through the inhibition of $PLC{\gamma}$ and Akt, leading to a decrease in $TXB_2$ formation and granule secretion.

• 한국식품영양학회지
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• 제37권3호
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• pp.129-138
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• 2024

In this study, in order to develop an foaming tablet product using yuzu powder, yuzu powder was manufactured using different drying methods such as freeze-drying, 60℃ drying, and 40℃ drying, and then quality characteristics and functionality were analyzed. The naringin content per g of yuzu powder was 8.9 mg for freeze-drying and 8.8 mg for 60℃ drying, and the hesperidin content per g of yuzu powder was highest at 53.6 mg for freeze-drying and 46.2 mg for 60℃ drying. followed by 40℃drying (41.7 mg). The tyrosinase inhibitory activity of 60℃ dried powder was found to be twice as high as that of freeze dried powder. Accordingly, in order to develop an inner beauty product, foaming tablets were manufactured using hot air dried powder, and the quality characteristics and functional ingredients of the final foaming tablets were investigated. The foaming tablet prepared with yuzu powder content of 10 and 15% showed an inhibitory activity of tyrosinase of 73.7 %, which was 1.6 times higher than that of ascorbic acid (1 mM), which was a positive control, confirming its melanin production inhibition effect.

• 한국식품저장유통학회지
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• 제21권6호
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• pp.799-807
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• 2014

본 연구는 유자즙의 첨가량을 달리한 마요네즈의 저장기간 중 항산화 활성 및 품질특성 변화를 비교하여 마요네즈의 저장성을 알아보고자 실시하였다. 점도는 유자즙 첨가군이 대조군에 비하여 유의적으로 높은 점도를 나타내었다(p<0.05). 색도에서 유자즙 첨가군의 L값은 대조군에 비하여 낮았으며, 저장기간이 지남에 따라 유의적으로 감소하였다(p<0.05). a값은 b값의 경우, 유자 마요네즈는 유자즙의 첨가량이 많아질수록 b값이 증가하였으며, 저장기간이 지남에 따라 Y-100군 및 L-100군은 b값의 감소를 나타내었다(p<0.05). ${\Delta}E$값은 유자즙 첨가량이 증가할수록 유의적으로 증가하였다(p<0.05). 대조군의 DPPH 라디컬 소거능은 35.90%이었으며, 유자즙 첨가군은 41.74~55.16%로 대조군에 비하여 높게 측정되었고 유자즙 첨가량이 많아질수록 라디컬 소거능이 유의적으로 증가하였다(p<0.05). 모든 실험군의 라디컬 소거능은 저장기간이 지남에 따라 감소를 보였으나, 유자즙 첨가군은 대조군에 비하여 높은 DPPH 라디컬 소거능을 보였다(p<0.05). 유자즙 첨가군의 산가는 대조군에 비하여 유자즙 첨가량이 증가할수록 낮은 산가를 나타내었고, 저장기간이 지남에 따라 산가가 증가하였으나 유자즙 첨가군이 대조군보다 낮은 산가를 나타내었다(p<0.05). 과산화물가도 산가와 같은 결과를 보였는데, 이는 첨가된 유자즙이 마요네즈 안에서 천연 항산화제 역할을 하여 유지의 산패를 억제한 것으로 보인다. 이러한 결과로 마요네즈 제조 시 유자즙의 첨가는 마요네즈의 항산화성을 높이고 저장 중의 산화안정성을 향상시켜 저장성 및 품질개선에 도움이 될 수 있을 것으로 사료된다.

• 한국식품저장유통학회지
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• 제11권1호
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• pp.38-41
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• 2004

유자 착즙액에 naringiase와 탁주용 당화 효소 3% 처리 결과 naringin과 hesperidin의 함량이 61.94 mg%, 9.98 mg%에서 각각 8.43 mg%, 0.06 mg%와 6.58 mg%, 1.11 mg% 감소하였다. Hunter value를 측정한 결과 적색도/녹색도(a값)는 효소처리구 모두 대조구보다 높게 나타났고, 황색도(b값)와 명도(L값)는 탁주용 당화 효소가 가장 높았다. 복합 효소 처리후 실제 관능적으로 고미제거에 대한 효과와 선호도를 조사한 결과는 각 제조사별 복합효소를 처리한 시료구가 대조구보다 전체적으로 선호도가 높았고, naringin의 함량이 적을수록 기호도는 증가하였다. 호소의 최적 첨가량은 3% 내외가 바람직한 것으로 사료된다.

• 한국식품영양학회지
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• 제36권4호
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• pp.236-243
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• 2023

The purpose of this study was to investigate the effects of sterilization, storage period and washing yuzu, according to the washing method, during the storage period. The results showed that the fungus size increased as the storage period increased, and no mold occurred in the yuzu washed with ozone water until 20 days. After 30 days of storage, a mold of 124.1±13.9 mm² was observed. The no-treatment sample had a fungus of 814.5±72.8 mm² in size on day 0 and the fungus the largest fungus was 6,362±636.7 mm² on day 30. In the case of water treatment, the fungus was 286.4±31.5~4,836.4±484.6 mm² in size. The results of the study confirmed that washing yuzu with ozone water has a sterilizing effect.

• The Plant Pathology Journal
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• 제31권3호
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• pp.290-298
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• 2015

Starting in 2012, severe diebacks usually accompanied by abundant gum exudation have occurred on yuzu trees in Goheung-gun, Jeonnam Province, where severely affected trees were occasionally killed. On-farm surveys were conducted at 30 randomly-selected orchards located at Pungyang-myeon, Goheung-gun, and the resulting disease incidences were 18.5% and 39.6% for dieback and gumming symptoms, respectively. Black spots on branches and leaves also appeared on infected trees showing a typical dieback symptom. Morphological and molecular identifications of the isolated fungal organisms from lesions on the symptomatic leaves and branches revealed that they are identical to Phomopsis citri, known to cause gummosis. In order to find the reason for this sudden epidemic, we investigated the weather conditions that are exclusively distinct from previous years, hypothesizing that certain weather extremes might have caused the severe induction of pre-existing disease for yuzu. There were two extreme temperature drops beyond the yuzu's cold hardiness limit right after an abnormally-warm-temperature-rise during the winter of 2011-12, which could cause severe frost damage resulting in mechanical injuries and physiological weakness to the affected trees. Furthermore, there was an increased frequency of strong wind events, seven times in 2012 compared to only a few times in the previous years, that could also lead to extensive injuries on branches. In conclusion, we estimated that the possible damages by severe frost and frequent strong wind events during 2012 could cause the yuzu trees to be vulnerable to subsequent fungal infection by providing physical entries and increasing plant susceptibility to infections.

• 식물병연구
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• 제25권2호
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• pp.71-78
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• 2019

2018년 전남 고흥군에서 발생한 유자나무의 집단 고사가 발생했다. 이에 대한 원인 조사를 위해 고흥군 풍양면에 있는 18개 유자 과수원을 무작위로 선정하여 조사를 수행한 결과 과수원별 고사증상을 보인 나무의 비율은 평균 43.6%(7.5%~100% 피해율), 증상을 보인 나무 중 56.5%는 나무 전체가 완전 고사되는 피해를 입은 것으로 나타났다. 고사 증상을 보인 대부분의 유자나무에서는 동해의 전형적인 증상인 표피 안 형성층과 목부의 갈변, 잎눈과 꽃눈의 무 발아, 가지나 줄기에 쪼개짐 증상 등이 관찰되었다. 따라서 기상 조건과 유자나무의 고사 증상이 연관 되어있을 것이라는 가설을 바탕으로 고흥지역의 과거 기상 자료를 분석하였다. 2017년 1월과 2월 고흥지역의 일평균 기온은 $-10^{\circ}C$ 이상이었으나, 2018년의 동 기간에는 $-10^{\circ}C$ 아래로 떨어진 날이 7일이나 되었다. 특히 2018년에는 1월과 2월에 유자의 내한성을 훨씬 넘어선 극최저기온(각각 $-12.6^{\circ}C$와 $-11.5^{\circ}C$)이 관측되었다. 또한 그해 3월 중순과 4월 초에 일 최저기온이 $13^{\circ}C$로 상승한 이상고온 직후 급격히 기온이 $0^{\circ}C$로 떨어지는 현상이 발생하였다. 결론적으로, 2018년 겨울철에 기록적인 극최저기온과 이상고온에 이은 급격한 기온의 저하로 인한 동해가 고흥지역에 대발생한 고사증상의 주요 원인이 되었을 것으로 추정하였다.