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.

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 purpose of this study was to investigate at how the quality of citron changed during storage as a result of the browning inhibitor treatment. In the browning inhibitor treatment, Vit.C, Vit.C+NaCl, Vit.C+NaCl+CD substances were used. As a result of investigating the browning degree, Vit.C+NaCl+CD showed the lowest value of 0.76 when stored for 12 weeks. The ΔE of the chromaticity value indicated that significant color change occurred when the value was high. As the Vit.C+NaCl+CD mixture showed the lowest value of 46.01 at 25℃, it was found that browning did not occur much compared to other treatments. The change in polyphenol oxidase (PPO) activity of citron increased as browning progressed. Among the browning inhibitor solutions, Vit.C+NaCl+CD solution showed the lowest value 118.8 u/g at 25℃ after 12 weeks. Based on these findings, it seems that CD mixing solution can be used as a citron browning inhibitor.

최근 기후변화와 더불어 국제 교역량, 여행객 및 외국 이주민 등의 증가로 인해 국내 농작물에 큰 피해를 입힐 수 있는 고위험 식물 병의 유입 사례가 꾸준히 증가하고 있는 추세다. 특히, ‘Candidatus Liberibacter asiaticus’가 원인병원균인 감귤황룡병의 경우, 발생하게 되면 감귤과원에 큰 피해를 야기한다. 이에 본 연구에서는 아직까지 국내 유입되지 않은 감귤황룡병과 매개충인 아시아감귤나무이(Asian citrus psyllid; ACP; Diaphotima citri)에 대한 예찰 조사를 남부지역에 집중된 유자 재배지 중심으로 수행하였다. 유자는 감귤황룡병의 기주가 될 수 있는 운향과(Rutaceae)에 속하는 작물로 기후 특성상 우리 나라 전라남도와 경상남도 해안지역을 중심으로 주로 재배되고 있다. 예찰 조사는 전남과 경남에 속하는 각 3개 지역 중심으로 수행하였는데, 전남 권역은 고흥, 보성 및 광양 중심으로 그리고 경남 권역은 거제, 통영 및 남해 지역이며, 지역당 3개 지점을 두고 조사하였다. ACP 포획을 위해 끈끈이 트랩을 이용한 조사를 병행하였다. 예찰 조사는 2018년부터 2020년까지 3년에 걸쳐 수행하였고 2018년은 6월부터 10월까지, 2019년과 2020년은 4월부터 10월까지 2주 간격으로 실시하였다. 예찰 조사 결과 감귤황룡병과 매개충 ACP는 국내에서는 아직 확인되지 않았다. 이 연구는 식물병을 조기에 탐지하기 위해 구축된 전국적인 모니터링 네트워크를 통해 수행할 수 있었고, 국외 고위험 식물 병들의 예찰 조사를 위한 지역 거점을 확보하는데 기여하였다고 평가된다.

The purpose of this study was to investigate the qualitative changes of the citron by identifying the type of solution and addition of the solution to prevent the browning reaction of the citron in a way that inhibits the browning of the citron. The browning inhibitor solution was investigated using the individual and mixture, and the results of the degree of browning and chromaticity showed that vitamin C+NaCl+cyclodextrin (CD) had the lowest browning of 0.52. In chromaticity, the ΔE values indicate that the higher the value, the greater the change in color, and the lowest value of the vitamin C+NaCl+CD mixture was 47.0, indicating that there was minimal browning compared to other treatment. The active change of the polyphenol oxidase (PPO) in the citron increased enzyme activity as the browning progressed, and the vitamin C+NaCl+CD solution was the lowest at 68.40 μ/g among the anti-browning solution. Based on these research results, it seems that the CD mixing solution can be used as a citron browning inhibitor.

The mesh selectivity of hairtail (Trichiurus lepturus) caught by coastal drift gill net was examined in field experiments with three different mesh sizes (45, 50 and 55 mm) from October to November, 2013 in the coastal areas of south-west of Jeju province. The mesh selectivity tests were conducted with the experimental net to be set middle part of conventional driftnets. The mesh selectivity tests were carried out the total of four times. The selectivity curve was estimated by the Kitahara’s and Fujimori’s method. In the results, the catch number of hairtail was 653 (125.8 kg) and occupied 34.8% in total catches weight. The optimal mesh size for 50% selection on the minimum landing size (180 mm, AL) and the first maturity size (260 mm, AL) of hairtail were estimated as 47.2 mm and 64.5 mm by master selectivity curves, respectively.

The small yellow croaker (Larimichthys polyactis) is one of the representative high-class fish species in Korea. The catch of small yellow croaker in adjacent water fisheries has been continuously decreasing from 59,226 tons in 2011 to 19,271 tons in 2016. The small yellow croaker is caught by gillnet, stow net and bottom trawl, among which about 55~65% is caught by gillnet. For the sustainable use of small yellow croaker, the fishing power of small yellow croaker drift gillnet is very important. Therefore, the change of fishing power index were analyzed to identify the development of the vessel and gear technology that may have improved the fishing efficiency of the small yellow croaker drift gillnet fishery from 1960s to 2010s. Gross tonnage and horse power per fishing vessel was increased annually. The mesh size was 75.0 mm in the 1960s, but reduced to 60.6 mm in the 1980s and to 51.0 mm in the 2000s. In the 1960s, it was hauled out by manpower. However, the net hauler were modernized and supply rate was also increased since 1970. Due to the mechanization of the net hauler, the number (length) of used net gradually increased from 1.5 km in the 1960s to 7.5 km in the mid-1980s and to 15 km in 2010. Colour fish finders and positioning system were introduced and utilized from the mid-1980s. Surveys on the supply and upgrading of fishing equipment utilized visiting research. Therefore, the relative fishing power index in the small yellow croaker drift gillnet fishery increased from 1.0 in 1980 to 0.8 in 1970, to 1.1 in 1990, to 1.6 in 2000 and to 1.9 in 2010. The results are expected to contribute to reasonable fisheries stock management of the small yellow croaker drift gillnet fishery.

The objective of this study was to estimate physical properties and fishing performances of net twine with improved PBS copolymer resin (Bio-new), the existing PBS/PBAT blending resin (Bio-old) and commercial Nylon (Nylon). The tensile strength of Bio-new monofilament was equal to Bio-old and the elongation of Bio-new was about 6 % higher than that of Bio-old in wet condition. The physical properties tests were carried out to estimate breaking load and stiffness in dry and wet conditions, respectively. In the results, the breaking load of Nylon netting was the highest whereas the elongation of Bio-new was 1.4 times higher than that of Nylon netting in wet condition. The breaking load of Bio-old netting was about 9.2 % higher than that of Bio-new netting. However, the elongation of the Bio-new netting was about 3% higher than that of Bio-old. The stiffness of the Bio-new compared to Bio-old was improved about 34 % in dry condition and about 32 % in wet condition. The filed experiments of the fishing performance were conducted with three kinds of drift nets with different netting materials in the coastal sea of Jeju. The each experimental drift net made of different materials showed the similar fishing performance. Bio-old drift net yielded less catches of small sized yellow croaker than other drift nets. The netting materials affected the fishing performance and length distribution of catches in the drift nets.

본 연구에서는 건조된 유자씨박 70% 에탄올 추출물 및 에틸아세테이트 분획물을 제조하고, 이들의 항산화능을 평가하였다. 유자씨박 추출물 및 분획물의 수율은 각각 5.1 및 0.9%로 나타났다. 1,1-Phenyl-2-picrylhydrazyl (DPPH) 라디칼 시험법에서 자유 라디칼 소거 활성(FSC50)은 70% 에탄올 추출물과 에틸아세테이트 분획물이 각각 512.1 및 514.0 μg/mL를 나타냈다. 라디칼 소거활성은 (+)- α-tocopherol(9.0 μg/mL)보다는 비교적 낮았다. Fe3+-EDTA계를 이용한 총 항산화능 평가에서 유자 씨박 70% 에탄올 추출물 및 에틸아세테이트 분획의 OSC50은 242.9 및 86.5 μg/mL이었다. 유자씨박 에틸아세테이트 분획은 70% 에탄올 추출물 보다 높은 총 항산화능을 보였지만, 대조군인 L-ascorbic acid (1.7 μg/mL)보다 낮게 나타났다. 1O2로 유도된 세포 손상에 대한 보호 효과(τ50)에서, 70% 에탄 올 추출물은 5, 10, 25, 50 μg/mL 에서 농도 의존적인 세포 보호 효과를 보였다. 유자씨박 에틸아세테 이트 분획은 5 μg/mL 에서 39.8 min으로 (+)-α-tocopherol (36.1 min)과 유사한 세포 보호 활성을 나타났다. 그러나 10 μg/mL 이상에서 농도가 증가함에 따라 낮은 세포 보호 효과를 나타냈다. 결과적 으로, 유자씨박 에틸아세테이트 분획물이 라디칼 소거활성이 아닌 총 항산화 활성을 통해 낮은 농도에서 는 세포 보호 효과를 나타냈으나 높은 농도에서는 세포 보호 효과가 농도 의존적으로 나타나지 않았다.

Yield per recruit model is the most popular method for fisheries stock assessment. However, stock assessment using yield per recruit model can lead to recruitment overfishing as this model only considers the maximum yield per recruit without spawning biomass for reproduction. For this reason, spawning biomass per recruit model which reveals variations of spawning stock biomass per fishing mortality (F) and age at first capture (tc) is considered as more proper method for stock assessment. There are mainly two methods for spawning biomass per recruit model known as age specific selectivity method and knife– edged selectivity method. In the knife–edged selectivity method, the spawning biomass per recruit has been often calculated using biomass per recruit value by multiplying the maturity ratio of the recruited age. But the maturity ratio in the previous method was not considered properly in previous studies. Therefore, a new method of the knife–edged selectivity model was suggested in this study using a weighted average of the maturity ratio for ages from the first capture to the lifespan. The optimum fishing mortality in terms of F35% which was obtained from the new method was compared to the old method for small yellow croaker stock in Korea. The value of F35% using the new knife–edged selectivity model was 0.302/year and the value using the old model was 0.349/year. However, the value of F35% using the age specific selectivity model was estimated as 0.320/year which was closer to the value from the new knife–edged selectivity model.