• Korean Journal of Organic Agriculture
• /
• v.15 no.3
• /
• pp.309-318
• /
• 2007

The effects of supplementation of organic citrus on the quality of rice straw silage was investigated in this study. The aim of the study was to improve the quality of rice straw silage using agricultural by-products and therefore to secure the good quality forage sources. Firstly, looking at chemical composition of citrus added rice straw silage, crude protein content appeared improved with the addition of citrus to rice straw silage compared to control while NDF and ADF contents decreased. pH of the silages were different between control(4.39) and treatments$(3.47\sim3.53)$. Lactic acid content was higher in citrus added silage(4.87mM) than in control (3.65mM). External quality of the silages was also better in citrus added silage when citrus added at the equal ratio with rice straw(1 : 1). This trend was the same as with pH and lactic acid content. Propionate was significantly higher in citrus addd silage but butyrate was significantly lower. DM and NDF disappearance rates in the rumen were highest when citrus added at the equal ratio with rice straw(1:1). In conclusion, supplementation of citrus to rice straw silage with equal ratio contributed the best to the improvement of the quality of silage and it may have been due mainly to abundant content of non-structural carbohydrate in citrus.

• Korean journal of food and cookery science
• /
• v.31 no.1
• /
• pp.1-8
• /
• 2015

Organic acids are known as natural sanitizers. We examined the sanitizing effects of five organic acids (acetic acid, propionic acid, citric acid, malic acid, and lactic acid) and their persistence on three pectinolytic yeast strains isolated from decayed citrus, and the persistence of their sanitizing effects was determined during storage at $4^{\circ}C$ and $16^{\circ}C$. The 7~8 log CFU/mL of the mixed three yeast mixture was exposed to various concentrations of each organic acid for 1 min. The yeast mixtures decreased under detection limit(1 log CFU/mL) in 1% of acetic acid, followed by in 3% of propionic acid with the reduction of 5 log CFU/mL. The citric acid, malic acid, and lactic acid decreased the number of yeasts under detection limit at 7.5%. When treated with deionized water and 1~5% of organic acids were treated on the surfaces of citrus contaminated by yeasts, total numbers of the yeasts decreased under detection limit(3 log CFU) at 5% of acetic acid and 4 log CFU/piece at 5% propionic acid compared with deionized water. When treated with acetic acid and propionic acid on the stem ends of the contaminated citrus, total numbers of the yeasts significantly decreased 0.5 log CFU/piece at 3% of both organic acids. During storage at $4^{\circ}C$ and $16^{\circ}C$ for 20 days, total number of yeasts significantly decreased at 2% acetic acid compared with deionized water. This study suggested that organic acids could be used to sanitize microbial contaminants from citrus for storage and transportation.

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

• Korean Journal of Food Science and Technology
• /
• v.30 no.2
• /
• pp.306-312
• /
• 1998

Free sugar, organic acid, naringin, hesperidin and inorganic elements change of six varities of Cheju citrus fruits; Citrus natsudaidai, C. grandis, C. platymamma., C. sudachi, C. aurantiun and C. unshiu Marc. var. miyagawa by harvest date were investigated. Changes in free sugar of citrus fruits on the different harvesting stages and varieties showed a little differencies. The content of sucrose, glucose and maltose in citrus juice were $44.9{\sim}66.0%,\;15.7{\sim}25.7%\;and\;17.5{\sim}30.1%$, respectively. As the fruits were matured, free sugar was increased, but organic acid was decreased gradually. The major organic acids from the fruit juice were citric acid, malic acid and oxalic acid. Citric acid content exceeded 90%, oxalic acid ranged less than 3.58% and malic acid ranged $0.98{\sim}9.45%$ in total organic acids. Both naringin and hesperidin content showed markedly high in immature fruits, and in rind compare to fruit juice. Naringin and hesperidin content decreased as peel coloration progressed. It was estimated that fully matured fruits would be useful for making processed products, which lead to less turbity and less bitterness.

• Food Science and Preservation
• /
• v.2 no.1
• /
• pp.139-146
• /
• 1995

Soluble solids and total carbohydrates of Citrus miyakawa wase harvested middle of November 1993 Topyung-Dong, Seogwipo-si, and Cheju were 10.7 and 8.57%, and carbohydrate was consisted of about 1/2 sucrose, 1/4 glucose and 1/4 fructose, respectively. Acid content of citrus Juice was 1.04%, and citric acid was 74.27% of total organic acids. Fruit weight, peel thickness, soluble solids, pH, hardness and edible part ratio had a good correlation in linear function with increasing fruit size. Total carbohydrate, reducing sugar and vitamin C of citrus jam made on optimum conditions were 65.33%, 27.98%, and 51.40mg/100g , respectively. Microbial growth on the products were not recognized at 3$0^{\circ}C$ for a month. Compared with other related citrus jellying products, the test sample was excellent in appear ance, taste and total preference degree on sensory evaluation.

• Korean Journal of Food Science and Technology
• /
• v.39 no.6
• /
• pp.630-636
• /
• 2007

Acidic citrus juices obtained from C. natsudaidai and C. grandis were electrodialyzed with bipolar and organic acid selective membrane (ion exchange membrane) cartridges. The pH levels of the acidic citrus juices gradually increased to 14.5% (C. grandis) and 25.2% (C. natsudaidai) by electrodialysis with the bipolar membranes, while levels remained consistent when organic acid selective membranes were applied. The total acidity levels decreased more with the organic selective membrane than with the bipolar membrane. Conductivity rose with the bipolar membranes while the value continued to fall rapidly with the organic selective membranes. Sugar and flavonoid contents remained relatively unchanged, without any significant differences before and after electrodialysis with each membrane. Also, ion contents were almost unchanged with the bipolar membranes and the electrolyte, $K_2SO_4$, as compared to rapid changes in sodium and potassium levels with the organic selective membranes and the electrolyte, $K_2SO_4$. In summary, the use of bipolar membranes provided juice with better sensory quality than that of the organic acid selective membranes.

• The Plant Pathology Journal
• /
• v.35 no.5
• /
• pp.417-424
• /
• 2019

Melanose, caused by Diaporthe citri, is one of severe diseases in citrus, a major economic resource in Jeju island. To reduce the usage amount of organic synthetic fungicide, bio-sulfur was tested as an alternative chemical to control citrus melanose in the present study. Direct antifungal activity of bio-sulfur against D. citri was determined through in vitro experiment using artificial nutrient media. Disease severity of melanose on bio-sulfur pretreated citrus leaves was lower than that on untreated ones. To illustrate the mechanism of disease suppression by bio-sulfur, infection structures were observed with a fluorescent microscope and a scanning electron microscope. In fluorescent microscopic observation, most conidia rarely germinated. In addition, hyphal growth on leaves pretreated with bio-sulfur was inhibited compared to that on untreated ones. In scanning electron microscope images of bio-sulfur pretreated leaves, surfaces of most conidia were shrunk while hyphae were morphologically changed and frequently branched. Such microscopic observations were also found for leaves pretreated with a commercial fungicide Dithianon. These results suggest that bio-sulfur may be used to control citrus melanose as an environment friendly alternative to organic synthetic fungicides

• Korean Journal of Organic Agriculture
• /
• v.14 no.3
• /
• pp.325-331
• /
• 2006

The experiment fields consisted of five plots as follows; 2, 4, and $8\;tons{\cdot}ha^{-1}$ citrus skin in combination with starch sludge and pig manure mixing compost (CSSP), $4\;ton{\cdot}ha^{-1}$ fermented pig manure compost (FPMC) treated plot, and untreated control. Plant height and stem diameter were significantly increased by CSSP. Most of all, average tuber weight and tuber yield per plant were significantly increased in 4 and $8\;tons{\cdot}ha^{-1}$ CSSP plots compared to the other plots. Marketable tuber (>50 g fresh weight) yield were superior in order of 4 and $8\;tons{\cdot}ha^{-1}$ CSSP plot, $4\;tons{\cdot}ha^{-1}$ FPMC plot, and $2\;tons{\cdot}ha^{-1}$ CSSP plot.

• Korean Journal of Organic Agriculture
• /
• v.28 no.2
• /
• pp.223-233
• /
• 2020

The aim of the present study was to investigate the suppressive effects of the bio-sulfur used by eco-friendly farms on the outbreak of citrus scab. To evaluate the inhibiting effect of bio-sulfur on citrus scab germ tube growth, the citrus scab pathogen Elsinoe fawcettiiwas cultured in PDB and agar media, and germ tube growth was observed after bio-sulfur treatment. At both 40 and 88 h after inoculation, germ tube formation was inhibited by 500-, 1000-, and 2000-fold diluted bio-sulfur, and at dilutions above 4000-fold, germ tube formation was observed, although growth was still inhibited, when compared to untreated cultures. Meanwhile, the occurrence of citrus scab on spring-flush leaves in the field was 40.3% in the untreated control and 5.3, 10.3, 12.3, 15.3, and 24.0% when treated with imibenconazole, 2-4 and 6-6 lime-Bordeaux mixtures, which are also used by eco-friendly farms, 500-fold diluted bio-sulfur, lime sulfur, and 1000-fold diluted bio-sulfur, respectively. The occurrence of citrus scab on citrus fruit was 79.3% in the untreated control and 4.0, 33.8, 42.0, 43.3, 44.8, and 78.0% when treated with imibenconazole, 2-4 lime-Bordeaux mixture, 6-6 lime-Bordeaux mixture, 500-fold diluted bio-sulfur, lime sulfur, and 1000-fold diluted bio-sulfur, respectively. Because citrus scab can infect citrus leaves as early as May, as the spring flush begins, preventative control should be implemented by mid- to late-April, thereby increase disease control and reducing both labor and farming costs.

• Korean Journal of Organic Agriculture
• /
• v.27 no.1
• /
• pp.77-86
• /
• 2019

This study was carried out to investigate the effect of legume cover crop culture on earthworm fauna in organic farmland. We compared sod culture with two kinds of legume crops of hairy vetch and crimson clover on organic citrus orchard to natural sod culture and conventional orchards in Jeju Island. We analyzed the soil characteristics and investigated the density of earthworms from the orchards. Organic matter content did not show much difference in soil analysis between organic and conventional orchard. But the biomass of earthworms in organic orchards is 3.8 times to 7.0 times higher than that in conventional cultivated orchards, and individuals of earthworms on organic orchards were 2.3~18 times higher than conventional orchards. The biomass of earthworms on hairy vetch and crimson clover cultivation was 44.8 g, 47.2 g in 2016, and 78.7 g, 31.8 g in 2017, respectively, which were higher than 32.8 g and 9.5 g of those on natural sod cultivation. Through this study, we found that hairy vetch and crimson clover cultivation improve the earthworm occurrence density in the soil on organic citrus orchard.