• Title/Summary/Keyword: mineral content

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Zeolitization of the Dacitic Tuff in the Miocene Janggi Basin, SE Korea (장기분지 데사이트질 응회암의 불석화작용)

  • Kim, Jinju;Jeong, Jong Ok;Shinn, Young-Jae;Sohn, Young Kwan
    • Economic and Environmental Geology
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    • v.55 no.1
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    • pp.63-76
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    • 2022
  • Dacitic tuffs, 97 to 118 m thick, were recovered from the lower part of the subsurface Seongdongri Formation, Janggi Basin, which was drilled to assess the potential for underground storage of carbon dioxide. The tuffs are divided into four depositional units(Unit 1 to 4) based on internal structures and particle componentry. Unit 1 and Units 3/4 are ignimbrites that accumulated in subaerial and subaqueous settings, respectively, whereas Unit 2 is braided-stream deposits that accumulated during a volcanic quiescence, and no dacitic tuff is observed. A series of analysis shows that mordenite and clinoptilolite mainly fill the vesicles of glass shards, suggesting their formation by replacement and dissolution of volcanic glass and precipitation from interstitial water during burial and diagenesis. Glass-replaced clinoptilolite has higher Si/Al ratios and Na contents than the vesicle-filling clinoptilolite in Units 3. However, the composition of clinoptilolite becomes identical in Unit 4, irrespective of the occurrence and location. This suggests that the Si/Al ratio and pH in the interstitial water increased with time because of the replacement and leaching of volcanic glass, and that the composition of interstitial water was different between the eastern and western parts of the basin during the formation of the clinoptilolite in Units 1 and 3. It is also inferred that the formation of the two zeolite minerals was sequential according to the depositional units, i.e., the clinoptilolite formed after the growth of mordenite. To summarize, during a volcanic quiescence after the deposition of Unit 1, pH was higher in the western part of the basin because of eastward tilting of the basin floor, and the zeolite ceased to grow because of the closure of the pore space as a result of the growth of smectite. On the other hand, clinoptilolite could grow in the eastern part of the basin in an open system affected by groundwater, where braided stream was developed. Afterwards, Units 3 and 4 were submerged under water because of the basin subsidence, and the alkali content of the interstitial water increased gradually, eventually becoming identical in the eastern and western parts of the basin. This study thus shows that volcanic deposits of similar composition can have variable distribution of zeolite mineral depending on the drainage and depositional environment of basins.

Growth, Productivity and Forage Values of Winter Cereal Crops at Paddy Fields in the Southern Region of Korea (남부지역 논에서 동계 맥류의 생육특성, 생산성 및 사료가치)

  • Seo Young Oh;Jong Ho Seo;Jisu Choi;Tae Hee Kim;Seong Hwan Oh
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.25 no.2
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    • pp.61-70
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    • 2023
  • In order to select high-quality winter cereal crops with high yield and to increase self-sufficiency rate of forage, their growth, yield, and feeding value of several cereal crops cultivated in winter were investigated in the paddy field of the southern region. Four wheat cultivars and green barley headed in early and mid-April, while oat and Italian ryegrass headed in early May. Fresh forage yields of wheats, green barley, and oat were significantly higher than that of Italian ryegrass, and dry forage yields of wheats and green barley were significantly higher than those of not only Italian ryegrass but also oat. In particular, the yield of a wheat cultivar 'Cheongwoo' was the highest. Mineral contents of wheat forages, even though low, were in the range 27.8~33.7mg·g-1 DW suitable for feeding cattle and young female cows. Crude protein content of a wheat cultivar 'Cheongwoo' was high up to 7.6%, similarly to 7.0% requiring for feeding cattle. Feeding values such as total digestible nutrients (TDN) and relative feed value (RFV) of wheats and green barley were superior to those of oat and Italian ryegrass. In addition, dry matter rates of 4 wheat cultivars and green barley were in the range 30~40%, indicating that wheat cultivars and green barley could be used for various feeding purposes such as green or dried forage, and silage. Based on these results, wheat cultivars including 'Cheongwoo' and green barley could be encouraged to be cultivated in paddy fields, as high-quality winter forage crops with high yield.

The Direction of Development of Leisure and Tourism Contents in Connection with Osaek District (강원도 오색지구 레저·관광 콘텐츠 개발 방향)

  • Lee, Gye-Young;Kim, Tae-Dong
    • Journal of Korea Entertainment Industry Association
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    • v.13 no.7
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    • pp.307-319
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    • 2019
  • This study aims to provide the basic materials for the development of leisure and tourism contents in connection with Osaek cableway for the revitalization of Osaek District. For such a purpose, the following policy directions were presented through the analysis of the present situation and conditions of Osaek District, the direction of development of leisure and tourism contents of Osaek District, etc. The first is increasing the participation of local residents and reinforcing their capabilities. The suggested promotion plans are ① establishing organizational system and strengthening support, ② reinforcing the capabilities of local residents and ③ constructing networks with external human resources. The second is setting the guidelines for contents development. It was proposed to prepare contents for leisure experience using the natural environment of Osaek District in response to the trend of increase of people who enjoy "contents using culture and arts" and leisure. The third is typological approach to contents. It was proposed to develop cultural contents with the theme of Osaek such as "Osaek Light Festival", "Osaek Concert", "Osaek Photo Exhibition" and "Osaek Good Men and Women Contest" for the promotion of the brand of the place name of Osaek and the creation of the "Picture Book Village" for the compilation of the history and culture of Osaek District with pictures. The fourth is securing marketing channels. For this, it was proposed to produce the website of Yangyang County or a website tentatively named as "Osaek-ri with Beautiful Osaek" and introduce an integrated travel product (transportation + lodging + foods + experience (hot spring, mineral water therapy, leisure experience, etc.) + purchasing local specialty products, etc.) composed of the leisure and tourism contents, transportation, lodging, foods, etc. of Osaek District through travel agencies. The final policy direction presented was phased implementation of the development and operation of the contents. Proposed policies include support of a consulting project to upgrade the organization of local residents; implementation of "Tourism Dure (Cooperative)" project for the solution of the problem of tourism in Osaek District by the residents themselves together using the space of culture and arts made by remodeling idle public and private facilities after benchmarking exemplary places; system improvement for the introduction of leisure and tourism contents appropriate for local conditions; and the establishment of a master plan for the introduction of various leisure and tourism contents in Osaek District.

Production of Lignan-Rich Eggs as Functional Food by Supplementing Schisandra chinensis By-Product in Laying Hens (사료에 오미자 가공부산물 분말의 첨가 급여가 계란의 리그난 함량에 미치는 영향)

  • Hye Mi Kang;Eun Ji Park;Sun Young Park;Dae Youn Hwang;Jong-Choon Lee;Myunghoo Kim;Young Whan Choi
    • Journal of Life Science
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    • v.34 no.1
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    • pp.18-27
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    • 2024
  • Laying hens are known to be able to 'bio-accumulate' the health-promoting ingredients of their diet into eggs. The purpose of this study was to characterize lignan-rich eggs as functional food fed with Schisandra fruit by-product (SCP). Experimental diets were formulated using yellow corn, rice bran, soybean meal, fish meal, meat bone meal, poultry meal, vitamin premix, mineral premix, CaCO3, and supplemented Schisandra chinensis by-product. This experiment conducted a completely randomized design with 5 treatments for 5 laying hens. Levels of SCP were fed control diet or each formulated diet containing 1%, 3%, 5% and 7% SCP powder. The weight of eggs and the lignan content in white and yolk of egg were investigated every 7 days. Egg production and egg weight were not affected by diet at less than 5% SCP in the diet, but were significantly reduced when the diet was supplemented with a high concentration of 7% SCP after 3 weeks. Yolks and white in eggs were analyzed by using a high performance liquid chromatography (HPLC) to determine the lignans profile. Higher dietary SCP supplementation significantly increased gomisin N and schisandrin C in Acetonitrile (p<0.05). Gomisin N in egg white increased in a concentration-dependent manner, but shisandrin C not detected. These results indicated that the use of SCP powder in layering diets was effective in egg quality and for the production of lignans fortified eggs. In conclusion, dietary supplementation of Schisandra by-product with less than 5% can produce lignans-enrich eggs used as functional foods.

Occurrence and Chemical Composition of Ti-bearing Minerals from Samgwang Au-ag Deposit, Republic of Korea (삼광 금-은 광상에서 산출되는 함 티타늄 광물들의 산상 및 화학조성)

  • Yoo, Bong Chul
    • Korean Journal of Mineralogy and Petrology
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    • v.33 no.3
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    • pp.195-214
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    • 2020
  • The Samgwang Au-Ag deposit has been one of the largest deposits in Korea. The deposit consists of eight lens-shaped quartz veins which filled fractures along fault zones in Precambrian metasedimentary rock, which feature suggest that it is an orogenic-type deposit. The Ti-bearing minerals occur in wallrock (titanite, ilmenite and rutile) and laminated quartz vein (rutile). They occur minerals including biotite, muscovite, chlorite, white mica, monazite, zircon, apatite in wallrock and white mica, chlorite, arsenopyrite in laminated quartz vein. Chemical composition of titanite has maximum vaules of 3.94 wt.% (Al2O3), 0.49 wt.% (FeO), 0.52 wt.% (Nb2O5), 0.46 wt.% (Y2O3) and 0.43 wt.% (V2O5). Titanite with 0.06~0.14 (Fe/Al ratio) and 0.06~0.15 (XAl (=Al/Al+Fe3++Ti)) corresponds with metamorphic origin and low-Al variety. Chemical composition of ilmenite has maximum values of 0.07 wt.% (ZrO2), 0.12 wt.% (HfO2), 0.26 wt.% (Nb2O5), 0.04 wt.% (Sb2O5), 0.13 wt.% (Ta2O5), 2.62 wt.% (As2O5), 0.29 wt.% (V2O5), 0.12 wt.% (Al2O3) and 1.59 wt.% (ZnO). Chemical composition of rutile in wallrock and laminated quartz vein has maximum values of 0.35 wt.%, 0.65 wt.% (HfO2), 2.52 wt.%, 0.19 wt.% (WO3), 1.28 wt.%, 1.71 wt.% (Nb2O3), 0.03 wt.%, 0.07 wt.% (Sb2O3), 0.28 wt.%, 0.21 wt.% (As2O5), 0.68 wt.%, 0.70 wt.% (V2O3), 0.48 wt.%, 0.59 wt.% (Cr2O3), 0.70 wt.%, 1.90 wt.% (Al2O3) and 4.76 wt.%, 3.17 wt.% (FeO), respectively. Rutile in laminated quartz vein is higher contents (HfO2, Nb2O3, As2O5, Cr2O3, Al2O3 and FeO) and lower content (WO3) than rutile in wallrock. The substitutions of rutile in wallrock and laminated quatz vein are as followed : rutile in wallrock [(Fe3+, Al3+, Cr3+) + Hf4+ + (W5+, As5+, Nb5+) ⟵⟶ 2Ti4+ + V4+, 2Fe2+ + (Al3+, Cr3+) + Hf4+ + (W5+, As5+, Nb5+) ⟵⟶ 2Ti4+ + 2V4+], rutile in laminated quartz vein [(Fe3+, Al3+) + As5+ ⟵⟶ Ti4+ + V4+, (Fe3+, Al3+) + As5+ ⟵⟶ Ti4+ + Hf4+, 4(Fe3+, Al3+) ⟵⟶ Ti4+ + (W5+, Nb5+) + Cr3+], respectively. Based on these data, titanite, ilmenite and rutile in wallrock were formed by resolution and reconcentration of cations (W5+, Nb5+, As5+, Hf4+, V4+, Cr3+, Al3+, Fe3+, Fe2+) in minerals of wallrock during regional metamorphism. And then rutile in laminated quartz vein was formed by reconcentration of cations (Nb5+, As5+, Hf4+, Cr3+, Al3+, Fe3+, Fe2+) in alteration minerals (white mica, chlorite) and Ti-bearing minerals reaction between hydrothermal fluid originated during ductile shear and Ti-bearing minerals (titanite, ilmenite and rutile) in wallrock.

Metamorphic Evolution of the central Ogcheon Metamorphic Belt in the Cheongju-Miwon area, Korea (청주-미원지역 중부 옥천변성대의 변성진화과정)

  • 오창환;권용완;김성원
    • The Journal of the Petrological Society of Korea
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    • v.8 no.2
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    • pp.106-124
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    • 1999
  • In the Cheongju-Minwon area which occupies the middle part of the Ogcheon Metamorphic Belt, three metamorphic events(M1, M2, M3) had occurred. Intermediate P/T type M2 regional metamorphism formed prevailing mineral assemblages in the study area. Low PIT type M3 contact metamorphism occurred due to the intrusion of granites after M2 metamorphism. M1 metamorphism is recognized by inclusions within garnet. During M2 metamorphism, the metamorphic grade increased from the biotite zone in the southeastern part to the garnet zone in the northwestern part of the study area. This result is similar to the metamorphic evolution of the southwestern part of the Ogcheon Metamorphic Belt. Garnets in the garnet zone are classified into two types; Type A garnet has inclusions whose trail is connected to the foliation in the matrix and Type B garnet has inclusion rich core and inclusion poor rim. Type A garnet formed in the mica rich part with crenulation cleavage whereas Type B garnet formed in the quartz rich part with weak crenulation cleavage. In some outcrops, two types garnets are found together. Compared to the rim of Type A garnet, the rim of Type B garnet is lower in grossular and spessartine contents but higher in almandine and pyrope contents. In some Type B garnets, the inclusion poor part is rimmed by muddy colored or protuberant new overgrowth. In the inclusion poor part and new overgrowth, a rapid increase in grossular and decrease in spessartine is observed. However, the compositional patterns of Type A and B are similar; Ca increases and Mn decreases from core to rim. Two types garnets formed mainly due to the difference of bulk chemistry instead of metamorphic and deformational differences. The metamorphic P-T conditions estimated from Type A garnets are 595-690 OC15.7-8.8 kb, which indicates M2 metamorphism is intermediate P/T type metamorphism. On the other hand, a wide range of P-T conditions is calculated from Type B garnets. The P-T conditions from most Type B garnet rims are 617-690 OC16.2-8.9 kb which also indicates an intermediate P/T type metamorphism. However, at the rim part with flat end or weak overgrowth, grossular content is low and 573-624OC14.7-5.8 kb are estimated. The P-T conditions calculated from plagioclase and biotite inclusions in garnet are 460-500 0C/1.9-3.0 kb. The P-T conditions from rim part with weak overgrowth and inclusions within garnet, indicate that low P/T type M1 regional metamorphism might have occurred before intermediate P/T type M2 regional metamorphism. The P-T conditions estimated from samples which had undergone low PIT type M3 metamorphism strongly, are 547-610 0C/2.1-5.0 kb.

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Characteristics of Manure and Estimation of Nutrient and Pollutant of Holstein Dairy Cattle (홀스타인 젖소 분뇨의 특성과 비료성분 및 오염물질 부하량 추정)

  • Choi, D.Y.;Choi, H.L.;Kwag, J.H.;Kim, J.H.;Choi, H.C.;Kwon, D.J.;Kang, H.S.;Yang, C.B.;Ahn, H.K.
    • Journal of Animal Science and Technology
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    • v.49 no.1
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    • pp.137-146
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    • 2007
  • This study was conducted to determine fertilizer nutrient and pollutant production of Holstein dairy cattle by estimating manure characteristics. The moisture content of feces was 83.9% and 95.1% for urine. The pH of feces and urine were in the ranges of 7.0~7.4 and 7.5~7.8, respectively. The average BOD5, COD, SS, T-N, T-P concentrations of the dairy feces were 18,294, 52,765, 102,889, 2,575, and 457mg/ℓ, respectively. Dairy urine showed lower levels of BOD5(5,455mg/ℓ), COD(8,089mg/ℓ), SS(593mg/ℓ), T-N(3,401mg/l), and T-P(13mg/ℓ) than feces. The total daily produced pollutant amounts of a dairy cow were 924.1g(Milking cow), 538.8g(Dry cow), 284.4g(Heifer) of BOD5, 2,336.5g (Milking cow), 1,651.8g(Dry cow), 734.1g(Heifer) of COD and 4,210.1g(Milking cow), 2,417.1g(Dry cow), 1,629.1g(Heifer) of SS and 194.8g(Milking cow), 96.4g(Dry cow), 58.3g(Heifer) of T-N and 24.0g(Milking cow), 10.2g(Dry cow), 6.1g(Heifer) of T-P. The calculated amount of pollutants produced by a 450kg dairy cow for one year were 181.3kg of BOD5, 492.5kg of COD, 899.9kg of SS, 36.0kg of T-N and 4.1kg of T-P. The total yearly estimated pollutant production from all head(497,261) of dairy cattle in Korea is 90,149 tons of BOD5, 244,890 tons of COD, 447,491 tons of SS, 17,898 tons of T-N and 2,008 tons of T-P. The fertilizer nutrient concentrations of dairy feces was 0.26% N, 0.1% P2O5 and 0.14% K2O. Urine was found to contain 0.34% N, 0.003% of P2O5 and 0.31% K2O. The total daily fertilizer nutrients produced by dairy cattle were 197.4g (Milking cow), 97.4g(Dry cow), and 57.9g(Heifer) of Nitrogen, 54.2g(Milking cow), 22.2g(Dry cow), and 14.2g(Heifer) of P2O5 and 110.8g(Milking cow), 80.4g (Dry cow), and 39.5g(Heifer) of K2O. The total yearly estimated fertilizer nutrient produced by a 450kg dairy animal is 36.2kg of N, 8.8kg of P2O5, 24.6kg of K2O. The estimated yearly fertilizer nutrient production from all dairy cattle in Korea is 18,000 tons of N, 4,397 tons of P2O5, 12,206 tons of K2O. Dairy manure contains useful trace minerals for crops, such as CaO and MgO, which are contained in similar levels to commercial compost being sold in the domestic market. Concentrations of harmful trace minerals, such as As, Cd, Hg, Pb, Cr, Cu, Ni, Zn, met the Korea compost standard regulations, with some of these minerals being in undetected amounts.

Mineral Nutrition of Field-Grown Rice Plant -II Recovery of fertilizer nitrogen, phosphorus, and potassium in relation to climatic zone and physical or chemical characteristics of soil profile (포장재배(圃場栽培) 수도(水稻)의 무기영양(無機營養) -II 삼요소(三要素) 이용율(利用率)과 기상권(氣象圈) 및 토양단면(土壤斷面)의 물리(物理)·화학적(化學的) 성질(性質)과의 관계(關係))

  • Park, Hoon;Shin, Chun Soo
    • Korean Journal of Soil Science and Fertilizer
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    • v.6 no.1
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    • pp.17-26
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    • 1973
  • A survey on nutrient recovery by rice plant was carried out countrywide in 1967 and 1968. The relationships between percent recovery of fertilizer nutrient and climatic zone or deposition mode, drainage grade, and texture of paddy soil profile, or chemical characteristics of surface soil were as follows. 1. The percent recovery of fertilizer nitrogen was highest in south and least in north, and that of potassium was highest in south and least in middle climatic zone. 2. Since the percent recovery of Phosphorus variates yearly with climatic zone, mode of deposition drainage grade or soil texture, it seemed to depend greatly on soil-weather interaction. 3. Nitrogen recovery was highest in alluvial colluvial (AC) and it was followed by alluvial (A), fluvomarine (FM) and old alluvial in decreasing order while potassium recovery was OA>AC>A>FM. 4. The greater the drainage was, the higher the nitrogen recovery. The recovery of potassium and phosphorus tended to show high in moderately well drain, and low in poorly and well drain. 5. Nitrogen recovery was highest in fine silty and gradually decreased with coarseness. That of potassium or phosphorus was greater in those below fine loamy than in those above coarse silty. 6. Nitrogen recovery was high in Jisan, Geugrag, and Sindab series, and low in Hwadong, Gyuam, Yongji and Hwabong series. 7. Nitrogen recovery showed significant positive correlation with the content of organic matter (OM), Ca, CEC of surface soil and only in the year of high phosphorus recovery it had significant negative correlation with soil phosphorus. Phosphorus recovery had significant posititive correlation with CEC, Mg or Ca. 8. Potassium recovery showed negative correlation with K/(Ca+Mg), P, OM or K while positive correlation with Ca, Mg, CEC but significant only with K/(Ca+Mg) in the year of low potassium recovery. In the year of high K recovery it showed positive correlation with P, OM, K/(Ca+Mg) or K while negative with CEC, Mg or Ca but significant only with P, OM or CEC. Soil potassium has significant positive correlation with soil OM and P only in the year of low potassium recovery. 9. The percent recovery of N, P or K showed negative correlation coefficient with pH without significant. 10. There was significant positive correlation between OM and P, K or K/(Ca+Mg), P and K or K/(Ca+Mg), K and K/(Ca+Mg), Mg or CEC, Ca and K/(Ca+Mg), Mg, CEC or pH, Mg and CEC while significant negative correlation between Mg and OM, P or K/(Ca+Mg), P and CEC, Ca and K/(Ca+Mg). 11. From the percent rcovery of fertilizer and soil chemical characteristics it was known that soil organic matter increase nitrogen uptake, that K uptake has closer relation to K/(Ca+Mg) than K, that Mg affects P ugtake, and that the annual difference of P and K recovery was partly explainable.

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The Ripening of Camembert Cheese Made with Mucor Miehei Rennet (Mucor Miehei 응유효소(凝乳酵素)로 제조(製造)한 Camembert Cheese의 숙성(熟成)에 관(關)한 연구(硏究))

  • Park, Mooh Il;Kim, Jong Woo
    • Korean Journal of Agricultural Science
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    • v.16 no.2
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    • pp.179-200
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    • 1989
  • Mucor miehei rennet(MR) was added as calf rennet(CR) substitutes in the fixed amounts of mixed rennets in making Camembert cheese. The conditions in the variations of chemical composition: water-soluble nitrogen, non-caseinic nitrogen, non-proteinic nitrogen, amino nitrogen, ammoniacal nitorgen, electrophoresis, molecular fractionation, mineral distribution, texture characterisitics, free amino acids and free fatty acids, were checked up with the sensory test and the chesse yields at each ripening period. The results obtained by investigating the utility of Mucor rennet were summarized as follows: 1. CR chesse, MR cheese and the mixed-rennet chesse failed to show any significant difference in their yields of 15%. 2. The contents of protein, fat and ash in MR cheese gave lower value than CR cheese did and with progress of ripening lactose decreased rapidly after 14 days of ripening. The difference among the rate of addition of mucor rennet was not recognized. 3. The WSN contents of 5 fresh sample chesse were from 14.7% to 17.3% and WSN increased from 39.7% to 41.0% with progress of ripening. After 21 days of ripening MR chesse had more WSN than CR cheese did. In NCN and ammoniacal nitrogen MR cheese showed higher value. 4. As the ripening progressed, MR chesse showed more cystein, phenylalanine and proline than CR chesse did but it failed to show any increase in aspartic acid, threonine and glutamic acid etc. 5. In the content of free fatty acid MR chesse showed higher value than CR cheese did and with the progress of ripening fatty acids increased from 8.36 mEq to 26.36 mEq but did not show any significant difference in the cheese types by the coagulant ratio. 6. Ca contents in the sample chesse were 0.238-0.27%, Mg 0.019-0.022%, Na 0.910-1.047%, and K 0.175-0.200%. The important non-sedimentable Ca in casein remained from 61 % to 77% without regard the ripening periods and added-rennets and Mg remained from 59.1% to 92.5% in non-sedimentable and water-soluble conditions. 7. In the fractionation of protein by ultrafilteration, MW> $5{\times}10^4$ decresed from 95% at the beginning period of ripening to 45% and MW< $10^4$ increased from 0.2% to 38% and definite caseinolysis was shown in all samples. 8. All the cheese showed to different electrophoretic patterns for the added-amounts of mucor rennet in the 14 days of ripenig. In the 28 days or ripening, MR cheese kept some bands on the patterns compared with CR cheese. 9. In vitro digestibility increased from 81.48-94.81 % to 94.47-98.61% but failed to show any significant difference in the cheese types by the coagulant ratio. 10. In hardness, MR cheese showed lower value compared with CR cheese as the ripening progressed. 11. The results of the sensory test failed to show any difference in flora rind, feelings in mouth and hands, deep structure, flavor and bitterness between CR Camembert cheese and MR Camembert chesse.

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Seasonal Variation of Potassium and Magnaesium Contents of Forage Plant Grown in Grazing Pasture and Meadow (방목이용과 채초이용시 나타나는 목초중 칼리 및 마그네슘 함량의 계절변화)

  • ;Shigekata Yoshida;Tadakatsu Okubo;Ryosei Kayama
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.10 no.1
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    • pp.27-35
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    • 1990
  • As a part of studies on potassium(K) behavior in grassland with respect to magnesium(Mg) balance of ruminants, seasonal variation of K and Mg contents of forages including native gasses grown in grazing pasture and meadow were investigated. During an experimental period from April to October of 1984, two times of grazings were carried out in the orchardgrass (Dacfylis glomerata L.) and the tall fescue (Festuca arundinacea Schreb.)dominant grazing pastures, and forage plants (forages and native grasses) were sampled monthly and also K and Mg contents were determined without separating into individual plant species (Experiment 1). All the plant species grown in the two meadows which situated in the grazing pastures were harvested five times during the same period, separated into individual plant species, and botanical composition (SDR, ) and K and Mg contents of the plant species were determined (Experiment 2). The results obtained were as follows: 1. During the experimental period in the orchardgrass grazing pasture K contents of the forage plants were the highest in spring, and the seasonal variation of the contents in the orchardgrass pasture (1.5-5.8 % in a dry matter basis) was more significant than that of forage plants in the tall fescue grazing pasture (3.0- 3.8 %). 2. The Mg contents of forage plants in the orchardgrass grazing pasture ranged under 2.0 mg/g DW from Arpil until July, and the contents in the orchardgrass pasture (1.5-3.1 mg/g DW) was in the lower range than that of forage plants in the tall fescue pasture (2.0-3.8 mg/g DW). (Experiment I). 3. Orchardgrass was the dominant species in the orchardgrass meadow until July, but several species of native grasses were observed from summer (July) and native grasses such as Digitaria adscendens and Echinochlw crus-galli became dominant in autumn (October). 4. Seasonal variation of K contents of orchardgrass was in the range of 3.9-5.9 %, and the contents was higher in spring (May) and in autumn (October). The variation of white clover (Trifolium repens L.) was in the range of 3.6-5.0 %, that of tall fescue 3.8-4.8 %, and that of Italian ryegrass (Lolium multiflorum Lam.) 2.7-3.5 %, respectively. 5 . Seasonal variation of Mg content of white clover was in the range of 2.9-3.7 mg, that of tall fescue 2.0- 3.3 mg, and that of orchardgrass 1.6-2.8 mg/g DW, respectively. The variation of the contents of Italian ryegrass was in the range of 1.3-1.9 mg/g DW. And Mg contents of the forage plants were higher in summer(July) 6. In autumn (October and November ) native grasses such as D. adscendens and E. crus-galli contained lower K contents (1.7-3.9 %), but higher Mg contents (3.2-10.1 mg/g DW) than the forages contained. (Experiment 2) From the results above, it is known that K contents ranged higher in younger forages in viewpoint of growth stage and higher in spring and autumn, and that Mg contents ranged lower in spring. Therefore, the mineral imbalance or hypomagnesaemic (grass) tetany can be triggered in spring or autumn, and more frequently by such plant species as orchardgrass and Italian ryegrass with lower Mg and/or higher K contents than by tall fescue. And it is suggested that the dominant native grasses in autumn such as D. adscendens and E. emsgalli can contribute to the prevention of the tetany with higher Mg and lower K contents.

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