• 한국식품과학회지
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• 제11권2호
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• pp.77-80
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• 1979

녹차중(綠茶中)의 L-ascorbic acid를 정량(定量)함에 있어서 흔히 사용되고 있는 DNP법(法)을 적용할 때 불순물(不純物)에 의한 방해(妨害)여부와 그의 제거방법(除去方法)에 대하여 검토(檢討)한 결과(結果)는 다음과 같다. 즉, DNP법(法)으로 AsA를 측정시 ethyl glyoxal, diacetyl, caffeine둥 불순물질 및 아미노산(酸)들이 방해하였으며, 이들 물질을 제거하는 수단으로 브롬산화(酸化)후 o-phenylenediamine을 반응시킨 다음 chloroform으로 추출제거(抽出除去)하고 Amberlite $IR-120(H^{+})$로 아미노산(酸)을 제거(除去)한 후에 DNP법(法)으로 비색정양(比色定量)하면 L-ascorbic acid 함량(含量)을 정확히 측정(測定)할 수 있었다. 또한 분석소요시간(分析所要時間)이 TLC법(法)에 비해서 현저히 단축되고 재현성(再現性)도 좋아서 녹차중(綠茶中)의 ascorbic acid 정량(定量)에는 본법(本法)이 적합함을 확인하였다.

• Carbon letters
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• 제24권
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• pp.1-9
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• 2017

We studied the basic properties and fabrication of reduced graphene oxide (rGO) prepared using eco-friendly reduction agents in the graphene solution process. Hydrazine is generally used to reduce graphene oxide (GO), which results in polluting emissions as well as fixed nitrogen functional groups on different defects in the graphene sheets. To replace hydrazine, we developed eco-friendly reduction agents with similar or better reducing properties, and selected of them for further analysis. In this study, GO layers were produced from graphite flakes using a modified Hummer's method, and rGO layers were reduced using hydrazine hydrate, L-ascorbic acid, and gluconic acid. We measured the particle sizes and the dispersion stabilities in the rGO dispersed solvents for the three agents and analyzed the structural, electrical, and optical properties of the rGO films. The results showed that the degree of reduction was in the order L-ascorbic acid ${\geq}$ hydrazine > glucose. GO reduced using L-ascorbic acid had a sheet resistance of $121k{\Omega}/sq$, while that reduced using gluconic acid showed worse electrical properties than the other two reduction agents. Therefore, L-ascorbic acid is the most suitable eco-friendly reduction agent that can be substituted for hydrazine.

• 한국식품조리과학회지
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• 제18권5호
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• pp.487-494
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• 2002

This study was conducted to investigate the thermal stability of water-soluble and fat-soluble vitamins dissolved in water and milk by various heat treatments. Vitamin samples were prepared by dissolving them in water and milk at various concentrations, and were heat treated for 30 min at 65$\^{C}$, 15 sec at 85$\^{C}$, 5 sec at 100$\^{C}$, 121$\^{C}$ at 15 min, the levels of residual vitamin were measured by using HPLC. Milk samples were fortified with vitamins before and after UHT treatment. As heating over 100$\^{C}$, riboflavin in water were destructed more than 92% but fortified in milk showed less than 20% destruction, suggesting that riboflavin was protected by milk components. Also retinol heated ever 100$\^{C}$ was more stable in milk than in water. L-Ascorbic acid and cholecalciferol(D$_3$) showed a similar destruction rate in water and in fortified milk. L-ascorbic acid was easily destructed by UHT treatment. Destruction of thiamin and tocopherol was increased in fortified milk. Among tour capsulated water-soluble vitamins, L-ascorbic acid was much more stable compared with powder form. Nicotinic acid and folic acid either in capsule or powder form showed a slight destruction by heat treatment. The results suggested that the fortification of unstable vitamins such as L-ascorbic acid, thiamin, tocopherol and cholecalciferol(D$_3$) should be made in milk after heat treatment.

• 한국식품조리과학회지
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• 제13권4호
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• pp.492-499
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• 1997

밀가루(80%)와 자색고구마가루(20%)를 이용한 복합분으로 고구마빵을 제조하기 위하여 L-ascorbic acid, potassium bromate, gluten, carboxy methyl cellulose 및 hydroxy propyl methyl cellulose 등의 물성개량제를 첨가하여 고구마빵의 제빵성을 비교.검토하였다. Alveograph에 의한 반죽특성은 물성개량제를 첨가함에 따라 P, L, W값이 증가하였으며, 특히 L-ascorbic acid, gluten, carboxy methyl cellulose 등의 영향이 컸다. 반죽의 표면구조는 산화제를 첨가한 경우 gluten의 얇은 막이 거의 관찰되지 않았고, gluten, carboxy methyl cellulose, hydroxy propyl methyl cellulose를 참가한 경우 전분입자의 형태는 비교적 선명하나 큰 전분입자를 중심으로 얇은 막으로 둘러싸여 있었다. 빵 내부색의 총체적인 차이를 구별할 수 있는 ΔE값은 첨가제에 의한 영향은 없었으며, 빵 내부의 물성은 최대하중치, 강도, 경도 특성치가 사용첨가제에 의해 감소하였으며, 탄성, 응집성의 특성치는 증가하였다. 빵 내부의 노화특성은 7일 냉장저장 결과 엔탈피($\Delta$H)값이 증가하였으나 각 첨가제 모두 노화지연 효과가 있었다. 빵의 부피도 첨가제를 사용함으로써 증가하였으며 특히 L-ascorbic acid, L-cystine, carboxy methyl cellulose 및 hydroxy propyl methyl cellulose 등의 효과가 좋았고, 관능검사결과 potassium bromate를 제외하고 전반적으로 제빵의 품질이 양호하였다.

• 대한화학회지
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• 제38권11호
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• pp.783-784
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• 1994

• 한국식품영양과학회지
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• 제12권1호
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• pp.27-30
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• 1983

전촌(田村)가 개량(改良)한 DNP법(法)에 의(依)하여 녹차(錄茶)의 침출조건(浸出條件)에 따른 ascorbic acid용출량(溶出量)에 대(對)하여 검토(檢討)를 하였다. (1) 녹차(錄茶)는 양질(良質)의 것 일수록 ascorbic acid의 용출율(溶出率)이 높고 저온(低溫)에서도 잘 용출되었다. (2) 녹차(錄茶)는 물의 온도가 높을수록 ascorbic acid의 용출율(溶出率)이 높고 $80^{\circ}C$의 온탕(溫湯)을 사용(使用)했을 때 제 1 회의 3 분(分)간 침출(浸出)에서 85%가 용출되었다. (3) 증류수의 비등시간(沸騰時間)과 ascorbic acid용출량(溶出量)과의 관계(關係)에 있어서는 비등시간(沸騰時間)이 길수록 용출량(溶出量)이 증가(增加)하였다.

• Food Science and Biotechnology
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• 제17권3호
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• pp.637-641
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• 2008

This study investigated the heat stability of L-ascorbic acid (AA) in acetic acid solution. To analyze the degradation of AA using high performance liquid chromatography (HPLC), AA was measured at a wavelength of 244 nm in acetic acid and 265 nm in distilled water. During the storage of AA in acetic acid or distilled water at $37^{\circ}C$, degradation of AA was slower in acetic acid than in distilled water. On examining various ratios of AA to acetic acid, the stability of AA at $100^{\circ}C$ for 30 min was the highest when the concentration of acetic acid was 10 times higher than the concentration of AA. After acetic acid was added into AA degraded by heating, the AA is stabilized by reheating. Ultimately, these results indicate that degraded AA is reduced by hydrogen ions dissociated from acetic acid, and the rate of reduction of degraded AA in acetic acid solution is improved with heat processing.

• 한국식품저장유통학회지
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• 제13권4호
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• pp.450-456
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• 2006

쌀을 주재료로 한 쌀 식빵의 제빵 적성을 향상시키고자 제빵 과정 중에 ascorbic acid와cysteine을 첨가하여 식빵의 품질특성을 조사하였다. 쌀 식빵의 RB-3의 경우, 부피는 2,467 mL/kg, 쌀 식빵의 비용적은 5.21 mL/g 그리고 제빵수율 148%로 나타나 상대적으로 다른 배합비로 제조한 식빵에 비해 큰 체적 및 제빵 수율을 나타냈다. 쌀 식빵 crust의 명도 L값은 쌀가루 함량이 높아질수록 높은 값을 나타내었고, crumb 값의 명도 L값도 동일한 결과를 나타냈다. 쌀 식빵의 a와 b값은 각각의 식빵에서 큰 차이가 나타나지 않았다. 쌀 식빵의 경도는 RB-1, 2, 3이 다른 식빵에 비해 상대적으로 낮았으며, 탄력성은 쌀가루 함량이 높을 수록 높게 나타났으며, 씹힘성은 쌀가루 함량이 높을수록 낮게 나타났다. 그리고 응집성은 쌀 식빵 조성에 무관하게 일정한 경향을 나타내지 않았다. 쌀가루 함량이 증가할수록 노화도는 빨리 증가한다는 것과 ascorbic acid 또는 cysteine이 무첨가된 식빵의 노화도가 높게 나타났지만 ascorbic acid과 cysteine이 첨가된 쌀 식빵 RB-3에서 노화도의 정도가 가장 낮게 나타났다. 관능검사 결과, 전체적인 기호도는 쌀 고유의 향과 부드러운 조직감을 갖는 RB-3의 선호도가 가장 높았다.

• 한국양식학회:학술대회논문집
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• 한국양식학회 2003년도 추계학술발표대회 논문요약집
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• pp.19-19
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• 2003

This presentation reviewed the dietary vitamin C requirements in main marine finfish culture in Korea. In experiment I, an II-week feeding trial was conducted to study the effects of the different levels of dietary vitamin C on growth, tissue ascorbic acid concentrations and histopathological changes in parrot fish. Casein and gelatin based diets were formulated to contain 0, 60, 120, 240, 480 and 2000mg L-ascorbic acid (AA)kg diets on Ah equivalent basis in the form of L-ascorbyl-2-monophosphate (AMP), 60 and 240 mg AA/kg diet as L-ascorbic acid. Broken line analysis of weight gain indicated that the dietary vitamin C requirement of parrot fish is l18$\pm$12 mg AA/kg diet in the form of L-ascorbyl-2-monophosphate for maximum growth. In experiment II, a 12-week experiment was conducted to compare L-ascorbyl-2-monophosphate-Ca (AMP-Ca) with L-ascorbyl-2-monophosphate-Na/Ca (AMP-Na/Ca) for supplying the dietary vitamin C for juvenile Korean rockfish Sebastes schlegeli. Fish were fed one of 11 semi-purified diets containing equivalent of 0, 50, 100, 200, 400, and 800 mg ascorbic acid (AA)kg diet in the form of AMP-Ca or AMP-Na/Ca for 12 weeks. Broken line analysis of weight gain indicated that the dietary vitamin C requirement of Korean rockfish is 100 mg AA/kg diet in the form of AMP-Na/Ca, and 117 nag AA/kg diet in the form of AMP-Ca. In experiment III, a 12-week experiment was conducted to study the effects of different dietary levels of vitamin C, L-ascorbyl-2-polyphosphate (ASPP), on growth and tissue vitamin C concentrations in juvenile olive flounder. Fish were fed one of six semi-purified diets containing an equivalent of 0, 25, 50, 75, 150, or 1500 mg ascorbic acid (AA) kg 1 diet in the form of ASPP for 12 weeks. Based on broken line analyses for WG and PER, the optimum dietary levels of vitamin C were 91 and 93 mg AA/kg diet, respectively.

• Journal of Nutrition and Health
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• 제7권1호
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• pp.37-43
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• 1974

Ascorbic acid수용액에 조미료 및 향신료를 단독독 또는 배합 첨가(添加)하였을 때의 ascorbic acid의 함량(含量)을 2,4 Dnitrophenylhydrazine method에 의하여 정량(定量)하였다. 조미료 및 향신료를 단독으로 ascorbic acid 수용액에 첨가(添加)하였을 때의 total ascorbic acid의 잔재율(殘存率)은 식초, 설탕, 소금, 미원, 파, 마늘, 깨, 엿, 간장, 고추, 고추장, 후추, 생강, 계피등이 ascorbic acid단독만의 수용액보다 높은치(値)를 나타냈으며 실백, 참기름, 된장의 첨가(添加)는 적은치(値)를 나타냈다. 또한 ascorbic acid의 자동산화율(自動酸化率)은 회향, 계피, 생강, 후추, 된장, 실백, 카레등이 가장 높은치(値)를 나타냈으며 마늘, 참기름, 미원, 설탕, 꿀, 소금, 새우젓, 고추장, 간장등이 대체적으로 얕은치(値)를 나타냈다. 또한 배합(配合)조미료에 있어서는 모두 ascorbic acid의 함량(含量)은 높은치(値)를 나타냈으며 콩나물, 무나물, 무침등 가장 빈용되는 조미료 배합(配合)인 No. 8,9,10이 높은 치(値)를 나타냈으며 겨자채의 조미료배합이 제일 적은치(値)를 나타냈다.