• 한국식품저장유통학회지
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• 제12권5호
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• pp.489-495
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• 2005

우엉 뿌리(Arctium lappa L.)에서 polyphenol oxidase가 DEAE-Cellulose 음이온 수지, 황산암모늄 침전법, Phenyl-sepharose CL-4B 친화크로마토그래피 그리고 Sephadex G-100 겔여과크로마토그래피 등의 과정으로 정제되었며 정제효소의 효소학적 특성을 검토하였다. 정제된 효소의 분자량은 약 30 kDa의 단일폴리펩티드 사슬로 구성되어 있었다. 효소반응의 최적 pH와 온도는 각각 7.0과 35$\circC$이었으며, pH 2와 6 사이의 산성조건과, pH 8과 10 사이의 알카리 조건에서는 활성이 감소되거나 상실되었다. 온도에 대한 영향을 살펴본 결과, 40$\circC$까지 비교적 안정한 활성을 나타내고 있었으나, 50$\circC$에서 30분간 정치 시 효소활성을 50%이상 감소하는 것으로 나타내었다. 이 효소는 catechol과 L-DOPA에 대하여 높은 효소활성을 나타내었으며, chlorogenic acid과 catechol에 대한 Km 값은 각각 16.18 mM과 23.11 mM이었다. Ascorbic acid와 L-cysteine은 우엉 뿌리 polyphenol oxidase의 효소활성을 감소시켰으며, 금속이온의 경우 $Cu^{2+}$가 효소의 활성을 감소시키는 인자로 나타났다.

• The Plant Pathology Journal
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• 제39권2호
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• pp.159-170
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• 2023

Spot blotch disease of wheat caused by Bipolaris sorokiniana (Sacc.) Shoem is considered as an economically important disease which affects all the growing stages of wheat crop. Therefore, it is important to search some effective management strategies against the spot blotch pathogen. Some synthetic elicitor compounds (salicylic acid, isonicotinic acid, and chitosan) and nano-particles (silver and aluminum) were tested against the pathogen to observe the change in biochemical activity and defense action of wheat plant against spot blotch disease. All the tested elicitor compounds and nano-particles showed a significant increase in activity of peroxidase, polyphenol oxidase (PPO), and total phenol over control. The highest increase in activity of peroxidase was recorded at 72 h from chitosan at 2 mM and 96 h from silver nano-particle at 100 ppm. Maximum PPO and total phenol activity were recorded from chitosan at 2 mM and silver nano-particle at 100 ppm as compared to pathogen-treated and healthy control. The lowest percent disease index, lowest no. of spots/leaf, and no. of infected leaves/plant were found in silver nano-particle at 100 ppm and chitosan at 2 mM, respectively. The use of defense inducer compounds results in significantly up-regulated enzymatic activity and reduced spot blotch disease. Therefore, chitosan and silver nano-particle could be used as alternative methods for the management of spot blotch disease.

• 한국식품영양학회지
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• 제24권3호
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• pp.406-413
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• 2011

천연 갈변 저해제 소재를 발굴하기 위하여 양파, 사과 그리고 감귤 과피를 열수 및 80% 에탄올로 추출하고, 그 추출물에 대하여 PPO 저해활성을 측정하고, DPPH radical 소거능, 총 페놀 함량, 총 플라보노이드 함량 등을 통하여 항산화 효과를 조사하였다. 또한 추출물을 사과슬라이스에 침지하여 외관의 변화를 관찰하였다. 그 결과, 양파 및 감귤 과피 추출물이 사과 추출물보다 PPO 저해활성, DPPH radical 소거능, 총 페놀에 대하여 높은 함량을 나타냈으며, 또한 $Fe^{2+}$의 chelating 효과가 우수하였다. 각 추출물에 대하여 사과 슬라이스에 침지하여 처리한 결과에서도 양파 및 감귤 과피 추출물에서 L값과 ${\Delta}E$값이 낮게 나타나, 색 변화가 적게 일어났음을 알 수 있었다. 본 연구를 통하여 양파와 감귤 과피 추출물이 천연 갈변 저해제로의 사용이 가능할 것이라 판단된다.

• 한국식품영양학회지
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• 제31권5호
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• pp.689-695
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• 2018

This study was carried out to select apple cultivars suited for the fresh cutting or minimal processing as investigating correlation between total phenol and ascorbic acid as browning factors and the enzymatic browning degree. In soluble solid-acid ratio, 'Gamhong' and 'Arisoo' were highest value of 71.69 and 71.52 compared with other cultivars. And the change of lightness (${\Delta}L$) and color (${\Delta}E$) in 'Gamhong' and 'Arisoo' showed lower than other cultivars while 'Arkansas black' was highest change of lightness and color as ${\Delta}L$ 8.27, ${\Delta}E$ 13.86 respectively. Total phenol and ascorbic acid contents in 'Arkansas black' were highest such as 334.3 mg GAE/100 g and 9.22 mg/100 g, respectively. And polyphenol oxidase (PPO) activity also was the highest such as 14.43unit in 'Arkansas black'. The correlation test showed browning of apple was significantly dependent on ${\Delta}L$, ${\Delta}E$, total phenol, ascorbic acid contents and PPO activity (p<0.01). On the contrary, no significant correlation had been determined between the browning and ascorbic acid oxidase (AAO) activity. Thus, it seemed that the browning of apple was not only due to oxidation of ascorbic acid but also total phenol. It was suggested that 'Gamhong' and 'Arisoo' were suitable for fresh cutting or minimal processing.

• 한국식품조리과학회지
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• 제28권3호
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• pp.319-326
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• 2012

This study was designed to investigate the properties related to browning of hot water and 80% ethanol extracts of green tea (Camellia sinensis) and propolis. The extracts were assessed for polyphenol oxidase (PPO) inhibitory activity and total phenolic and flavonoid contents. In addition, apples were cut into 15 mm thick slices and dipped for 1 min in 0.5% of the green tea extracts and the propolis solutions and stored at room temperature for 24 h. The PPO inhibitory activity of the green tea extracts was better than that of the propolis. The highest DPPH free radical scavenging activity (90.81%), total phenol contents (170.42 mg/mL) and the metal chelating effects (45.93%) were measured in the green tea hot water extracts. The mineral content of the green tea water extracts was 69,328.44 ppm potassium and 2,409.42 ppm magnesium. After 24 h, the ${\Delta}E$ value of the apple slices treated with the green tea water extracts was the lowest (1.35). The antibrowning effects of the green tea extracts were higher than those of propolis in the apple slices.

• 한국식품과학회지
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• 제38권2호
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• pp.183-187
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• 2006

감초와 녹차추출액에 신선절단한 감자를 침지하고 각각 LDPE 필름으로 포장하여 $4^{\circ}C$에서 저장하면서 저장 중 품질 특성을 조사하였다. 저장함에 따라 L value는 전반적으로 감소하는 경향을 나타냈으며 ascorbic acid를 함께 처리한 경우 하락 폭을 줄여 줄수 있었다. 저장 중 포장내의 이산화탄소 함량은 증가하였고 산소의 함량은 감소하였다. 저장 7일경까지는 녹차와 ascorbic과의 병용처리구를 제외하고는 큰 변화 가 없었으나 저장 14일경에는 모든 구에서 급격한 증가 현상을 보였다. Chlorogenic acid의 경우에도 총페놀과 유사한 경향을 나타내었으며 저장 기간 경과에 따라 직선적으로 증가하는 양상을 띠었다. PRO activity를 측정한 결과 저장 기간 경과에 따라 증가하고 있었으며 갈변이 효과적으로 저해되었던 저장 7일경의 감초 및 녹차에서 가장 낮은 활성을 나타내고 있으나 이후 14일경 갈변의 심화와 함께 효소의 활성도 함께 증가하는 것으로 나타났다. 따라서 천연물인 감초추출물과 ascorbic acid를 병용하여 사용할 경우 냉장저장 시 일정기간 동안 천연물을 이용한 갈변저해 및 품질유지가 가능할 것으로 판단된다.

• 한국식품영양학회지
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• 제30권5호
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• pp.853-859
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• 2017

This study was conducted in an effort to investigate the effect of Maillard reaction products (MRPs) on enzymatic browning of burdock and their anti-oxidant activity. The MRPs were prepared by heating glucose and amino acids at $90^{\circ}C$, which served to produce a strong inhibitory effect on burdock polyphenol oxidase. As the reaction time of the solution containing glucose and amino acid increased at $90^{\circ}C$, the production of MRPs increased and intensity of the brown color deepened. When MRPs were prepared by heating at $90^{\circ}C$ for five hours, the absorbance of MRPs from glucose and lysine was 6.44, while those of glucose and glycine was 1.95. The MRPs synthesized from the glucose and lysine also reduced the pH of MRPs from 5.60 to 4.51, but those from glucose and glycine decreased slightly from 5.57 to 5.33. The Michealis-Menten constant value ($K_m$) of burdock PPO with pyrocatechol as a substrate was 16.0 mM, and MRPs were a non-competitive inhibitor against burdock PPO. The anti-oxidant activity of MRPs was measured by evaluating its radical scavenging activities of DPPH radicals, ABTS radicals and reducing power. The color intensity of MRPs produced by lysine and glucose were deeper than that produced by glucose and glycine. It was also found that MRPs produced from glucose and lysine exhibited stronger anti-oxidant properties than those produced by glucose and glycine.

• 약학회지
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• 제30권5호
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• pp.220-227
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• 1986

Polyphenol oxidase was purified from an extract of tea leaf by ammonium sulfate fractionation followed by Sephadex G-150 column chromatography, which resulted in a 67-fold increase in specific activity. The enzyme had optimum pH 6.5 and was relatively heat stable. The substrate specificity of the tea leaf PPO showed high affinity toward pyrogallol and catechol. Potassium cyanide, sodium diethyldithiocarbamate, L-cysteine, 2-mercaptoethanol and ascorbic acid were potent inhibitors.

• Current Research on Agriculture and Life Sciences
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• 제33권2호
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• pp.65-68
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• 2015

Hunter's color value "a" in dried-persimmon of table and full ripe fruit was higher than that in unripe fruit. In case of soluble solid content, full ripe fruit was $50^{\circ}Brix$, the highest degree, while unripe fruit was $40^{\circ}Brix$, the lowest degree. PPO activation of unripe fruit was 4.7, which was higher than table-ripe fruit (0.7) and full ripe (1.0). Polyphenol oxidase activation remained even while drying, but there was no difference in PPO activation degree as drying period increased. Total phenol content of unripe fruit was 101.4, which was higher than table-ripe fruit (57.5) and full ripe fruit (67.4). Total phenol content level increased as drying period increased, which was based on fresh weight. Hardness of unripe and table ripe fruit continued to decrease until three weeks during softening. After that, hardness was high and it started drying. However, in full ripe fruit, hardness increased after two weeks and softening was fast during the drying period, and its weight reduction rate was lower than that of unripe and table ripe fruit.

• 한국식품영양학회지
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• 제33권4호
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• pp.419-427
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• 2020

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.