• Korean Journal of Plant Resources
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• v.26 no.3
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• pp.347-354
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• 2013

Apple and pear are popular fruits consumed in Korea and are common fruit in daily diet. In order to compare the antioxidant activity of the apple and pear peels, total polyphenol contents, total flavonoid contents, $ABTS^+$ free radical scavenging activity, and DPPH free radical scavenging activity were measured from hot water, ethanol, and methanol extracts of the two fruit peels. The total polyphenol and flavonoid contents were highest in 95% methanol extracts of the apple peelsand 70% ethanol extract of the pear peels, respectively. Total polyphenol contents of the pear peels were higher than that of apple peels, and total flavonoid contents of the apple peels were higher than that of pear peels. The apple and pear peels had the highest $ABTS^{+{\cdot}}$ and DPPH free radical scavenging activity in 95% methanol extracts and 70% ethanol extracts, respectively. $ABTS^{+{\cdot}}$ and DPPH free radical scavenging activity of pear peels was higher than that of apple peels, and the DPPH free radical scavenging activity of apple and pear peels were detected in hot water, 95% methanol, and 70% ethanol extracts, respectively. Ascorbic acid, a synthetic antioxidant used as positive control, had significantly higher scavenging activity than the apple and pear peels. In conclusion, the apple and pear peelshave great potential as natural antioxidants. Therefore, above results should be considered to provide the possibility for the development of high functional antioxidants.

• Culinary science and hospitality research
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• v.23 no.3
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• pp.166-173
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• 2017

This study was performed to compare the vitamin A, E, ${\beta}-carotene$, polyphenol content, and DPPH radical scavenging activity of carrot, apple, and blueberry juices as affected by extraction methods using slow juicer (HJ), no vacuum blending (NVJ) and vacuum blending (VJ). Juice yields of carrot, apple, and blueberry were 100% in NVJ and VJ groups. Vitamin A content of all juices was the highest in VJ group. Vitamin E content in carrot and apple juices increased most in the HJ group, followed by the NVJ and VJ group; Vitamin E content in blueberry juice was higher in the NVJ group than VJ or HJ group. ${\beta}-carotene$ and polyphenol content in all juices were highest in the VJ group. In addition, the differences between vacuum blending and non-vacuum blending were only shown on apple and blueberry juices. Polyphenol content in carrot and blueberry juices increased most in the HJ group, followed by the NVJ, and VJ groups, and in apple juice, polyphenol content was higher in the VJ group than the HJ or NVJ group. DPPH radical scavenging activity in the VJ group was significantly higher than the NVJ group. The results of this study showed the vacuum blending method had outstanding antioxidative nutrients compared to other juicing methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1301-1304
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• 2001

Deodorizing activity of polyphenol cxidase (PPO) extracted from apples was investigated by measuring the changes of methyl mercaptan as an indicator of halitosis in human mouths. In the studies of apple extracts on deodorizing activity, the deodorizing activity was increased with the amount of apple extracts. In the cases of adding PPO to the low molecular fraction of apple extracts, the deodorizing activities were increased with the amount of the law molecular fraction of apple extracts and the reaction time of the extracts with PPO. Deodorizing activities of PPO is thought that o-quinone as an intermidiate produced by an oxidative reaction of PPO during enzymatic browning reactions may react with methyl mercaptan to form a non-volatile and sulfur-containing compound .

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.6-13
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• 2001

The study was conducted to investigate the effect of the browning inhibitors such as PVPP(polyvinylpoly-pyrrolidone), A.A.(ascorbic acid) on nonezymatic browning factors [free sugar, total amino acid, organic acid, A.A., HMF (hydroxymethylfurfural)] and enzymatic browning factors [PRO (polyphenoloxidase) activity, polyphenol compounds] in concentrated apple juice during 90 days storage. Considering color value (L value, $\Delta$E), absorbance at 420 nm, concentrated apple juice during 90 days storage. Considering color the effect of browning inhibition. According to the storage period, the changes of nonenzymatic factors in concentrated apple juice added with browning inhibitors were similar to those in control (concentrated apple juice without browning inhibitors), which were the decreased of sucrose(0.24~0.35% at 90 days), the slight increase of glucose and fructose, the decrease of total amino acid (530.4~573.1 mg/10g at 90 days), same value of A.A. at 90 days (38.5~78.6 mg/100g), and the increase of HMF (27.8~30.6 mg/100g at 90 days). On the contrary, enzymatic browning factors were significantly inhibited in concentrated apple juice added with PVPP, judging from the slow increase of PRO activity and the significant decrease of initial value in polyphenol compounds (especially chlorogenic acid). These results suggest that PVPP plays an important role as enzymatic browning inhibitor, that is, a scavenger of polyphenol compounds by adsorption in concentrated apple juice.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.413-417
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• 1984

To examine enzymatic browning of apple wine, changes of active bands of polyphenol oxidase (EC 1.10.3.1) as well as polyphenol substances related to browning of apple wine were investigated during wine brewing. The decrease of total phenol was remarkably inhibited by the addition of sodium metabisulfite. In the meantime, auto-oxidation of catechol in a model system increased proportionally as the reaction pH and temperature increased. Catechol oxidation, however, was not detected at $4^{\circ}C$ below pH 5.0. Polyacrylamidegel electrophoretic patterns showed that the apple (Jonathan) indicated 4 bands with polyphenol oxidase activity, designated a, b, c and d whose Rm were 0.21, 0.30, 0.41 and 0.51, respectively. Among these, 2 bands, a and c remained until 5th day fermentation and only c band after 6th day fermentation. After pasteurization of apple wine at $60^{\circ}C$ for 30min, c band also remained.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.454-458
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• 2002

The effect of antibrowning agents such as PVPP (polyvinylpolypyrrolidone), bentonite, gelatin, celite 545, tannic acid and sodium sulfite in apple concentrate was investigated for the control of enzymatic browning by comparing physicochemical properties (pH, color, turbidity), polyphenoloxidase activity and contents of polyphenol compounds. In color value, apple concentrate containing PVPP showed higher L value (lightness) than control and other antibrowning agents. The turbidity (absorbance at 660 nm) of apple concentrate added PVPP, gelatin celite 545, tannic acid and sodim sulfite were 0.003, 0.038, 0.018 and 0.022, respectively. PVPP was regarded to remove suspended solids effectively. Polyphenoloxidase activity and polyphenolics(catechol, catechin, chlorogenic acid, epicatechin) content of apple concentrate used PVPP significantly reduced. Therefore PVPP was proved to be effective for enzymatic antibrowning agent considering to color, turbidity, polyphenoloxidase activity and polyphenol compounds in apple concentrate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.7
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• pp.1018-1023
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• 2010

This study was conducted to investigate quality changes of apple slab after pretreating with supercritical $CO_2$. L, a, b and color difference values were little changed at increasing temperature and pressure. Polyphenol oxidase was inhibited according to increment of supercritical $CO_2$ temperature and pressure. Springiness and hardness were increased at increasing pressure and temperature condition of pretreatment but hardness showed lower value than untreatment. The texture like sponge of dried apple slab was probably due to channels which were made during penetration and release of carbon dioxide.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.168-173
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• 2000

Anticariogenic activity of the unripe apple extract was studied by observing the inhibitory effects on GTase(glucosyltransferase) activity, cell adherence and acid production of Streptococcus mutans. Among the four S. mutans strains, S. mutans MT 8148 had the highest water-insoluble glucan forming activity. (+)-Catechin and tannic acid, the major components of the unripe apple polyphenols inhibited GTase activity by 60% at 1 mg/ml and 90% at 5 mg/ml. Tannic acid and unripe apple extract inhibited adherence ability of S. mutans by 50% and 30%, respectively. But the acid production of S. mutans was not influenced by the polyphenols. Disc diffusion test showed that the polyphenols have no antimicrobial activity against S. mutans, which indicates that the inhibition of GTase activity and cell adherence were not resulted from the cell growth inhibition. Our results convinced the possible application of the unripe apple extract as the anticariogenic food additives.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.4
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• pp.397-402
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• 1984

As a basic research for inhibition of enzymatic browning of apple wine, polyphenol oxidase (EC 1.10.3.1) from apple (Jonathan) was extracted, partially purified, and some properties of the enzyme and changes o( active bands by heat treatment were investigated. Optimum conditions for the enzyme reaction were pH6.5 and temperature of $30^{\circ}C$, and o-diphenol was the main substrate for the enzyme. Approximately 35% and 15% of initia lpolyphenol oxidase activity remained after heating at $60^{\circ}C$ and $70^{\circ}C$ for 1 hour, respectively. About 0.5mM of the inhibitor such as sodium metabisulfite, cysteine and ascorbic acid was required for effective inhibition of the enzyme reaction. However, EDTA was found to be a very poor inhibitor. Ethanol did not affect the enzyme activity. The number of active bands of polyphenol oxidase from apple(Jonathan) was found to be four, but two bands and one band were observed after heating at $60^{\circ}C$ and $70^{\circ}C$ for 1 hour, respectively, which showed a significant difference in thermal stability among active bands.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.618-624
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• 1990

The antimutagenic effects of apple enzymatic browning reaction products(AEBRP) which resulted from the reaction of catechol, hydroquinone, homocatechol, hydroxyhydroquinone and pyrogallol with polyphenol oxidase extracted from apple(Jona gold) were investigated. Test strain used in SOS spot test and SOS chromotest was E. coli PQ 37/plasmid pKM 101. In SOS spot test, all of five AEBRPs showed strong antimutagenic effects on mytomycin C(MMC), 4-nitroquinoline-1-oxide(4NQO), N-me-thyl-N'-nitro-N-nitrosoguanidlne(MNNG) as increasing concentrations of AEBRP solution. In SOS chromotest, most of AEBRPs also showed strong antimutagenic effects on MMC, MNNG, 4NQO and 3-amino-1,4-dimethyl-5H-pyrido(4,3-b)indole (Trp-P-1), as increasing concentration of AEBRP solution.