• Food Science and Biotechnology
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• v.16 no.3
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• pp.421-425
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• 2007

The inhibitory effect of onion extract on polyphenol oxidase (PPO) and browning of peach juice was investigated. Various reducing agents such as L-ascorbic acid, L-cysteine, dithiothreitol, glutathione, and sodium pyrosulfite strongly inhibited polyphenol oxidase extracted from peach. The enzyme was also inhibited by addition of water extract of onion. Regardless of substrates used, the addition of heated onion extract exhibited stronger inhibitory effect on peach polyphenol oxidase activity than that of the fresh one. The inhibitory effect of onion extract was dependent on heating temperature and time. The onion extract inhibited the peach polyphenol oxidase non-competitively. The heating of onion extract in the presence of glucose, glycine stimulated the inhibitory effect of the onion extract, which suggests non-enzymatic browning products produced during heating might be responsible for the stronger inhibitory action of the heated onion extract. The retardation of peach juice browning by onion extract seems to be caused by inhibition of peach PPO.

• Korean journal of food and cookery science
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• v.13 no.4
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• pp.390-395
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• 1997

The inhibitory effects of cereal extracts and concentrates from barley, waxy rice flours and malt on enzymatic browning were measured using apple polyphenol oxidase (PPO). Malt concentrate showed the largest inhibitory effect on PPO among all. The relationship between the properties of malt concentrate such as browning intensity and reducing power and their inhibitory effect on PPO was also studied. As the heating time increased, the browning intensity and the reducing power of malt concentrates were increased, while PPO activities were decreased. Inhibitory effect of malt concentrates on PPO increased with heating time and their concentration. L-value and compression force of the apple slices dipped in malt concentrate decreased by 6.9% and 14.3%, respectively, showing the smallest changes compared with raw and water-dipped apple slices during cold storage for 9 days. These results suggest that malt concentrate can be a potential source for the control of enzymatic browning.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.6
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• pp.1013-1016
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• 2004

The inhibitory effect of MRPs (Maillard reaction products) on enzymatic browning of taro was investigated. The MRPs prepared by heating glycine and glucose at 9$0^{\circ}C$ for 7 hr exhibited a strong inhibitory effect on taro polyphenol oxidase (PPO). The maximum inhibitory activity of MRPs against taro PPO was detected toward (＋)-catechin, catechol, 4-methylcatechol followed by L-$\beta$-3,4-dihydroxyphenylalanine (L-DOPA) and pyragallol as a substrate. The MRPs synthesized from fructose and glucose with glycine as a amino acid significantly reduced the taro PPO activity. MRPs prepared by higher glycine or glucose concentration showed stronger inhibition against taro PPO. Increasing reaction time of the glycine and glucose promoted the inhibitory effect of MRPs against the PPO activity of taro, whereas the color formation was gradually increased.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.291-297
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• 2000

Oleoresin was extracted from fresh garlic by microwave-assisted extraction (MAE) and its functionality and antibrowning effect were investigated at various extraction conditions. The yield and polyphenol contents of the garlic oleoresin were inversely related to extraction time. The highest yield was l2.9% and maximum polyphenol contents was 574.3 mg% when the oleoresin was extracted for 5 min with ethanol. Apparently, the electron donating abilities of garlic oleoresin increased with extraction time, but there were no significant differences among extraction time intervals. The highest nitrite scavenging effect was found at pH 1.2 and decreased as pH increased. Tyrosinase inhibitory effect was less than 30% for most garlic oleoresin but the 15 minute extraction with ethanol resulted in higher inhibitory effect. Angiotensin I-converting enzyme (ACE) inhibitory effect was highest (89.2%) when oleoresin extracted with ethanol for 20 min. The addition of cysteine, ascorbic acid and citric acid to oleoresin extracts retarded browning action of garlic oleoresin during 10 day storage. 0.1 % cysteine retarded browning reaction and some synergistic effect was found in the combination of citric acid and ascorbic acid.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.1
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• pp.70-73
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• 2004

The browning rate of potato juice alone and potato juice with added carrot juice or water(1:1 by volume) were studied. As the amount of carrot juice added was increased, the browning rate proportionally decreased: from 1.86 of potato juice alone to 0.36 for the potato juice and carrot juice mixture(l:1). This inhibitory effect of carrot juice on browning led us to assume that $\beta$-carotene, the major constituent of carrot carotenoids, may be involved in impeding the browning reaction of potato juice. Therefore, model system of enzymatic browning, consisting of chi orogenic acid/tyrosine and $\beta$-carotene/carrot carotenoids, were studied. The results shows the browning rates of chlorogenic acid alone and chlorogenic acid with added $\beta$-carotene. The initial browning rate of chlorogenic acid was faster($\delta$L= 1.1/min.)than that of chlorogenic acid with added $\beta$-carotene($\delta$L=0.6/min.).

• Culinary science and hospitality research
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• v.13 no.2
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• pp.254-259
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• 2007

The control of enzymic browning in potato slices by the use of citrate and phosphate buffer at different pH values and concentration was investigated. Minimally processed potatoes were stored at $5^{\circ}C$ and $20^{\circ}C$ followed by dipping in distilled water, citrate buffer (pH $3.0{\sim}5.0$) and phosphate buffer (pH $5.0{\sim}7.0$). The color characteristic was measured after storage at $5^{\circ}C$ and $20^{\circ}C$ for 24 hours. Treatment effectiveness was greatly improved by reducing pH and temperature. The citrate buffer was more effective than phosphate buffer in the browning inhibitory capacity. The citrate buffer (pH 3.0) showed the most anti-browning effect in this condition and more effective inhibition of browning by increasing concentration of treatment solution. The phosphate buffer (pH 5.0) treatment showed more effectiveness than concentration of 0.5 M of citrate buffer treatment.

• Korean journal of food and cookery science
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• v.9 no.3
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• pp.181-186
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• 1993

Potato and carrot are the main sourses of vitamin C and vitamin A each. As a folk ramedy, potato-carrot mixtures have been used to cure a stomach ulcer in Korea. To investigate the effects of carrot juice on the browning of potato juice, we examined the brewing in various ratio of two juices. We also investigated the role of potato juice in the carotene oxidation of carrot juice. Delta "L" values of potato juice were abruptly decreased after 5 min. reaction and they were very different from the juice mixture of potato and carrot. Those containing higher ratio of potato were decreased greatly. In blanching treatment to eliminate the effect of the enzymes in potato and carrot, delta "L" values of cooked potato were decreased a little but those of cooked carrot were decreased greatly. To investigate the fact that the inhibitory effect of carrot juice in potato browning was due to the dilution of polyphenolics of potato juices by carrot juice mixing, we added H20 equivalent to carrot water content to potato juice. The diluted sample showed less decreasing pattern than nondiluted sample. We also added appropriate amount of ${\beta}$-carotene to the same samples. Delta "L" values of with added B-carotene were more slowly decreased than those of without added B-carotene.

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1417-1422
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• 2009

This study was conducted to investigate the effect of ultrasound with ascorbic acid on the quality of fresh-cut apples. Prepared apple cubes were dipped in distilled water (US) or in 1% ascorbic acid solution (AS), both were treated with ultrasound at 40 kHz, while the other sample was just dipped in 1% ascorbic acid solution for 1 min (AA). All samples were stored at $4^{\circ}C$ for 12 days. AS treatment had an effect on apple cube color as indicated by its significantly higher L values and lower ${\Delta}E$ value whereas AA- and US-treated samples showed a considerable browning. Higher inhibition rate on browning and polyphenol oxidase (PPO) activity of 46 and 98%, respectively, were observed after AS treatment. The highest total phenolic content of AS-treated samples was shown during whole storage periods. This investigation revealed that the use of ultrasound in combination with ascorbic acid had a positive effect on quality maintaining of fresh-cut apples.

• Food Science of Animal Resources
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• v.34 no.4
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• pp.403-407
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• 2014

Changes in Maillard reaction of pidan white were monitored with $A_{294}$, fluorescence intensity, and browning intensity during pickling in the absence and presence of Chinese black tea extract (Camellia sinensis) at levels of 2% and 5% together with 0.2% $ZnCl_2$ or 0.2% $CaCl_2$ up to 3 wk, followed by ageing for another 3 wk. Browning intensity and $A_{294}$ of pidan white increased with increasing pickling/ageing, while fluorescence intensity decreased during ageing (p<0.05), irrespective of treatments. At wk 6, pidan white treated with 0.2% $ZnCl_2$ and 0.2% $CaCl_2$ showed slightly higher browning intensity, fluorescence intensity and $A_{294}$ than those treated with divalents together with Chinese black tea (p<0.05). Free amino group and sugar contents showed continuous decrease during pickling and ageing irrespective of tea and cations used. However, pidan treated without Chinese black tea extract showed significantly lower free amino group and sugar during the ageing of 6 wk (p<0.05). Thus, Chinese black tea extract had an inhibitory effect on the Maillard reaction during ageing of pidan white.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.4
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• pp.574-580
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• 2003

Optimal extraction conditions for yield, browning color, electron donating ability, nitrite scavenging effect, total polyphenol content and tyrosinase inhibitory activity of Lyophyllum ulmarium were determined by using response surface methodology (RSM) through the central composite design. The extraction yield of Lyophyllum ulmarium was effected by ethanol concentration and browning color was improved with the increase of ethanol concentration than microwave power. The nitrite scavenging effect was improved with the increase of ethanol concentration and decrease of microwave power The electron donating ability, browning color, tyrosinase inhibitory activity and total polyphenol content were improved with the increase in ethanol concentration and microwave power. The optimal ranges of extraction conditions for effective components of Lyophyllim ulmarium were predicted as 60.05~102.75 watt of microwave power, 53.20~64.01% of ethanol concentration and 7.77 min of extraction time.