Purification and some properties of o-diphenolase from white yam tubers

Ikediobi, Christopher O.; Obasuyi, Helen N.

doi:10.1016/0031-9422(80)85047-3

Cited by 42 publications

(32 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These observations are consistent with the results of Adamson and Abigor (1980), Anosike and Ayaebene (1981), Ikediobi and Obasuyi (1982) who associated yam tissue browning with PPO activity. The results with D dumentorum suggest that browning in this yam is not PPOmediated, rather, the process of a non-enzyme-mediated browning is predominant.…”

Section: Discussionsupporting

confidence: 95%

“…The remaining 60% appears to be nonenzyme mediated. This may explain why previous attempts to prevent tissue browning in instant yam powder preparation based on D rotundata tissue by incorporation of PPO inhibitors was not completely successful (Ikediobi and Obasuyi 1982). The attempt merely removed 40% of the browning potential of D rotundata flour, leaving the remaining 60% unaffected.…”

Section: Discussionmentioning

confidence: 91%

See 1 more Smart Citation

Time Course ofPPO-Related Browning of Yams

Omidiji

Okpuzor

1996

J. Sci. Food Agric.

View full text Add to dashboard Cite

Section: Discussionsupporting

confidence: 95%

Section: Discussionmentioning

confidence: 91%

Time Course ofPPO-Related Browning of Yams

Omidiji

Okpuzor

1996

J. Sci. Food Agric.

View full text Add to dashboard Cite

“…The results were in line with the reported results of Victoria grape [8], Concord grape [14], De Chaumac grapes [10], and Ravat 51 and Niagara grapes [9] and similar to those of pear PPO [18] and Amasya apple PPO [19]. The inhibitor reaction mechanism of thiol compounds is attributed to either an addition reaction with O-quinones that forms stable colourless products [20] or a binding reaction to the active centre of PPO, like metabisulfite [12]. Ascorbate acts more as an antioxidant than as an enzyme inhibitor by reducing the initial quinone formed by the enzyme to the original diphenol before it undergoes secondary reactions causing browning.…”

Section: Effect Of Inhibitors On Ppo Activitysupporting

confidence: 94%

“…Apparent K m and V max values for different substrates are listed in Table 3. With catechol and D, L-DOPA as substrates, the K m value [20] and Concord (K m = 67 mM) [14] and that with D, L-DOPA as a substrate was lower than that of grape Victoria (K m = 68.2 mM, V max = 362 OD/min) [8].…”

Section: Substrate Specificitymentioning

confidence: 88%

Biochemical characteristics and thermal inhibition kinetics of polyphenol oxidase extracted from Thompson seedless grape

Zheng

Shi

Pan

2012

Eur Food Res Technol

View full text Add to dashboard Cite

Polyphenol oxidase (PPO) was isolated from Thompson seedless grape (Vitis vinifera 'Thompson Seedless'), and its biochemical characteristics were studied. The PPO showed activity to catechol and D, L-DOPA, but not towards monophenol L-Tyrosine, diphenols guaiacol and caffeic acid, and triphenols pyrogallic acid and gallic acid. Apparent Michaelis-Menten constant (K m ) and maximum velocity of the reaction (V max ) values were 45.0 ± 0.05 mM and 500.0 ± 15.3 OD 400 nm /min for catechol, and 34.6 ± 0.03 mM and 384.6 ± 11.7 OD 478 nm /min for D, L-DOPA, respectively. The obtained similar specificity values of V max / K m ratio of catechol and D, L-DOPA indicated their similar affinity to Thompson seedless PPO. The most effective inhibitor was L-cysteine, followed in decreasing order by ascorbic acid, sodium metabisulfite, EDTA, NaCl, and citric acid. It was discovered that metal ions of Mg 2? and Cu 2? increased, while Zn 2? and K ? reduced the PPO activity. Sugars showed inhibition on the PPO activity, with higher effect by sucrose and lower effect by fructose and glucose. Optimum pH and temperature for grape PPO activity were 6.0 and 25°C with 10 mM catechol as substrate. The enzyme was heat stable between 10 and 25°C, but showed significant activity loss at temperatures higher than 40°C and completely inactivation at 70°C for 10 min. Thermal inactivation of PPO showed a firstorder kinetic with an activation energy (E a ) of 146.1 ± 10.8 kJ/mol at pH 6.0.

show abstract

“…By comparison, Ikediobi et al [15] reported a peroxidase activity close to 1000 units/g fresh tissue in D. rotundata yam. The lack of activity for high-temperature (75 • C) precooked yam flours was in accordance with the results of Ikediobi and Obasuyi [30], who observed that purified yam PPO activity dropped sharply after few minutes beyond 60 • C. In the case of flours obtained from yams steeped at 30 • C before drying, the lack of PPO activity should indicate that an inactivation also proceed during drying at 45 • C. Accordingly, Omidiji and Okzupor [16] observed a total inactivation of PPO for yam slices stored at or above 40 • C for several hours.…”

Section: Chemical Characterization Of Yam Floursupporting

confidence: 90%

Prediction of Sensorial Properties (Color and Taste) of Amala, a Paste From Yam Chips Flour of West Africa, Through Flour Biochemical Properties

Mestres

Dorthe

Akissoé³

et al. 2004

Plant Foods Hum Nutr

View full text Add to dashboard Cite

Color and taste are permanent features of amala, a traditional thick paste obtained from yam chips flour. To assess these attributes, 23 yam chips presenting various quality attributes were processed. The sensory attributes of their derived amala were determined and some biochemical characteristics of yam flours measured. A panel defined five main taste attributes for amala: sweetness, bitterness, acidity, fermented, and roasted tastes. Amala color was measured instrumentally and sensory scores were highly correlated with flour biochemical analyses; amala sweetness was positively correlated with glucose and fructose content of the flour, whereas amala acidity and fermented taste were linked to organic acids and lactic acid contents of flour, respectively. In addition, darkness, bitterness, and roasted tastes of amala could be tightly predicted by multiple regression analysis from phenolic compound and glucose-fructose contents. Phenolic content of yam flour plays thus a key role on sensorial quality of amala. However, polyphenol oxidase and peroxidase activities were almost null in yam flours and their specific role on yam flour phenolic content needs to be clarified.

show abstract

Purification and some properties of o-diphenolase from white yam tubers

Cited by 42 publications

References 42 publications

Time Course ofPPO-Related Browning of Yams

Time Course ofPPO-Related Browning of Yams

Biochemical characteristics and thermal inhibition kinetics of polyphenol oxidase extracted from Thompson seedless grape

Prediction of Sensorial Properties (Color and Taste) of Amala, a Paste From Yam Chips Flour of West Africa, Through Flour Biochemical Properties

Contact Info

Product

Resources

About