ACC Oxidase in Papaya Sections After Heat Treatment

Chan, Harvey T.; Maindonald, John M.; Laidlaw, W. G.; Seltenrich, M.

doi:10.1111/j.1365-2621.1996.tb10956.x

Cited by 4 publications

(3 citation statements)

References 17 publications

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“…The TPME showed activation at 50, 55 and 57.5 7C, whereas no activation was observed for the IPME at the temperatures studied. The activation of enzymes during heat treatment has been reported by many workers for different enzymes [9,11,12] and attributed to the release of latent enzyme fractions [9]. 2 Heat inactivation of the ionically bound PME from cucumbers Fig.…”

Section: Temperature Stabilitymentioning

confidence: 96%

Separation and thermal characterization of ionically and tightly cell-wall-bound pectin methylesterase from cucumbers ( Cucumis sativus )

Yemenicioğlu¹,

Cemeroğlu²

1999

Zeitschrift f�r Lebensmitteluntersuchung und -Forschung A

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Thermal characteristics of cell-wall-bound pectin methylesterase (PME) from cucumbers were determined. Heat inactivation of PME followed first-order reaction kinetics. Biphasic inactivation curves indicated the presence of heat-labile and heat-stable fractions. Inactivation of PME accelerated above 65 7C.The z values between 70 7C and 80 7C were 7.6 7C and 9.0 7C for heat-stable fractions of ionically (IPME) and tightly cell wall bound PME (TPME), respectively. Temperature optima for the initial activities of IPME and TPME were 65 7C and 60 7C, respectively. However, for longer periods of activity determination, both IPME and TPME showed a temperature optimum at 50 7C. The E a values for initial activities were 5 kcal mol -1 (20-65 7C) and 7.2 kcal mol -1 (20-60 7C) for IPME and TPME, respectively.

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Section: Temperature Stabilitymentioning

confidence: 96%

Separation and thermal characterization of ionically and tightly cell-wall-bound pectin methylesterase from cucumbers ( Cucumis sativus )

Yemenicioğlu¹,

Cemeroğlu²

1999

Zeitschrift f�r Lebensmitteluntersuchung und -Forschung A

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“…The observed increase in activity during heat treatment may be attributed to the release of latent enzymes (Yemenicioglu et al, 1997) or transformation into active forms (Vámos-Vigyázó, 1981). The activation of enzymes during heat treatment has been reported by Lee et al (1991) for cocoa polyphenol oxidase (PPO), Chan et al (1996) for papaya ethylene forming enzyme and Yemenicioglu et al (1997) for apple PPO. Also, Vámos-Vigyázó (1981) noted the activation of kholrabi POX by heat in a detailed review.…”

Section: Activationmentioning

confidence: 99%

Thermal Stabilities of Peroxidases from Fresh Pinto Beans

Yemenicioğlu

Özkan

Cemeroğlu

1998

Journal of Food Science

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Heat stabilities of crude and partially purified soluble (SPOX), ionically bound (IPOX) and total peroxidase (TPOX) from fresh pinto beans were investigated at 55-90°C. Heat inactivation of peroxidase (POX) followed first-order reaction kinetics. Each inactivation curve consisted of two linear parts: initial rapid inactivation (heat-labile) followed by slower inactivation (heat-stable). IPOX showed activation during heat treatment with a highly heat-stable isoenzyme (D 90 =40 min) which was more heat-stable than SPOX. Activation energies for heat-stable parts of crude IPOX and SPOX were, respectively, 12.1 and 36.4 kcal·mol-1 with z values 45.4 and 14.1C°. Heat stable SPOX isoenzymes (D 70 =22.6) were obtained by 65-95% (NH 4 ) 2 SO 4 precipitation from crude SPOX. Two POX fractions (F1 and F2) were separated from TPOX by ion-exchange chromatography.

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“…This is because the fractions lost 50-60% and 60-75% of their activities within 5 min at 60 and 65 °C (Figure 2), respectively. The heat activation of various enzymes was reported by Yemeniciog ˇlu et al (1997) for apple PPO, by Lee et al (1991) for cocoa PPO, by Va ´mos-Vigya ´zo ´(1981) for kohlrabi POX, and by Chan et al (1996) a Ea(HL) ) 37.0 kcal mol -1 (r ) 0.978); z(HL) ) 13.8 °C (r ) 0.976); HL ) heat labile. Ea(HS) ) 37.8 kcal mol -1 (r ) 0.962); z(HS) ) 13.5 °C (r ) 0.957); HS ) heat stable.…”

Section: Resultsmentioning

confidence: 93%

Partial Purification and Thermal Characterization of Peroxidase from Okra (Hibiscus esculentum)

Yemenicioğlu

Özkan

Cemeroğlu

1998

J. Agric. Food Chem.

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Thermal characteristics and substrate specificity of peroxidase (POX) from okra were determined. Crude POX was separated into eight fractions (P1-P8) by DEAE-cellulose chromatography. Heat inactivation of POX was biphasic and fitted to a first-order kinetic model. Inactivation rates of crude POX and eight POX fractions at 70°C varied between (63.499 and 123.809) × 10 -2 min -1 for the heat-labile fractions and (11.255 and 31.441) × 10 -2 min -1 for the heat-stable fractions. Activation energies for the inactivation of crude extract were 37.0 kcal mol -1 with a z-value of 13.8°Cfor the heat-labile fraction and 37.8 kcal mol -1 with a z-value of 13.5°C for the heat-stable fraction. Optimum temperatures were between 30 and 35°C for the crude extract, 60°C for P1-P5 fractions, and more than 65°C for P6-P8 fractions. Among substrates, guaiacol was oxidized primarily by P1-P6 fractions; whereas, pyrogallol and catechin were preferred by P7 and P8, respectively.

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ACC Oxidase in Papaya Sections After Heat Treatment

Cited by 4 publications

References 17 publications

Separation and thermal characterization of ionically and tightly cell-wall-bound pectin methylesterase from cucumbers ( Cucumis sativus )

Separation and thermal characterization of ionically and tightly cell-wall-bound pectin methylesterase from cucumbers ( Cucumis sativus )

Thermal Stabilities of Peroxidases from Fresh Pinto Beans

Partial Purification and Thermal Characterization of Peroxidase from Okra (Hibiscus esculentum)

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