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Effect Of Frequency On Polyphenoloxidase Activity During Moderate Electric Field Treatment

de la Torre, Jerry James Murillo
http://rave.ohiolink.edu/etdc/view?acc_num=osu1231859740

Abstract Details

2009, Master of Science, Ohio State University, Food Agricultural and Biological Engineering.
Polyphenoloxidase (PPO, EC 1.14.18.1) is one of the major enzymes in fruits and vegetables that causes undesirable browning when it reacts with phenolic substrates in the presence of oxygen to yield dopaquinone and eventually form melanin pigments. In this study, a purified PPO from mushroom was subjected to a constant electric field strength (10 V/cm) at different frequencies (60, 600 and 6000 Hz) at three isothermal conditions (40, 50, 60°C) for 5, 10 and 15 min. To isolate the effect of frequency, samples were also heated conventionally at the same temperature-time history. Enzyme activity was measured using spectrophotometric method and compared with that of untreated samples. Results showed that moderate electric field treatments (MEF) stimulated higher enzyme activity (p<0.05) compared to conventional heating at 60 and 6000 Hz 40°C 10 min, 6000 Hz 40°C 15 min and at all frequencies at 60°C 15 min. Reduced activity (p<0.05) was observed at all frequencies but at different conditions in the first 10 min of 60°C treatments: 60 Hz 5 min as well as 600 and 6000 Hz both at 10 min. The data suggests that MEF activation is likely to occur at higher frequency (6000 Hz) and at longer holding periods (15 min). Both the activation and inactivation results can be useful in medical and food processing applications. Further studies on the isolated effect of frequency treatments on specific enzyme isoforms and oxidized states may clarify the response mechanism of PPO to electric field stimulation.
Sudhir Sastry, PhS (Advisor)
VM Balasubramaniam, PhD (Committee Member)
70 p.
Agricultural Engineering; Engineering; Food Science
MEF Frequency Effect; polyphenoloxidase; tyrosinase; moderate electric field; enzyme activity

Recommended Citations

Citations

  • de la Torre, J. J. M. (2009). Effect Of Frequency On Polyphenoloxidase Activity During Moderate Electric Field Treatment [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1231859740

    APA Style (7th edition)

  • de la Torre, Jerry James. Effect Of Frequency On Polyphenoloxidase Activity During Moderate Electric Field Treatment. 2009. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1231859740.

    MLA Style (8th edition)

  • de la Torre, Jerry James. "Effect Of Frequency On Polyphenoloxidase Activity During Moderate Electric Field Treatment." Master's thesis, Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1231859740

    Chicago Manual of Style (17th edition)

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© 2009, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.