Progress 09/01/11 to 08/31/15
Outputs
Target Audience:Food industry Academic researchers Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?Two refereed journal articles, one submitted on in final editing prior to submission. One presentation at an international meeting. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Traditional thermal processing methods, such as hot-break and cold-break processes, are commonly used in controlling enzyme activities during processing of tomatoes. This project investigated the possibility of process improvement using controlled-frequency moderate electric field (MEF) treatments on pectin methylesterase (PME) and polygalcturonase (PG) activities in tomato homogenate. We investigated the concept by subjecting identically treated control and MEF-treated samples to the same temperature history. The key results of this project are: Both PME and PG are almost completely present in the solid matter of the homogenate and highlight the importance of the food matrix when studying electric field effects on enzymes; The application of electric fields to tomato homogenate at a low field strength (0.4 V/cm) constant temperature (65 °C) shows a statistically significant inactivating effect on pectin methylesterase (PME), typically at frequencies at or lower than 60 Hz. At higher frequencies, the effects are negligible; The efficacy at low frequencies may be due to the amplitude of motion, with displacements being of the order of the intermolecular distance for water. Higher frequencies result in small overall displacements due to rapid reversals in the direction of motion; The presence of electric field (60 Hz, sine wave) causes activation of PME at 70 (± 1) °C. At higher temperatures, the electric field results in acceleration of PME inactivation in comparison to control samples treated at the same temperature history. The nonthermal effect of electric field on PME activity can be fine-tuned by MEF field strength and temperature. Particularly, the efficacy of electric field on PME inactivation increases with increasing field strength. No conclusions could be drawn relative to the response of PG to the electric field, due in part to the variability inherent in the measurement methodology. An alternate enzyme assay for the measurement of PME activity was developed and validated.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2015
Citation:
Samaranayake, C.P., and Sastry, S.K. 2015. Effects of controlled-frequency moderate electric fields on pectin methylesterase and polygalacturonase activities in tomato homogenate.
- Type:
Journal Articles
Status:
Other
Year Published:
2015
Citation:
Samaranayake, C.P., and Sastry, S.K. 2015. Effect of moderate electric fields on inactivation kinetics of pectin methylesterase and polygalacturonase in tomatoes: the roles of electric field strength and temperature. To be submitted
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2015
Citation:
Samaranayake, C.P., Durham, E.K., and Sastry, S.K. 2015. Chemical reactions during electric field processing. Presented at the 1st World Congress on Electroporation and Pulsed Electric Fields, Portoroz, Slovenia, September 6-9, 2015. (presented).
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Progress 09/01/13 to 08/31/14
Outputs
Target Audience: Scientists. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Kinetics of enzyme activity under electric fields has now been included in a course module in FABENG 5410: Advanced Food Process Engineering, offered at Ohio State. How have the results been disseminated to communities of interest? Presentations have been made at AFRI Project Directors' meetings. We are planning publications on the project in the upcoming year. What do you plan to do during the next reporting period to accomplish the goals? Work on enzyme activities will continue, including work on structure of enzymes under a field. Also, we will work on an enzymatic control reactor to use our findings on electric field effects. We will also be preparing manuscripts for publication.
Impacts
What was accomplished under these goals?
Kinetics of pectin methylesterase (PME) inactivation in tomato puree were investigated under conventional and moderate electric field (MEF) treatments using the Linearly Increasing Temperature Method (LITM). Data collected at nearly identical temperature histories show that at temperatures approaching the thermal inactivation range, the electric field activates enzymes, and at slightly higher temperatures, rapidly inactivates them in comparison to conventional heating. The extent of the effect was found to depend on electric field strength. At sufficiently high field strength, the activation-inactivation effect was statistically significant. However, no significant effects were found with polygalacturonase (PG).
Publications
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Progress 09/01/12 to 08/31/13
Outputs
Target Audience: This is currently aimed at the scientific research community. However, we anticipate that by the end of the project, we will beging talking to the tomato processing industry about the possibilities of moderate electric field effects. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? Progress report was presented at the NIFA Project Directors' Meeting in Chicago in July 2013. What do you plan to do during the next reporting period to accomplish the goals? Studies on effects of field strength and frequency have begun. We are investigating an approach for in-situ monitoring of PME (Pectin Methyl Esterase)activity during processing. Thereafter, we will proceed to development of electric field treatment equipment.. Results from prior study will be analyzed
Impacts
What was accomplished under these goals?
Model for determination of oscillation rate for enzymes under moderate electric fields have been developed. The predicted extent of oscillatory motion of the enzyme decreases with frequency in the low range of frequency. At the highest frequencies, little motion occurs in the enzyme. Studies on the effect of food matrix on enzyme activity have shown that a careful blending protocol is needed to minimize variability of results on PME (Pectin Methyl Esterase) activity. Currently, studies are under way to study the effect of frequency, field strength and temperature on enzymatic activity. For this purpose, we have developed a test cell that ensures that two otherwise identical samples may be treated with and without electric fields in the same test vessel simultaneously
Publications
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Progress 09/01/11 to 08/31/12
Outputs
OUTPUTS: Sastry S.K. 2012. Ohmic and Moderate Electric Field Processing: The Progression from the Macroscopic to the Molecular. Plenary lecture at the second International Conference on Bio and Food Electrotechnologies, Salerno, Italy, Sept. 25-28, 2012. PARTICIPANTS: The Ohio State University, Dr. Chaminda Samaranayake University of California, Davis, Dr. Diane Barrett, Dr. Gordon Anthon TARGET AUDIENCES: Fruit and Vegetable Industry, Food Safety Industry PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Enzymes play important roles in food processing. In particular, pectin methylesterase (PME) is responsible for tomato texture, and can break down tomato viscosity if not inactivated shortly after tomatoes are crushed for further use. It is currently inactivated by heat. Recently, we have found that it is possible to control enzyme activity using moderate electric fields, and are attempting to obtain a deeper understanding to improve processed tomato quality. Towards this end, models have been developed for molecular dynamics of as influenced by electric fields of various frequencies. The predicted extent of oscillatory motion of the enzyme decreases with frequency in the low range of frequency, and at the highest frequencies, little motion occurs in the enzyme Studies are under way to probe the effect of food matrix on enzyme activity
Publications
- No publications reported this period
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