NC-136, IMPROVEMENT OF THERMAL PROCESSES FOR FOODS

1999 ANNUAL REPORT

 S. Barringer,G. Kaletunc, S. Sastry, T. Shellhammer, Q. Zhang

  I.  PROGRESS AND ACCOMPLISHMENTS

Studies on enhanced diffusion during ohmic heating are continuing.  Results suggest that the enhancement is due to an electroporation mechanism within cellular tissue.  A study on electrode processes during ohmic heating has been initiated.

The efficiency of electrostatic powder coating was tested using different particle sizes and shapes.  The effect of powder properties on evenness of coating was measured.  The dielectric properties of egg, fish, pork, beef and whey protein gels were measured across a range of frequencies and temperatures.  The temperature at which the proteins denatured could be detected by the change in dielectric property values.  Change in viscosity and yield stress of tomato juice and sauce were measured after different processing methods, at various stages during processing, and during storage.

 Objective B.

A study on electrode fouling and arcing processes was conducted.  Results indicated that the occurrence of arcing in ohmic heaters increases with the field strength, temperature and protein content.   A set of arcing diagrams were developed, which specify the operating ranges where arcing may occur.

An investigation of ohmic heating for blanching of mushrooms has indicated that substantial water savings could occur as a result of this technology. 

A pilot-scale ohmic heater with a rapid cooling feature has been constructed, and is in the testing phase.

Objective C.

A detailed study has been conducted to characterize the worst-case scenarios during ohmic heating.  Studies consistently show that the static condition results in more rapid heating than situations in which convection is present.  This has been found to be true both when solids are either more or less electrically conductive than the fluid medium.  When the solid is less conductive, the heating of a mixed-fluid system was found to be signficantly slower than a static system.  When the solid was more conductive than the fluid, the mixed fluid heating system heated slower than the static; however, the difference was gradually perceivable, and less pronounced than in the former case.  Some previous studies have involved experiments conducted in two-dimensional systems, where such effects were not observed. We are in the process of verifying whether significant differences exist between two- and three-dimensional systems, and are investigating the relevance of a two-dimensional approach for such an instance.

 II.  USEFULNESS OF FINDINGS

Studies on ohmic heating will help develop novel processes and equipment for a wide variety of processes, including food sterilization and pasteurization.

Determination of the effect of powder properties on electrostatic powder coating efficiency will be used to optimize the coating system, for use in the snack food industry. 

The dielectric property measurements are used in microwave sterilization experiments, aimed at commercializing the process.  Viscosity measurement of tomato products will be used to determine viscosity loss by different processing methods. 

III.  WORK PLANNED FOR NEXT YEAR

Objective A.

Studies on enhanced mass transfer and fermentations will continue.  In particular, further work will be done on the effect of electrode materials, waveforms/frequency, and electrode design on electrochemical reactions.

Measure charging efficiency properties of various powders, and determine how that affects electrostatic powder coating efficiency.  Experiment with different types of coatings.  Optimize methods for measuring the evenness of the powder coating.  Continue to measure dielectric properties at elevated temperatures. Finish the studies on the effects of processing and storage on viscosity of tomato products. 

Objective B.

The pilot scale ohmic heater will be available for further work.  In particular, rapid cooling methods will be tested.

Objective C.

Further work is planned to compare worst-case scenario results during ohmic heating based on two and three-dimensional experiments.  A modeling study for PEF processing has begun.

 IV. PUBLICATIONS

Manuscripts

Sastry, S.K., and Salengke, S. 1998. Ohmic heating of solid-liquid mixtures: a comparison of mathematical models under worst-case heating conditions.  J. Food Proc. Engr. 21(6):441-458.

Cho, H-Y; Yousef, A.E., and Sastry, S.K. 1999. Kinetics of inactivation of Bacillus subtilis spores by continuous or intermittent ohmic or conventional heating.  Biotechnol. & Bioeng. 62(3):368-372.

Sahin, S., Sastry, S.K., and Bayindirli, L. 1999.  Heat Transfer During Frying of Potato Slices. Lebensm-Wiss. u.-Technol. (Food Science and Technology). 32:19-24.                      

Lima, M., Heskitt, B.F., and Sastry, S.K. 1999.  The effect of frequency and wave form on the electrical conductivity-temperature profiles of turnip tissue. J. Food Proc. Engr. 22:41-54. 

Lima, M., and Sastry, S.K. 1999.  The effects of ohmic heating frequency on hot-air drying rate, desorption isotherms and juice yield.  J. Food Engr. 41:115-119.      

Sahin, S., Sastry, S.K., and Bayindirli, L. 1999. The Determination of Convective Heat Transfer Coefficient During Frying. J. Food Engr. 39:307-311. 

Bircan, C. and S. A. Barringer.  1998. Effect of viscosity on the dielectric properties of a starch solution when salt is present.  Journal of Food Science 63(6): 983-986. 

Barrett, A.H. and Kaletunç, G. 1998. Quantitative description of fracturability changes in puffed corn extrudates affected by sorption of low levels of moisture. Cereal Chemistry, 75(5):695-698 

Sahin, S., Sastry, S.K., and Bayindirli, L. 1999.  Effective Thermal Conductivity of Potatoes During Frying: Measurement and Modeling.  Intl. J. Food Properties. (In press). 

Lima, M., Heskitt, B.F., Burianek, L.B., Nokes, S.E., and Sastry, S.K. 1999.  Ascorbic acid degradation kinetics during conventional and ohmic heating.  J. Food Proc. & Pres. (In press).

Das, D. J. and. Barringer, S. A. 1999.  Use of organic solvents for improving peelability of tomatoes.   Accepted to the Journal of Food Processing and Preservation 1/12/99

Barringer, S. A. , M. A. Bennett, and W. D. Bash.  1999.  Effect of nitrogen fertilizer levels and fruit maturity on tomato peeling efficiency. Journal of Vegetable Crop Production 5(1)  in press 

Pandrangi, S. and S. A. Barringer. Effect of calcium on peelability of tomatoes (Lycopersicum esculentum).  Journal of Vegetable Crop Production accepted 7/7/99.  

L.A. Lucore, L.A., Shellhammer, T.H., and Yousef, A.E. Inactivation of Listeria monocytogenes in artificially contaminated frankfurters by high pressure processing. J. of Food Prot. In review.

Wang, W-C., and Sastry, S.K. 1999.  Thermal pretreatment effects on hot air drying and water activity.  Abstract No. 22D-50.  1999 IFT Annual Meeting, Chicago, IL, July 24-28.

Sensoy, I., Sastry, S.K., and Beelman, R.B.  1999.  Ohmic blanching of mushrooms. Abstract No. 79B-1.  1999 IFT Annual Meeting, Chicago, IL, July 24-28.

Salengke, S., and Sastry, S.K. 1999.  Comparative modeling study of ohmic heating of solid-liquid mixtures. Abstract No. 79B-2.  1999 IFT Annual Meeting, Chicago, IL, July 24-28.

Kulshrestha, S.A., and Sastry, S.K. 1999. Low-frequency dielectric changes in vegetable tissue during ohmic heating. Abstract No. 79B-3.  1999 IFT Annual Meeting, Chicago, IL, July 24-28.

Pandrangi, S. & Barringer S. A. 1998. Effect of foliar calcium on peelability of tomatoes. Institute of Food Technologists Annual meeting Paper No. 34B-30.

Pandrangi, S. & Barringer S. A. 1998. Coagulation of tomato industry effluent using ferric chloride. Institute of Food Technologists Annual meeting Paper No. 34B-28.

Pandrangi, S. & Barringer S. A. 1998. Effect of maturity on peelability of tomatoes. Institute of Food Technologists Annual meeting Paper No. 34B-29.

Barringer, S. A. 1999.  Peeling efficiency studies. Ohio Valley Fruit and Vegetable Growers Congress p132. Not peer reviewed.

Apaiah, R. K. & Barringer S. A. 1999. Quality changes in tomato sauce during shelf storage at different temperatures. Institute of Food Technologists Annual meeting Paper No. 22D-32.

Whitaker, A.M. & Barringer S. A. 1999. A study of the cake-baking process--a phenomenological theory for high-ratio layer cake. Institute of Food Technologists Annual meeting Paper No. 37B-17.

Bircan, C. & Barringer, S.A.. 1999.  Use of the dielectric properties to determine protein denaturation using a frequency sweep at different temperatures. American Institute of Chemical Engineers Annual Meeting Paper No. 463.

Miller, M. & Barringer, S.A..  1999. Electrostatic coating of popcorn. American Institute of Chemical Engineers Annual Meeting Paper No. 436.

Shellhammer, T.H. and Krochta, J .M.  1998.  Microstructural Evaluation of heat annealed edible  whey protein and beeswax emulsion films.  ASAE Annual International Meeting. Paper# 60-39. July, Orlando, Fl.

Nienaber, U. and Shellhammer, T.H,  1999. Stabilization of fresh orange juice by combining high pressure and thermal treatments. Annual Meeting of the Institute of Food Technologists, Paper # 22B-6.  July. Chicago, Il.

Nienaber, U. and Shellhammer, T.H,  1999. Shelf life study of high pressure processed orange juice. Annual Meeting of the Institute of Food Technologists, Paper # 83A-16.  July. Chicago, Il.

Shook, C., Shellhammer, T.H, and Schwartz, S.J.  1999. High pressure inactivation of lipoxygenase, pectin methylesterase, and polygalacturonase in diced tomatoes. Annual Meeting of the Institute of Food Technologists, Paper # 22D-55.  July. Chicago, Il.

Kaletunc, G. 1999. FTIR microspectroscopy of wheat extrudate compositional microstructure. IFT Annual Meeting, Paper No. 60-10. July. Chicago, Illinois.

A.H. Barrett, A.V. Cardello, P. Maguire, M. Richardson, G. Kaletunc, and I.A. Taub. 1999. Textural stability of shelf-stable bread:  surfactant, dough conditioner, and storage temperature effects. American Association of Cereal Chemists Annual Meeting.  Seattle, Washington.

 Approved Manuscripts, Theses and Miscellaneous Reports

Wongsa-Ngasri, P. 1999.  Effects of inlet temperature, electric field strength and composition on the occurrence of arcing during ohmic heating.  M.S. Thesis.  The Ohio State University.

Pandrangi, S. 1998.  Treatment of Tomato industry effluent by coagulation using ferric chloride and factors affecting peelability.  M.S. Thesis, The Ohio State University.

Gunawan, M. I. 1998. Chlorophyll degradation of processed broccoli during refrigerated storage. M.S. Thesis, The Ohio State University.

Shook, Carla.  1999.  The effects of high pressure processing on peeled tomatoes. M.S. The Ohio State University.