JOHN M. KROCHTA, Professor

Ph.D., Chemical Engineering, University of California, Berkeley, 1971
Department of Food Science and Technology /Biological and Agricultural Engineering
237 Cruess Hall
Phone: 530-752-2164
Email: jmkrochta@ucdavis.edu
Web: http://foodscience.ucdavis.edu/fst/faculty/KrochtaWeb/index.htm

Current Research

Professor Krochta's research involves study of polymer film formation, transport characteristics, modeling, and application to food packaging and biological systems.

Edible Films: The focus of this research includes the underlying chemistry and mechanisms affecting film formation and morphology, and the resulting film permeability and mechanical and sensory characteristics of the films. New approaches to forming films from proteins have been developed. Results show that milk protein films are excellent oxygen barriers at RH < ~50%. Utilizing the emulsifying ability of milk proteins has produced protein-lipid composite films with >90% reduction in moisture permeability. Lipid type, amount, and particle size all have important impact on film morphology and properties. Work continues to further improve the moisture barrier of composite films, extend the oxygen barrier over a larger RH range, and quantify the aroma and lipid barrier properties of films. Lack of understanding of edible films prevents selection of appropriate materials and design of systems with the desired characteristics.

Edible Coatings: Other research is underway to take advantage of moisture, oxygen, aroma, and lipid barrier properties of edible films formed as coatings on food products. Research in this area involves investigation of coating formulation surface tension and viscosity effects on wetting and spreading of coating formulations on foods with hydrophobic and/or porous surfaces, coating formulation and drying condition influences on adhesion and integrity of food surfaces, and assessment of oxygen, moisture, aroma, and lipid barrier properties of optimized film coatings on different classes of food products. This research involves mathematical modeling of film-coated foods, methodology for forming films as coatings on foods, and shelf-life studies of coated foods to confirm modeling approaches.

Controlled Release: Additional research extends to the areas of controlled release of food ingredients, pharmaceuticals, and pheromones from edible and biodegradable materials. This includes synthesis and characterization of useful biodegradable polymers from lactose.

Representative Recent Publications

Dangaran, K. L. and J. M. Krochta. 2006. Kinetics of Sucrose Crystallization in Whey Protein Films. J. Agric. & Food Chem. 54(19): 7152-7158.

Hong, S.-I. and J. M. Krochta. 2006. Oxygen Barrier Performance of Whey Protein Coated Plastic films as Affected by Temperature, Relative Humidity, Base film and Protein Type. J. Food Engineering. 77(2006): 739-745.

Krochta, J. M. 2006. Food Packaging. In Handbook of Food Engineering (D. R. Heldman & D. B. Lund, eds.) Marcel Dekker Inc., New York.

Lin, S.-Y. and Krochta. 2006. Fluidized-Bed System for Whey Protein Film-Coating on Peanuts. J. Food Process Engineering. 29(2006): 532-546.

Min, S., L, J. Harris and J. M. Krochta. 2006. Inhibition of Salmonella enterica and Escherichia coli O157:H7 on roasted turkey by edible whey protein coatings incorporating the lactoperoxidase system. J. Food Protection. 69(4): 784-793.

Min, S., J. M. Krochta, T. R. Rumsey. 2007. Diffusion of thiocyanate and hypothiocyanite in whey protein films incorporating the lactoperoxidase system. J. Food Engineering. 80(2007): 1116-1124.

Sothornvit, R., C. W. Olson, T. H. McHugh, J. M. Krochta. 2007. Tensile properties of compression-molded whey protein sheets. J. Food Engineering. 78(2007): 855-860.

Membership in Professional Societies

American Chemical Society
American Institute of Chemical Engineers
American Society of Agricultural Engineers
American Society for Engineering Education
Institute of Food Technologists
Institute of Packaging Professionals
Sigma Xi Scientific Research Society

Courses Offered

FST 50 - Introduction to Food Preservation
FST 131 - Food Packaging
EBS/FST 133 - Packaging with Plastics (proposed)
EBS 231 - Mass Transfer in Food and Biological Systems

Research Support

California Milk Advisory Board
Dairy Management, Inc.