The Peter J. Shields Chair in Dairy Food Science

John M. Krochta

Peter J. Shields

Peter J. Shields was a great friend of the Dairy Industry, the State of California, and the University of California.  A dairy farmer, attorney, Secretary of the State Agricultural Society, Superior Court Judge, President of the California State Dairy Association and the California Livestock Breeder Association, he continuously promoted dairy improvement and was instrumental in drafting the bill which created what is now the Davis campus of the University of California (UC-Davis).

Peter J. Shields was recognized by UC-Davis with the first honorary degree ever awarded by the Davis campus and was also recognized by the naming of a major street, the main library, and a grove of oak trees on the Davis campus.  He and his wife bequeathed the major portion of their estate to The Regents to support scholarships and enrich the Arboretum on the Davis campus.

CMAB and CMMAB Creation of Shields Chair

It was appropriate that the visionary decision by the California Milk Advisory Board (CMAB) and the California Manufacturing Milk Advisory Board (CMMAB) to create a Chair in Dairy Food Science in the Department of Food Science and Technology on the Davis campus would include the determination that the Chair be named after Peter J. Shields.  Thus, the Peter J. Shields Chair in Dairy Food Science recognizes the historic relationship of the founder of the Davis campus to the Dairy Industry.

The purposes of the Shields Chair are to:

§  Attract and sustain outstanding Dairy Food Science scholars in the Dept. of Food Science and Technology

§  Provide the occupant with opportunities to conduct exemplary research, teaching, and continuous interaction with the Dairy Food Industry. 

During my service as Shields Chair (1998-present), I have worked hard to establish a strongly positive and contributing presence for the Shields Chair on the UC Davis campus.  In particular, my goals have been to:

o    Conduct research highly relevant to the California Dairy Industry

o    Provide mentoring to graduate students that familiarizes them with the dairy industry and prepares them to be leaders in industry, academia and government

o    Offer classroom teaching that enables student intellectual achievement in food preservation and packaging, with emphases on food safety and quality

o    Provide dedicated service to the university and my profession that supports quality teaching, research and outreach

o    Enhance the ability of UC Davis to serve the California Dairy Industry


California produces 20% of the milk in the U.S., with about half going to production of cheese. As cheese production has increased, so has production of whey.  Given the composition of whey, it is an underutilized resource, with approximately one-third of whey production going to waste and much simply being dried to low-value whey solids to be used as a filler in foods.

Thus, utilization of whey has been a high priority of the dairy industry.  During my time as Shields Chair, I have focused my research almost exclusively on the utilization of the whey protein and lactose derived from whey.  This has resulted in establishment of UC Davis as the world leader in research on formation, properties and applications of edible films and coatings, in particular the utilization of whey protein for films and coatings.

Over the years, this research has ranged from fundamental studies, into the relationship between molecular structure of film components and film formation and properties, to application studies of the usefulness of film and coating properties to food quality and safety. During the years of my Shields Chair appointment, my research has investigated several areas:

Oxygen-barrier Coatings.  An oxygen-barrier coating is desirable for nuts and other products vulnerable to oxidation.  Our work has demonstrated that whey protein films are excellent oxygen barriers and that forming whey protein films as coatings on nuts has a strong impact on quality and shelf life.   Our research into this application included fundamental studies on modification of nut and coating surface energies to enhance coating efficiencies. We further demonstrated that the formation of oxygen-barrier coatings on peanuts is especially enhanced in a fluidized-bed system.  Our work has also shown that whey protein coatings can modify the internal atmosphere of fresh fruits and vegetables for extending shelf life.

Gloss Coatings. Surface gloss is a desirable feature for many confectionery, bakery and produce products. Our work showed that the gloss of whey protein coatings is significantly affected by type and amount of plasticizer added to improve coating durability and that whey protein-sucrose coatings have gloss that rivals commercial ethanol-based shellac coatings, which have worker-safety and air-pollution problems.  Furthermore, our consumer tests revealed that the water-based whey protein coatings have greater acceptance than commercial ethanol-based shellac coatings.  We showed that the tendency for the sucrose to crystallize over long times can be greatly reduced by addition of crystallization inhibitors, thus maintaining the excellent gloss, mechanical and oxygen-barrier properties of the coatings.   

Antimicrobial and Antioxidant Coatings. Goals of greater food safety and higher food quality have motivated investigations on a wide range of antimicrobial and antioxidant compounds. However, when used in sprays or dips, these compounds quickly diffuse into the food interior, rather than remaining at the food surface to provide protection against surface contamination and oxygen. Our research has shown that whey protein film-coatings can hold antimicrobial and antioxidant compounds at the food surface, where they are effective at preventing microbial growth and oxidation. We have demonstrated the inhibition effects of lactoferrin, lysozyme and lactoperoxidase systems incorporated into whey protein films against the food-spoilage mold Penicillium commune and the pathogens Listeria monocytogenesSalmonella enterica, and Escherichia coli O157:H7.  Our measurements of the diffusion coefficients for antimicrobials in whey protein films, combined with information on minimum inhibitory concentrations, allow prediction of time during which foods can be protected against microbial growth.  Similar to the antimicrobials, we have shown the antioxidants ascorbic acid, ascorbyl palmitate and tocopherol maintain their activities in whey protein film-coatings, with no negative effect on the other properties of the films.  These antioxidants complement the excellent oxygen-barrier properties of whey protein films and coatings to protect foods against oxidation.

Coatings for Paper and Plastics. Replacements of synthetic barrier coatings are being sought for paper and plastic, to eliminate undesirable interactions with food and improve biodegradability or recycling of packaging waste.  We have determined that whey protein coatings on paper decrease the water vapor permeability (WVP), improve printability and provide excellent grease-resistance. We have also determined that whey protein coatings formed on plastic films have optical, surface and oxygen-barrier properties that are competitive with synthetic coatings.  Whey protein coatings formed on plastic films are more easily removed than synthetic coatings, to allow easier recycling of the base plastic film.

Thermoplastic Processing of Protein for Films.   Edible films from whey protein have previously been made by solution casting of aqueous solutions of whey protein.  While appropriate for studying the properties of edible films that would be formed as coatings on foods, the solution-casting method does not lend itself well to production of films that could be sealed to form food pouches.  We have demonstrated that films can also be made from whey protein powder mixed with a limited amount of glycerol and water.  By treating this mixture with the correct combination of temperature and pressure, the plasticized whey protein undergoes thermal transitions that lead to fusion of the powder and production of flexible, transparent films.  Guided by these results and the identification of the thermal transitions using DSC, it is possible to use an extruder for continuous production of films.  These results point to the possibility of commercial production of whey-protein-based films for wraps, separation layers and sealed food pouches.

Teaching and Mentoring

Over many years, I have taught FST 50 (Introduction to Food Preservation) annually, FST 131 (Food Packaging) annually, and EBS 231 (Mass Transfer in Food and Biological Systems) semi-annually.

FST 50 is a 3-unit lecture course required for all Food Science majors.  It provides students an overview of Food Science and Technology and is intended to introduce topics that are explored in greater depth in subsequent courses in Food Chemistry, Microbiology and Engineering.  FST 50 is also an opportunity to attract new students to the Food Science major. My 18 years of experience in the USDA-Agricultural Research Service, working on several food commodities and preservation techniques, adds value to my teaching of this course.

FST 131 is 4-unit lecture and discussion course required or recommended as an elective for options within the Food Science major. The topics covered include the functions of packaging, properties of materials available for fabricating packaging, food shelf life issues and determination, food-package mathematical models for package design, packaging waste reduction approaches, and food packaging law.  Students perform surveys of food stores to determine what packaging materials are found in different store sections for different types of foods and relate these materials to the functions they serve for the type of food.  Students also design packages for different food types.

EBS 231 is a 3-unit lecture course that presents in depth principles of mass transfer and then explores applications to food and other biological systems. I stress the assumptions made in mass transfer equations and experiments.   Students apply this knowledge in homework on determination of diffusion, solubility and permeability coefficients; food dehydration; food leaching; controlled-release of bio-active compounds; and food-package systems.  As a course project, students prepare a written review and a presentation on a selected mass-transfer paper, in which they critique the mathematical models, experimental design, results and conclusions of the paper.

Awards.  In 2003, 2004 and 2009, I received undergraduate teaching awards from the Associated Students of UCD, the official student government of UC Davis students.  These were particularly gratifying, because this award process is totally student run.      

        A very rewarding part of teaching at a research university is the mentoring of graduate students.  My approach is to provide a starting point from which my students can form their questions and hypotheses and apply their creativity.  I familiarize students with proposal writing, budgets, progress reports, oral presentations, lab book management, patents, and lab safety.  My research group meets frequently to give students practice on presenting research progress and plans and to stimulate interaction based on questions and suggestions.  I believe this preparation has helped my students win eight 1st, 2nd &/or 3rd place awards in poster competitions in the Institute of Food Technologists (IFT) Food Packaging Division since 2000, more than any other university.  In one year, my students won 1st and 2nd place in both the Food Packaging Division and the Dairy Foods Division. 

          Based on my contributions to the teaching and research of food processing and food packaging, I was selected in 2008 as a Fellow of the Institute of Food Technologists (IFT).  In 2008, I was also winner of the IFT-Food Packaging Division Riester-Davis Award for lifetime achievements in teaching and research of food packaging.  In 2010, I was selected to be a member of the International Academy of Food Science and Technology.   

Service and Outreach

Most of my service and outreach have been highly relevant to the goals of the Peter J. Shields Chair.  I have directed planning for a dairy foods teaching and research facility through many iterations, involving initially the Cruess Hall Pilot Plant and eventually the new August A. Busch III Brewery and Food Science Lab.  The purpose of the facility is to help realize the full potential of dairy foods teaching, research and outreach at UC Davis. 

          My efforts began by writing a proposal to the CAES and DANR, including a $250,000 matching-fund pledge from Shields endowment income, which resulted in a $250,000 award toward a new dairy foods facility.  I then organized a Dairy Foods Facility Advisory Committee comprising Dairy Industry and UCD faculty and staff to advise this effort.  After defining needs with input from all interested parties, I worked with the campus facilities office and an architect, who developed a feasibility study for the Facility involving remodeling of the Cruess Hall Food Processing Lab (Pilot Plant).  Although this approach was eventually abandoned for the Robert Mondavi Institute (RMI), the information and feasibility study that were developed have been valuable for use in planning a Milk Processing Lab for the RMI facility, and I worked to make sure the $250,000 award was carried forward to the new facilities.  In addition to the original $250,000 pledge, I have committed an additional $250,000 of the Shields endowment income collected during my time as Shields Chair to purchase of equipment for the Milk Processing Lab.

          In order to improve interaction with the California dairy industry, I chaired a Panel established by Dean Van Alfen to prepare a response to the dairy product innovation component of the California Dairy Industry strategic plan (McKinsey Report).  The report that I prepared incorporated input from the dairy industry, UC Davis faculty, and faculty from Cal Poly–San Luis Obispo and California State-Fresno.  I recently presented the Panel report to the California Dairy Research Coordinating Council.  I believe that my efforts will result in improved support for dairy foods research at UC Davis, as well as improved coordination with dairy research at Cal Poly-SLO and California Sate-Fresno.   

          During the review period, I also served as coordinator for the RMI Center for Advanced Materials, Methods and Processing (CAMMP).  My initial interest was in developing a Dairy Foods Research Center, but faculty were more inclined towards a broader center that would encompass both dairy foods research and other research that could be relevant to the dairy industry. CAMMP was awarded $50,000 in start-up funds from the CAES based on a proposal written by me with input from both FST and VEN faculty. The $50,000 was used to award a total of 9 seed grants over the past two years for collaborative research, on the basis of peer-review of proposals that was coordinated by me.  Each of the seed-grant projects has had relevancy to dairy food science.  

        I have given additional visibility to the Shields Chair by becoming more involved in the Institute of Food Technologists (IFT) Food Packaging Division (FPD).  I was successful in being elected as Secretary and then moved sequentially to the Chair-Elect, Chair, Nominations and Election Committee Chair positions. During the review period, I also served as a Councilor of the FPD, member of the IFT-FPD Annual Meeting Program Committee, and FPD Newsletter Editor.  FPD sessions at the annual IFT meeting have been a great venue for presentation of our research on whey protein edible films to a wide audience, including a wide range of food companies with interest in adopting our concepts.

           Our research has been exposed to an even wider audience because of interactions with the National Geographic Society, Associated Press, Scientific American and others that have led to extensive national coverage in popular TV, newspapers and magazines.


I believe that my efforts have resulted in restoring the positive presence of the Peter J. Shields on the UC Davis campus.  My research on whey protein, planning and equipment support for the new Milk Processing Lab with the August A. Busch III Brewery and Food Science Lab, efforts at improving relations and interaction with the dairy industry, and overall efforts at providing excellent teaching, research and service on the UC Davis campus are consistent with the goals established for the Shields Chair.