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United States Department of Agriculture

Agricultural Research Service

Research Project: PROTEIN PROCESSING USING HIGH-PRESSURE GASES AND SUPERCRITICAL FLUIDS
2007 Annual Report


1a.Objectives (from AD-416)
The objectives of this research are to:.
1)develop new, cost effective technologies for processing protein fractions from NFDM into food and non-food products by utilizing concepts from physical chemistry, (2) develop new environmentally benign processes for dairy protein modification that utilize supercritical fluids as reaction media and solute carriers; and.
3)develop new processes for producing enriched fractions of the whey and casein proteins to utilize surplus NFDM and whey.


1b.Approach (from AD-416)
This research will focus on the means of developing new food and non-food uses for whey and casein, as well as nonfat dry milk (NFDM), through basic research and process development engineering. Specifically, new processing techniques for production of edible films from the milk proteins will be investigated to expand their utilization into new food and nonfood products. High pressure and supercritical carbon dioxide will be investigated as media for creating modified casein and whey proteins to increase the functionality of the proteins for food uses. A new environmentally benign process will be designed based on one that was developed in our laboratory for fractionation of whey proteins concentrate into two enriched fractions, alpha-lactalbumin (a-LA) and beta-lactoglobulin (B-LG). Process simulation will be incorporated into the study to guide process development for the most efficient production scheme. In addition, the possibility of producing a fully soluble form of a-LA and a form in the so-called molten-globule state will be investigated. This will ultimately expand the range of products that can be obtained from a single process thereby reducing the costs associated with whey protein concentrate. Finally, casein molecular models developed previously in our lab will be used to guide production of enriched fractions of the individual caseins.


3.Progress Report
Most research on biobased films is done on the laboratory scale which is often not representative of commercial scale production. If biobased films are to be produced on a large-scale and be competitive with petroleum-based high performance packaging materials, their unit cost should be similar to currently used materials such as EVOH (ethylene vinyl alcohol). This study determined the optimal drying temperature, drying time and solution concentration for making casein-based films in a manner that mimics large-scale continuous production along with the associated costs of production. Preliminary results from a cost estimate indicate that casein-based films may be produced at the same costs as EVOH films, which is typically in the $2-$4/lb range. Using dairy protein-based films as high performance barriers instead of synthetic materials can create a new outlet for dairy proteins and make packaging systems more environmentally-friendly.

Sweet whey is usually concentrated using membrane processing or ion-exchange to produce whey protein concentrates and whey protein isolates. In a past study, we have demonstrated that carbon dioxide (CO2) may be used instead of acids to produce enriched fractions of the whey proteins, alpha-lactalbumin and beta-lactoglobulin. Recovery of the alpha fraction using CO2 was approximately 55% while that of the beta fraction was 78%, at a relatively non-acidic pH, compared to the pH of 3.5 to 4 that is required when using acids. Kinetic studies are being conducted to identify the optimal conditions of temperature and pH that will improve recovery of the individual whey proteins using CO2.

The use of genipin, a cross-linking agent for casein-based polymeric networks, was investigated using various caseins. The reactions were followed and products were examined by spectroscopic and microscopic techniques including UV-VIS, circular dishroism (CD), FTIR, Scanning Electron microscopy (SEM) and Atomic Force Microscopy (AFM). Results indicated that the rate of crosslinking reactions increased as a function of temperature and pH. The mechanism for the crosslinking is currently being investigated.


4.Accomplishments
High-performance oxygen barriers for packaging systems. Edible films made from dairy proteins such as CO2-casein and sodium or calcium caseinate would serve the current need for environmentally-friendly alternatives to petroleum based packaging. Researchers from the Dairy Processing and Products Research Unit, Eastern Regional Research Center, Wyndmoor, PA, have demonstrated that films made from casein and caseinate proteins have oxygen permeabilities similar to materials such as ethylene vinyl alcohol (EVOH), commonly used as an oxygen barrier in synthetic films and packaging for food protection in the home and for business use. Composite films made of casein-coated low density polyethylene (LDPE) have an oxygen permeability 10 times lower than that of LDPE alone. An added plus is that the casein in the CO2-casein films is produced using carbon dioxide, a byproduct of ethanol production, and the CO2-casein films, also contains glycerol, a byproduct of biodiesel production. This work demonstrates that films made from agricultural materials have the potential to perform as well as synthetic materials in packaging systems. (NP 306 Action Plan Component 2. New Processes, New Uses and Value-Added Foods, and Biobased Products. Problem Areas 2a. New Product Technology and 2c. New and Improved Processes and Feedstocks.)


5.Significant Activities that Support Special Target Populations
None


6.Technology Transfer

Number of new CRADAs and MTAs1
Number of active CRADAs and MTAs2
Number of patent applications filed1
Number of web sites managed1
Number of non-peer reviewed presentations and proceedings13
Number of newspaper articles and other presentations for non-science audiences11

Review Publications
Tomasula, P.M., Kozempel, M.F., Konstance, R.P., Gregg, D.A., Boettcher, S., Baxt, B., Rodriguez, L.L. 2007. Thermal inactivation of foot-and-mouth disease virus in milk using high-temperature short time pasteurization. Journal of Dairy Sci. 90:3202-3211.

Gutierrez, A.M., Farrell, H.M., Attaie, R., Mcwhinney, V.J., Wang, C. 2007. Effects of bovine and caprine monterey jack cheeses fortified with milk calcium on bone mineralization in rats. International Dairy Journal. 17:255-267.

Sood, S.M., Lekic, T., Harbir, J., Farrell, H.J., Slattery, C.W. 2006. Reconstituted micelle formation using reduced, carboxymethylated bovine k-casein and human b-casein. Protein Journal. 25(352-360).

Qi, P.X.. 2006. Importance of c-terminal region of bovine b-casein. American Chemical Society Symposium Series 935. p.71-92.

Barone, J.R., Dangaran, K.L., Schmidt, W.F. 2006. Blends of cysteine-containing proteins: i. physical properties. Journal of Agricultural and Food Chemistry. 54:5393-5399.

Last Modified: 4/16/2014
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