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United States Department of Agriculture

Agricultural Research Service

Research Project: Sustainable Strategies to Lower the Environmental and Economic Impacts of Food Processing Using Fluid Milk As a Template

Location: Dairy and Functional Foods

2013 Annual Report


1a.Objectives (from AD-416):
Develop simulation models that quantify the effects of process modifications on energy use, economics and greenhouse gas emission data for fluid milk processing plants.

Evaluate the impact of high temperature short time(HTST) and ultrahigh temperature (UHT) processing on the physical and/or chemical properties of milk proteins and minerals on the molecular level, and explore the implications of processing technologies on the bioactivity and bioavailability of key dairy ingredients.

Evaluate milk-based films and coatings as a means to reduce and/or improve packaging associated with food processing.


1b.Approach (from AD-416):
Research will be conducted to develop mathematical models that will be used to quantify the effects of various processing operations and parameters on energy use, economics, waste streams and greenhouse gas (GHG) emissions of fluid milk and other dairy and food processing plants. The models will be used in a simulation program that will also allow the examination of the impact of alternative processing techniques or alternative energy management systems on energy use, economics, waste streams and GHG emissions of processing plants and the nutrition of the products. The impact of high temperature short time (HTST), ultrahigh temperature processing (UHT), and alternative processing on some of the properties of the milk proteins and minerals on the molecular level will be evaluated using techniques that include HPLC, enzymatic digestions, and spectroscopic, microscopic and proteomics techniques. The bioactivity and bioavailability of a key dairy protein – mineral peptide will be evaluated using in vitro digestion simulation followed by analytical study. The mechanical and barrier properties of edible films and coatings as a function of technique of calcium caseinate and CO2-casein film preparation will be explored under a variety of humidity and temperature conditions to determine their application limits and potential to replace petrochemical films. Microscopy will be used to examine changes in protein conformation with environmental changes. Additional properties using ASTM techniques will also be determined.


3.Progress Report:
The computer simulation model of the fluid milk process to reduce GHG emissions and energy use has been published and disseminated to industry. The model has been extended to accommodate alternative processing methods such as the ultrahigh temperature (UHT) process, milk microfiltration (MF) followed by high temperature short time (HTST) pasteurization, and pulsed electric field processing (PEF). Data from the U.S. dairy industry is being used to help complete validation of the UHT process model. A colleague in Australia will provide data for further validation of the model. Milk MF followed by HTST is not in use in the US but may help eliminate dairy wastes by consumers which contribute to GHG emissions of the fluid milk supply. PEF is not in use in the U.S. but we are including it into a virtual milk processing scheme to predict the GHG emissions of non thermal technologies (Objective 1).

Studies to evaluate the effect of processing on digestion of milk have begun by comparing raw, homogenized, and heat treated (pasteurized or sterilized) whole and skim milk. Initial experiments are comparing fatty acids, clot sizes, and other parameters in the milk during and following each treatment to measure simulated gastrointestinal digestion of the protein and lipids in the milk. Preliminary results suggest that fatty acids break off of triglycerides at different rates during gastric and intestinal digestion, with most of the breakdown occurring by the first hour of intestinal digestion. Homogenization of the milk appears to increase this effect. The solid particles suspended in milk are reduced in size by a factor of ten during gastric digestion, and clot to form a stable dispersion during intestinal digestion. The clot size was larger when skim milk was used. This information may be helpful for designing processing schemes that relate sustainable processing technologies to food security, as well as provide a new view of the impact of processing on the health and nutrition of dairy and other food products. Parts of this project are performed in collaboration with project -091 (Objective 2).

Although they are inexpensive sources for the production of edible dairy-based packaging films, acid whey (AW) and dried milk (DM) present strong challenges when it comes to forming polymers that have enough structural integrity for film-casting and handling, due to their very high content of lactose. To produce films from AW and DM, the procedures for formulation of the solutions, for film-casting and drying, and for various testing procedures are being optimized as a function of several operating parameters. The order of film-making ingredients (water, protein/lactose mix (AW, DM or casein), plasticizers, crosslinkers, pH adjustment) has tremendous effects on polymerization rate and the proteins, and thus the microscopic and macroscopic structure of the films. The prevention of lactose crystallization by incorporation of various polysaccharide crosslinkers is showing great potential. Calcium caseinate is being used as a template to understand the formulation/structure/properties relationships of the complex AW and DM films (Objective 3).


Review Publications
Tomasula, P.M., Yee, W.C., Mcaloon, A.J., Nutter, D.W., Bonnaillie, L. 2013. Computer simulation of energy use, greenhouse gas emissions and process economics of the fluid milk process. Journal of Dairy Science. 96:3350-3368. Available: http://dx.doi.org/10.3168/jds.2012-6215

Tomasula, P.M., Mukhopadhyay, S., Datta, N., Porto Fett, A.C., Call, J.E., Luchansky, J.B., Renye Jr, J.A., Tunick, M.H. 2011. Pilot-scale crossflow-microfiltration and pasturization to remove spores of Bacillus anthracis (Sterne) from milk. Journal of Dairy Science. 94:4277-4291.

Farrell Jr, H.M., Brown, E.M., Malin, E.L. 2013. Higher order structures of the caseins: a paradox? In: McSweeney, P.L.H., Fox, P.F., editors. Advanced Dairy Chemistry, Volume 1A: Proteins: Basic Aspects, 4th edition. New York, NY: Springer Publisher. p 161-184.

Leggett, L.N., Tomasula, P.M., Van Hekken, D.L., Porto Fett, A.C., Shoyer, B.A., Luchansky, J.B., Renye Jr, J.A., Farkye, N. 2012. Effect of storage at 4 and 10 C on growth of Listeria monocytogenes in Queso Fresco. Journal of Food Safety. 32:236-245.

Last Modified: 12/21/2014
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