Location: Dairy and Functional Foods Research2012 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:
While work on the basic fluid milk process model to enable computer simulation to reduce greenhouse gas emissions (GHG) and energy use has been completed, an additional model is under development to simulate ultrahigh temperature (UHT) processing of milk as part of Obj. 1. It is believed that adoption of UHT processing throughout the industry will eliminate the need for refrigeration of the processed milk in the plant and on store shelves thus reducing up to 50% of GHG and energy in milk processing. The accessibility of minerals in milk to biological processes in humans may be affected by processing. Studies are underway to measure this bioavailability by digesting milk samples in digestive enzymes and then determining the concentrations of the key minerals by using inductively coupled plasma. Raw, pasteurized, and ultrapasteurized milk, as well as milk pasteurized using alternative technologies and homogenized at various pressures, will be assayed consistent with Obj. 2. Also consistent with Obj. 2, pilot-scale quantities of up to 97% pure peptide isolate containing up to about 60% un-glycosylated kappa-casein macropeptide (CMP), the purest form of GMP, and up to 37% other small peptides, including various degrees of glycosylated GMP and many other small milk peptides, with numerous potential nutritional benefits (to be determined), were produced. This CMP/GMP isolate powder is instantly soluble at most pH values at both cold and hot temperatures and is an ideal product for the fortification of pasteurized beverages, with pasteurization studies under way. In addition, residual beta-lactoglobulin (LG) and alpha-lactalbumin (LA) can be removed with ultrafiltration to use the pure CMP/GMP peptide product in foods for phenylketonuria patients. Commercial whey protein isolate (WPI) is composed of alpha-LA, beta-LG, GMP and minor whey proteins. Previously, an environmentally-friendly process using carbon dioxide was developed to sequentially separate the different proteins of WPI. The different stages of this process were modeled to perform cost estimates. The fractions are useful new ingredients for various food applications; in particular, the excellent solubility of GMP and beta-LG fractions on a wide range of temperature and pH will enable their use in pasteurized fortified beverages. The gel-forming abilities of beta-LG will be useful in edible milk-based films and coatings as part of Obj. 3. Also consistent with Obj. 3, the rheological properties of edible films made from calcium caseinate (CaCas) are being investigated as a function of temperature and relative humidity, to identify phase changes, water-swelling and mechanical properties under extreme environmental conditions. Various new ingredients, such as acid whey and dried milk, are being tested for formulation into the films, to enhance films properties and utilize these surplus dairy products.
1. Computer-based milk processing plant simulator to lower greenhouse gas emissions. A recent life cycle assessment of the environmental impact associated with fluid milk production, which begins at the farm and ends with the consumer, showed that on-farm activities contributed approximately 70% of total greenhouse gas (GHG) emissions mainly due to methane emissions by cows and manure. Off-farm activities, arising from milk processing, packaging and refrigeration, contributed the remaining GHG emissions in the form of energy-related carbon dioxide (CO2) emissions. Significant reductions in energy use would lower CO2 emissions and the costs associated with off-farm processes but it is impossible for processors to upgrade their plants if they do not know where the energy hotspots in their plants occur or if the costly upgrades will have significant effects on CO2 emissions. In this study, ARS researchers at Wyndmoor, Pennsylvania, collaborated with the dairy industry to create a computer model for the fluid milk process so that milk processors can test various ways of making changes in their plants to lower CO2 emissions and instantly calculate the cost savings in energy and their costs to implement the changes. The model has been distributed to over 100 processors in the U.S. and will help the dairy industry realize its goal of reducing CO2 emissions by 25% per gallon of milk by the year 2020.
Yver, A., Bonnaillie, L., Yee, W.C., Mcaloon, A.J., Tomasula, P.M. 2011. Fractionation of whey protein isolate with supercritical carbon dioxide – process modeling and cost estimation. International Journal of Molecular Sciences. 13(1):240-259.