Location: Dairy and Functional Foods Research
2022 Annual Report
Objectives
1: Integrate new processes into the Fluid Milk Process Model (FMPM) to determine the effects of reductions in energy use, water use or waste on commercial dairy plant economics and greenhouse gas emissions.
1a: Develop benchmark simulations for configurations of stirred, set and strained curd yogurt processing plants in the U.S. that quantify energy use, economics, and greenhouse gas emissions, validated using data from industry.
1b: Use process simulation for evaluation of possible alternatives of whey utilization for the strained curd method of yogurt manufacture.
2: Integrate properties of edible films and coatings from dairy and food processing wastes with formulation strategies to better target commercial food and nonfood applications.
2a: Investigate thermal and mechanical properties of dairy protein-based edible films and coatings in real-life storage and utilization conditions.
2b: Apply new property findings to the investigation of useful and/or sustainable applications utilizing edible milk protein films.
3: Investigate the effects of different film-making technologies to manipulate the physical and functional properties of films and coatings made from agricultural materials.
3a: Investigate the effect of protein conformation on the ability to electrospin caseinates in aqueous solution and in the presence of a polysaccharide.
3b: Investigate the use of fluid milk, nonfat dry milk and milk protein concentrates as a source for production of electrospun fibers.
3c: Investigate the effects of edible and non-edible additives to the electrospun polysaccharide-caseinate fibers in aqueous solution.
4. Investigate techniques for separating components of dairy waste to determine their potential as ingredients. [C1,PS1A]
5. Investigate technologies for large-scale production of the ingredients identified in Objective 4, with products targeted to food applications. [C1, PS1A].
Approach
Research will be conducted to extend the use of the Fluid Milk Process Model (FMPM) to simulate different types of U.S. dairy production plants to identify the main sources of energy use and greenhouse gas emissions, propose ways to reduce water usage, and utilize waste streams more efficiently, either by water recovery or recovery of valuable constituents. Simulation results will be validated with data from industry, university and other partners. New edible packaging films and coatings from dairy proteins that can improve food quality and functionality, protect foods from spoilage and extend shelf - life, increase nutrition, reduce landfill waste, and utilize protein-rich surpluses and by-products of the dairy industry to boost their value such as nonfat-dry milk, or its derivatives casein and whey, will be designed with an emphasis on formulation and film-processing technique, for performance under commonly encountered storage and ambient conditions. Finally, those same protein-rich surpluses and by-products will be blended with other edible polymers then structurally modified using the novel electrospinning technology, to create micro- and nanofibers that can form new highly-value-added food and non-food products. This research is expected to help the US dairy and other food industries improve their sustainability, productivity, and profitability while providing new and better products to US consumers.
Progress Report
This is the final report for the Project 8072-41000-107-000D which ended November 30, 2021. New NP306 OSQR approved project 8072-41000-114-000D-, entitled “Reclaiming value from coproducts of dairy food manufacture” has been established.
Simulation of yogurt processes. The dairy industry conducted one of the first Lifecycle Assessments (LCA) for Fluid Milk Production from the farm to the consumer. We collaborated with them to develop a process simulator for a fluid milk plant that would calculate GHG emissions, energy and process water use, and costs. We are again collaborating with them to develop a simulator for the set, stirred or strained methods of yogurt. They have provided industry data to us. Because the yogurt processors were not able to provide as much data as the fluid milk processors, the simulated models, which are built on basic principles of conservation of mass and energy and use physicochemical data for yogurt manufacture will be used to fill in data gaps for the LCA. This is an entirely new approach for conducting LCA of a process and will change the way LCA for any process is conducted in the future.
Digestion of homogenized, pasteurized, and skim milk. Some Americans avoid milk because of trouble they have in digesting it. To investigate the source of these problems, ARS researchers at Wyndmoor, Pennsylvania, used a digestion model that simulated gastric and intestinal conditions to monitor the digestibility of protein and fat from pasteurized skim milk and raw milk that had undergone homogenization and pasteurization. The protein digestibility was improved by homogenization and by skimming the milk. Ultra-high temperature (UHT) pasteurization destroyed the protein structure and reduced fat digestibility. Protein and fat digestibility are affected by skimming, homogenization, and heat processing, which has implications with people who have difficulties in digesting milk. In collaboration with -091, the protocols to characterize casein phosphopeptides (CPP) have been adapted and are being used to monitor CPP levels in store-bought homogenized HTST and UHT milk samples, and in milk samples that were obtained from a local farm that underwent a variety of homogenization and pasteurization processing protocols followed by in vitro digestibility studies.
A new methodology to characterize biomaterials under extreme environmental conditions. ARS researchers at Wyndmoor, Pennsylvania, were the first to propose and publish a very precise and versatile methodology for the study of biopolymers produced using hydrophilic materials, such as carbohydrates or proteins, which are extremely sensitive to the temperature and humidity in their environment. Biobased plastic films destined for food packaging must be able to withstand all of the processing and storage conditions they are subjected to during manufacturing, packaging, storage, and utilization by the consumer, in order to preserve their strength and integrity and effectively protect food products. For example, food packaging may be subjected to periods of refrigeration at low humidity that can render the material 'glassy' and brittle; or storage in warm and humid warehouses or consumer kitchens may cause the biopolymer to melt and stick. Characterizing the intrinsic mechanical response of moisture-sensitive biopolymers and their physical changes on the broad range of T and H that may be encountered during real-life utilization is critical to develop performant bio-based plastics for food packaging and other 'green' applications.
Method to characterize caseinate-based edible films. Caseinate films are extremely sensitive to the ambient conditions of temperature and humidity, which strongly affect the possible storage and utilization conditions of the films. To be able to characterize, improve, and optimize the films for use in real-life food-packaging applications, a new methodology was developed that applies high-precision dynamic mechanical analyses to hydrophilic protein-based films in a precisely humidity-controlled environment (DMA-RH). This new technology was used to map the mechanical properties of casein films under various environmental conditions encountered in everyday life or in extreme storage/transportation conditions and identify the different sets of conditions that trigger critical property variations or breakage of the films and limit their use for food packaging. The films’ compositions were then modified with blending of polysaccharides to strengthen the films and improve their resistance to temperature and humidity and tested with dry-milk powder to lower the cost of the films. For each new formulation and composition, the DMA-RH technology helps identify and quantify the precise mechanical and structural changes induced by the new formulations, and the implications for real-life utilization of the films.
Simulator with anaerobic digester. The sustainability of the Greek-style yogurt (GSY) process has been questioned because unlike the more popular stirred and set curd yogurt processes, it generates an acid whey stream, which is usually spread on farms or fed to animals and is costly to utilize. Proposed regulatory measures may limit land application in the future. The dairy industry is in the process of developing a Lifecycle Analysis of the yogurt industry for examination of yogurt processing and has provided us with data and information from their subject matter experts so that we may construct simulation models of the various processes used to make yogurt. We are also using our models to assist the industry in filling in process data that they don’t have to conduct a robust Lifecycle Analysis. Using our preliminary simulations, we provided them with information for stirred, set and GSY processes to estimate their energy use, greenhouse gas emissions (GHG), and acid whey production, and also developed an acid whey process in which the acid whey is fed to an anaerobic digester to produce biogas. We also devised an alternative GSY process made from fortified milk without acid whey production. In all plants, production of nonfat yogurt with blended fruit was simulated assuming a raw milk input of 27,300 L/h (113.2M L/y). Simulations of the plants were conducted and energy use and GHG emissions were similar for the stirred and set curd processes, but higher values were obtained for the GSY processes because of less yogurt, but more concentrated yogurt was produced with whey removal. Addition of an on-site anaerobic digester to the process increased energy use and GHG for the GSY process to operate the digester with production of unrefined biogas and additional wastewater and digestate. Simulation of biogas refining was not conducted in this study, but this would eliminate the GHG associated with the trucks that haul the acid whey from the plant to farms where it is used in animal feed or as a soil amendment and help prevent water pollution.
Even though calcium and sodium caseinates (CaCAS and NaCAS) are both obtained through neutralization of acid casein, with either calcium or sodium hydroxides, the functional properties of the edible films prepared from them differ. The differences in the two ions are shown in the electrostatic and ionic interactions between the proteins and other ingredients in the film-forming suspensions, which in turn affect the film-casting process and the structure and properties of the dried films. Extensive characterization of NaCAS films under normal and extreme environmental conditions was performed to leverage the functional differences with CaCAS films and enable a broader variety of food preservation and packaging applications. The calcium ions in CaCAS create additional electrostatic bonds between and within the casein particles that render the structure of CaCAS suspensions and films more complex than that of NaCAS and more sensitive to formulation changes. A variety of single-serve food pouches (instant coffee, soup, cheese) were prepared to measure the moisture-transfer kinetics and solubility of the films, as well as the shelf-life of the food in different storage conditions. This work was featured in a Press Release and short video documentary by the American Chemical Society. It should also be noted that this is the first research to be conducted on concentrated casein suspensions at elevated pH levels and will have implications on the manufacture of dairy protein-based films and other dairy proteins research.
Nanofibers from casein. Building upon previous films work, the technique of electrospinning, which is used to produce nanofibers from synthetic polymers, was used to create porous mats from fibers of casein, to explore new applications for the proteins, other milk components, and other food ingredients. Each casein-based fiber in the mats has a diameter as small as 160 nanometers, equivalent to 0.0000063 inches, and a surface area which is about 1000 times greater than its volume. Owing to the large surface area, these fibers have the potential to introduce intense colors, flavors or textures within or on foods, may deliver controlled amounts of nutrients such as vitamins and minerals, or therapeutics, from foods. This is the first example of an edible nanofiber from a milk protein. (Patent awarded.)
CaCAS films with Non Fat Dairy Milk (NFDM). The characterization of edible films from different dairy protein sources was continued. Films made from nonfat dry milk and/or calcium caseinate and/or other dairy powders were prepared at different concentrations and alkaline additives, and evaluated for their appearance, structure, strength and elasticity, solubility, and oxygen barrier properties. In addition, film suspensions were examined via optical microscopy and dynamic rheometry before casting. Films ranging from low to an instant solubility, and with a high strength to high elasticity, were prepared for a wide range of applications. Patent awarded.
Accomplishments
