Location: Dairy and Functional Foods Research
2022 Annual Report
Objectives
Objective 1: Use process simulation to develop cost-effective processes for valorization of waste dairy streams to reduce environmental impact and reuse water.
Objective 2: Investigate technologies for large-scale production of edible coatings, made from predominately dairy proteins and waste dairy streams; their storage stability; and, as films for secondary packaging.
Objective 3: Develop fermentation technologies for utilizing dairy coproducts or waste streams to produce antimicrobial peptides by lactic acid bacteria, and assess their activity against bacterial pathogens and spoilage microorganisms.
Objective 4: Develop a process for recovering food-grade, allergen-free fat from frozen dessert waste.
Approach
Dairy processing generates waste streams ranging from those that are mostly water to packaged products that did not meet a manufacturer’s quality standards. This project aims to utilize the watery acid whey streams generated from Greek-style yogurt (GSY) manufacture, cheese whey, permeates, and wasted products such as ice cream through computer simulation and laboratory and pilot plant research. Computer simulation of an actual GSY plant will be used to investigate ways to recover and reuse water from the waste streams and for optimizing extraction of nutrients with economic value. The model will be customized by choosing conditions for straining based on the properties of a finished GSY with properties that consumers appreciate using knowledge-based systems and advanced simulation methods. Laboratory and pilot plant experiments will examine the manufacture of edible films and coatings from the watery streams for food and nonfood uses by standardizing the feed material used for each type of film. Other research will determine if the dairy waste streams or byproducts can be utilized as fermentation substrates for the production of antimicrobial peptides by dairy lactic acid bacteria. Preliminary studies will seek to optimize antimicrobial peptide production by varying substrate composition and fermentation parameters. Additionally, molecular techniques will be investigated for developing bacterial strains capable of producing higher concentrations of antimicrobial peptides, and fermentates will be assessed for novel antimicrobial peptides generated via the degradation of native milk proteins. Fermentation technologies will be assessed for pilot-scale production of antimicrobial peptides and resulting fermentates will be investigated for food safety and functional food applications. Finally, research will determine whether allergen free butterfat can be recovered from waste ice cream using a cost-appropriate process. This will be accomplished by studying the stages of fat separation and refining individually, and at each stage testing a variety of technologies for efficacy and projected cost. Pilot plant implementation of the chosen technologies will be used along with techno-economic analysis to generate results that enable ice cream manufacturers to evaluate the process for possible adoption. This project will introduce several sustainable approaches for reducing energy and water use, and recovery of process wastes with added value for food or nonfood uses.
Progress Report
Research addressing the 12-month milestone for Objective 1 involved updating the Fluid Milk Process simulator to improve its ability to process separate cow water, which is the water in milk, from process water for sustainability studies. Parameters such as biological oxygen demand and chemical oxygen demand were also updated. To include knowledge-based calculations and then predictive ability for a future version of the simulator, subroutines were added to the simulator to generate rheological data for milk and milk products.
Research addressing the 12-month milestones for Objective 3a included the screening of the project in-house collection of Lactobacillus (L.) strains for production of antimicrobial compounds. The 122 strains were cultured in MRS broth or skim milk overnight and the collected cell free supernatants are being assessed for antimicrobial activity. Antimicrobial activity against opportunistic enterococcal pathogens was identified, and several strains of Lactobacillus plantarum and L. casei were shown to inhibit the growth of Pseudomonas fluorescens, a milk spoilage organism. Additionally, one L. casei strain which inhibited Pseudomonas growth also inhibited the growth Campylobacter jejuni. Anti-camplylobacter activity is the focus of an ongoing collaboration with a project scientist fron another in-house research unit. Studies assessing the potential for wasted ice cream to serve as a fermentation substrate for production of Streptococcus thermophilus bacteriocins was initiated. Preliminary results showed that thermophilin 110 was produced in 14 samples of melted vanilla ice cream. Production occurred similarly in whole ice cream and aqueous by-products generated from the removal of ice cream fat. Production was observed to vary depending on the brand of ice cream. Studies are ongoing to investigate how emulsifiers, specifically Tween 80, affects bacteriocin production. Ongoing collaborative studies include the characterization of the genes encoding the bacteriocin produced by Streptococcus thermophilus ST34 with a scientist at Carnegie Mellon University. Several mutant strains have been generated and tested for loss of activity, and further studies are focusing on the over expression of specific genes within another S. thermophilus strain that does not produce a bacteriocin. Work is ongoing to complete a study assessing the antimicrobial activity of thermophilin 110, a bacteriocin produced by S. thermophilus B59671, against Propionibacterium acnes; and access the potential for encapsulating thermophilin 110 in arabinoxylan gels (in collaboration with CIAD). A collaborative project was initiated with ARS researchers in Albany, California to express antibodies specific for Escherichia coli toxins on the surface of lactic acid bacteria. Bacterial strains and plasmids were exchanged, and cloning strategies are beginning.
Addressing the 12-month milestones for Objective 4, a diversity of ice cream products were studied to quantify their tendency to separate into distinct water, fat, and air phases upon melting. No commercial products were found to separate well, but the separation is progressively improved and accelerated when heated. Studies showed that proteins play a major role in stabilizing liquid ice cream, and that treatment with inexpensive commercial enzymes effectively degrades these proteins, consequently improving the separation of fat. The results provide the information required for designing low-cost fat separation processes that are appropriate for industrial scale implementation.
Accomplishments
Review Publications
Huang, L., Hwang, C., Liu, Y., Renye Jr, J.A., Jia, Z. 2022. Growth competition between lactic acid bacteria and Listeria monocytogenes during meat fermentation – A Mathematical Modeling. Food Control. 158(2022):111553. https://doi.org/10.1016/j.foodres.2022.111553.
Ceruso, M., Liu, Y., Gunther, N.W., Pepe, T., Anastasio, A., Qi, P.X., Tomasula, M.M., Renye Jr, J.A. 2021. Anti-listerial activity of thermophilin 110 and pediocin in fermented milk and whey. Food Control. https://doi.org/10.1016/j.foodcont.2021.107941.
Renye Jr, J.A., White, A.K., Hotchkiss, A.T. 2021. Identification of Lactobacillus strains capable of fermenting fructo-oligosaccharides and inulin. Beneficial Microbes. https://doi.org/10.3390/microorganisms9102020.
Cao, F., Liang, M., Liu, J., Liu, Y., Renye Jr, J.A., Qi, P.X., Ren, D. 2021. Characterization of an exopolysaccharide produced by Streptococcus thermophilus ZJUIDS-2-01 isolated from traditional yak yogurt. International Journal of Biological Macromolecules. https://doi.org/10.1016/j.ijbiomac.2021.10.055.
Renye Jr, J.A., Steinberg, D.H. 2021. Thermophilin 110 inhibits growth and biofilm formation of Streptococcus mutans. Current Microbiology. https://doi.org/10.1016/j.btre.2021.e00647.
Lee, C., Garcia, R.A., Bumanlag, L.P., Liang, C. 2022. Influence of methylation and polymerization on flocculant properties of bovine blood. ACS Omega. https://doi.org/10.1021/acsomega.1c06126.
