Robert F. Roberts, Ph.D.

Professor and Head of Food Science


    Dairy Products Processing



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    About Me

    Research Interests:

    My research program at Penn State addresses problems related to the microbiology of dairy products.  Currently my research is focused on quality of fermented dairy products such as yogurt and sour cream, on developing molecular techniques to characterize and enhance survival of probiotic bacteria, specifically bifidobacteria, used in dairy products, and development of probiotic-containing dairy products for use in clinical trials.  Projects underway in the laboratory include development for procedures for manufacture of probiotic dahi, allelic typing of commercial strains of Bifidobacterium animalis subsp. lactis and sequencing the complete genome of Bifidobacterium animalis subsp. animalis.


    I lead a number of outreach programs focused on the dairy foods industry including:

    • Ice Cream Shortcourse
    • Successful Ice Cream Retailing
    • Cultured Products Shortcourse

    Selected Publications: 

    Merenstein DJ, D'Amico F, Palese C, Hahn A, Sparenborg J, Tan T, Scott H, Polzin K, Kolberg L, Roberts R. 2013. Short-term, daily intake of yogurt containing Bifidobacterium animalis ssp. lactis Bf-6 (LMG 24384) does not affect colonic transit time in women. The British journal of nutrition:1-8.

    Loquasto JR, Barrangou R, Dudley EG, Stahl B, Chen C, Roberts RF. 2013. Bifidobacterium animalis subsp. lactis ATCC 27673 is a genomically unique strain within this conserved subspecies. Appl Environ Microbiol.

    Harwood ML, Loquasto JR, Roberts RF, Ziegler GR, Hayes JE. 2013. Explaining tolerance for bitterness in chocolate ice cream using solid chocolate preferences. Journal of Dairy Science 96:4938-4944.

    Tmanova L, Onyenwoke AC, Roberts RF. 2012. Identification and differentiation of bifidobacteria obtained from Ukraine. Journal of Dairy Science 95:91-97.

    Miller DM, Dudley EG, Roberts RF. 2012. Technical note: Development of a quantitative PCR method for monitoring strain dynamics during yogurt manufacture. Journal of Dairy Science 95:4868-4872.

    Merenstein, D., J. Gonzalez, A. G. Young, R. F. Roberts, M. E. Sanders, and S. Petterson. 2011. Study to investigate the potential of probiotics in children attending school. Eur. J. Clin. Nutr. 65(4):447-453.

    Loquasto, J. R., E. G. Dudley, R. Barrangou, and R. F. Roberts. 2011. The complete genome sequence of Bifidobacterium animalis subsp. animalis ATCC 25527T and comparative analysis of growth in milk with Bifidobacterium animalis subsp. lactis DSM 10140T. J. Dairy Sci. 94:5864–5870.

    Liu, S. M., D. M. Miller, and R. F. Roberts. 2011. Cloning of genes encoding colicin E2 in Lactococcus lactis subspecies lactis and evaluation of the colicin-producing transformants as inhibitors of Escherichia coli O157:H7 during milk fermentation. J. Dairy Sci. 94(3):1146-1154.

    Jaramillo, D. P., R. F. Roberts, and J. N. Coupland. 2011. Effect of pH on the Properties of Soy Protein-Pectin Complexes. Food Res. Int. 44: 911–916.

    Pape-Zambito, D. A., R. F. Roberts and R. S. Kensinger (2010). "Estrone and 17B-estradiol concentrations in pasteurized-homogenized milk and commercial dairy products." Journal of Dairy Science 93: 2533-2540.

    McCowen, K. C., P. R. Ling, E. D. Decker, D. Djordjevic, R. F. Roberts, J. N. Coupland and B. R. Bistrian (2010). "A simple method of supplementation of n-3 polyunsaturated fatty acids: Use of fortified yogurt in healthy volunteers." Nutrition in Clinical Practice 25(6): 641-645.

    Briczinski, E. P., J. R. Loquasto, R. Barrangou, E. G. Dudley, A. M. Roberts and R. F. Roberts (2009). "Strain-specific genotyping of Bifidobacterium animalis subsp lactis by using single-nucelotide polymorphisms, insertions and deletions." Appl Environ Microbiol 75(23): 7501-7508.

    Barrangou, R., E. P. Briczinski, L. L. Traeger, J. R. Loquasto, M. Richards, P. Horvath, A. C. Coute-Monvoisin, G. Leyer, S. Rendulic, J. L. Steele, J. R. Broadbent, T. Oberg, E. G. Dudley, S. Schuster, D. A. Romero, and R. F. Roberts. 2009. Comparison of the complete genome sequences of Bifidobacterium animalis subsp. lactis DSM 10140 and Bl-04. Journal of Bacteriology 191:4144-51.

    Briczinski, E. P., A. T. Phillips, and R. F. Roberts. 2008. Transport of glucose by Bifidobacterium animalis subsp. lactis occurs via facilitated diffusion. Applied and Environmental Microbiology 74:6941-8.

    Briczinski, E. P., and R. F. Roberts. 2007. Characterizing probiotic microorganisms, p. 359-390. In M. Saarela (ed.), Functional Dairy Products, vol. 2. CRC Press, New York, NY.

    Chee, C. P., D. Djordjevic, H. Faraji, E. A. Decker, R. Hollender, D. J. McClements, D. G. Peterson, R. F. Roberts, and J. N. Coupland. 2007. Sensory Properties of Vanilla and Strawberry Flavored Ice cream Supplemented with Omega-3 Fatty Acids. Milchwissenschaft. 62:66-69.

    Gevorgyan, A., L. Tmanova, and R. F. Roberts. 2007. Effect of cold adaptation on cryotolerance of two strains of bifidobacteria. Journal of Agrobiology and Ecology 3:60-75.

    Briczinski, E. P., and R. F. Roberts. 2006. Technical note: A rapid pulsed-field gel electrophoresis method for analysis of bifidobacteria. Journal of Dairy Science 89:2424-2427.

    Chee, C. P., R. F. Roberts, and J. N. Coupland. 2006. Effect of temperature, time, medium form and casein on lipid oxidation of polyunsaturated fatty acids in algae oil. Milchwissenschaft 61:142-145.

    Kauffman, N. M., and R. F. Roberts. 2006. Staphylococcal enterotoxin D production by Staphylococcus aureus FRI 100. Journal of Food Protection 69:1448-1451.

    Potineni, R. V., L. A. Dalby, J. N. Coupland, and R. F. Roberts. 2006. Sensory and microstructural properties of ice cream manufactured at high draw temperatures in a vertical barrel freezer at different dasher speeds. Journal of Food Science and Technology 43:242-246.

    Chee, C. P., J. J. Gallaher, D. Djordjevic, H. Faraji, D. J. McClements, E. A. Decker, R. Hollender, D. G. Peterson, R. F. Roberts, and J. N. Coupland. 2005. Chemical and sensory analysis of strawberry flavoured yogurt supplemented with an algae oil emulsion. Journal of Dairy Research 72:311-316.

    Gallaher, J. J., R. Hollender, D. G. Peterson, R. F. Roberts, and J. N. Coupland. 2005. Effect of composition and antioxidants on the oxidative stability of fluid milk supplemented with an algae oil emulsion. International Dairy Journal 15:333-341.

    Walker, S. P., A. Demirci, R. E. Graves, S. B. Spencer, and R. F. Roberts. 2005. Response surface modelling for cleaning and disinfecting materials used in milking systems with electrolysed oxidizing water. International Journal of Dairy Technology 58:65-73.

    Walker, S. P., A. Demirci, R. E. Graves, S. B. Spencer, and R. F. Roberts. 2005. Cleaning milking systems using electrolyzed oxidizing water. Transactions of the Asae 48:1827-1833.

    Elwell, M. W., R. F. Roberts, and J. N. Coupland. 2004. Effect of homogenization and surfactant type on the exchange of oil between emulsion droplets. Food Hydrocolloids 18:413-418.

    Murinda, S. E., K. A. Rashid, and R. F. Roberts. 2003. In vitro assessment of the cytotoxicity of nisin, pediocin, and selected colicins on simian virus 40-transfected human colon and Vero monkey kidney cells with trypan blue staining viability assays. Journal of Food Protection 66:847-853.

    Palanuwech, J., R. Potineni, R. F. Roberts, and J. N. Coupland. 2003. A method to determine free fat in emulsions. Food Hydrocolloids 17:55-62.

    Briczinski, E. P., and R. F. Roberts. 2002. Production of an exopolysaccharide-containing whey protein concentrate by fermentation of whey. Journal of Dairy Science 85:3189-3197.

    Chikthimmah, N., R. C. Anantheswaran, R. F. Roberts, E. W. Mills, and S. J. Knabel. 2001. Influence of sodium chloride on growth of lactic acid bacteria and subsequent destruction of Escherichia coli O157 : H7 during processing of Lebanon bologna. Journal of Food Protection 64:1145-1150.

    Kimmel, S. A., and R. F. Roberts. 1998. Development of a growth medium suitable for exopolysaccharide production by Lactobacillus delbrueckii ssp. bulgaricus RR. International Journal of Food Microbiology 40:87-92.

    Kimmel, S. A., R. F. Roberts, and G. R. Ziegler. 1998. Optimization of exopolysaccharide production by Lactobacillus delbrueckii subsp. bulgaricus RR grown in a semidefined medium. Applied and Environmental Microbiology 64:659-664.

    Murinda, S. E., S. M. Liu, R. F. Roberts, and R. A. Wilson. 1998. Colicinogeny among Escherichia coli serotypes, including O157 : H7, representing four closely related diarrheagenic clones. Journal of Food Protection 61:1431-1438.

    Swarts, A. J., J. W. Hastings, R. F. Roberts, and A. von Holy. 1998. Flow cytometry demonstrates bacteriocin-induced injury to Listeria monocytogenes. Current Microbiology 36:266-270.

    Hess, S. J., R. F. Roberts, and G. R. Ziegler. 1997. Rheological properties of nonfat yogurt stabilized using Lactobacillus delbrueckii ssp. bulgaricusproducing exopolysaccharide or using commercial stabilizer systems. Journal of Dairy Science 80:252-263.

    Murinda, S. E., R. F. Roberts, and R. A. Wilson. 1996. Evaluation of colicins for inhibitory activity against diarrheagenic Escherichia colistrains, including serotype O157:H7. Applied and Environmental Microbiology 62:3196-3202.

    Maust, J. A., and R. F. Roberts. 1995. Composition and microbiological quality of refrigerated non-fat and low-fat yogurts available at retail outlets. Cultured Dairy Products Journal 30:2-6.

    Murinda, S. E., R. F. Roberts, and S. Doores. 1995. Evaluation of Lactic-Acid-Producing Bacillus and Sporolactobacillusfor Antilisterial Activity. Journal of Food Protection 58:570-572.

    Zottola, E. A., T. L. Yezzi, D. B. Ajao, and R. F. Roberts. 1994. Utilization of Cheddar Cheese Containing Nisin as an Antimicrobial Agent in Other Foods. International Journal of Food Microbiology 24:227-238.

    Roberts, R. F., and E. A. Zottola. 1993. Shelf-Life of Pasteurized Process Cheese Spreads Made from Cheddar Cheese Manufactured with a Nisin-Producing Starter Culture. Journal of Dairy Science 76:1829-1836.

    Roberts, R. F., E. A. Zottola, and L. L. Mckay. 1992. Use of a Nisin-Producing Starter Culture Suitable for Cheddar Cheese Manufacture. Journal of Dairy Science 75:2353-2363.

    Eckner, K. F., R. F. Roberts, A. A. Strantz, and E. A. Zottola. 1990. Characterization and Behavior of Salmonella-Javiana During Manufacture of Mozzarella-Type Cheese. Journal of Food Protection 53:461-464.

    Roberts, R. F., and G. S. Torrey. 1988. Inhibition of Psychrotrophic Bacterial-Growth in Refrigerated Milk by Addition of Carbon-Dioxide. Journal of Dairy Science 71:52-60.



    University of Minnesota, Ph.D., Food Science, May 1991 South Dakota State University, M.S., Dairy Science, August 1986 University of Vermont, B.S. Animal Science, May 1984