@article{ryan_vardhanabhuti_jaramillo_zanten_coupland_foegeding_2012, title={Stability and mechanism of whey protein soluble aggregates thermally treated with salts}, volume={27}, DOI={10.1016/j.foodhyd.2011.11.006}, abstractNote={The formation of whey protein aggregates, often termed soluble aggregates, with specific physicochemical properties has been shown to result in improved functionality in gels, foams, emulsions, encapsulation, films and coatings. This work evaluated the potential of whey protein soluble aggregates to improve thermal stability in the presence of salts and determine the mechanism of improved thermal stability. Solutions of whey protein isolate (WPI) or β-lactoglobulin (β-lg) (7% w/w, pH 6.8) were heated for 10 min at 90 °C to form soluble aggregates. Native proteins and soluble aggregates were diluted to 3% w/w in solutions containing 0–108 mM NaCl and thermally treated (90 °C, 5 min). Turbidity, solubility, and viscosity were evaluated, in addition to ζ-potential and So (surface hydrophobicity). Size exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS) and dynamic light scattering were used to determine aggregate size and transmission electron microscopy (TEM) was used to evaluate aggregate shape. Use of soluble aggregates improved thermal stability due to their altered aggregate shape and higher charge, and resulted in final aggregates that were smaller and less dense, leading to reduced viscosity and turbidity, and increased solubility compared to native proteins. It is concluded that soluble aggregates formed under the appropriate conditions to produce the desirable physicochemical properties can be used to improve whey protein thermal stability with a possible application in beverages.}, number={2}, journal={Food Hydrocolloids}, author={Ryan, K. N. and Vardhanabhuti, B. and Jaramillo, D. P. and Zanten, J. H. and Coupland, J. N. and Foegeding, E. A.}, year={2012}, pages={411–420} }
 @inproceedings{vardhanabhuti_foegeding_2010, title={Evidence of interactions between whey proteins and mucin their implication on the astringency mechanism of whey proteins at low pH}, booktitle={Gums and Stabilisers for the Food Industry 15}, author={Vardhanabhuti, B. and Foegeding, E. A.}, year={2010}, pages={137–146} }
 @article{kelly_vardhanabhuti_luck_drake_osborne_foegeding_2010, title={Role of protein concentration and protein-saliva interactions in the astringency of whey proteins at low pH}, volume={93}, ISSN={["1525-3198"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77952051521&partnerID=MN8TOARS}, DOI={10.3168/jds.2009-2853}, abstractNote={Whey protein beverages are adjusted to pH <4.5 to enhance clarity and stability, but this pH level is also associated with increased astringency. The goal of this investigation was to determine the effects of protein concentration on astringency and interactions between whey and salivary proteins. Whey protein beverages containing 0.25 to 13% (wt/wt) beta-lactoglobulin and 0.017% (wt/wt) sucralose at pH 2.6 to 4.2 were examined using descriptive sensory analysis. Controls were similar pH phosphate buffers at phosphate concentrations equivalent to the amount of phosphoric acid required to adjust the pH of the protein solution. Changes in astringency with protein concentration depended on pH. At pH 3.5, astringency significantly increased with protein concentration from 0.25 to 4% (wt/wt) and then remained constant from 4 to 13% (wt/wt). Conversely, at pH 2.6, astringency decreased with an increase in protein concentration [0.5-10% (wt/wt)]. This suggests a complex relationship that includes pH and buffering capacity of the beverages. Furthermore, saliva flow rates increased with increasing protein concentrations, showing that the physiological conditions in the mouth change with protein concentration. Maximum turbidity of whey protein-saliva mixtures was observed between pH 4.6 and 5.2. Both sensory evaluation and in vitro study of interactions between beta-LG and saliva indicate that astringency of whey proteins is a complex process determined by the extent of aggregation occurring in the mouth, which depends on the whey protein beverage pH and buffering capacity in addition to saliva flow rate.}, number={5}, journal={JOURNAL OF DAIRY SCIENCE}, author={Kelly, M. and Vardhanabhuti, B. and Luck, P. and Drake, M. A. and Osborne, J. and Foegeding, E. A.}, year={2010}, month={May}, pages={1900–1909} }
 @article{vardhanabhuti_kelly_luck_drake_foegeding_2010, title={Roles of charge interactions on astringency of whey proteins at low pH}, volume={93}, ISSN={["1525-3198"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77952066147&partnerID=MN8TOARS}, DOI={10.3168/jds.2009-2780}, abstractNote={Whey proteins are a major ingredient in sports drink and functional beverages. At low pH, whey proteins are astringent, which may be undesirable in some applications. Understanding the astringency mechanism of whey proteins at low pH could lead to developing ways to minimize the astringency. This study compared the astringency of beta-lactoglobulin (beta-LG) at low pH with phosphate buffer controls having the same amount of phosphate and at similar pH. Results showed that beta-LG samples were more astringent than phosphate buffers, indicating that astringency was not caused by acid alone and that proteins contribute to astringency. When comparing among various whey protein isolates (WPI) and lactoferrin at pH 3.5, 4.5, and 7.0, lactoferrin was astringent at pH 7.0 where no acid was added. In contrast, astringency of all WPI decreased at pH 7.0. This can be explained by lactoferrin remaining positively charged at pH 7.0 and able to interact with negatively charged saliva proteins, whereas the negatively charged WPI would not interact. Charge interactions were further supported by beta-LG or lactoferrin and salivary proteins precipitating when mixed at conditions where beta-LG, lactoferrin, or saliva themselves did not precipitate. It can be concluded that interactions between positively charged whey proteins and salivary proteins play a role in astringency of proteins at low pH.}, number={5}, journal={JOURNAL OF DAIRY SCIENCE}, author={Vardhanabhuti, B. and Kelly, M. A. and Luck, P. J. and Drake, M. A. and Foegeding, E. A.}, year={2010}, month={May}, pages={1890–1899} }
 @article{vardhanabhuti_yucel_coupland_foegeding_2009, title={Interactions between beta-lactoglobulin and dextran sulfate at near neutral pH and their effect on thermal stability}, volume={23}, ISSN={["1873-7137"]}, DOI={10.1016/j.foodhyd.2008.09.006}, abstractNote={The effect of interactions between β-lactoglobulin (β-LG) and dextran sulfate (DS) on thermal stability at near neutral pH was investigated. Samples containing 6% w/w β-LG and DS (Mw = 5–500 kDa) at different biopolymer weight ratios, pH (5.6–6.2), and NaCl concentrations (0–30 mM) were heated at 85 °C for 15 min. Turbidity results showed that the presence of DS at appropriate biopolymer weight ratio and pH significantly lowered the turbidity of heated β-LG. Solutions containing DS:β-LG weight ratios of 0.02 or less showed improved heat stability as indicated by decreased turbidity. Analysis of the unheated mixture by size exclusion chromatography coupled with multi-angle laser light scattering (SEC–MALLS) showed an interaction between β-LG and DS. The size of the aggregates increased as pH decreased. The β-LG–DS aggregates had a greater negative charge as seen from electrophoretic mobility measurement. Addition of 30 mM NaCl inhibited complex formation and the effect of DS on reducing the turbidity of heated β-LG, suggesting that the interaction was electrostatic in nature. Other than charge property, the amount and size of native aggregates appeared to be the major factor in determining how DS altered heat-induced aggregation. The presence of DS decreased denaturation temperature of β-LG, indicating that DS did not improve thermal stability of β-LG by stabilizing its native state but rather by altering its aggregation. The results provide information that will facilitate the application of whey proteins and polysaccharides as functional ingredients in foods and beverages.}, number={6}, journal={FOOD HYDROCOLLOIDS}, author={Vardhanabhuti, Bongkosh and Yucel, Umut and Coupland, John N. and Foegeding, E. Allen}, year={2009}, month={Aug}, pages={1511–1520} }
 @article{vardhanabhuti_foegeding_2008, title={Effects of dextran sulfate, NaCl, and initial protein concentration on thermal stability of beta-lactoglobulin and alpha-lactalbumin at neutral pH}, volume={22}, DOI={10.1016/j.foodhvd.2007.03.003}, number={5}, journal={Food Hydrocolloids}, author={Vardhanabhuti, B. and Foegeding, E. A.}, year={2008}, pages={752–762} }
 @article{vardhanabhuti_foegeding_mcguffey_daubert_swaisgood_2001, title={Gelation properties of dispersions containing polymerized and native whey protein isolate}, volume={15}, ISSN={["1873-7137"]}, DOI={10.1016/S0268-005X(00)00062-X}, abstractNote={Whey protein polymers (WP-polymers) were prepared by heating whey protein isolate below the critical concentration for gelation at neutral pH and low salt conditions. The effects of WP-polymers and salt types (CaCl2 or NaCl) on rheological properties (large-strain and small-strain analysis), water holding properties, turbidity and microstructure of heat-induced whey protein isolate gels were investigated. Replacement of native whey protein isolate with WP-polymers increased fracture stress, fracture modulus, held water, and the translucency of gels. With both salt types, the addition of WP-polymers changed the gel structure from particulate to fine-stranded. However, the effect of WP-polymers on rheological properties was salt specific. Addition of 20–100% WP-polymers in the presence of 10 mM CaCl2 caused a continued increase in fracture stress. In contrast, protein dispersions containing 30 mM NaCl did not form self-supporting gels when ≥60% WP-polymers were added. Dispersions containing 200 mM NaCl formed self supporting gels at all levels of WP-polymer addition but fracture stresses for gels containing 20–100% WP were similar. Dispersions containing 80% WP-polymers and 200 mM NaCl had lower gel points (time and temperature) than dispersions with 80% WP-polymers and 10 mM CaCl2. It appeared that CaCl2 was more effective in increasing gel fracture stress while NaCl was more effective in decreasing gelation time. Different gel properties may be prepared by altering the amount of WP-polymers and salt types.}, number={2}, journal={FOOD HYDROCOLLOIDS}, author={Vardhanabhuti, B and Foegeding, EA and McGuffey, MK and Daubert, CR and Swaisgood, HE}, year={2001}, month={Mar}, pages={165–175} }
 @article{vardhanabhuti_foegeding_1999, title={Rheological properties and characterization of polymerized whey protein isolates}, volume={47}, ISSN={["0021-8561"]}, DOI={10.1021/jf981376n}, abstractNote={Whey protein polymers were formed by heating whey protein isolate solutions at 80 degrees C. Flow behaviors of whey protein polymers produced from different protein concentrations and heating times were comparable to various flow behaviors of hydrocolloids. Polymer formation was found to be a two-phase process. The initial protein concentration was a significant factor that determines the size and/or shape of the primary polymer in the first phase as shown by intrinsic viscosity. Heating time was a factor in determining the aggregation in the second phase as shown by apparent viscosity. Intrinsic viscosity of whey protein polymers was as high as 141.7 +/- 7.30 mL/g, compared to 5.04 +/- 0.20 mL/g for native whey proteins. The intrinsic viscosity and gel electrophoresis data suggested that disulfide bonds played an important role in whey polymer formation.}, number={9}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Vardhanabhuti, B and Foegeding, EA}, year={1999}, month={Sep}, pages={3649–3655} }