@article{yong_forgeding_2010, title={Caseins: Utilizing Molecular Chaperone Properties to Control Protein Aggregation in Foods}, volume={58}, ISSN={["1520-5118"]}, DOI={10.1021/jf903072g}, abstractNote={Denaturation and aggregation of proteins are reactions that are relevant to functional applications of proteins in foods. Depending on concentration, ionic strength, and pH, aggregation can result in turbidity, precipitation, or gelation. Aggregation may be desirable, as in the case of gelation, or undesirable, as in the case when it causes phase separation in beverages. One approach to improve the stability of globular proteins against heat stresses is through the addition of other compounds that alter aggregation. Numerous studies have shown the ability of molecular chaperones to assist proper folding/unfolding and assembly/disassembly of proteins, especially during stressed conditions. Recently, several papers have reported the molecular chaperone-like properties of caseins, especially using alpha(s)- and beta-caseins. Caseins appear to function like small heat shock proteins (sHSP). We have compared the results among investigations from the perspective of food processing conditions and related them to the mechanism for sHSP. Caseins possess three of the four common features among sHSP; lacking a similar sequence domain. Their function may be explained in part by having structures fitting the intrinsically unfolded class of proteins. With a few exceptions, most investigations were done at solution conditions that poorly represent foods; lacking investigations at pH < 4.5 and concentrations above 20 mg/mL. While it is clear that caseins can alter aggregation at neutral pH, their effectiveness at low pH, high protein concentration, and high thermal treatment (T >or= 100 degrees C) remains to be fully established.}, number={2}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Yong, Yie Hui and Forgeding, E. Allen}, year={2010}, month={Jan}, pages={685–693} }
 @article{yong_foegeding_2008, title={Effects of Caseins on Thermal Stability of Bovine beta-Lactoglobulin}, volume={56}, ISSN={["1520-5118"]}, DOI={10.1021/jf801658u}, abstractNote={Casein fractions have been shown to act as molecular chaperones and inhibit aggregation of whey proteins in dilute solutions (< or =1% w/v). We evaluated if this approach would stabilize protein solutions at higher concentration and thermal processing temperatures desired for beverage applications. Mixtures of beta-lactoglobulin (BLG) (6% w/v) with either beta-casein (BCN) (0.01-2% w/v) or alpha s-casein (ACN) (2% w/v) were adjusted to pH 6.0 and heated (70-90 degrees C) for 20 min, cooled, and then analyzed to determine the degree of aggregation. Aggregation was determined by solution turbidity as optical density (OD) at 400 or 600 nm. The addition of 0.05% (w/v) BCN or greater caused a drop in turbidity for solutions heated at 70-90 degrees C. In contrast, inhibition was observed in BLG-ACN mixtures at 70 degrees C but not at > or =75 degrees C. Moreover, prolonged heating (90 min) of BLG with 2% (w/v) BCN (pH 6.0) at 90 degrees C produced a clear solution while BLG-ACN solutions formed translucent gels after heating for 15 min. The weight-averaged molar mass and root-mean-square (rms) radius of soluble aggregates were determined by size exclusion chromatography in conjunction with multiangle laser light scattering (SEC-MALS). SEC-MALS confirmed the turbidity results by showing that the BLG-BCN mixture (8% w/v protein) produced aggregates with lower molar mass and smaller rms radius (majority 20-40 nm). These results showed that BCN is a feasible component to stabilize higher concentrations of whey proteins in beverages.}, number={21}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Yong, Yie Hui and Foegeding, E. Allen}, year={2008}, month={Nov}, pages={10352–10358} }