Light-Scattering Study of the Structure of Aggregates and Gels Formed by Heat-Denatured Whey Protein Isolate and β-Lactoglobulin at Neutral pH

Université du Maine, Le Mans, Pays de la Loire, France
Journal of Agricultural and Food Chemistry (Impact Factor: 3.11). 04/2007; 55(8):3104-11. DOI: 10.1021/jf063029g
Source: PubMed

ABSTRACT The structure of aggregates and gels formed by heat-denatured whey protein isolate (WPI) has been studied at pH 7 and different ionic strengths using light scattering and turbidimetry. The results were compared with those obtained for pure beta-lactoglobulin (beta-Lg). WPI aggregates were found to have the same self-similar structure as pure beta-Lg aggregates. WPI formed gels above a critical concentration that varied from close to 100 g/L in the absence of added salt to about 10 g/L at 0.2 M NaCl. At low ionic strength (<0.05 M NaCl) homogeneous transparent gels were formed, while at higher ionic strength the gels became turbid but had the same self-similar structure as reported earlier for pure beta-Lg. The length scale characterizing the heterogeneity of the gels increased exponentially with increasing NaCl concentration for both WPI and pure beta-Lg, but the increase was steeper for the former.

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    • "The pD was measured with a standard pH electrode and the value was corrected according to pD ¼ pH þ 0.4. The solutions of aggregated BLG were prepared according to the work of Mahmoudi et al. (2007). The principles are reported in Scheme 1. "
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    Food Hydrocolloids 12/2013; 33(2):178–185. DOI:10.1016/j.foodhyd.2013.03.011 · 4.28 Impact Factor
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    • "Centrifugation of WPI solutions did not show either a top layer or a precipitate and were filtered through 0.2 mm pore size filters. The protein concentration was measured by absorbance at 280 nm using extinction coefficient 0.93 L/g/cm for k-casein, 0.81 L/g/cm for sodium caseinate (Oliva, Llabres, & Farina, 2001; Schmidt, Koops, & Westerbeek,1977) and 1.046 L/g/cm for WPI (Mahmoudi et al., 2007). "
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