Effect of thermal behavior of β-lactoglobulin on the oxidative stability of menhaden oil-in-water emulsions.
This study reports how emulsion oxidative stability was affected by the interfacial structure of β-lactoglobulin due to different heat treatments. Four percent (v/v) menhaden oil-in-water emulsions, stabilized by 1% (w/v) β-lactoglobulin at pH 7, were prepared by homogenization under different thermal conditions. Oxidative stability was monitored by the ferric thiocyanate peroxide value assay. Higher oxidative stability was attained by β-lactoglobulin in the molten globule state than in the native or denatured state. From atomic force microscopy of β-lactoglobulin adsorbed onto highly ordered pyrolytic graphite in buffer, native β-lactoglobulin formed a relatively smooth interfacial layer of 1.2 GPa in Young's modulus, whereas additional aggregates of similar stiffness were found when β-lactoglobulin was preheated to the molten globule state. For denatured β-lactoglobulin, although aggregates were also observed, they were larger and softer (Young's modulus = 0.45 GPa), suggesting increased porosity and thus an offset in the advantage of increased layer coverage on oxidative stability.
Department of Food Science, Purdue University, West Lafayette, Indiana 47907, United States.
Pui Yeu
PY
Phoon
Ganesan
G
Narsimhan
Maria Fernanda
MF
San Martin-Gonzalez
D004655:Emulsions / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000737:chemistry*; D010084:Oxidation-Reduction; D055550:Protein Stability
D004655:Emulsions; D007782:Lactoglobulins