RESUMO
The effect of environmental factors (protein concentration, pH, ionic strength) on emulsification properties of beta-lactoglobulin (beta-Lg) was analysed. The protein was obtained from phospholipoprotein-free whey 25-fold concentrated by ultrafiltration (10 kDa cut off) after precipitation of alpha-lactalbumin (alpha-La) with 6% trichloroacetic acid. The Sauter diameter D(vs) of oil droplets in the emulsion stabilised by beta-Lg was found to increase with increases in the protein concentration in the range of 0.5 to 2.0% and medium acidity in the pH range of 5.0 to 7.0. An increase in ionic strength in the range of 0 to 100 mM caused that the emulsification properties of the protein worsened as compared with control emulsion.
Assuntos
Emulsões/análise , Lactoglobulinas/fisiologia , Proteínas do Leite/química , Queijo , Concentração de Íons de Hidrogênio , Lactoglobulinas/isolamento & purificação , Concentração Osmolar , Tamanho da Partícula , Solubilidade , Ultracentrifugação/métodos , Proteínas do Soro do LeiteRESUMO
The effects of acidity (pH 5.0 to 7.0) and protein concentration (0.5 to 2.0%) on coalescence stability of o/w emulsion stabilised by alpha-lactalbumin (alpha-La), that was salted out from rennet whey with 7% NaCl at pH 2.0, were studied Irrespective of pH and alpha-La concentration, the Sauter diameter (D(vs)) of an oil droplet was found to increase on storing the emulsion for 4 h at room temperature and the conditions preventing from creaming and accelerating destabilisation of the emulsion. The effect of pH on emulsion coalescence stability was greater than that of protein concentration.
