Main content area

Optimization and characterization of walnut beverage emulsions in relation to their composition and structure

Gharibzahedi, Seyed Mohammad Taghi, Mousavi, Seyed Mohammad, Khodaiyan, Faramarz, Hamedi, Manouchehr
International journal of biological macromolecules 2012 v.50 no.2 pp. 376-384
beverages, droplet size, emulsions, equations, gum arabic, models, opacity, principal component analysis, response surface methodology, surface area, surface tension, viscosity, walnut oil, walnuts
A central composite rotatable design (CCRD) was used to evaluate the effects of walnut oil (WO, 3–6%, w/w) and gum arabic (GA, 5–10%, w/w) on the average droplet size (D₃₂), specific surface area (SSA), polydispersity index (span), apparent viscosity, interfacial tension and opacity of walnut-beverage emulsions. The response surface methodology (RSM) showed that the significant second-order polynomial regression equations with high R² (>0.95) were successfully fitted for all responses as function of independent variables. The linear effect of WO had a significant term in all reduced models. The overall optimum region was found to be at the combined level of 10% (w/w) GA content and 5.84% (w/w) WO concentration. At this optimum point, D₃₂, SSA, span, apparent viscosity, interfacial tension and opacity of emulsions were 0.609μm, 8.236m²/ml, 0.886, 1.336Pas, 51.37mN/m and 0.810, respectively. No significant (p>0.05) difference was found between the actual values and predicted values. Moreover, principal component analysis (PCA), conducted via PCA variable loadings and cluster dendrogram was able to discriminate the emulsions with different formulations into separate classes.