Properties of microparticles from a whey protein isolate/ alginate emulsion gel

Abstract

Designing soft, palatable and nutritious texture-modified foods for the elderly is a challenge for foodtechnologists. The aim of this work was to produce and characterize emulsion-gelled microparticles (EGM)made from whey protein isolate (WPI) and sodium alginate (NaAlg) that may be used to modify the rheologyof liquid foods and as carriers of lipids and lipophilic nutrients and bioactives. Olive oil microdroplets becameembedded in the WPI/NaAlg gel matrix in the form of an emulsion produced by ultrasound (US) or high-speedblending (HSB). Oil microdroplets were obtained by US and HSB, with an average equivalent diametervarying between 2.0–3.2 mm and 4.5–6.7 mm, respectively. Oil incorporation increased compression stressof bulk emulsion gels at small deformations compared to the no-oil microgel, but this effect was reversed athigh strains. EGM were prepared by shear-induced size reduction. Rheological tests at 20 C and 40 Cshowed that US-EGM and HSB-EGM exhibited a predominant elastic behavior, with G0 > G00 throughout thefrequency range. However, when HSB-EGM were heated at 60 C their rheological behavior changed to amore fluid-like condition, but not that of US-EGM. Consequently, EGM have the properties needed to improvefood texture for people with masticatory/swallowing dysfunctions or needing special nutrition.