Rheological properties and stability of low-in-fat dressings prepared with high-pressure homogenized yeast

Abstract

The aim of present study was to investigate the feasibility of application high-pressure homogenized (HPH) yeast aqueous dispersions with low nucleic acid content for the formulation of low-in-f at dress-ings. The HPH treatment (1500 bar, 3 passes) in alkaline medium improved the protein dispersibility (>50%). Emulsions were prepared using sunflower oil (12.0% or 25% w/w oil), xhantan/guar gums (0.5% w/w), modified starch (0?4.0% w/w), salt, sucrose, acidulants, EDTA, and antimicrobial agents. All emul-sions (pH 3.97 ± 0.27; aw = 0.97 ± 0.01), whatever the starch content, beh aved clearl y as pseudoplastic fluids in steady flow measurements. Moreover, as the frequency sweep measurements were made they also exhibited a weak gel behavior. Although the presence of starch produced an increase of mean par-ticle size ( D 3,2 values), the rheological parameters (consistency index, proportionality coefficient and coordination number) also increased, so that the starch contributes to reinforce the three-dimensional network formed by oil droplets, protein aggrega tes and other polysaccharides. Yeast dressings were sta-ble to coalescence after 28 days of quiescent storage (7.0 ± 0.5 C) and only the highest starch concentra-tion at 25% w/w oil was sufficient to maintain the stability of network.