Rheological properties of functional spread of hull-less pumpkin seed flour and wheat fibre gel

Abstract

Rheological properties of the spread based on hull-less pumpkin seed flour were determined. Sunflower oil, as fat phase of control sample, was totally replaced with colloidal wheat fibre gel. The gels were prepared in different concentrations, 0.1 to 10%, and were added in different amounts, 60, 70 and 80%, calculated on the total mass of the spread. Wheat fibres formed liquid gels in water at low concentrations, 0.1 and 0.5%. Stable gel structures were obtained at concentrations above 1% and had anti-thixotropic flow properties. The spreads of hull-less pumpkin seed flour and wheat fibre gel were thixotropic systems. Statistically insignificant (p>0.05) changes pointed that application of fat replacer, compared to control spread, regardless amount and concentration of the gel, did not affect the yield stress of the spreads. The interaction of these factors, as well as their separate influence, were statistically significant (p<0.05) for rheological parameters thixotropic loop area and tan δ. Creep and recovery compliance increased with increasing amount of the gel in spread composition. Optimal rheological properties of the spreads were achieved with low concentrated gel, 0.5 or 1%, in amount of 70%.