Effect of thickeners and sweeteners on the release of blended aroma compounds in fat-free stirred yoghurt during shear conditions

Abstract

Abstract The present study was conducted on aromatised fat-free stirred yoghurts and dealt with the influence of some thickeners and sweeteners on aroma compounds release and rheology. Thickeners (starch, pectin, locust bean gum and guar) and sweeteners (fructose, fructo-oligosaccahrides, aspartame and acesulfame) were added and mixed together in fruit preparations, which were then introduced in yoghurt. Different concentrations of thickeners and sweeteners were used in the fruit preparations and were obtained with an experimental design. The headspace composition was assessed by solid-phase microextraction during shear conditions in a closed vessel. Rheological properties of yoghurts were determined to obtain the flow behaviour index n and the consistency index K with the Ostwald law. The presence of pectin in yoghurts, tended to reduce the concentration of aroma compounds in the headspace of the samples. We observed also a significant decrease of aroma compounds in the headspace of yoghurt in the presence of starch. In the case of locust bean gum, a significant increase of flavour release was observed. Sweeteners and guar appeared to have no effect. We concluded that rheological parameters did not explain the difference on aroma release and it seemed that during shear conditions, the composition of fruit preparations showed a major role on aroma release. The influence of aroma compounds characteristics on the flavour release was observed, but experiments must be performed to highlight this observation.