Rheological Properties of Spread

Abstract

The consumption of low-fat spread, which contains more water and less fat is significantly increasing in recent days compared with traditional butter and margarine. For processing low-fat spread, it is necessary to use a certain amount of emulsifiers and stabilizers. However, these additives are konwn to considerably affect the properties such as texture, spreadability and flavor release, which were required for the final products. In particular, the texture and spreadability are most easily deteriorated by addition of the additives, althogh the mechanism has not been fully understood. It is necessary to clarify the relation between the additives and the rheological properties of fat spread.
The effects of the composition on the rheological properties of fat spread were investigated. The mouthfeel was evaluated with temperature sweeps (5-50°C) of the storage modulus G', while the spreadability was with flow curves (0-100s^-1). As a standard sample, we prepared a commercial spread which contained 70% fat and emulsifiers without stabilizer. This sample exhibited lower G'around inside temperatures of mouth and a rapid decrease in the shear stress with increasing shear rate. By contrast, other low-fat spreads, which had lower fat contents, emulsifiers and a stabilizer, showed higher G' and no decrease with increasing shear rate. It was also found that the type of the emulsifiers markedly changed the shape of flow curves at low shear rates and that the solid fat content shifted the curve vertically. These results suggest that appropriate selection of the fat content, the solid fat content and the type of emulsifiers enables us to control the rheological properties of fat spread.