Sensory and rheological properties of transgenically and chemically modified starch ingredients as evaluated in a food product model

Starches derived from five genetically modified potato lines, two chemically modified potato starches and two native starches from potato and maize were subjected to physical and chemical analyses and their functionality evaluated in a milk-based food product model. The transgenic starches were specifically modified with respect to amylopectin chain length and phosphorous content by suppression of the starch branching enzyme and overexpression of glycogen branching enzyme. Transgenic starches with long amylopectin chains and high phosphorous content had increased gelatinisation temperatures, produced gels with a higher tendency to retrograde and a low freeze/thaw stability as compared to starches with shorter amylopectin chains and lower phosphorous content. The textural properties of the food product model prepared from genetically and chemically modified starches were characterised by sensory and rheological analyses. To clearly visualise the effects of the modifications, data was evaluated by radar plots and multiple regression analysis (chemometrics). Genetically modified potato starches with longer amylopectin chains and increased phosphorous content gave a more gelled and a shorter texture as compared to starches with shorter amylopectin chains and decreased phosphorous content. Acetylated and hydroxypropylated potato starches gave sticky and stringy textures. Correlations between rheology parameters and sensory parameters were found. The sensory parameter stringy/long could be predicted from the rheological data.