Assessing the microstructural and rheological changes induced by food additives on potato puree

•The rheological effect of additives on starch interpreted at the microstructural level.•Agar and alginate exerted a moderate stabilizing effect on the starch in potato puree.•Glycerol and lecithin exerted a strong un-stabilizing effect on starch in potato puree.•A higher effect on the elastic rather than the viscous modulus of purees was observed.•The applicability of the Cox-Merz rule was evaluated.

The effects of agar, alginate, lecithin and glycerol on the rheological properties of commercial potato puree were investigated and interpreted in terms of starch microstructural changes, and the applicability of the Cox-Merz rule was evaluated. Each additive was applied separately at two concentrations (0.5 and 1%). Microscopic observations revealed more swollen starch aggregations in lecithin and glycerol compared with those of potato puree and agar, consequently affecting the rheological properties of potato puree. All samples exhibited shear thinning non-Newtonian behaviour. Rheological measurements were strongly concentration dependent. At 0.5% concentration, additives exerted decreases in all the rheological properties of potato puree in the order of glycerol > alginate > lecithin > agar, while at 1% concentration, the order changed to glycerol > lecithin > alginate, whereas 1% agar behaved differently, increasing all rheological values. This study also showed that agar and alginate in addition to potato puree could be valuable and advantageous for further technological processes, such as 3D printing.