Caramel stickiness: Effects of composition, rheology, and surface energy

Abstract

Formulated with varied moisture contents (10–12%), dextrose equivalence (DE) of corn syrups (28, 42, 63 DE), and the concentrations of mono-and diglycerides (MDG, 0–2%), 9 caramel samples were compared in terms of rheology, surface energies, hardness, and stickiness. Results indicated that moisture and DE significantly altered the rheology of the caramel matrix, whereas MDG reduced the surface energies. Results from a peel test showed that the adhesive forces between caramel and a packaging material followed a bell-shaped trend with G’ and G” of the caramels and decreased with the surface energies of both the caramels and the materials. On the other hand, the caramel structure was sensitive to pressure. Increased penetration strain resulted in structural collapse, which reduced cohesion while facilitating adhesion. At 50% strain, the pressure-induced adhesive forces decreased with moisture content, DE of corn syrup, and MDG concentration. MDG (>1%) in caramel was an effective anti-sticking agent, which reduced both peel and pressure-induced adhesion. • Mono- and diglycerides (MDG) reduced the surface energy of caramel. • Caramel moisture and DE of corn syrup affected the rheology but not surface energy. • Stickiness of caramel changed with both rheology and surface energy. • MDG reduced both surface stickiness and pressure-induced stickiness. • Caramel hardness and pressure-induced stickiness were positively correlated.