Control of microgel particle growth in fresh cheese (concentrated fermented milk) with an exopolysaccharide-producing starter culture

The hypothesis whether or not the microgel particle growth in fresh cheese (pH = 4.50) during post-processing is mainly a diffusion-limited process was tested by increasing the shear viscosity by adding polyethylene glycol and, in a natural way, by using an exopolysaccharide (EPS)-producing adjunct culture (0–0.1%, w/w) in fresh cheese production. EPS increased water-binding capacity and storage modulus. Subsequent tempering (23–54 °C for 1–300 min) generally increased particle size whereas EPS caused a decrease. Based on the activation energies (EA ∼ 60 kJ mol−1), and as EPS was mainly localised at the protein–serum interface, a reaction-limited particle growth was proposed. The EPS may interact with proteins protecting the core from aggregation and acting as an active filler. Concentrations of EPS-producing culture <0.005% (w/w) may be applied to reduce the formation of rough particles, which decrease in-mouth creaminess, providing potential to compensate for temperature variations, e.g., during process stops, and to reduce hydrocolloid addition.