Effect of refining degree on particle size, sensory and rheological characteristics of anhydrous paste for ice creams produced in industrial stirred ball mill

- Refining of a hazelnut and cocoa based paste in stirred ball mill was characterized.
- The refining pastes showed a time-independent pseudoplastic behavior.
- The particle size distribution curves were mainly unimodal.
- Most texture attributes showed small changes in the fineness range 22.4-30.4 μm.
- A product with fineness equal to 30.4 μm appeared as optimal.

Refining of an anhydrous hazelnut and cocoa based paste for ice cream in a stirred ball mill was characterized in terms of energy use and product viscosity, particle size and sensory characteristics. With a specific milling power of 0.03 kW per kg of paste, the fineness of practical interest, 22.4-30.4 μm, was reached in 225-150 min, respectively. The pastes showed a time-independent pseudoplastic behavior with n and K in the range 0.62-0.69 and 14.2-27.2 Pa sn, respectively. The particle size distribution (PSD) curves, as determined by laser diffractometry, were mainly unimodal, with 90% percentiles [D(v, 0.9)] higher than the micrometer readings, suggesting the presence of flat particles, as confirmed by scanning electron microscopy. Most of the textural attributes showed a small difference among the samples with fineness 22.4-30.4 μm, thus suggesting a product with fineness, D(v, 0.9) and specific energy equal to 30.4 μm, 41.8 μm and 0.074 kWh/kg, respectively, as optimal.