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

Abstract

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.