The Influence of High Hydrostatic Pressure on Physical Properties and Stability of Smoothie

Smoothie is a valuable nutritional product, whose popularity is constantly growing. The main goal of this research was to investigate the effects of high hydrostatic pressure (150, 300, 450 MPa), filter diameters (0.3 and 0.5mm) and time of treatment (3, 9, 15 minutes) on physical properties (absorbance, density, apparent viscosity, particle size distribution) and stability of smoothies.

In addition to the direct measurement of physical properties and stability, measurement by near – infrared (NIR) spectroscopy was also carried out on all the samples. Training of artificial neural networks (ANN) is performed using obtained NIR data to investigate the possibility of prediction of any of the previously analyzed physical properties.

The results showed that all the process parameters had a significant influence on all observed physical properties. Furthermore, a smoothie made with filter of 0.3 mm pore diameter had more extended stability, based on measured absorbance, which was in range of t = 50 – 740 hours. Applied pressure of P = 450 MPa increased the stability of the multi – component smoothie with a particle size distribution between d = 0.48 – 1.44 µm. Results for NIR spectroscopy in combination with ANN showed excellent prediction of experimental data for changes in physical properties of the treated smoothie.

Keywords: high hydrostatic pressure, smoothie, physical properties, stability, particle size distribution, spectroscopy.