Abstract:

The aim of this study was to develop instant walnut diaphragm powder by spray drying. The operating parameters
of spray drying were optimized. First of all, the one-factor-at-a-time method was used to investigate the effects of air inlet
temperature, feed flow rate and hot air flow rate on the wettability, dispersibility, moisture content and particle size of
walnut diaphragm powder. Then, we selected air inlet temperature, feed flow rate and hot air flow rate for the optimization
experiments carried out by using response surface methodology. The responses were wettability and dispersibility. The
results showed that the spray drying process was optimized as follows: air inlet temperature, 170 ℃; feed flow rate, 1.8 L/h;
and hot air flow rate, 35 m3/h. The measured wetting time for the product under the optimized conditions was 13.2 s and the
experimental dispersion time 5.8 s, which were in good agreement with the model predicted values.

Key words: walnut diaphragm, spray drying, reconstitution properties, wettability, dispersibility