Spray Drying of Green Corn Pulp

Abstract

Maize (Zea mays) is a cereal grown in Brazil, and its availability is limited to the harvest season. An alternative processing route is based on the production of green corn powder, which has a longer shelf-life and increased versatility. This study aimed to evaluate the influence of drying conditions on the physical characteristics, size, and morphology of green corn powder. Drying experiments were performed on a spray dryer according to a central composite rotational design to evaluate inlet air temperature, feed flow rate, and pulp concentration. The yield of dried pulp corn had an average value of 36.19%. The following mean values for the physical properties of the powder were measured: solubility of 94.37 g/100 g, wettability of 128.05 seconds, moisture content of 1.97%, water activity of 0.13, density of 0.79 g/mL, and a particle diameter of 31.02 µm. The powder was also yellow with less intensity, and the particle surface was smooth at higher temperatures and had a tendency to form agglomerates. The estimated optimal conditions for spray drying were 48% (w/w) pulp concentration, 172°C inlet air temperature, and feed flow rate of 0.56 L/h.

Keywords:

• Drying
• Green corn
• Morphology
• Physical properties

Notes

x ₁: pulp concentration (% w/w); x ₂: temperature of the air (°C); x ₃: feed flow (L/h).

Yield (Y), moisture (Mc), water activity (a_w), wettability (Wet), solubility (Sol), density (Dp), hue angle (h°), chroma (C*), particle size D₅₀ µm.

n.s.: non-significant (p > 0.05); significant at 5% probability; *significant at 10% probability.