Spray Drying of Chicken Meat Protein Hydrolysate: Influence of Process Conditions on Powder Property and Dryer Performance

Abstract

The influence of operational conditions of a spray dryer on powder properties and equipment performance during spray drying of chicken meat hydrolysate was evaluated by a central composite rotatable design. The independent variables were inlet air temperature (120 to 200°C) and feed flow (0.1 to 0.38 kg/h). Spray dryer performance was assessed through estimation of product recovery, outlet air temperature, thermal efficiency, and energy on the dryer, obtained by mass and heat balance in the dryer system. Powder property was characterized in respect to antioxidant activity. The stable free radical diphenylpicrylhydrazyl (DPPH) was used to estimate the antioxidant activity of protein hydrolysate powder. This response varied from 38.7 to 59.4% and was only affected by inlet air temperature. Moreover, the results demonstrate a significant effect of the processing conditions on dryer performance. The increase of feed flow results in higher thermal efficiency and lower energy on dryer. Higher product recovery values were obtained at lower inlet air temperature and feed flow.

Keywords:

• Antioxidant activity
• Feed flow
• Heat and mass balance
• Screening design
• Temperature

ACKNOWLEDGMENTS

The authors gratefully acknowledge the financial support of Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnologico (CNPq).

Notes

T_in = temperature;  = feed flow; X_w = powder moisture content; AA = antioxidant activity; T_out = outlet air temperature; PR = product recovery; η = thermal efficiency; ED = energy on dryer (kJ/kg evaporated water); EE = evaporation energy (kJ/kg evaporated water).

^a Mean value obtained from equation: Cp_{air,in or out} = Cp_water × Y_{in or out} + Cp_{dry air}. Values of specific heat of water and dry air were obtained from Perry and Chilton.^{[ 33 ]}

^b Value calculated from the equation: Cp = 0.837 + 3.349 × X_w.^{[ 34 ]}

Q_total = total heat input to the system; Q₁ = sensible heat necessary to heat up the atomized solution to wet bulb temperature; Q₂ = latent heat of evaporation; Q₃ = sensible heat necessary to heat up the particles; Q₄ = loss heat.

Ns = nonsignificant (p > 0.1); AA = antioxidant activity; T_out = outlet air temperature; η = thermal efficiency; ED = energy on the dryer.

SS = sum of squares; DF = degrees of freedom; MS = mean square; F_c = calculated F distribution value; F_t = tabulated F distribution value (p ≤ 0.1).