CIDCA   05380
CENTRO DE INVESTIGACION Y DESARROLLO EN CRIOTECNOLOGIA DE ALIMENTOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Variation of fluidization velocities during drying-toasting of precooked whole soybeans
Autor/es:
TORREZ IRIGOYEN,RICARDO MARTIN; GINER, SERGIO ADRIÁN
Lugar:
Athenas
Reunión:
Congreso; ICEF 11. International Congress on Engineering and Food; 2011
Resumen:
Abstract Soybean (Glycine max) contains a high proportion of proteins (40% w/w) with good aminoacid profile, and a lipid content reaching 20% w/w, mostly insaturated. Whole soybean consumption is still low in western countries, possibly because of the long preparation times required for soaking and cooking. This last stage is important to enhance digestibility and to inactivate antinutritional factors. In view of the growing demand for ready-to-eat snacks and of the healthful character of soybean, a whole soybean product was developed by a process consisting of soaking/cooking and a main stage of fluidized bed drying-toasting at 140ºC. Final moisture content should provide microbial stability and a crispy texture. As soybean experiences shrinkage, deformation and density changes, samples of soaked-cooked material, and of partially and totally dried toasted soybeans were taken at 0, 10, 20, 30, 40 and 60 min of the drying-toasting stage. A small part of each sample was used in computerized image analysis to determine geometric characteristics of soybean. The rest was utilized to study the pressure drop of air through fixed and fluidized beds of soybeans as a function of the superficial air velocity, to determine the coefficients of the Ergun equation and the Minimum fluidization velocity (Vmf) for each sample. The required Vmf decreases during the drying-toasting process from 2.6 m/s in soaked-cooked soybean (CS) to 1.2 m/s in the totally dried/toasted sample (60 min or DT 60). From the experimental times, bed moisture contents and Vmf, empirical correlations were determined. However, from the technological viewpoint, the operating fluidization velocity (Vf) is more practical, being considered 50% higher than the Vmf. A mathematical correlation was obtained where the required Vf decreases with time. This constitutes valuable information for automatic process control with time-varying target value. Otherwise, an uncontrolled fan will increase the fluidization velocity in drying- toasting.