Short-Time Drying of Beatsensitwe, Biologically Active Pulps and Pastes

Abstract

Tomato concentrate and baker's yeast suspension were dried in the laboratory scale Mechanically Spouted Bed dryer with inert packing. Due to a large contact d a c e provided by the inert particles, very fast drying process can be achieved, ifthe thickness of the wet coating formed on the surface of the inert packing is film-like. The d&ion resistance can be then considered negligible and dq4mg can be performed at "quad-constant" rate. Derived fiom hydrodynamic characteristics the contact time between hot air and the wet coating is very short, therefore gentle drymg process can be performed. The quality of the dried yeast was controlled by counting the living cells (relative viabilny) and by measurement of the dough rise time. During continuous drying of thermoplastic tomato purCe the "case hardening" periods could be shortened and tomato powder with insignificant quality loss was produced.

Drying and Shrinkage Kinetics of Solid Waste of Olive Oil Processing

“…It has been reported that each plateau on the drying curves corresponds to one such case-hardened state. [42] According to Jumah et al, [43] several kinds of fruits have similar characteristics that make the drying treatment more complicated. Materials exhibiting such behavior are characterized by low melting sugars and present serious drying problems arising from the properties of the solid phase.…”

Spray drying of tomato pulp in dehumidified air: I. The effect on product recovery

“…To provide a smooth drying operation any case hardening, drying rate must be low. For this, it is possible to operate either at low temperature or increase the humidity of the medium, or both as to keep the surface of the drying material plasticized (Karatas & Esin, 1994;Szentmarjay, Pallai, & Regenyi, 1996). Prolonged drying could, however, cause severe degradation in the sensory and the nutritional properties of the tomato.…”

Drying of Liquid Feedstocks in a Spout‐Fluid‐Bed with Draft‐Tube Submerged in Inert Solids: Hydrodynamics and Drying Performance

“…Since then, this technique has been used for drying chemicals (Mathur and Epstein, 1974;Ormos and Blickle, 1980) as well as biological products such as: animal blood, animal blood plasma, egg white, and protein-containing solutions, among others (Fane et al, 1980;Pham and Pooley, 1981;Pham, 1983;Rashkovskaya et al, 1979;Kutsakova and Utkin, 1983). More recently, reports by Markowski (1992), Reyes et al (1998), Brereton and Lim (1993), Ochoa-Martínez et al (1993), Szentmarjay et al (1996) and Tia et al (1995) who dried a variety of products, ranging from chemicals to liquid foods, have shown the feasibility of the process to obtain good quality dry powdered solids, which make the system, a low-cost, compact alternative to spray drying. Most of these authors have worked with conventional spouted beds, and practically none of them mention any limitations to the system employed.…”