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Standardized dried extracts of Brazilian medicinal plants: assessment of technical and economical feasibility of the spouted bed drying

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Author(s):
Claudia Regina Fernandes de Souza
Total Authors: 1
Document type: Doctoral Thesis
Press: Ribeirão Preto.
Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
Defense date:
Examining board members:
Dermeval José Mazzini Sartori; Sandra Cristina dos Santos Rocha; Suraia Said; Maria Aparecida Silva; Vania Passarini Takahashi
Advisor: Wanderley Pereira de Oliveira
Abstract

The aim of this work was to investigate the technological and economical feasibility of the spouted bed drying process for production of the standardized dried extracts of Brazilian medicinal plants using the Bauhinia forficata Link as an experimental model. The objective was to demonstrate the potential of this technology for the processing of medicinal plants, a world market of 22 billions of dollars a year. Vegetable extracts have a complex chemical composition (fatty acids, sugars, fibers, proteins and resins), making the dehydration of these materials a challenging task, mainly for drying on the surface of inert bodies, like the spouted bed drying. Thus, the use of drying aids like maltodextrins, starch, colloidal silicon dioxide is mandatory. Among the operating problems frequently observed, there is the product accumulation on the surface of the inert material increasing its weight, causing hydrodynamic instabilities and reduction of the equipment productivity. A high increase in the thermal degradation of the active substances is also observed. This behavior is attributed to the increase in the exposure time of the material at high temperatures. The effects of the different proportions of drying aids (20 to 80 %) on the physical properties of the extracts were evaluated through determination of the surface tension, contact angle, detachment of the extract film from the surface of the inert material, density and rheological behavior. Drying tests carried out with several drying aids showed a better performance with the colloidal silicon dioxide, being the selected material for the further tests. Drying runs were carried out in two spouted bed configurations (conventional and with draft tube), according to a central composite design. The variables studied were the % of the drying adjuvant, the drying gas flow rate, parameterized by the ratio Q/Qjm, and the flow rate of the extract fed to the system (Ws/Wg). The statistical analysis results and the effects presented by independent variables (% Adj, Q/Qjm and Ws/Wg), on the responses product recovery (Rec), product accumulation in the bed (Ac), loss on drying (Xp), flavonoid degradation (DTF), and mean powder diameter (Dp), showed a significant effect of the parameters % Adj and Q/Qjm, for the operating conditions investigated. Physical and chemical analysis of the dried product, such as loss on drying, degradation of the active substances, particle size distribution, chromatographic profiles, X-ray diffraction, thermal behavior, and the monitoring of the equipment performance (Rec and Ac) were performed. Evaluation of the antioxidant and hypoglycemic activity were carried out for the extracts obtained at optimized conditions, presenting promising results. After the technological investigation, an evaluation of the economical viability of the process was carried out. The installation costs of a small scale unity for production of dried extracts, and the average costs involved for the obtaining of the final product were estimated. The results of this work indicated the technical and economical feasibility of the spouted bed drying for the production of dried extracts of medicinal plants, emerging as an alternative to the spray drying, commonly used in the phytotherapic processing industries. (AU)

FAPESP's process: 03/08317-1 - Standardized dried extracts of Brazilian medicinal plants: assessment of technical and economical feasibility of the spouted bed drying
Grantee:Cláudia Regina Fernandes de Souza
Support type: Scholarships in Brazil - Doctorate