The paper reviews and analyses the advantages and disadvantages of the existing technologies of drying shiitake mushrooms, which are a valuable source of bioactive polysaccharides, vitamins, antioxidants, etc. The findings presented in the paper show how various drying methods and their thermotechnological operating parameters affect the mechanostructural properties, chemical composition, content of aromatic substances and other compounds of mushrooms. It has been demonstrated that the traditional convection drying of shiitake in the temperature range 50–60°C allows maximum preservation of phenolic compounds, organic acids, nucleotides, sulphuric aromatic substances, and enhances the unique aroma of the mushroom. Radiation drying has such advantages as lower shrinkage of dried shiitake mushrooms, a higher coefficient of rehydration and higher hardness, and the drying time reduced by 66% compared with freeze-drying. Vacuum drying makes it possible to obtain high quality products, but significantly increases the duration of the process and reduces the content of aromatics. Radiation drying combined with hot air allows obtaining a dry form of shiitake rich in protein and bioactive polysaccharides and having high physicochemical properties, and reduces the duration of the process by 37.5% compared with convection drying. Spray drying of shiitake mushrooms is highly practical economically and allows organising industrial manufacture of high-quality dry mushroom powder in large volumes. It is characteristic of this drying method that its temperature effect on the product is slight, which makes it possible to preserve thermolabile bioactive substances. When using spray drying, it is advisable to add dextrin additives. This improves the structuring and moisture-conducting properties of the suspensions and their thermal stability, and helps preserve the unique aroma of shiitake mushrooms due to encapsulation of aromatic compounds. Studying the effect of various drying methods on the physicochemical properties of shiitake will lead to improving the existing technological processes and will make it possible to obtain products with desired properties.
The use of discrete-pulse energy input (DPEI) mechanisms in various industries has become a reliable tool for the intensification of heat and mass transfer processes in various technological lines and reduction of specific energy consumption. The study of structural transformations in heterogeneous systems under influence of mechanisms of DPEI opens up new possibilities for their use as evidenced by this article. Under certain conditions it is possible to prepare a mushroom suspension with specified characteristics for drying and enhance medicinal properties of the obtained powder product while retaining all valuable components of feedstock. The article presents the results of research of DPEI-processing effect of the shiitake mushroom fruit body on the on physical and mechanical properties and structural characteristics of the mushroom suspension. The influence of hydro module, temperature of the suspension and the layout of the working bodies of the rotor-pulse apparatus (RPA) on its dynamic viscosity was studied and the possibility of reducing viscosity by 2-3 times is shown. An analysis of mushroom suspension microstructure has showed that with a certain layout of the working bodies of the RPA it is possible to control the degree of dispersion of particles and change the spatial structure of the aggregates in the volume of the dispersion medium. It is determined that self-organization of spatial aggregates from individual hyphae in such suspensions occurs over time. Moreover, the smaller the size of hyphae (≤ 25 microns after the RPA of the first version of the arrangement: rotor-stator-rotor) are, the larger the size of the spatial aggregates are formed. After the RPA with the second layout option, the fragments of hyphae had sizes ≥ 50 μm, but the dimensions of the spatial aggregates were three times smaller. It is found that after three times passing of the mushroom suspension through the RPA and its subsequent treatment in the cavitation device, the dynamic viscosity of the suspension is reduced by 20%. Confirmation of the the effectiveness of the DPEI-mechanisms in obtaining mushroom suspension is that due to the hydromechanical destruction of the polysaccharide structures of the chitin-glucan complex of the shiitake mushroom the content of the bioavailable complex of water-soluble oncostatic and immunoregulatory polysaccharides in the powder obtained by drying the mushroom suspension in an experimental spray dryer increased 6 times. References 13, figures 6.
Spray dryer Thermoplasticity Adhesion properties Improvement Powder cooling SeparationThe dry powder form of food products obtained from aqueous extracts of various vegetable raw materials may receive more common demand for their use as valuable with high content of biologically active components. But due to the problems arising in spray drying of complex colloidal and heterogeneous systems, which are the majority of plant extracts, and their thermoplastic, adhesion and hygroscopic properties, their production in powder form in Ukraine is still not established.Approbation of the technology of drying malt extract, which was carried out on an industrial spray dryer universal modified (DUM) with a diameter of 1.5 m, with a productivity of 20-25 kg/h for evaporated moisture with a centrifugal disk sprayer, revealed number of problems in obtaining a powder product.The purpose of the work was to improve the units of separation, cooling and unloading of the industrial sawing drying plant DUM-1.5 with determination of rational thermotechnical parameters of drying for obtaining powder form of malt extracts of low final moisture and increasing its yield from the spray dryer.Improvement of the plant included increasing the height of the bunker under the cyclone and organizing the cooling of the powder in two stages using a screw cooler on the exit of the dryer and determination of rational heat technological modes of drying. This allowed to obtain powder with a moisture content of up to 2%, which contributed to lengthening its shelf life to 2 years, and due to better flowability of powder and lack of deposits of product, increases its yield to 93-95%.The obtained experience of improving the DUM-1.5 dryer proves the necessity of taking into account the properties of such complex spray drying objects in the production of dry forms of malt or other extracts with similar properties under industrial conditions.
Key words: ABSTRACT Shiitake mushroom Dispersion Homogenization Suspension Microstructural analysisExpensive immunomodulatory and antitumor drugs produced by leading pharmaceutical companies are made by chemical isolation of therapeutic polysaccharides from shiitake fruit bodies, but in doing so the biologically active complex of proteins, vitamins and minerals of the fungus is lost.The Institute of Engineering Thermophysics of National Academy of Sciencies of Ukraine has proposed a nanotechnological processing technique of shiitake body or its cap at the preparation phase for spray drying. In particular, during the homogenization a hydromechanical destruction of highstrength chitin-glucan structures is achieved and a high degree of dispersion of particles of insoluble fractions in the mushroom suspension is obtained, which should improve its fluid properties. However, in case of DPEI-processing of the shiitake bodies, stable, high-viscosity heterogeneous colloidal systems are formed and even diluted in water they are still non flowing and it is impossible to bring them into the spray dryer. That fact requires studying the nature of these phenomena.A purpose of research is to study the microstructure of dispersed particles of the mushroom suspension obtained under different technological conditions at DPEI-processing of the shiitake bodies in the process of preparation for spray drying.The microstructural analysis has shown that stems and caps of the fungus differ from each other not only in chemical composition, but also in structure, that determines their strength properties and the effeciency of dispersion and homogenization processes. Thus an aggregation of developed gif structures occurs in the mushroom suspension, that worsens the conditions of its spray drying.Suspensions that are made of fungus caps have better viscosity characteristics and addition of 5% cyclodextrin to them contributed to a decrease in their viscosity by 25-35%. When spray drying such mushroom suspension, an increase in the yield of power from the drying chamber by 2 times, improvement in its quality and shelf life extention of product up to 1 year were achieved.
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