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In this paper we present the reactive extrusion process to extract the phycocolloids from the sea products. By comparing with other techniques, this process has a several advantages like the economic return, the flexibility, the production of various products with different characteristics and time gains. There are two types of extruder: single-screw and double-screw, each one has its specific properties. The solid products are introduced by means of the hopper that is equipped with a dosage pump for the regulation of the flow. Liquid products are, generally, injected in the not filled zones, through an external pump. The products undergo thermo mechanical modifications and then the shaping of the final products was done in the die. The reactive extrusion is applied in several fields: agri-food where there are three main types of operating conditions (simple extrusion, extrusion-cooking, reactive extrusion), in the plastic industry for the recycling of household plastic waste and also to create mixtures between different polymers, as well in the field of chemistry and pharmaceutics. The reactive extrusion is used also to add value to the sea products like to extract phycocolloids especially the alginate from the seaweeds, also the chitin from crustacean by-product. A further interesting application of the reactive extrusion process is the energy production. Recent research is aimed to the valorization of fish by-products for the extraction of lipids for biofuel purpose.
This document presents the basic concepts of heat transfer related to the microwave heating process of food products. The process parameters and product properties are detailed with the different mechanisms responsible for the temperature rise under microwave. Theoretical aspects of wave propagation in guided structures are also presented, including thermal effects on the processed material. Some focus will be on the various existing experimental devices for research and development applications as well as microwave heating modelling approaches to predict the thermal behaviour of the product during the process. Finally, the major applications of microwave heating technology are presented by including both thermal and non-thermal effects on food materials.
