Novel Mechanical Treatments of Biomaterials

Abstract During the last few years novel mechanical techniques have been shown to have great potential in food processing. Sterilization of food materials by high pressure treatment at relatively low temperatures has been intensively investigated with promising results. Microbial spore sterilization by adiabatic expansion of water pressurized to over 600 MPa has been demonstrated. The sterilization of Bacillus stearothermophilus spores has been achieved by six consecutive adiabatic expansion cycles at temperatures below 70 °C. Twin-screw extrusion has been successfully applied to destroy allergens in proteinaceous food and feed materials such as soy flour, but could not be demonstrated with soybean hulls of high carbohydrate content. It has been shown that allergens of buckwheat and soy flours can be partially destroyed by high shear using twin-screw extrusion cooking. Microparticulation technology using a jet mill has been employed to increase the surface hydrophobicity of proteinaceous particles milled to less than 3 μm in diameter in order to prepare fat replacers. Biodegradable loose fill packing material has been prepared from corn starch by extrusion cooking. An extrudate prepared with high amylose (70 g/100g) starch containing about 9 g/100g of polyvinyl alcohol and 9 g/100g moisture was shown to be a high quality biodegradable, shock absorbing packing material. The biodegradable packing fill obtained also had a good bulk density, elasticity and compressibility. Clearly, novel mechanical methodologies such as high pressure, high shear, and microparticulation techniques offer great potential in food and feed processing, and in the production of environmentally friendly, biodegradable packing materials.