The aim of this review is to show the relationships between the structure, the process, and the properties of biodegradable multiphase systems based on plasticized starch (PLS), the so‐called “thermoplastic starch.” These mutiphase materials are obtained when associating association between plasticized starches and other biodegradable materials, such as biodegradable polyesters [polycaprolactone (PCL), polyhydroxyalkanoates (PHAs), polylactic acid (PLA), polyesteramide (PEA), aliphatic, and aromatic copolyesters], or agro‐materials (ligno‐cellulosic fiber, lignin etc.). Depending on materials (soft, rigid) and the plastic processing system used, various structures (blends, composites, multilayers) can be obtained. The compatibility problematic between these hetero‐materials is analyzed. These starchy products show some interesting properties and have some applications in different fields: packaging, sports, catering, agriculture and gardening, or hygiene.

Biodegradable Multiphase Systems Based on Plasticized Starch: A Review

The use of ultrasonics as an analytical technique for providing information about the physicochemical properties of foods is becoming increasingly popular in the food industry. Ultrasound can be used to rapidly and nondestructively measure properties such as food composition, structure, flow rate, physical state, and molecular properties. As well as being used as an analytical instrument in the laboratory, ultrasound can also be used for continuous monitoring of food properties on-line during processing. This article critically reviews the current status of ultrasound in the food industry, presents the basic principles of ultrasonic testing of foods, and highlights areas where ultrasound will prove to be most useful in the future.

Ultrasonic characterization of foods and drinks: Principles, methods, and applications

Rheology to understand and optimize processibility, structures and properties of starch polymeric materials

Rheological and thermal properties of thermoplastic starch with high glycerol content

Relations between rheological properties of molten starches and their expansion behaviour in extrusion

The shear viscosity of commercial maize grits, potato powder and a low density polyethylene has been measured under a range of extrusion processing conditions using an extruder-fed slit die viscometer and a capillary rheometer. The results show the strong dependence of the viscosity of food melts on the processing history undergone during extrusion. To this end, the shear viscosity data for the food materials have been fitted to relationships including the effects of temperature, shear rate and moisture. The effect of the shear processing history on the viscosity has been represented by a power-law relationship with extruder screw speed.

An experimental study of food melt rheology

A twin-screw extruder-fed slit die viscometer (SDV) and a piston capillary rheometer have been used to measure the end pressure losses of a low density polyethylene, maize grits and potato powder. The entrance and exit pressure losses have been measured as a function of extrusion conditions. The entrance pressure losses were found to be less than 10% of the total pressure drop in the SDV for LDPE and maize grits. For the potato material, this loss was found to be as large as 58%. The exit pressures for the potato were between 10–20% of the total pressure drop compared to negligible values for the maize and LDPE. Various approaches due to Bagley, Han and Cogswell were used to investigate the elastic properties of these materials.

An experimental study of food melt rheology. II. End pressure effects

A slit die viscometer has been used in conjunction with a co-rotating twin screw extruder to study the rheological behaviour of maize grits, potato powder and low density polyethylene, as a function of feed rate, screw speed and temperature. The shear viscosity of both maize and potato decreased with increasing feed rate. Increasing the temperature or screw speed at any given feed rate also reduced the viscosity. The ultrasonic velocity through the material has also been shown to be sensitive to the extruder operating conditions. Overall, the ultrasonic velocity decreased as screw speed and temperature increased and feed rate decreased.

A. Senouci

Papers

An experimental study of food melt rheology

An experimental study of food melt rheology. II. End pressure effects

Measurement of rheological and ultrasonic properties of food and synthetic polymer melts

Automatic Control and Optimisation of food processes