Extrusion Processing Technology

Food and Non-Food Biomaterials

Jean-Marie Bouvier, Osvaldo H. Campanella

• Publisher: Wiley-Blackwell
• Year: 2014
• ISBN:
  9781118541722
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Extrusion is the operation of forming and shaping a molten or dough-like material by forcing it through a restriction, or die. It is applied and used in many batch and continuous processes. However, extrusion processing technology relies more on continuous process operations which use screw extruders to handle many process functions such as the transport and compression of particulate components, melting of polymers, mixing of viscous media, heat processing of polymeric and biopolymeric materials, product texturization and shaping, defibering and chemical impregnation of fibrous materials, reactive extrusion, and fractionation of solid-liquid systems. Extrusion processing technology is highly complex, and in-depth descriptions and discussions are required in order to provide a complete understanding and analysis of this area: this book aims to provide readers with these analyses and discussions.

Extrusion Processing Technology: Food and Non-Food Biomaterials provides an overview of extrusion processing technology and its established and emerging industrial applications. Potency of process intensification and sustainable processing is also discussed and illustrated. The book aims to span the gap between the principles of extrusion science and the practical knowledge of operational engineers and technicians. The authors bring their research and industrial experience in extrusion processing technology to provide a comprehensive, technical yet readable volume that will appeal to readers from both academic and practical backgrounds.

This book is primarily aimed at scientists and engineers engaged in industry, research, and teaching activities related to the extrusion processing of foods (especially cereals, snacks, textured and fibrated proteins, functional ingredients, and instant powders), feeds (especially aquafeeds and petfoods), bioplastics and plastics, biosourced chemicals, paper pulp, and biofuels. It will also be of interest to students of food science, food engineering, and chemical engineering.

Also available

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Chapter 1
Generic Extrusion Processes

Extrusion, one of the most important innovations of the 20th century, is often presented as a model of scientific and technology transfer between different processing industries, such as the polymer and plastics, food and feed, and paper-milling industries in particular. Although the first technical designs of screw extruders were introduced in the latter years of the 19th century, extrusion processing really established itself approximately 60 years later, with the development in the plastics industry of polymer-based materials. It was later successfully exploited by the industries that processed plant biopolymers and has developed into a widespread extrusion processing culture over the past 80 years.

The purpose of this introductory chapter is to give a brief historical overview of the emergence of screw extruders and of the extrusion processing culture that owes its existence to the remarkable transfers of technology from polymer processing to food and feed processing and to paper milling.

1.1 A history of extrusion processing technology

Extrusion is commonly defined as the operation of forming and shaping a molten or dough-like material by forcing it through a restriction, or die. This operation is extensively applied in many processes as a batch or continuous operation. While adhering strictly to this definition, the understanding and analysis of extrusion are quite simple and straightforward.

Extrusion processing technology relies on a continuous process operation which uses extruders to handle process functions such as the transport and compression of particulate components, melting of polymers, mixing of viscous media, cooking of polymeric or biopolymeric materials, product texturization and shaping, defibering and chemical impregnation of fibrous materials, reactive extrusion, fractionation of solid–liquid media, etc. Extrusion processing technology is highly complex and in-depth descriptions and discussions are required in order to provide complete understanding and analysis of this subject.

Extrusion processing technology uses two different equipment designs: the single screw extruder and the twin screw extruder. Within each design, there are various engineering options, which depend upon the equipment manufacturers and/or the processing requirements. Readers who are interested in a complete historical review of the development of extruders should refer to the excellent and well-documented book by White (1990). This introductory chapter focuses mainly on single screw extruders and intermeshing co-rotating twin screw extruders.

1.1.1 The introduction of screw extruders

Single screw and intermeshing co-rotating twin screw extruders appeared over the last 30 years of the 19th century. An 1871 US patent to Sturges (1871) presents a single screw machine for pumping and forming soap. Gray (1879) developed a single screw extruder for processing and extruding gutta percha with specific application to wire coating. In fact, the rubber industry was an early user of screw extrusion machinery for the continuous compounding of rubber. Throughout the period from 1880 to 1930, though no notable industrial application emerged, there was significant mechanical engineering activity that brought remarkable improvements to the designs of the single screw extruder (segmented screws, threaded and grooved liners, pin barrel designs, steam-heated barrels, etc.).

In 1869, the first patent for a fully intermeshing co-rotating twin screw extruder was granted to Coignet (1869). This patent described a machine called a malaxator, which pumped and processed artificial stone paste. There was real development of the intermeshing co-rotating twin screw extruder design in the late 1930s, when Colombo (1939) proposed an advanced design which was manufactured by the Italian company Lavorazione Materie Plastiche (LMP). LMP machines were deployed extensively to the polymer industry over the period between 1940 and 1956, through manufacturing licenses (to Clextral, formerly CAFL and then Creusot-Loire in France, to R.H. Windsor in England and to Ikegai Iron Works in Japan), and through exportation sales, to IG Farbenindustrie in Germany, for example.

The introduction of thermoplastics in the 1930s gave a boost to the development of extrusion processing technology. In Germany in 1939, Paul Troester Maschinenfabrick (PTM) built an electrically heated, air-cooled single screw extruder, with automatic temperature control and variable screw speed. This was the precursor to modern automated extrusion technology for the emerging plastics industry. In following years, various ancillary equipments were introduced to meet the process requirements of the polymer-processing industry (venting, breaker plates, screen packs, co-extrusion dies, film blowing, etc.).

As the polymer industry burgeoned, along with the complexity of polymer formulations, single screw extruders showed real processing limitations in their ability to efficiently mix, compound and pump polymer melts of specific characteristics. Then, following World War II and at the request of plastics manufacturers, twin screw extrusion technology was introduced, adding significant value to the process. For example, in July 1956 CAFL delivered its first intermeshing co-rotating twin screw extruder (72.5 mm interaxis) to the French Pechiney company (Pennaroya factory of Noyelles-Godault in France), for manufacturing plastic pipes. At the same time, at the request of Bayer, the German company Werner and Pfleiderer made the first prototype of the ZSK 83 intermeshing co-rotating twin screw extruder. Figure 1.1 shows a vertical intermeshing co-rotating twin screw machine supplied by CAFL in 1963, for nylon and tergal spinning.

Figure 1.1 Intermeshing co-rotating twin screw extruder designed in 1963 for nylon and tergal spinning.

Source: Reproduced with permission of Clextral, France.

It must be noted that screw extruders played a determinant role in the spectacular growth of the polymer-processing industry (plastics and rubber) between 1940 and 1960, when world production of plastics exploded from 300,000 to 12 million metric tonnes per year (Utracki, 1995). And extrusion technology really established its processing potential with the development of the polymer-processing industry, where, together with the availability of reliable machinery, flexible and productive processing could be carried out at a competitive cost-to-performance ratio.

1.1.2 The generic extrusion process concept

The success of extrusion processing technology in the polymer industry resulted in a close relationship between extrusion equipment designers and plastics manufacturers. Both industries pragmatically combined their efforts and skills to make the use of screw extruders technically and economically viable at an industrial level, in order to produce marketable plastic materials.

The term “use of screw extruders” means extrusion processing. This term combines all the relevant technical expertise, know-how and knowledge that allow the process developers to properly operate screw extruders in order to produce the targeted materials with the expected functional and end-use properties. In other words, extrusion processing completes the synthesis, revealing the technical harmony between equipment engineering and product design. This technical harmony, which has revealed itself in the numerous extrusion applications, has led to a few generic processes whose characteristics are worth presenting and analyzing. At this point, the authors wish to introduce the generic extrusion process (GEP) concept as one way of manifesting the synthesis and revealing the fundamentals of extrusion processing technology.

Currently, the GEP concept is fundamental to the presentation and analysis of the extrusion processing culture in a comprehensive way, and is important in achieving the following aims:

• understanding the complexity of extrusion processing technology
• allowing extrusion practitioners to be less dependent on long-term experience when carrying out experimental developments
• linking extrusion science and the long-term experience, the lack of which often dramatically places a limit on the optimal use of screw extruders
• creating the potential for generating new ideas for extrusion applications.

The GEP includes the basic process functions which govern the performances of screw extruders and resulting products in certain groups of extrusion applications. They are presented in the following sections and take into account the industrial application of extrusion processing technology in different fields.

1.1.3 Extrusion technology in the polymer-processing industry

The technical synergy which occurred between extrusion equipment manufacturers and the polymer-processing industry led to the first main generic extrusion process, GEP I, “Thermomechanical Plasticating of Polymers and Polymer Melt Forming.” Its process functions are applied in a vast number of industrial applications, to process polymeric materials into marketable products. In the extrusion world, this initial generic extrusion process can essentially be considered as the “big bang” of extrusion ...

Table of contents

• Cover
• Title page
• Copyright page
• Foreword
• Acknowledgements
• Chapter 1: Generic Extrusion Processes
• Chapter 2: Extrusion Equipment
• Chapter 3: Extrusion Engineering
• Chapter 4: The Generic Extrusion Process I
• Chapter 5: The Generic Extrusion Process II
• Chapter 6: The Generic Extrusion Process III
• Chapter 7: Quality Analysis of Extrusion- Textured Food Products
• Chapter 8: The Generic Extrusion Process IV
• Chapter 9: The Generic Extrusion Process V
• Chapter 10: Extrusion Technology and Process Intensification
• Supplemental Images
• Index
• End User License Agreement