Extrusion is widely used for the preparation of a variety of foodstuffs including breakfast cereals, snack food and pasta, as well as pet food and animal and aquaculture feed. Extrusion problems solved provides responses to more than 300 frequently asked questions about the process of food extrusion and the techniques and equipment involved, in a practical question-and-answer format.The book is divided into twelve chapters for ease of reference: the opening chapters concentrate on introductory queries and on different components of an extruder system, followed by two chapters that help the reader select the correct type of extruder for a product. Chapters five and six discuss the impact of factors such as protein content and particle size on the extrusion process, while the use of pre-conditioners is discussed in chapter seven. The latter part of the book discusses specific types of extruder and die and knife assemblies, followed by a chapter on issues relating to drying extruded food products. The final chapter offers practical guidelines and rules of thumb for the most common issues relating to food and feed extrusion.Written by two leading experts in the field, Extrusion problems solved is an essential reference source and troubleshooting guide for professionals working in food, pet food and feed extrusion. It will also be a valuable training resource for students of extrusion. - Offers practical guidelines and rules of thumb for the most common food and feed extrusion problems - Chapters concentrate on introductory queries, types of extruder and components of extruder systems, knife assemblies, the use of pre-conditioners and issues in drying extruded food products - Provides responses to more than 300 frequently asked questions about the processes, equipment and techniques of food extrusion in a practical question-and-answer format

Mian N. Riaz is the Director of the Food Protein R&D Center and Head of the Extrusion Technology Program at Texas A&M University, USA.

About the authors

Woodhead Publishing Series in Food Science, Technology and Nutrition

Preface

Sources of further information

Chapter 1: An introduction to food and feed extrusion and associated terminology

1 What is extrusion cooking?

2 What is cold extrusion?

3 What is dry extrusion?

4 What are the functions of a typical extruder?

5 What are the advantages of extrusion compared to other thermal processes?

6 What is the quality of the products produced by extrusion?

7 What is the waste stream from extrusion processing?

8 How easy is it to scale up the extrusion process?

9 Can I use extruders as continuous reactors?

10 Do extruders need to be shut down every day?

11 What is feedstock in extrusion?

12 What is a pellet?

13 What is the recipe or formulation?

14 What is the compression ratio?

15 What is L/D (length to diameter) ratio?

16 What is screw geometry?

17 What does pitch mean?

18 What is the flight depth?

19 What is the flight angle?

20 What does 'venting concept' mean?

21 What does shear mean?

22 What are long-cut and short-cut products?

23 What does collet mean?

24 What is kibble?

25 What is starch gelatinization?

26 What is the gelatinization temperature of starch?

27 What is dextrinization?

28 What is the Maillard reaction?

29 What is meant by retention time?

30 What is surging?

31 What are fines?

32 What is meant by grind?

33 What is meant by HTST?

34 What is a PLC?

35 What is the glass transition?

36 What is the melt phase transition?

Chapter 2: Components of a food or feed extrusion system

37 What is a feeder?

38 What is a volumetric feeder?

39 What is a gravimetric feeder?

40 What is a hopper or bin?

41 What is a preconditioned

42 What is a diverter spout?

43 What is an extruder barrel?

44 What does the phrase 'barrel section' mean?

45 What is the feeding section of the barrel?

46 What is the compression section of the barrel?

47 What is the metering section of the barrel?

48 What is a barrel liner?

49 What are rifling grooves?

50 What does the term 'jacket' mean?

51 What is a screw?

52 What are screw crests and troughs?

53 What is the root?

54 What is a screw element?

55 What is a hollow-core screw?

56 What is a screw flight?

57 What is a continuous flight?

58 What is a cut flight screw?

59 What is an interrupted flight screw?

60 What is the screw bore?

61 What is a worm?

62 What is a shear ring?

63 What are shearing bolts and what are they for?

64 What is a vent in the context of extrusion?

65 What is a die?

66 What is a die insert?

67 What is die land length?

68 What is the die orifice?

69 What is a die plate?

70 What is a choke plate?

71 What is a single-face die plate?

72 What is a breaker plate?

73 What is the cutter?

Chapter 3: Selecting the right type of extruder: single screw and twin screw extruders for food and feed production

74 What are the different types of extruders that are available?

75 What is a single screw extruder?

76 What is a wet extruder?

77 What is a segmented screw/barrel single-screw 'wet' extruder?

78 What does a typical single screw consist of?

79 How much internal fat can be present in a recipe to be processed by a single screw extruder?

80 What is the range of particle sizes that can be used in a single screw extruder?

81 What are the typical applications of single screw extruders?

82 What are the pros and cons of single screw extruders?

83 What are the different types of single screw extruder that are available?

84 What are cold forming extruders?

85 What are high-pressure forming extruders?

86 What is a low-shear cooking extruder?

87 What are collet extruders?

88 What are high-shear cooking extruders?

89 What is a twin screw extruder?

90 What are the different types of twin screw extruders that are available?

91 What is the most common design used for twin screw extrusion?

92 Are there any benefits of using twin screw versus a single screw extruder?

93 What is the maximum fat level used in a twin screw extruder?

94 What is the minimum size of the pellet that can be produced with a twin screw extruder?

95 What is the range of particle sizes of raw material that can be used in a twin screw extruder?

96 What is the maximum level of fresh meat that can be incorporated in a recipe to be processed in a twin screw extruder?

97 What are the typical applications of twin screw extruders?

98 What are the disadvantages of using twin screw extruders rather than single screw extruders?

Chapter 4: Selecting the right type of extruder: dry extruders and expanders for food and feed production

99 What is a dry extruder and what does dry extrusion mean?

100 What kinds of ingredients can be processed by a dry extruder?

101 How much moisture loss occurs in dry extrusion?

102 Can we inject water into a dry extruder?

103 Can a preconditioner be used with a dry extruder?

104 What is the basic principle of dry extrusion?

105 What temperatures and pressures can be reached in dry extrusion?

106 What are the main applications of dry extrusion?

107 Are there any other applications of dry extrusion?

108 What are the pros and cons of dry extrusion?

109 What is the main difference betw…