Danish Cancer Society Research Center, Denmark
Chapter 12
Guri Skeie, The Arctic University of Norway, Norway
David R. Jacobs Jr., University of Minnesota, USA
Chapter 13
Sabine Ibrügger, University of Copenhagen, Denmark
Kia Nøhr Iversen, Chalmers University of Technology, Sweden
Mette Kristensen, University of Copenhagen, Denmark
Rikard Landberg, Chalmers University of Technology, Sweden
Chapter 14
Marion G. Priebe, University Medical Center Groningen, The Netherlands
Coby Eelderink, University Medical Center Groningen, The Netherlands
Roel J. Vonk, University Medical Center Groningen, The Netherlands
Chapter 15
Johan Dicksved, Swedish University of Agricultural Sciences, Sweden
Emma Ivarsson, Swedish University of Agricultural Sciences, Sweden
Chapter 16
Anne‐Maria Pajari, University of Helsinki, Finland
Riitta Freese, University of Helsinki, Finland
Susanna Kariluoto, University of Helsinki, Finland Anna‐Maija Lampi, University of Helsinki, Finland Vieno Piironen, University of Helsinki, Finland
Chapter 17
Afaf Kamal‐Eldin, United Arab Emirates University, UAE
Agneta Åkesson, Karolinska Institutet, Sweden
Maria Kippler, Karolinska Institutet, Sweden
Karl‐Erik Hellenäs, National Food Agency, Sweden
Nathalie Scheers, Chalmers University of Technology, Sweden
Ann‐Sofie Sandberg, Chalmers University of Technology, Sweden
Chapter 18
Amanda J. Lloyd, Aberystwyth University, UK
Kathleen Tailliart, Aberystwyth University, UK
Manfred Beckmann, Aberystwyth University, UK
John Draper, Aberystwyth University, UK
Chapter 19
Kati Hanhineva, University of Turku, Finland, University of Eastern Finland, Finland and Chalmers University of Technology, Sweden
Chapter 20
Marjukka Kolehmainen, University of Eastern Finland, Finland
Chapter 21
Frank Thielecke, Thielecke Consulting, Switzerland
Wolfgang Bindzus, Cereal Partners Worldwide S.A., Switzerland
Chapter 22
Heddie Mejborn, Technical University of Denmark, Denmark
Caroline Sluyter, Oldways Whole Grains Council, USA
Supplementary Material
Additional materials, including multiple choice questions and supplementary chapters, can be found under the #8220;Downloads#8221; section online at https://www.wiley.com/en-gb/Whole+Grains+and+Health-p-9781118939437
1 The Structure of Cereal Grains and Their Products
Maud Langton1, and José Luis Vázquez Gutiérrex1,2
1Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
2Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden Present address: Centro Technológico ITENE, Valencia, Spain
1.1 Introduction
Through the senses, consumers can subjectively detect properties in food. However, other qualities such as long‐term health benefits of food that cannot be easily detected. A deep knowledge of cereal grain structure and how it is modified by processing is necessary to understand the physical and health properties of the different cereal products. This chapter focuses on the microstructure, at different levels, of cereal grains and their products. The structure of the grain is briefly overviewed and followed by the effect of processing on the structure of different food products. Based on the microstructure of the final product, three groups are distinguished: rolled cereals and porridge, protein network‐based products and starch network‐based products. This different organization is important for food production and technological aspects. The impact on the health‐related aspects of the product is currently investigated.
1.2 Grain structure
Cereals are the most important crops in the world and are destined to become both human food and animal feed. Cereals, which belong to the grass family (Gramineae), produce dry, one‐seeded fruits. These fruits are, botanically speaking, caryopses, but they are commonly referred as “grains” or “kernels.” The cereal grains such as wheat, rice, maize, barley, oats, rye, sorghum and millet provide 50% of the food energy and 50% of the protein consumed on earth. Wheat, rice and corn constitute around 75% of world’s grain production (Ramaswamy and Riahi 2003). In this chapter, wheat is used as reference to explain the structure of cereal grain. Its kernels contain three main parts: embryo, endosperm and their covering layers. The last are, in milling, often separated as the bran fraction (Figure 1.1A). If all the parts of the kernel are retained in processing, one can speak of whole grain. If either the bran or germ is separated from the kernel during milling, then it is a “refined grain.”
Figure 1.1 A: General structure of a cereal grain); B: Epifluorescence micrograph of parts of rye grain. The sections were stained with Acid Fuchsin and Calcofluor: protein appears red, cell walls rich in β‐glucan appear light blue and lignified cell walls of the pericarp appear yellowish‐orange. Structure of cereal foods
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