Bread Making

Improving Quality

Stanley P. Cauvain

• Publisher: Woodhead Publishing
• Year: 2003
• ISBN:
  9781855737129
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

There has been a wealth of recent research on the complex changes involved in bread making and how they influence the many traits consumers use to define quality. Bread making: improving quality sums up this key research and what it means for improved process control and a better, more consistent product.After an introductory review of bread making as a whole part one discusses wheat and flour quality. Chapter 3 summarises current research on the structure of wheat, providing the context for chapters on wheat proteins (chapters 5 and 6) and starch (chapter 7). There are also chapters on ways of measuring wheat and flour quality, and improving flour for bread making. Part two reviews dough formation and its impact on the structure and properties of bread. It includes chapters on the molecular structure of dough, foam formation and bread aeration together with discussion of the role of key ingredients such as water. A final group of chapters then discusses other aspects of quality such as improving taste and nutritional properties, as well as preventing moulds and mycotoxin contamination.With its distinguished editor and international team of contributors, Bread making: improving quality is a standard work both for industry and the research community.

1

Introduction

S. Cauvain Campden and Chorleywood Food Research Association, UK

Mention the word ‘quality’ and on a good day my eyes normally glaze over as pictures of detailed and often meaningless ‘procedures’ apparently designed to ensure the quality of a process or a product spring to mind. On a bad day I might run screaming from the room. The big problem with most ‘quality systems’ is that they fail to take sufficient account of the ‘real’ purpose of the procedure or product concerned. This is especially the case in breadmaking where the perception of product quality is very personal. We all have our selection of criteria which classify bread as ‘good’ or ‘bad’, ‘correct’ or ‘wrong’ and while there are some common characteristics on which many of us would agree (for example, the bread should not be mouldy) the final judgement will always be highly personal.

In the final analysis if we define quality as being ‘fitness for purpose’ then for the each of us bread quality may be described as being the sum of those quality traits which confer the sensory pleasures associated with smell, taste and texture. In summary, when we taste and eat the product we experience pleasure. Our individual perception will then depend on the combination of those parameters which characterise the mix of product appearance, texture, smell and flavour which best suits each of us. We must also recognise that our perception of quality will change with the passage of time and personal circumstances, not least our health.

While there are many factors which characterise the quality of bread products that can be easily defined and measured, e.g. loaf height and volume, there are many others which are ephemeral in nature and therefore more difficult to define, e.g. smell and flavour. In defining quality, the term ‘consistency’ is often used as frequently as fitness for end use. Consistency is indeed a desirable quality trait with most products but for the highly individual perception of bread quality even this ‘simple’ quality trait is difficult to apply with absolute certainty. If you are a sandwich maker then you certainly want consistency of volume, shape and cell structure but in a craft bakery context customers may still want to choose between light and dark crust coloured products. The variability in bread qualities sought by consumers demands that bakers be able to meet all of the quality requirements concerned. All in all, breadmaking requires a deep understanding of the many complex raw material and process interactions that all play a part in determining final product quality.

1.1 Wheat and its special properties

Almost every discussion of bread and its quality will start with a reference to the special nature of wheat, given that wheat flour is the largest ingredient in dough and bread formulations it is hardly surprising. In the contributions which follow much will be made of the special properties of wheat flour proteins to form gluten after hydration and during mixing. Dough mixing is the process which starts dough aeration as the gluten forms a network which traps and retains bubbles of air for inflation by carbon dioxide gas from yeast fermentation.

It is because of the special properties of wheat proteins that much research has been devoted to them. Chapter 3 provides a comprehensive insight to the many different aspects of wheat chemistry and biochemistry and this theme is continued in Chapters 6 and 26. Improvements in wheat quality to make it better suited to its end uses are considered in Chapters 8 and 11, along with opportunities for future development. The key role of the gluten forming proteins rightly receives considerable attention in several chapters but to address the balance the role of starch is considered in Chapter 7.

Fundamental to achieving a given bread quality is the ability to measure wheat quality and predict the likely breadmaking performance of any given wheat sample. This has been the ‘holy grail’ for farmers, millers and bakers for centuries. Cereal science has developed many techniques and tools to help but the complexity of those little wheat grains and the impact of farming practices on grain quality means that the goal still remains largely unattained. Much progress has been made and is considered in several of the chapters which follow. However, if you read on expecting to encounter a single test to make the perfect prediction you will be disappointed. It remains unlikely that there will be a single test which will predict bread quality with certainty and that is hardly surprising given that there are many different types of bread and breadmaking processes, each requiring a degree of variation in the ‘quality’ predictors. For the moment we will have to content ourselves with using a range of analytical techniques but I hope that the chapters, for example 4, 5 and 9, which address this general aspect will enable you to decide which combination best suit your particular needs.

Cereals and cereal-based products are amongst the safest of foods that we have available. However, growing and processing grain is not without its hazards. Some of the most deadly toxins are those which occur naturally. In cereals such unwanted materials may come in the form of mycotoxins. With the widespread transport and longer term-storage of cereal products issues of food safety have become increasingly important and for these reasons the detection and control of mycotoxins materials are the subject of Chapter 25.

1.2 Converting wheat to flour

In order to make an aerated bread structure it is necessary to process the wheat grains into another, more suitable form. Over the centuries techniques have evolved which permit the separation of the white endosperm from the darker coloured bran skins and germ. The progression towards greater availability of white flour has spawned the large number of bread products that we see in bakeries today. There are a number of factors which have driven the move to white flours, not least the greater gluten forming potential of the wheat proteins in the starchy endosperm. As discussed in Chapter 10 the flour milling process has evolved into a sophisticated process but its efficiency and economic viability still depend on the quality of the raw material entering the flour mill. Because of this flour millers remain acutely aware of the need to assess wheat quality and link its qualities with the final product for which it is destined. Flour millers therefore continue to use a range of tests to assess both the reliability and consistency of their own operations, as discussed in Chapter 9.

Since the nutritional properties of the wheat grain are not homogeneously distributed throughout the wheat grain the separation of the endosperm from the other components to yield white flour is not without its penalties. In those circumstances where nutrition is at a premium the fortification of flour- and wheat-based products has become a political and humanitarian issue. The role of fortification and the means by which it may be achieved are discussed in Chapter 12 and they provide an insight to another important aspect of bread quality.

The nutritional-quality link is also covered in Chapter 23 where the role for increasing fibre levels in bread are discussed. It is somewhat ironic that the Western world approach to breadmaking which has become dominated by white flour-based products should be advocating a return to higher extraction flours. The conversion of all of the wheat grain to flour has always been with us but the quality attributes of wholemeal or wholewheat bread have not had sufficient appeal for the mass market. In the UK when the technology for making wholemeal and similar breads as large and similar in softness to white bread were developed sales rose from 2 to 20% of breads sold. This increase in sales was truly quality driven since the fibre hypothesis had been around for quite some years with little impact on the dietary habits of the average UK consumer.

1.3 Making bread

Breadmaking is a centuries old traditional craft, practised in any country capable of growing or importing wheat. This has meant the evolution of a diverse range of breadmaking processes designed to achieve a wide range of bread products. There are a number of central themes which are common to all bread products and breadmaking processes. They are, the mixing of wheat flour, water, yeast and other functional ingredients and the expansion of the dough mass through the generation of carbon dioxide gas.

In the Technology of Breadmaking (Cauvain and Young, 1998, 2002) it has been stated that for no-time doughmaking processes that ‘About 90% of final bread quality is decided by what bakers chose to do in the mixer’. This aspect of quality embraces the choice of raw materials and formulation as well as decisions on how to mix and develop the gluten structure in the dough. The relationship between mixing and dough development is still not fully understood. This is a theme which is visited in many of the chapters in this book.

It is well known that simply blending the bread recipe ingredients is not enough to initiate the development of the gluten structure. The technological aspects associated with gluten development and their place in the different breadmaking processes are discussed in Chapters 2, 13 and 14. If you want convincing of the relative importance of mixing and dough development, try mixing your own bread dough by hand. The harder you work the dough (that is the more energy you put into the mixing/development process) the greater will be the gas retention in the dough, the larger the loaf and the softer its crumb. However, the mixing times concerned may last for 30 minutes so be prepared for some hard work!

In-depth considerations of the molecular changes during dough mixing will be encountered in several chapters. The molecular interactions involved depend very significantly on the key quality traits of the proteins in the wheats and as discussed in Chapters 13 and 14 we can see how the genetic puzzle that is wheat protein is slowly being solved.

The role of water in gluten development is commonly taken for granted with water being seen simply as an ingredient which varies in level of addition with flour properties. It is true that the level of water addition to bread flour is critical in providing a dough rheology which is suitable for subsequent processing but as discussed in Chapters 15, 16 and 19 it is also part of the underpinning essential molecular changes which occur during the mixing/development process. Experiments with powdered ice or pre-hydrated flours reveal the complex relationship between hydration and development.

Water plays a key role all through the breadmaking process starting with mixing and ending with contributions to end product eating and keeping quality. These pivotal roles are described in Chapter 21. Critical reference to dough rheology, its control and contribution to final product quality is made in many chapters. Techniques for assessing dough rheology have changed and the latest developments are described in Chapter 18.

There was a time when many bakers considered water to be a ‘free’ ingredient or at least a cheap one. Those days have gone and the only truly cheap ingredient left for the baker is air. It is ironic that a plentiful, cheap ingredient plays such a key role in the breadmaking processes. The role of air assumes equal importance with that of wheat flour, water and yeast. It has been said that gases are the neglected ingredients in breadmaking but after reading Chapter 17 you would be forgiven for thinking that this is far from true. The study of the contribution of gases goes back over 60 years and the latest research is providing a fascinating insight into the role of gas bubbles in bread doughs and how they change during breadmaking. Gases may well have been taken for granted and overlooked by the baker but that is certainly not the case for the cereal scientist.

The concept of bread flavour is perhaps the most contentious of all the quality issues associated with bread. The formation of bread flavour arises in part from fermentation processes and in part from the complex interactions between the heat of the oven and the recipe ingredients. Factors which influence bread flavour are discussed in Chapter 22 and readers are left to form their own opinions on this highly individual subject.

1.4 Functional ingredients

An alternative term for functional ingredients in common usage is ‘improvers’. Every ingredient used in breadmaking has a function and in the alternative sense ‘improves’ bread quality. An ‘improving’ effect could be put forward for the use of yeast added to flour and water to produce leavened rather than unleavened bread (although as discussed in Chapter 17 leavened bread in some contexts is considered impure). On the one hand an ‘improving’ effect can be claimed for salt additions (sodium chloride) which contribute to control of gluten rheology and yeast fermentation, but a counter argument would certainly be put by the advocates for lower salt levels in bread for medical reasons, though their case is not fully proven.

The foregoing comments show the ambiguous position that functional ingredients (improvers) hold in the psychology of breadmaking. While purists may argue for no ‘artificial’ additives (whatever that means) the demands of the modern consumer for consistent quality and safe food continue to make a strong case for additions of functional ingredients. Loss of bread quality is commonly associated with microbial spoilage as discussed in Chapter 24. Consumer shopping patterns in many parts of the world have changed such that the daily trip to the bakery is not the norm and such consumers expect that bread products remain spoilage free for significant periods since they have no desire to throw away uneaten product. Given these constraints it is not surprising that bakers have turned to the use of preservatives to limit microbial growth. ‘Natural’ anti-microbial agents may become more readily available as scientific studies continue.

From the moment that bread leaves the oven its qualities begin...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright page
• Contributor contact details
• 1: Introduction
• 2: Breadmaking: an overview
• Part I: Wheat and flour quality
• Part II: Dough and bread quality
• Index