The Science of Bakery Products - Hardcover

Edwards, William P

Hardcover

ISBN 10: 0854044868 ISBN 13: 9780854044863

Verlag: Royal Society of Chemistry, 2007

Inhaltsangabe

The Science of Bakery Products is an interesting and easy to read book, aimed at anyone with an interest in everyday chemistry.

Über diesen Titel

Über die Autorin bzw. den Autor

Charlotte y Peter Fiell son dos autoridades en historia, teoría y crítica del diseño y han escrito más de sesenta libros sobre la materia, muchos de los cuales se han convertido en éxitos de ventas. También han impartido conferencias y cursos como profesores invitados, han comisariado exposiciones y asesorado a fabricantes, museos, salas de subastas y grandes coleccionistas privados de todo el mundo. Los Fiell han escrito numerosos libros para TASCHEN, entre los que se incluyen 1000 Chairs, Diseño del siglo XX, El diseño industrial de la A a la Z, Scandinavian Design y Diseño del siglo XXI.

Von der hinteren Coverseite

Ever wondered why bread rises? Or why dough needs to rest? From cakes and biscuits to flat breads and loaves, the diversity of products is remarkable as is the chemistry behind these processes. This book explains the science behind bread making and other baked goods. It looks at the chemistry of the ingredients, flour treatments, flour testing and baking machinery. Individual chapters focus on the science of breads, pastry, biscuits, wafers and cakes. The book also looks at experiments and methods and discusses ideas for the future. This is an interesting and easy to read book, aimed at anyone with an interest in everyday chemistry or working in the food industry.

Auszug. © Genehmigter Nachdruck. Alle Rechte vorbehalten.

The Science of Bakery Products

By W. P. Edwards

The Royal Society of Chemistry

Copyright © 2007 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-0-85404-486-3

Contents

Chapter 1 Introduction, 1, 
Chapter 2 Science, 11, 
Chapter 3 Raw Materials, 56, 
Chapter 4 Analytical Chemistry, 135, 
Chapter 5 Flour Testing, 139, 
Chapter 6 Baking Machinery, 154, 
Chapter 7 Bread Making, 167, 
Chapter 8 Products Other than Bread, 208, 
Chapter 9 Bread-making Experiments, 233, 
Chapter 10 The Future, 241, 
Glossary, 243, 
Bibliography, 244, 
Subject Index, 245, 

CHAPTER 1

Introduction

1.1 HISTORY

Baking, particularly the baking of bread, is one of the oldest of human activities – indeed one of the oldest surviving papyri appears to be a set of instructions for making bread. Another document is part of a correspondence explaining that pyramid construction is falling behind because the supply of beer and bread to the labourers has been insufficient, thus revealing that the diet of labourers has changed relatively little in thousands of years.

Western civilisation is based on the cultivation of wheat, a practice that seems to have started in Mesopotamia, the area that is currently Iraq. Wheat is a member of the Grammacidae, i.e. it is a member of the grass family. The cultivation of wheat spread from the Middle East across Europe. Settlers took wheat seeds with them to the Americas and started to cultivate wheat there. Those settlers from Great Britain took wheat that had evolved to grow in British conditions. These wheat varieties would grow on the eastern seaboard but were not successful in the American Midwest. Subsequently, however, wheat from Eastern and Central Europe was found to thrive in the Midwest. The cultivation of wheat also spread to Canada and Australia.

In Great Britain, the industrial revolution in the nineteenth century was initially good for the farming community – as people moved from subsistence agriculture to the factories it created markets for agricultural products. This situation continued up to the 1880s when quantities of imported grain started to become available. This imported grain was much harder than English wheat and created a problem since the wind and watermills could not grind it. A solution appeared in the form of the roller mill, a Hungarian invention, which could cope with hard North American wheat. These roller mills could easily produce much whiter flour than the old stone mills. The large milling companies set up mills on dockside sites as the most economic way of handling imported grain. The large wind and water mills that had supplied the cities started to close as they could not compete with these new dockside roller mills. Small rural mills, though, continued to trade locally.

The imported grain triggered a farming recession that ran from the 1880s to 1939. British governments became aware of the strategic problems caused by relying on imported food. Research on wheat breeding led to varieties of wheat with good bread making potential that would grow in the British climate. Other research led to the Chorleywood Bread Process that was intended, among other things, to reduce the dependence on imported wheat.

The next stage was Britain's accession to the European Economic Community [EEC, commonly known then as the Common Market, and now known as the European Union (EU)], which meant that the Common Agricultural Policy (CAP) applied. The policy in the form then current sought to penalise the use of food crops from outside the EEC when the crop could be produced inside the EEC.

Originally, the policy had sought to support small farmers by guaranteeing a stable high price for their products. When the supply of a commodity exceeded the demand the surplus was bought and placed in store. This process was called intervention. Keeping stocks of intervention wheat was easier than some other commodities as neither refrigeration nor freezing was needed, unlike the position for butter and beef. There was also the distinct possibility that a bad harvest would allow the grain to be brought out of intervention. The other way of disposing of intervention wheat was subsidised sales on the world market. This was the feature that the traditional wheat-exporting nations objected to most strongly.

If the EEC price was higher than the world price, which it usually was, then imports from outside the EEC had to pay a levy. This provided strong financial motive to try and move from using Canadian wheat. The British wheat that was mainly used instead was not, and is not, as fundamentally well suited to making bread by a long process. Thus, although there were other issues in the move to shorter processes for bread making, the CAP supplied a push because it provided financial advantages for using EEC wheat.

At the time of writing, the World Trade Organisation is pushing for the abolition of agricultural subsidies. If this happens, wheat imported into the EU will no longer be at a financial disadvantage. However, the baking industry is most unlikely to shift back to longer bread making processes. The one area where the use of long processes for bread making has increased is in domestic bread machines, which have increased domestic bread production markedly. Because these machines use a fairly long process the demand for very strong bread flour sold retail has also increased markedly.

The baking industry is not just concerned with the production of bread, there is an important difference between bread and other baked products. Bread is regarded as a staple food and as such attracts regulation of its composition and sometimes price. Biscuits, cakes, pastries and pies are regarded as discretionary purchases and avoid regulation. Bread production is an extremely competitive business while the production of other baked goods is not quite so competitive.

Some supermarkets use cheap bread to attract customers. The supermarket management, knowing that bread is a basic necessity, reckon that if the customer can be lured into the supermarket with the offer of cheap bread then their trade can be captured. Producing the cheapest possible bread does not have a positive effect on quality.

Some small bakers use a variant of the same trick by arranging the shop so that customers need to queue for bread in front of a display of cakes and pastries – which is intended to produce impulse sales.

Another modern trend is the increased sale of filled rolls and pre-packed sandwiches. The sale of filled rolls provides many small bakers with a very satisfactory source of profit. The manufacture of pre-packed sandwiches is now a large industry, consuming large quantities of bread. Such sales growth is obviously caused by a population that is short of time rather than money.

The two hardest decisions in writing this book are what to put in and what to leave out. While the length is decided by the publisher there is no room to produce an encyclopaedia. An attempt has been made to cover examples of the commonest types of product. Inevitably there has to be a great deal about bread in this work but it is not solely about bread, other baked goods have their place in the book just as they do in the bakery industry.

In deciding what to put in and what to leave out, preference has been given to items that are thought likely to be useful to the reader or give an understanding of the current situation. This leads to information on nutrition being included while the genetics of yeast have been left out.

It is a sign of the times that information on nutrition has been included; if this work had been written some years ago it is doubtful if information on nutrition would have been included. At the time of writing there is considerable pressure on the food industry over the unhealthy diet of the general population. The major dietary problem of the western world at present is a diet with too much energy and, particularly, too much fat and salt. The excess energy might be explained by changes in working life as employment becomes less physical and more sedentary. A diet that would be entirely satisfactory for a manual labourer contains far too much energy for an office worker.

1.2 LANGUAGE AND UNITS

The language used will be the Queen's English or that subset of it as approved by the Royal Society of Chemistry (RSC). Where chemical names are concerned there are some lost causes, such as caustic soda, where little would be gained if those who clean factories called this substance sodium hydroxide. Arguably, the name caustic soda conveys more useful information. Similar lost causes are spirits of wine (ethyl alcohol or ethanol) and spirits of salts (hydrochloric acid). While lipid chemists may insist on referring to triacylglycerols many people in industry continue to refer to triglycerides. Similarly trivial names for fatty acids such as lauric will continue to be used. The principle in all of this is to use the proper name but to mention other names that are in common use.

There are a few areas in the subjects covered by this book where unfortunately the same words or are used to describe different things. They are gluten and flour improver. In food law a flour improver would cover a substance added to flour to improve its performance, usually in bread. Such a substance is ascorbic acid. In a bakery, the expression flour improver covers a mixture that is added to the dough. In this context a flour improver will contain not only substances like ascorbic acid but also, for example, enzyme active soya flour, emulsifiers and possibly fat.

Gluten is used to refer to dried wheat gluten, all the proteins in a dough, and by chemists as a class of proteins.

The names given to products can also cause problems. The worst possible case is the English and the American muffin, where the same word is used to describe two completely different products! Product names are a problem not only between the farthest flung parts of the English speaking world but also within the UK. Products that could be classified as a bread roll are known as a breadcake in Yorkshire, a cob in the Midlands, and a huffer in Essex.

These differences occur because there is not a national market in baked products. Short life products of low value have to be made near to where they are consumed, otherwise the cost of transport will exceed the value of the product. In some cases products are not known away from their local market. Such a product is the Scots morning roll. Other products such as Eccles cakes and Chorley cakes are still associated with their area of origin.

While there is a world market for grain and flour there is not a world market for low value short life baked products. The only sort of baked products that can be traded internationally are long life products such as biscuits and rich fruit cakes.

When it comes to units of measurement that subset of the metric system known as SI should be used. The three base units that are relevant here are the metre, kilo and second (replacing the earlier system based on the centimetre, gram and second, i.e. cgs units). In practice, some cgs units continue in use. While the UK has officially gone metric the USA continues to use "English Units". Confusingly, some of these units, although they have the same name, are not the same size as the units of the Imperial system used in Britain. The units that cause trouble tend to be the pint, the gallon, and the ton. The Imperial pint is 20 fluid ounces while the US pint is 16 fluid ounces, which leads to the discrepancy between the US ton and the Imperial ton. Curiously, the Imperial ton at 2240 lbs is nearly the same weight as the metric tonne at 1000 kg (= 2120 lbs). In this work, tonne means the metric tonne; the other two tons will not be used.

There is one other set of units: the bag and the sack. Recipes were often classified by so many bags or sacks, meaning bags or sacks of flour. The two should not be confused as a sack of flour held 20 stone of flour, i.e. 280 lbs, while a bag held half a hundredweight, i.e. 56 lbs. Modern British bags of flour normally hold either 25 or 32 kg. Flour for domestic use normally comes in 1.5 kg bags.

1.3 FOOD LAW

Legislation has its effects on all parts of the food industry and anyone working in the food industry needs to be aware of this. Although both science and the law try to be exact there are differences between the scientific and legal approaches. In particular, the use of language is different. In the "Bread and Flour Regulations 1998", for example, there is not unreasonably a definition of bread which is that "bread" means

a food of any size, shape or form which – (a) is usually known as bread, and (b) consists of a dough made from flour and water, with or without other ingredients, which has been fermented or otherwise leavened and subsequently baked or partly baked, but does not include buns, bunloaves, chapatis, chollas, pitta bread, potato bread or bread specially prepared for coeliac sufferers.

It is obviously entirely reasonable that bread specially prepared for coeliac sufferers, i.e. those allergic to gluten, should be outside the regulations. Chapatis are clearly outside the regulations anyway as they are unleavened but chollas and pitta bread are clearly bread in common parlance. The case of pitta bread is interesting as the regulations specifically exclude it from the category of bread yet it is called bread. This is a product that in common parlance is bread, but is not bread within the scope of the Bread and Flour Regulations 1998.

In Great Britain, modern food law developed from the Food and Drugs Acts. This law came about after an outbreak of arsenic poisoning among beer drinkers. The cause of the problem turned out to be glucose that had been used in making the beer. The glucose had been made by hydrolysing starch with sulfuric acid. In turn, the acid had been made by the lead chamber process from iron pyrites, which contained arsenic as an impurity. The approach adopted was that all foods should be "of the substance and quality demanded". This was obviously intended to cover any future problems with some other contamination, not necessarily with arsenic.

The arsenic in beer incident has led to the rule that all food ingredients must be food grade, as must any food contact materials or materials used in the process. This rule can have the consequence that a material such as coke must be food grade. If a food is to be roasted over coke then that coke must be food grade. A non-food grade coke might, possibly, contain a substance such as arsenic.

The only food law prior to this time was the statutes of bread and ale. These set out to regulate the brewing of ale and the quality of bread. As no modern analytical methods were available the beer was assessed by pouring some on the end of a barrel and an official, called the ale conner, sat on the beer in leather breeches. If the breaches stuck to the beer the ale failed. Presumably, the test detected residual sugar. Bread was tested by examining loaves, probably to detect contamination with the fungus known as rope. A baker whose loaf failed had the offending loaf strung round their neck followed by being whipped around the town or stood in the pillory. Other countries, particularly those whose legal systems follow Roman rather than Anglo-Saxon law, have tended to more prescriptive laws.

The British approach is to allow any ingredient that is not poisonous unless the ingredient is banned. Additives are regulated by a positive list approach. Unless the substance is on the permitted list it can not be used. There are anomalies where a substance can be legal in foods but not be permitted to be described in a particular way. An example is the substance glycherrzin. This is naturally present in liquorice and has a sweet flavour. It would be illegal to describe it as a sweetener as it not permitted as a sweetener. The substance is permitted as a flavouring, however, and can be added to a product. This will make the product taste sweeter than it would without the addition. Conversely, the protein thaumatin is permitted as an intense sweetener. In practice, thaumatin has more potential as a flavouring agent. It would have been much easier and cheaper to obtain approval for thaumatin as a flavouring than as a sweetener.

The British system does not automatically give approval to ingredients merely because the ingredient is natural. This is in contrast to the position in some other countries. There will always be grey areas. One example is the position of the oligo-fructose polymers that are naturally present in chicory. Chicory is undoubtedly a traditional food ingredient; however, oligo-fructoses extracted from it are not necessarily a traditional food ingredient. If the fructose polymers are hydrolysed to fructose then that is a permitted food ingredient. However, if they are partially hydrolysed what is the status of the resulting product? The issue of fructose polymers is further complicated because one of their interesting properties is that they might not be completely metabolised. If that is the case then they would be considered as additives rather than ingredients. Additives need specific approval while ingredients do not.

(Continues...)

Excerpted from The Science of Bakery Products by W. P. Edwards. Copyright © 2007 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 2007
• Sprache: Englisch
• ISBN 10: 0854044868
• ISBN 13: 9780854044863
• Einband: Tapa dura
• Anzahl der Seiten: 276
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: Nicht verfügbar