Preface to the Seventh Edition Free
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Published:11 Oct 2023
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Product Type: Textbooks
Food
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In 1980 when the Royal Society of Chemistry first invited me to write this book the proposed readership was clear; namely chemistry teachers whose pupils were in their final two years of secondary school before going on to study chemistry at university level. Apparently these teachers were badly in need of background information to help them prepare their students for the new topic of Food Chemistry that had appeared on some of their syllabuses. By the time the first edition actually appeared (in 1984) the need for an up to date textbook of introductory food chemistry to support my own BSc Food Science students (at what was then the Polytechnic of the South Bank, London) had also become apparent. To my surprise the favourable response to the first and subsequent editions came from a much wider readership than was originally envisaged, not only in the UK but around the world. As a result demand for new editions has continued, including translations into Spanish, Portuguese and Chinese. Interesting new topics have demanded attention and chapters devoted water, minerals, undesirables and enzymes have been added.
My determination to ensure that the chemical formula is included for virtually every food substance mentioned in the text may make the contents look a little intimidating. However I have always tried to make the actual words as approachable as possible, lending them to being ‘read’, even ‘browsed’ as well as ‘looked up’. In spite of appearances readers with only modest recollections of school chemistry should find much that is within their grasp, especially in the later chapters.
Selections of texts for ‘Further Reading’ (books and review articles) are appended to each chapter, wherever possible restricted to 21st century editions. Extensive references to research literature are not included but each chapter concludes with a selection of relatively recent review articles that will provide access to the original research. By the use of citation indexing the same article may continue to provide an entry into the most up to date literature for many years. The temptation to include addresses of relevant and authoritative websites has generally been resisted since, unlike the printed scientific literature, websites tend to be rather ephemeral and are unlikely to remain available throughout the lifetime of a textbook. Undoubtedly the internet can provide a wealth of information but it must be used with very great caution. It has always been the case that one should not necessarily believe something just because it was printed in a book, but such cynicism is absolutely essential when looking at websites. One exception is legislative and other official information published by government authorities and other similar organisations. This material is frequently very difficult to obtain in print and appropriate websites, accessible in 2023, are listed in Appendix II. The appropriate authorities, such as, in the UK, the Food Standards Agency, must always be consulted when accurate details of the legal position regarding, for example, the use of a particular food additive, are called for.
E Numbers
It will not have escaped the notice of readers of this book that the UK has now left the European Union. However, it appears that the possible implications of this departure on the regulation of food standards, food additives etc. in the UK are still some years away from serious consideration. It seems quite likely that within a few years the E prefix (“E” meaning “Europe”) in the numbering of permitted food additives on food product labels will change. Throughout this book all references to legislation and regulation refer to the situation that prevailed at the time of writing, i.e. 2022/23.
A Brief Note on Concentrations
- (a)
However they are expressed, concentrations always imply the amount contained, rather than added. Thus “5 g of X per 100 g of foodstuff” implies that 100 g of the foodstuff contains 95 g of substance(s) that are not X.
- (b)
The abbreviation “p.p.m.” means “parts per million” i.e. grams per million grams, or more realistically milligrams per kilogram. One “p.p.b.”, or part per billion, corresponds to one microgram per kilogram.
- (c)
Amounts contained in 100 g (or 100 cm3) are often referred to as simple percentages. Where necessary the terms “w/w”, “v/v” or “w/v” are added to indicate whether volumes or weights or both are involved. Thus “5% w/v” means that 100 cm3 of a liquid contains 5 g of a solid, either dissolved or in suspension. Although the millilitre (mL), cubic centimetre (cc) and litre (L) are no longer officially regarded as SI units they are widely used, by both the scientific community and the general public. Although the replacement for the ml, ‘the centimetre cubed’ (“cm3”) is widely recognised there is little sign that the cubic decimetre, or “dm3” has taken over from the litre, except in school and college teaching laboratories that must always be seen to ‘toe the party line’. As might be expected different abbreviations for the litre are in use on the different sides of the Atlantic, in the USA “L” is preferred, in Europe (and in this book) “l”. (d) Very often a strictly mathematical style is adopted, with “per” expressed as the power of minus one. Since mathematically:
5 mg kg−1 becomes a convenient way of writing 5 micrograms per kilogram. This brief but mathematically rigorous style comes into its own when the rates of intake of substances such as toxins have to be related to the size of the animal consuming them, as in “5 milligrams per day per kilogram body weight”, which abbreviates to: 5 mg per day per kg body weight.
The term “body weight” may be abbreviated to “bw” or in some contexts omitted altogether. A concentration of, e.g. 10 mg per cubic centimetre, cm3, would be written: 10 mg cm−3.
Tom Coultate
