Food Safety

The Science of Keeping Food Safe

Ian C. Shaw

• Editore: Wiley-Blackwell
• Anno: 2018
• ISBN:
  9781119133681
• Edizione: 2
• Argomento: Technology & Engineering
• Categoria: Food Science

Food safety is a multi-faceted subject, using microbiology, chemistry, standards and regulations, and risk management to address issues involving bacterial pathogens, chemical contaminants, natural toxicants, additive safety, allergens, and more.

This revised edition has been updated with the latest information on food safety. It addresses all the topics pertinent to a full understanding of keeping the food we eat safe. Each chapter of Food Safety: The Science of Keeping Food Safe, Second Edition proceeds from introductory concepts and builds towards a sophisticated treatment of the topic, allowing the reader to take what knowledge is required for understanding food safety at a wide range of levels. Illustrated with photographs and examples throughout, this new edition also boasts 4 new chapters covering radioactivity in food; food terrorism; food authenticity; and food supplements.

•This second edition has been revised and updated throughout to include the latest topics in this fast-moving field
•Includes 4 brand new chapters on radioactivity in food, food terrorism, food authenticity, and food supplements
•The most readable and user-friendly food safety book for students, scientists, regulators, and general readers

Food Safety is the ideal starting point for students and non-specialists seeking to learn about food safety issues, and an enjoyable and stylish read for those who already have an academic or professional background in the area.

Chapter 1
Introduction

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Introduction

Food safety is a relatively recent ‘invention’. It was introduced in the developed world to increase confidence in food. In our modern world it simply is not acceptable to have food that might make us ill. Sadly even now a good proportion of the world's people are very much more concerned about getting food and stemming their unrelenting hunger than they are about whether they might get a stomach upset as a result of eating the food. We must always remember these horrifying facts when we study food safety. Food safety and the legislation emanating from it are for the relatively rich countries that have the luxury of having sufficient food to allow them to make rules about what is safe to eat.

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A brief history of food safety

Prehistoric times

The risk of eating in prehistoric times was very much more an issue of the dangers of catching the beast to eat than the ill effects suffered after eating it. To survive, cavemen had to eat and their animal instincts dominated their behaviour with respect to food. These instincts, no doubt, made them avoid food they had learned made them sick, but their overriding instinct was ‘eat to live’. Some foods, however, might have been so toxic that they threatened the early man's survival. Behaviour that minimised consumption of toxic food would have been selected in because individuals that succumbed to toxins in their food simply did not survive. This is the raw material of Darwinian evolution and could be considered a very early manifestation of food safety issues! Whether this happened or not thousands of years ago is impossible to know, but we do know that modern‐day animals avoid toxic plants in their diet. This might be because some of the toxins (e.g. alkaloids) have a bitter taste that warns the would‐be consumer of the risk. Prehistoric man probably behaved in exactly this way which is why he was able to survive in such a harsh environment in which every day posed new and unknown food challenges.

This is hardly prehistoric food safety policy, but it illustrates our inborn survival instinct that extends to the food we eat. We have an innate desire not to eat something that will make us ill. This has not changed over the millennia.

Evolution of cellular protection mechanisms

It is important to remember too that our metabolic systems (and avoidance strategies) evolved during the tens of thousands of years of prehistoric times. Metabolism of toxins from food in order to reduce their toxicity and so make the food ‘good’ developed over millions of years. There are highly complex metabolic systems ‘designed’ to detoxify ingested toxins that evolved long before man, but the enzyme systems from the primitive cells in which they evolved were selected into the human genome through the evolutionary process and were inevitably expressed by the earliest hominids. These detoxification systems gave man an advantage because he could eat food that contained chemicals which if not detoxified would make the food too toxic to eat. These enzyme systems are now very well understood; they include the cytochromes P₄₅₀ mixed function oxidases (termed Phase I metabolism) and the conjugating enzymes (termed Phase II metabolism) (Figure 1.1).

Figure 1.1 Phase I and II metabolism for a simple compound, benzene, showing how the molecule is detoxified, made water soluble and excreted (e.g. in urine).

There are many food toxins that are detoxified by these systems, so making the food safe to eat (this will be discussed further in Chapters 7 and 8); for example, parsnips contain bergapten, a photosensitising toxin that also causes cancer (see Chapter 8, Furocoumarins in parsnips, parsley and celery); bergapten is detoxified by Phase I and II metabolism (Figure 1.2) thus making parsnips safe to eat. These metabolic processes are the cell's internal food safety mechanisms and broaden the range of foods we can eat without suffering the ill effects that some of their components would cause.

Figure 1.2 A proposed metabolic pathway for bergapten.

There are significant differences in the susceptibility of different animal species to toxic chemicals; these are due to the evolutionary selective pressures under which the particular species developed. This means that safe foods for some species might be highly toxic to others. For example, the toxin in the swan plant (Asclepias fruticosa), labriformidin, is very toxic to birds but harmless to the monarch butterfly (Danaus plexippus) (see Chapter 8, Why produce natural toxins?).

The monarch butterfly uses this differential toxicity as a means of protection. Its caterpillar eats swan plant leaves and incorporates labriformidin into its body; this makes it toxic and unpalatable to predatory birds. This interesting means of survival is by no means unique amongst animals. Indeed, some plants that are eaten by animals are very toxic to humans. For example, it would only take a few leaves of hemlock (Conium maculatum) to kill a person, but the skylark (Alauda arvensis) is unaffected by its toxin (Figure 1.3). Indeed, there have been cases of human poisoning in Italy following consumption of skylarks which (strange as it may seem) are a delicacy in that country. The toxin in hemlock is coniine (Figure 1.3) – it is very toxic; about 200 mg would be fatal to a human. Hemlock was the poison used to execute Socrates in 399 BC for speaking his mind in the restrictive environment of ancient Greece.

Figure 1.3 Socrates (469–399 BC), coniine, the poison from hemlock used to execute him, and the skylark (Alauda arvensis) which is unaffected by coniine.

(Pictures from http://en.wikipedia.org/wiki/File:Socrates_Louvre.webp, © Sting; http://en.wikipedia.org/wiki/File:Alauda_arvensis_2.webp, © Daniel Pettersson; photograph of hemlock taken by the author.)

Tudor England (1485–1603)

In the 1500s I doubt whether many people thought about illness being linked to what they had eaten, but I imagine food‐borne illness was prevalent in that rather unhygienic society. In fact spices were introduced into Tudor England to mask the putrid taste of some foods particularly meat – this is a ‘head in the sand’ approach where masking the bad taste was thought to take away the bad effects. Whether the Tudors thought that masking the taste of putrefying meat stopped them getting ill I cannot know, but they certainly thought that masking the terrible smells of putrid plague‐ridden London prevented them catching fatal diseases like the Plague. The gentry used, amongst other things, oranges stuck with cloves, and ornate necklaces with receptacles for sweet‐smelling spices and resins (pomanders – derived from the French pomme d'ambre meaning apple of amber; ambergris, a sweet‐smelling substance produced by sperm whales was often used to scent pomanders) to waft in front of them to take away the evil smells as they walked the streets. This is hardly food safety legislation, but it might just be the beginning of people connecting off‐food with illness – a key step in making food safe.

The times of King George III of England (1760–1820)

The Georgian era was a time of great social division. The rich ate well, if not exuberantly, and the poor just about found enough food to keep the...