As you read this, enzymes will be at work within your body. They act as catalysts, controlling chemical reactions involved in digestion, respiration and metabolism. Our own bodies produce many different types of enzyme, as do all living things, right down to the humblest mould and the smallest bacteria.
Enzymes are able to break down, or modify, chemical compounds such as starches and proteins and this ability has been utilised by humans for thousands of years.
Perhaps the best known use of an enzyme in food production is rennet, traditionally derived from the stomach linings of young calves. Rennet contains enzymes that coagulate milk causing it to separate into solids (curds) for cheese production and liquid (whey).
Enzymes have traditionally been sourced from the tissues of plants and animals, where they occur naturally. However,
micro-organisms such as mould and fungi can also be used to produce vast quantities of enzymes. Some of these microorganisms produce the enzymes naturally, but many more have been genetically modified to produce ‘copies’ of animal or plant enzymes.
Microbial production has many advantages over plant and animal sources. The raw products required – the micro-organisms and the substrate on which they feed – can be supplied wherever they are required. This frees companies from having to rely on a regular supply of enzyme-rich, plant or animal-based materials, which may be expensive to collect and transport, and which will also need processing and purifying.
No matter what it is, almost all commercially manufactured bread in the UK is made with enzymes.
Enzymes allow manufacturers to pump up loaf volume significantly, adjust texture, produce a better crust colour and prolong shelf life. They make the dough easier to put through machines, increase dough stability and control ‘crumb structure’ – which in a sliced white loaf might be silky and uniform, but in a baguette may be chewy and variable, with large holes. Enzymes can even give bread a whiter appearance.
What most of us would recognise as a modern loaf would be impossible to produce without enzymes. But what does all this mean for the consumer? Andrew Whitley warns that some enzymes are potential allergens, notably the very widely used alpha-amylase
(used in baking to break starches down into sugars, for yeast to feed on). Click here to read more of Andrew's warnings.
Bakery workers can become sensitised to enzymes from bread improvers. Industry experts warn that liquid or granular preparations of enzymes are safer than powdered forms, because of the allergenic potential of enzyme dust. This should not be a problem to the end consumer if enzymes are destroyed during processing, but Whitley has quoted research from the University of Bochum, in Germany, which shows that up to 20% of the allergenicity of alpha-amylase can survive in the crusts of bread.
Whitley has also revealed that an enzyme called transglutaminase, which may be used to make dough stretchier in croissants and some breads, may render part of the wheat protein toxic to people with a severe gluten intolerance.
Such unintended and unanticipated effects suggest that the safety testing of some enzymes may not be up to scratch, and raises the possibility of other, as yet unnoticed, side affects. However, unless enzymes are fully labelled on ingredients lists, it will be virtually impossible to correlate possible side effects with enzyme use.
Enzymes are essential to cheese production. They act by coagulating milk, allowing the ‘solid’ curds to be separated from the ‘watery’ whey. The curds are then pressed and matured to produce cheese.
Traditionally the enzymes would have come from the
stomach linings of young calves, where they are naturally
produced to enable the calf to digest its mother’s milk. Commercially produced preparations of standardised, enzyme-rich matter for cheese production were first made in Denmark in 1874.
Today, over half of the enzymes used in UK cheese production are microbial in origin. The enzymes are produced from genetically modified (GM) yeast and moulds which contain copies of the calf gene for the production of chymosin, the main enzyme involved in milk clotting.
Modern food production can be extremely efficient; when it comes to meat production, nothing is left to waste. Cattle and pig bones are turned into gelatine, a standard ingredient in jellies, chewy sweets and many desserts. Before the bones can be processed they must be cleaned, and enzymes can be used to do this.
The bones are first crushed and mixed with hot water. Enzyme preparations with names such as NeutraseTM, AlcalaseTM, EsperaseTM or FlavourzymeTM are then added singly or in combination. The enzymes break down the meat protein which is still sticking to the bones, and this dissolves into the water around it.
The cleaned bones are used for gelatine production and the protein solution is extracted for use as a flavour enhancer in processed meat products, soups, sauces and snack foods. This ‘hydrolysed protein’ should be listed in the ingredients list, although you will not be able to tell how it was produced.
Similar protein ex-traction processes can be used for plant-based protein – for example, the production of soya milk from soya beans.
Some meat just isn’t meat anymore. If you choose to buy your meat in processed form, sliced and shaped and ‘ready to eat’ it is worth a close look at the ingredients label.
Alongside added water you may find other, unexpected, meat ingredients, such as chicken in your ham. Other proteins may also be added, such as soy, casein and gluten (beware allergy sufferers!). Food manufacturers use a small arsenal of food additives to bind all these ingredients together, but new enzymatic technology may also be giving them a helping hand.
For instance, transglutaminase (produced by microorganisms - see ‘bread’ on previous page) can be used to ‘cross-link’ these proteins, sticking them together. The food industry refers to this as a ‘food adhesive’.
Fruit and vegetable juices
If you thought that your fruit juice had been ‘freshly squeezed’ and that was all, think again.
Juice manufacturers want to extract as much juice as they can from fruit or vegetables, and enzymes can help them to break the fruit structure down, releasing more juice.
Enzymes can also be used to clarify and prevent clouding in juices. Modern ultrafiltration processing (the use of very fine filters to remove solid matter) is highly reliant on enzymes, which are used to completely break down pectin and starch solids and to remove blockages that form on the costly filtration membranes.
Juices are heat treated before being sold, and this inactivates the enzymes, although their remnants invariably make it into the final product.
An orange comes with its own perfect packaging, but that has not stopped food companies from selling us pre-peeled oranges and other fruit, plastic wrapped for our ‘convenience’ or mixed into ‘ready to eat’ fruit cocktails. Removing the skin of such fruit by hand is time consuming, messy and can damage the fruit, but enzymes can provide
a high-tech, quick-fix and cheap alternative. The peel is scored and the
fruit is immersed in a solution of the enzyme pectinase. This is followed
by an ‘infusion’ stage where the solution is forced deep into the fruit using low or high pressure processes. After two hours the enzyme will have worked on the fruit and the skin can be easily peeled off, and the segments easily separated without damage.
Enzymes and the law
Enzymes are not listed as food ingredients because they are regarded as ‘processing aids’, which do not have to be mentioned on food labels. A processing aid is a substance added during food processing for technical reasons, but which has no function (e.g. flavour, colour, preservation) in the final food product. Most enzymes are
inactivated (broken down) during processing and are no longer technically active in the final product, but residues often remain.
However, enzymes have hugely important functional roles during food processing. They are used specifically to affect flavour, texture, aroma, colour, and many other food qualities – often dramatically.
Despite their widespread use in the UK, there is little specific legislation regarding the use of enzymes. Throughout the EU they are regulated as processing aids, covered by laws which vary from country to country.
In the UK there is no list of ‘permitted’ enzymes, although enzymes must be considered safe under General European Commission (EC) Food Law. It is worth noting that there is neither safety evaluation nor authorisation of food enzymes at European level, except for those that are considered as food additives (just two, E1103 and E1105).
In July 2006, the EC proposed to regulate food enzymes on the grounds that rapid advances in production technology have resulted in, ‘more complex and sophisticated’ enzymes which could cause, ‘potential hazards arising from their chemical nature and source such as allergenicity, activity-related toxicity, residual microbiological activity, and chemical toxicity.’
The EC proposal, which has yet to be formally approved, would seek to create a harmonised list of food enzymes, following safety evaluation by the European Food Safety Authority. It suggests that ‘all food enzymes and their use in food should be evaluated for safety, technological need, benefit to the consumer and (to ensure) that the consumer is not being misled by their use.’
As with food additives, terms such as these can be subject to very loose interpretation. And even after approval, enzymes will still be classed as ‘processing aids’ so will not appear on the label. Assuming the proposal is accepted, companies will be allowed two years to submit data for evaluation, so nothing much will happen until after 2010.
Most enzymes appear to be produced using genetically modified micro-organisms, but with no public access to the food industry’s secret files it is impossible to know which or where. Although we can be sure that almost all vegetarian cheese uses enzymes from GM micro-organisms. The GM process is approved by the Vegetarian Society, who regard it as preferable to the wholesale slaughter of calves.
The only way to avoid GM enzymes is to purchase organic food, as organic standards completely forbid all use of GM ingredients or derivatives.
This article first appeared in the Food Magazine Oct-Dec 2007
• If this article was of interest you will find many other articles on unlikely allergies and allergy connections here – and links to many relevant research studies here.
• For more on the more 'mainstream' allergies check in to our 'allergy and intolerance home page' – and for ideas on alternative foods go here.
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