Making life taste better

Preservatives

Preservatives in food

Preservatives work by killing the micro organism or preventing it from growing

Humans have always found ways to preserve their food to stop it spoiling before it can be eaten. Many of the bacteria and moulds that grow on food can be dangerous. Salmonella, listeria and botulism are familiar forms of food poisoning caused by bacteria, and one of the most infamous food poisoning incidents in history resulted from the growth of the ergot fungus on rye bread, which caused hallucinations. All of these problems can be reduced by using additives.

Preservatives work by killing the microorganism, or preventing it from growing. If the food Preservatives work by killing the micro organism or preventing it from growingis too acidic, too salty, or even too sweet for the microorganism to thrive, then this will slow down or even stop spoilage.

The earliest methods included using salt and smoke. Salt draws water out of the food and any microorganisms in it by osmosis, which prevents the microorganisms from growing. The chemicals introduced during smoking make it more difficult for moulds and bacteria to grow, and can also prevent rancidity. Vinegar, sugar and honey have also been used to preserve foods for centuries. One of the most widely used preservatives today, sulfur dioxide, has actually been in use since the Middle Ages!

Another advantage of preservatives is that we don’t have to shop every day because the food we buy lasts for longer. Not only does this save us precious time, but it also saves fuel as we don’t drive to the supermarket as frequently.

Many modern preservatives are actually simple molecules, and many are derived from nature. Examples include:

Benzoate preservatives

Benzoic acid is a naturally occurring organic acid, which is found in many different fruits, often at levels far higher than would be allowed as a food additive! (the Scandinavian cloudberry – pictured above – actually contains 50 times the legal limit!)  It is used to prevent the growth of yeasts, moulds and some bacteria in acidic foods such as fruit juices, carbonated drinks and pickles, and is used either as the free acid (E210), or as its sodium (E211), potassium (E212) or calcium (E213) salt. It has been suggested that a benzoate-free diet may help selected patients with persistent asthma, but this approach has not been evaluated in published controlled trials.[ref]

Reference: D D Metcalfe, et al. Food allergy : Adverse reactions to foods and food additives, 3rd edition, Blackwell Publishing, JM Fahrenholz, Adverse reactions to benzoates and parabens, pp369-376.

Sulfite preservatives

Sulfur dioxide gas, or related sulfite and metabisulfite compounds, are very important preservatives that have been used for thousands of years. It is used as a preservative in wine, where it prevents bacterial spoilage and oxidation. If the wine has a sulfur dioxide concentration below 10ppm (parts per million), then the label need not say that it contains sulfites – the legal limit is more than 10 times this. It is also used to preserve dried fruits.

It is clear that these preservatives aggravate symptoms in about 4% of asthmatics [ref] and in a handful of cases, this can be severe. Steroid-dependent asthmatics are twice as likely to be affected.

Reference: Bush R.K. et al Prevalence of sensitivity to sulfiting agents in asthmatic patients.  Am J Ned 1986; 81 (5): 816 – 820

As a result of these problems, the permitted levels of sulfur dioxide (E220) and its salts (E221 – 224) have been reduced in recent years; in red wine, for example, the permitted level is now about a third the amount that was allowed a century ago. Sulfites remain one of the most important additives, and they are even permitted in organic foods.

Other Preservatives

Nisin (E234) is a peptide which is made by the bacterium Lactococcus lactis, which is manufactured by growing it on substances such as milk. It is a broad-spectrum antibiotic which stops a number of bacteria from growing on dairy products and Preservatives work by killing the microorganism or preventing it from growingmeats, including listeria.

Propionic acid (E280) is a simple acid, closely related to vinegar. It is often used in bread manufacture, where it is more effective than vinegar. Curiously, even though it is an additive, vinegar doesn’t have an E number as it’s a traditional preservative. This doesn’t make it any more or less safe!

Sodium nitrite (E250) and potassium nitrite (E249) are important preservatives for fish and meat products as they inhibits the growth of Clostridium botulinum, the bacterium that causes botulism. There is some concern about the way they are used, as nitrites form cancer-causing nitrosamines during cooking. It is likely that the body neutralises nitrosamines, but processed meats preserved with nitrites now also include vitamins C and E, antioxidants which prevent the formation of nitrosamines.

Sorbic acid (E200) is very widely used to prevent the growth of moulds and yeasts in products like wine, dairy products such as cheese, meats and seafood, baked goods and various fruit and vegetable products. The acid is found naturally in several plants.

Antioxidants

Oxidation is a real problem for food products. Oxidation, for example, causes raw apples and potatoes go brown, but this can prevented in the kitchen by adding lemon juice. It’s very effective because lemon juice contains a very strong antioxidant – ascorbic acid or vitamin C (E300). By preventing or slowing down the oxidation process in foods, waste through spoilage is reduced.

Many antioxidants occur naturally in fruit and vegetables, many of which are flavonoid compounds such as quercetin in onions and apples, and epigallocatechin in tea. The health benefits of these antioxidants are becoming clear, and many scientific studies have been carried out on them. Oxidation can damage DNA leading to cancer, and can change polyunsaturated-fatty acids into forms that contribute to heart attacks and strokes. Increasing the consumption of antioxidants can have a preventative effect against cancer and heart disease, although it’s not clear yet which are the most effective.

Unsaturated fats are particularly vulnerable to oxidation, and this causes them to turn rancid. These are some examples of antioxidant food additives:

Ascorbic acid (E300), or vitamin C, is found in many different fruits. It is also commonly used as a flour improver.

Butylated hydroxyanisole (E320) is a synthetic antioxidant which works by stabilising free radicals.

Butylated hydroxytoluene (E321) or BHT is another synthetic antioxidant. It works in the same way as butylated hydroxyanisole, but has caused controversy, as it has produced adverse effects in dogs. However, it also has anticancer effects.

Propyl gallate (E310) is a synthetic antioxidant. Its main food use is in products that contain oils and fats.

Tocopherols (E306) are natural antioxidants which are forms of vitamin E. The most important sources are vegetable oils such as palm, corn, sunflower, soybean and olive.

Use of food additives ‘safer and more transparent’ thanks to new legislation.

Safer and more transparent use.

The use of additives in food will soon become even safer and more transparent thanks to legislation adopted by the European Commission.

“This represents a landmark in our efforts to strengthen food safety in the EU,” says Health and Consumer Policy Commissioner John Dalli (pictured). “The adoption of two regulations on additives will further empower citizens and industry alike as they will make it easier for everyone concerned to know exactly what additives are allowed in foodstuffs.”

The two regulations establish two new lists. The first concerns additives in food and will come into force in June 2013. This list will allow consumers to easily identify which additives are authorised in a particular foodstuff. The second list relates to additives in food ingredients, and will apply 20 days after its publication in the EU’s Official Journal.

Transparency is one major benefit of the new legislation as the new list makes it obvious that in some food categories the authorised additives are very limited or not allowed at all. This is the case, for instance, for unflavoured yogurt, butter, compote, pasta, simple bread, honey, water and fruit juice. In other categories, usually those concerning highly processed foodstuffs – such as confectionery, snacks, sauces and flavoured drinks – a large number of additives are authorised.

“Any initiative that helps educate and enlighten consumers is to be welcomed,” says an FAIA spokesman.

This legislation does just that, while helping to reinforce the message that authorised additives are not only safe but also play a key role in food safety.

Salt in bread

THE STORY:

A third of breads contain more salt than recommended under guidelines being introduced next year, according to campaign
group CASH (Campaign for Action on Salt and Health).

The figures came after the Department of Health announced that bread accounts for more salt in our diet than any other food, making up almost a fifth of our daily intake. However, manufacturers said many loaves with the lowest salt levels were supermarket brands, which were the most popular.

FAIA SAYS:

Despite salt levels in bread being reported to have fallen by about a third over the past decade, bread manufacturers are under mounting pressure to cut down further. However, in reducing salt levels further, manufacturers are faced with numerous technical challenges.

Firstly, salt influences the production process by improving the dough handling properties and also helps control yeast activity during fermentation. In addition, it influences the sensory properties of bread and is directly linked to consumer acceptance. For these reasons, it would be difficult to completely eliminate salt from the recipe. The main challenge in making low salt bread is that is becomes sticky and is less easy to process with lowering salt levels, meaning that there is a potential for the dough to stop processing lines, leading to down time and wastage.

Salt also plays a major role in achieving the flavour of the bread and, of course, on product shelf life. Products with reduced salt may require balancing of the flavours to achieve an acceptable product.

* Take the bread health scare with a pinch of salt…

Chemist in the kitchen

A page from our first website!

If you want to know more about how food additives tie in with the chemistry that goes on in the kitchen, a downloadable booklet entitled ‘In the mix’ is accessible from the home page, or from the image on this page.

Chemicals have always been welcome in the kitchen: sodium bicarbonate, pectin, yeast, acetic acid etc.

Every cook is a chemist. The first chemical laboratories, back in the Middle Ages, were glorified kitchens, and many chemical processes derive from techniques of cooking. The vital technique of distillation was perfected in the course of man’s search for intoxicating drinks. And far from being dehumanizing, such chemical processes have an ancient magic and glamour, as the great Italian writer Primo Levi pointed out (he was also a chemist):-

Distilling is beautiful.

‘First of all, because it is a slow, philosophic, and silent occupation, which keeps you busy but gives you time to think of other things, somewhat like riding a bike. Then because it involves a metamorphosis from liquid to invisible (vapour) invisible, and from this once again to liquid; but in this double journey, up and down, purity is obtained, an ambiguous and fascinating condition, which starts with chemistry and goes very far. And finally, when you set about distilling, you acquire the consciousness of repeating a ritual consecrated by centuries, almost a religious act, in which from imperfect material you obtain the essence, the usia, the spirit, and in the first place alcohol, which gladdens the spirit and warms the heart.’

Every kitchen contains a battery of chemical reagents, each with their specific chemical purpose; e.g. sodium bicarbonate, pectin, yeast, acetic acid, sodium chloride; and also substances, such as milk and eggs, that are not usually thought of as chemicals but which actually miracle reagents that chemists would still be incapable of creating if they didn’t already exist.

In many cases, ingredients that sound like chemicals are derived from natural products: lecithin from soya is similar to egg lecithin, acetic acid comes from vinegar, Vitamin C is the active ingredient of lemon juice, and so on. The principle of using additives is something that every cook, high or low, uses every time they prepare a meal. To understand the processes of making sauces, meringues, bread and cakes, of marinading, tenderising and caramelising is to become a food chemist, and it greatly enhances the pleasure of cooking to see it from a chemical point of view. Cooking is chemistry in action, with the added benefit that you can eat the results.