Küchengeflüster – ein paar Fakten über Gesundheit und Hygiene

Kitchen whispering - a few facts about health and hygiene

You might think that we have been surrounded by enough plastic for a long time, but especially in the kitchen area we come across many products that could be aptly described as "things the world doesn't need". Somewhere between insanity and a strange sense of humour, things like bread stamps, tap descaler attachments, fried egg moulds and stink remover or corer for almost every fruit and vegetable are produced. Directly a little creative are the sausage roller, which notches the sausage and gives it a really barbecue-like look or the banana slicer, thanks to which bananas no longer have to lie crosswise in the mouth from now on.

It goes without saying that before buying these gadgets you should first sleep on them long and comatose. But what about the normal kitchen utensils? Cooking spoons, whisks and co. are mainly made of plastic, as well as dishes for children and microwave ovens. They are all cheap, often colourfully designed and seem to have some other advantages. What can be quickly cleaned in the dishwasher is surely more hygienic. Or?

In 2016/2017 the Federal Institute for Risk Assessment (BfR) conducted experiments on 33 kitchen utensils made of polyamide (PA). These were exposed to a temperature of 100 °C for 30 min. or two hours and depending on the intended use, in order to demonstrate their conventional use between 70 °C and 100 °C; values which are usually reached and exceeded in our kitchens. In order for the pasta water to boil, it must be heated to 100 °C. In the experiments, the BfR also took into account the fact that in most cases the same kitchen utensil is used in daily cooking.

In this statement, the Institute recommended that the manufacturers of corresponding products ("food contact materials") should compile toxicological data in accordance with the specifications of the European Food Safety Authority and then submit this to the BfR. Thus, in September last year, a final risk assessment could be carried out on the basis of these data.

The BfR writes: "Components of this plastic (PA) can pass from the utensils into the food and thus be absorbed by consumers during consumption. These components are oligomers, compounds made up of similar molecules of plastic building blocks that are unintentionally created during the production of the plastic. Because some oligomers are very small, they can pass from the plastic into the food. In the BfR study, the oligomers from those polyamides that are most commonly used in the production of kitchen utensils - PA 6 and PA 6.6 - were considered. The BfR assumes that the entire amount of oligomers released is transferred to the meal and thus absorbed (the same applies, by the way, to polyamide tea bags).

The measured values of the detected oligomers are between 0.13 and 5.1 mg/kg of food (the meal of an adult is estimated to weigh 1 kg). In ten of the 33 utensils examined, the values are above this value. The BfR classifies a transition value of 5 mg/kg food as "toxicologically acceptable" and not genotoxic.

However, high doses can have health consequences ("effects", as the BfR calls them) in the liver and thyroid gland. The reason for this is the metabolism.

The kitchen gadgets should therefore only have the shortest possible contact with hot food - or you can use other materials and thus play it safe; because the manufacturers of kitchen gadgets are not obliged to state the type of plastic used. So anyone who wants to buy new cooking spoons should pay attention to appropriate labelling. It is not uncommon for the information to be found only on the outer packaging or as a tag or sticker, and it is also difficult to read. The consumer advice centre therefore provides a list with the most important pictures (pictograms) concerning kitchen utensils.

Another popular material for the production of cooking utensils is melamine. Children's crockery is also often made of it, as it is light and unbreakable. The melamine resin used to make these products usually contains formaldehyde. These substances can also dissolve in high heat and contact with acidic foods, can be transferred to the food and cause "health effects". Formaldehyde is considered carcinogenic and irritates the mucous membranes. Tests have shown that toxic effects on the bladder are due to melamine. For this reason, there are legally prescribed limits for the proportions of these substances in kitchen utensils. When used properly, these are considered harmless.

Leider also contains bamboo tableware in most cases melamine resin (as a binding agent) and rather small amounts of bamboo wood powder. Here too, the labelling of the manufacturers often leaves something to be desired. However, one indication of melamine in bamboo crockery is the abbreviation "MF".

Both types of crockery should only be used as dinnerware and should not be filled with food above 70 °C. Melamine spatulas and cooking spoons should only be used for a few seconds at most when cooking.

Apropos, speaking of food and plastic: According to WWF, the University of Newcastle has evaluated 50 studies in which food and water samples were examined. The results show that up to five grams of microplastics enter our bodies via food, water and breathing air every week; that's equivalent to a ballpoint pen. These values are of course dependent on the person, region and product and vary accordingly.

However, all the facts researched can be summarised in one drastic statement: We cook plastic with plastic.

On the wooden path

Alternative materials for kitchen utensils and are wood, stainless steel, ceramics and glass. They are more stable than plastics and do not release any substances to food. The latter two materials are well suited for heating food in the microwave. Pan turners, wooden cooking spoons and chopping boards made of wood also have other advantages: They are also available from fair and/or regional production and pure wood does not contain any toxic substances. The different types of wood have different properties, so that a suitable product can be chosen depending on the intended use. But aren't they more unhygienic ?

The fact is, people who cook their food with a wooden spoon don't get sicker than people who use other materials. Many generations before us, people have been cooking with wooden spoons. Even if wooden utensils cannot be cleaned in a dishwasher, this does not mean that those made of plastic are more hygienic. Germs that have settled in the fine scratches of a plastic spoon or board can sometimes survive a hot shower in the dishwasher. Food safety research confirms that with every new scratch in the plastic, germs also accumulate.

Wooden products made of olive, beech, bamboo, rubber or walnut are suitable for use in the kitchen. These types of wood are particularly hard, but do not damage the coating of the pot and pan. Due to the high inner surface, wood absorbs water quickly. However, all woods have the property of binding moisture from the environment (hygroscopic effect) and this ensures that the living conditions of bacteria deteriorate quickly and die off due to the removal of water.

Nevertheless, the correct cleaning of wooden utensils should not be underestimated, after all, wooden products can also take on discolouration or odours. Baths in vinegar or lemon are helpful here, and salt is also a highly recommended household remedy. Wooden spoons and turners can also be boiled occasionally for six to ten minutes. Otherwise, it is sufficient to clean them with water and a sponge immediately after they have been used (but without rinsing, as they could otherwise absorb the taste). A vegetable oil treatment from time to time will make the wood happy and if it becomes rough or looks worn out over time, it can be refreshed with fine sandpaper. Afterwards, clean it well and oil it again.

In terms of service life, wooden kitchen gadgets are therefore extremely sustainable.

Straight wooden chopping boards are said to be unable to keep up with their artificial counterparts in terms of hygiene. But studies show that wooden boards do not contain more germs than plastic or glass boards.

Wooden boards are durable, protect the knives and can be completely recycled. Due to the tannins they contain, they have a natural antibacterial effect. However, it should be noted that this effect only lasts for a certain time and also depends on correct cleaning and drying. Wooden boards should be thoroughly scrubbed from both sides with hot water, washing-up liquid and the rough sponge side. The board should be left in the air until it is completely dry. Otherwise germs can quickly spread in the damp wood. To really get rid of all germs, the board should be confronted with 60 degrees every now and then. Either by using hot water or by the heat in the oven or microwave.

However, there are often studies about whether wooden cutting boards are more hygienic or not, which lead to different results. Why is that? Firstly, because different materials, but never all types of wood and plastic, have been investigated. For another, the test phases were rather short. A longer service life could probably give different results. In addition, there were also different circumstances, for example different knives were used and sometimes the boards were cleaned by hand, sometimes by machine.

However, the studies still show that whether wooden boards are hygienic or not depends on the way they are used and how they are cleaned afterwards.

Plastic boards are more susceptible to cutting marks. Bacteria and food residues accumulate in unevenness and grooves, so that a plastic board is irreparably damaged. Wood can even out small cuts by itself, as it can swell (therefore, rinsing from both sides. If you clean one side only, the wood could eventually crack). With the drying process the traces of use close again. To round off the proper treatment, a wooden board should occasionally be rubbed with linseed oil. This is virtually a natural impregnation: it draws less moisture into the wood and the board also dries faster. In the meantime, fewer germs are formed in the moist board.

Handling is therefore important; it is not appropriate to judge wooden utensils in general as unhygienic. So maybe it would be good to get rid of some wooden prejudices and let more wooden products move into our kitchens again. Apart from that, it seems a little strange that legal regulations decide which artificial, partly toxic substances are acceptable for us and in what quantity. In this case, it is probably better to go the wooden way.