An aspect of certain relevance to good food behaviour, and more specifically in respecting the best hygienic standards associated with food preparation and consumption, concerns the utensils that are commonly used to contain and especially to cook food. An incorrect choice can in fact compromise their nutritional, organoleptic and hygienic characteristics.

The requirements for food cooking utensils

All utensils used for cooking food should meet specific requirements. Let us look at them:

1. thermal conductivity: a utensil with good thermal conductivity allows perfect spatial and temporal distribution (in the different cooking phases) of heat and a reduction in the risk of burning the food or parts of it;
2. thickness: a good utensil should have a fairly thick cooking surface, so that it can withstand long cooking times while transmitting heat evenly;
3. hygienic safety: it is well known that by cooking a food in a certain utensil, the utensil releases some of its material, which is ingested with it. Now, the WHO (World Health Organisation), in collaboration with the FAO (Food and Agriculture Organization), has set acceptable ingestion limits for the various materials, while the ISS (Istituto Superiore della Sanità), in collaboration with the CSCUE (Scientific Committee of the Council of the European Union), has assessed the hazard limits in the case of daily use of utensils made of the same material.

The characteristics of certain materials

  Below is a table summarising the characteristics of some of the materials from which food cooking utensils are most commonly made according to the parameters described in the previous section:

Material	Components	Cession (mg/day)	Maximum limit (mg/day)	Heat capacity	Thickness
Aluminium	Aluminium (Al)	6	60	Excellent	3-5mm
Non-stick aluminium	Aluminium (Al)	6	60	Excellent	3-5mm (30micron coating)
	Non-stick coating (various materials)	None	None
Tin-plated copper	Copper (Cu)	3	30	Very high	2mm
	Tin (Sn)	4	120
Stainless steel	Various components	None	None	Scarce	0.8-1.2mm (6-7mm for aluminium bottom)
Iron	Iron (Fe)	15	48	Scarce	2mm
Fire glass (Pyrex or pyrex dishes)	Various components	None	None	Scarce	3mm
Terracotta	Various components	None	None	Scarce	4mm

It can be seen from the table that kitchen utensils fulfil these requirements to varying degrees, but some, regardless of this, are more suitable than others for use by virtue of certain specific properties.

Properties of certain kitchen materials

We will now consider in more detail the properties of certain materials used in the production of kitchen utensils.

Stainless steel

  It is the absolute best material for cooking food. The stainlessness that characterises this material allows food to be heated up to 86°C without being depleted of electrons (with consequent lowering of pH), vitamins and minerals. It also does not interact with the food in any way. This last aspect is important from a toxicological point of view, as a cooker that does not affect food will not add any toxic substances to it. It is, however, necessary that the pans used are of the best quality, i.e. that they do not contain nickel and chromium alloys, since, if they did, they would cause these elements to penetrate any food containing acids or salts.

Cast iron

  Cast iron is a difficult material to clean, since, being highly permeable, the grease contained in foodstuffs gets into the pores of the utensil during cooking. During the cleaning process, it is difficult to empty the pores of the grease that has entered them and it will inevitably become rancid, contaminating the pan and the food that is subsequently cooked with it. It is sometimes heard that the iron in cast iron cookware somehow ‘enriches’ the food being cooked in it. In reality, the iron contained in cast iron is ferric iron, which is difficult to assimilate.

Pyrex dishes

  In addition to having a low thermal capacity, glass also contains lead, which is knownto be toxic.

Toxicological notes

Some materials have toxic characteristics that others do not. A number of materials will be considered here in order to investigate their possible hazardousness to the user.

Aluminium (Al)

  The intake of modest amounts of aluminium does not lead to actual intoxication, although it may give rise to symptoms due to its ability to interfere with calcium and phosphorous metabolism. Storing food or, worse, cooking it in aluminium pots or vessels is therefore a behaviour to be avoided, especially for foods with an acidic pH (<5).

Aluminium with non-stick coating

  The non-stick coating of some aluminium cookware contains perfluorooctanoicacid (PFOA), a substance that, once ingested, can remain in the bloodstream for many years. Nevertheless, they are safe mainly because PFOA is not transferred from the utensils to food in any way. It is only possible for PFOA to be transferred to food if the non-stick coating of the utensil is affected, but even in this case, although PFOA may enter the bloodstream and remain there for a long time, it is not toxic. It is worth pointing out that the latter case is not uncommon, as pans made of this material are often very fragile and it is sufficient to rub a fork or kitchen knife gently over them to nick them.

Lead (Pb)

  Many dishes are enamelled with paints containing this metal, which can easily contaminate food (it can also contaminate drinking water when the metal pipes through which it flows are old). The FAO/WHO. has set a maximum weekly intakelimit for lead of 0.05mg/kg body weight for an adult individual.

Antimony (Sb), copper (Cu), tin (Sn) and zinc (Zn)

  If the containers or pots in which food is cooked or stored contain excessive amounts of these elements, the consumer may experience toxicological problems, the symptoms of which are vomiting, abdominal pain, diarrhoea and headaches.