Let's try to scientifically and chemically analyze why in some pizzas the effect of the leopard spot cornice occurs and what it entails.
In the pizza dough there are chemical components and biological structure that are established in different forms of interrelations that change from case to case, inside the pizza disc it is possible to identify two different fractions of water: one defined free even if it can be more or less held back by the presence of structures capable of incorporating it, and a second one defined as linked as it is fixed by the solid components of the system by means of real bonds.
With high temperatures such as 400/480 ° C, a reduction in the cooking times of the pizza limits the percentage of gelatinized starch with evident repercussions on the digestibility of the corresponding product obtained. The fundamental importance, in addition to the temperature, of the cooking time on the quality of the product is also confirmed by acceptability studies, carried out through "consumer tests", which have highlighted the influence of the time / temperature combination on quality crust and crumb. Reducing the cooking time with high temperature gradations leads to a pigmentation of the crust on the pizza edge (the so-called leopard spot pizza) which are the dextrinization and caramelization of starches a reduction in cooking times that does not allow to reach a temperature adequate affects both the nutritional and organoleptic quality of the finished product; nutritional as health. In this case, burning a pizza means producing very dangerous substances called “pyrene”. Pyrene is a tetracyclic aromatic hydrocarbon of formula C16 H10. Belonging to the class of polycyclic aromatic hydrocarbons (PAHs). This hydrocarbon is formed with intense burns which are also called "leopard spots" which in reality are dark brown pigments and also in rather large patches this because the intensity of the heat of the oven is very high when it comes to temperatures that exceed the 380 up to even 450 degrees centigrade. The pizza cornice thus burned becomes like coal tar. It exhibits high toxicity in particular in the form of Nitro derivative, due to its strong carcinogenic and mutagenic potential. Of course it is not my intention to create alarmism but it is also true that eating large quantities of burnt material can lead to a potential health problem. But beware, I didn't say that pizza is carcinogenic but only that if we eat significant amounts of burnt crust it can certainly be.
Pizza burn is an organic compound whose molecules contain exclusively hydrogen carbon atoms. These black dots are burns that are also present in hard coal and therefore aromatic hydrocarbons. The burns of pizzas in this case are generally composed of silica, carbonates, oxides of sodium, potassium, calcium, magnesium, etc. The pyrazine gives a particular smell to hot bread and pizza, pyrrole also gives a characteristic odor and aroma typical to the crust they can come from a reaction of thermal action of amino acids sugars for example pyrrole is a heterocyclic nitrogenous organic compound of formula C 4H5N and possesses aromatic characteristics.
The effect of heat on the sugars that make up the pizza dough can give rise to three different processes: caramelization, pyrolysis, Maillard reaction. While the Maillard reaction involves the interaction of reducing sugars with proteins (and in particular the amino groups) the other two processes occur by direct heating of sucrose, glucose syrups. Caramelization, pyrolysis differ in the technological conditions used (pyrolysis, for example, requires a much more drastic heat treatment) and give rise to very different products both in color and in aroma and which, depending on their characteristics, are used in different sectors . The formation of brown pigments or melanoidins is a reaction through a heating of a solution of glucose and glycine. The reaction was later termed the Maillard reaction and similar reactions between amines, amino acids and proteins with sugars, aldehydes and ketones were observed. The Maillard reaction appears to be the main cause of browning during heating or prolonged storage of food.
In the technique of rolling out the ball turned upside down so as not to make the pizza take on certain particular pigmentations, the moisture content and the quantity of maltose that is produced must also be considered, all this forms a sort of gel and the latter reacts with cooking. In the ball that is turned upside down, the degree of expansion of the gases must also be considered and inside the ball the state of maturation of this and the quality of the flours used. In the ball there is a content of carbon dioxide and nitrogen, the latter is eliminated because it is consumed by the yeasts, the turned ball does not caramelize easily because the humidity is absorbed directly by the flour which is adopted for the drafting first of all the ball below the the part that has defined key the one where it rests on the Marne has its own weak structure, there is a migration of water that goes downwards, the water and carbon dioxide are resolved or rather the carbonic snow with the cold is dissolves in the water a chemical activity takes place in which there is more weight therefore the water is heavier in some respects the pigmentations defined leopard are too excessive firing reactions because a very important step in the Maynard reaction is omitted, which is the browning or better the caramelization obtained at moderate temperatures 200/180. You should understand the physical activity of what cooking really is for example even if you make an excessive fermentation of the ball and then let it cool, problems are created, too lean formulations can create problems during storage in the fridge, when putting the ball in the fridge for a certain time of at least 48-72 hours it is advisable to use fatty formulations that is to use balanced fats at a molecular level therefore unsaturated and saturated because this also prevents the leopard effect defined in this way.
The browning of the crust that burns too much is also due to the storage of the balls too low in the fridge so the longer the storage time is at low temperatures and the greater the browning of the crust. First of all, because an endogenous enzymatic activity occurs in the flour is very slow, due to the Beta amylase which is an isoamylase that is, it acts through a mechanism due to the partial breaking of starch and starch granules, low temperatures however produce maltose and maltodextrins the dextrins they are erroneously called sugars but are not metabolized by yeasts from saccharomyces, maltodextrins in particular dextrins remain on the pizza crust i.e. on the pizza edge and these dextrins which are caused by an excess of enzymatic maturation in the fridge also produce very accentuated pigmentations such as dark color but there are also other colors: red, dark red, light red.
For the direct method it is advisable to use a little bit of carry-over dough, a previously leftover pizza dough, it could be useful because it enriches the dough itself with those microorganisms capable of using maltose and producing metabolites that also participate in the formation. aroma of the pizza, the dough must be developed especially during the kneading operation because in this way it is possible to incorporate as much air as possible. In fact, when kneading, bubbles of air consisting of 80% nitrogen and about 20% oxygen are incorporated.The oxygen is largely consumed by yeast until it disappears completely at the end of the kneading even if you put very little yeast remember that a gram of yeast has 9/10 billion cells. Leopard spots are caused when the doughs are left to mature for too long in the refrigerator at low temperatures due to an excessive production of maltose.
Dr. Claudio Poli
Chemistry degree
Pizzaitalianacademy Instructor
