What's this
What is sugar?
In common parlance, sugar is the name of a granular table food used as a sweetening ingredient.
In truth, the sugar on the market is not all the same; the various types differ in appearance, raw material and extraction technique, nutritional properties and impact on the organism. It is however necessary to specify that, on balance, these discrepancies are not so significant. In contrast to speculations and commercial trends, we can say with certainty that the effect of sugar on the organism does not depend so much on its typology, as on the global consumption entity.
Types
Discretionary sugar, hidden and natural sugars
When we talk about "sugar consumption" we mean above all the use of the discretionary one - which is added by the consumer directly to food or beverages. Instead, simple carbohydrates naturally contained in natural foods, such as fruit, vegetables and milk, are excluded. However, contrary to what many think, discretionary sugars should also be considered those used in recipes, both of home-made preparations and in industrial foods. This is because the so-called "hidden sugars" have a fundamental importance on the total daily intake and, not taking it into account, increases the risk of excess with the diet. This is the case of desserts, snacks and sweet drinks: cakes, biscuits, ice cream, sweets, coca cola and other carbonated, fruit juices, certain liqueurs, herbal teas, coffee, tea etc. Note : they contain sugars - especially maltose - also many bread substitutes such as, for example, rusks - especially the sweet rusks.
deepening
Other liquid products, completely natural or partially processed, have the same characteristics as granular sugar, such as: honey, maple syrup, agave syrup, honeydew, molasses and the like.
Types of sugar
On the Italian table there are various types of sugar, both white and dark, of a granulated type and with variable consistency and granulometry. Saccharose and fructose, which as we will see are the most common granular sweet and soluble carbohydrates as table sugar, can be obtained from two raw materials: sugar beet ( Beta vulgaris var. Rapa form altissima or saccharifera ) and cane sugar ( Saccharum officinarum ). Marginally on the market, other types can be found such as, for example, apple sugar, coconut sugar, etc.
Curiosity
Why is dextrose or glucose, cheaper than sucrose and fructose, not used as table sugar? Simply because it has a lower sweetening power!
The color of granular table sugar does not establish its quality or, significantly, its nutritional properties. The white one is more refined, since during the production cycle it is deprived of molasses - typically dark in color. However, this is not a significant discriminating factor. This means that brown sucrose and in large crystals, or rather that commonly understood as raw cane sugar, has the same characteristics as white - even beet.
It is different if we consider integral sugars. These are not subjected to centrifugation and refining, or are in part. An example is made up of certain types of muscovado, which contain higher percentages of minerals and vitamins, and a lower glycemic and caloric load. On the other hand, this means that they are also less sweet and most consumers use more than normal to get the same sensation on the palate - thus nullifying their nutritional meaning.
Then there is the well-known icing sugar, consisting of nothing but sucrose of lower grain size and powdered starch - necessary to ensure a powdery consistency.
In practice, the various types of sugar differ from one another above all in terms of appearance, while the physical characteristics, on which the interactions in the kitchen and the health implications that we will mention later depend on, are more or less superimposed.
Nutritional Properties
Nutritional properties of sugar
Due to its chemical characteristics, white table granular sugar is also called "refined sugar". It supplies 392.0 kcal / 100 g, is entirely made up of sucrose or fructose, while the water is almost absent. Fibers, vitamins and minerals can be identified only in traces, except for some products known as "whole sugar".
Does sugar make you fat?
Sugar is the subject of much criticism and controversy. This is because, as we have already said and as we will reiterate, it has a questionable or even harmful impact on the organism. This is determined not only by its energy potential, but also by the metabolic impact it involves. The state of nutrition, in fact, is directly and inversely correlated to the hormonal balance of the organism. When energy macronutrients are introduced with food, after absorption, the endocrine system modifies the hormonal proportions to optimize the metabolic use of what has been eaten. Above all glucose, but also certain amino acids and lipids, in relation to the quantity taken - glycemic load - and the speed of perfusion in the blood - glycemic index - increase the production of insulin - insulinemia, measured with the so-called insulin or insulinemic index.
Insulin is a bioregulator that performs very important anabolic and anticatabolic functions. In particular: it increases glycogen synthesis, increases liposynthesis, increases proteosynthesis, reduces glycogenolysis, reduces lipolysis, etc. However, it has the characteristic of not being specific, targeting both muscle and adipose tissue. In this regard we recall that muscle fibrocells have a different and limited need for storage; moreover, in sedentary people, they do not even have a marked anabolic tendency - rather superior in sportsmen. However, we must not fall into the common misunderstanding that it is only insulin that makes us fat; there is no doubt that this hormone promotes the anabolism of adipose tissue, but the storage process also occurs completely independently and only in the presence of excess substrate - see below. This means that the tendency to increase the deposit of fat is caused above all by the co-presence of the two factors but, between the two, the fundamental one is the excess of substrate.
The excess of substrate, which once the reconstruction of the reserves and the tissues ends determines the synthesis of fatty acids, triglycerides and adipose accumulation, consists of an excess of Acetyl-coenzyme A - (CH3COSCoA), abbreviated: acetyl -CoA. This fundamental molecule derives from the metabolism of glucose, as much as fatty acids and amino acids; this means that, on balance, it is the indiscriminate caloric excess that favors the increase of substrate responsible for the adipose accumulation, not only of one or the other energy macronutrient.
Does fructose hurt?
Sucrose has a very high glycemic load and a rather high glycemic-insulin index, surpassed only by glucose or dextrose and maltose - commonly not used in the formulation of table sugar. Fructose, on the other hand, entered the market of table-top sweeteners only twenty years ago, due to the lower glycemic-insulin content compared to glucose and sucrose. This does not require any digestive enzyme and therefore, like dextrose, should quickly trigger insulin production. However, this does not happen because, to affect blood glucose - or quantity of glucose in the blood (mg / dl) - it requires a metabolization by the liver. Precisely because of this characteristic, it took the name of "sugar for diabetics"; soon, however, the clinical - almost disastrous - evidence of excess fructose in type 2 diabetes patients forced scientific research to shed more light on the metabolic impact of this nutrient. In summary: if it is true that fructose slowly increases blood sugar and insulin, it is equally true that its excess in the blood worsens independently many complications of type 2 diabetes mellitus - for example the lesions of the ocular microcirculation; furthermore, the liver has a limited capacity to metabolize fructose and, once this loading potential is exceeded, all the remainder is converted into fatty acids to be stored in triglycerides in adipose reserves.
Diet
Dietary sugar
Sugar should be considered a high energy density food. Abusing it in the diet can determine the onset or aggravation of some diseases; among others: tooth decay, overweight or obesity, hypertriglyceridemia, hyperglycemia and type 2 diabetes mellitus, alimentary hepatic steatosis, etc.
According to what is reported by the Reference Levels of Nutrients and Energy for the Italian population (LARN), a portion of sugar should correspond to 5 g. Having a specific gravity of 1.59 g / cm3, this quantity can be measured by filling a teaspoon with tea; if the teaspoon is full and forms the typical "montagnola", the grams rise to 10. Note : instead, a large soup spoon, satin, contains 9 g each, up to 16 g.
Many people wonder how much sugar is allowed to eat in a balanced diet. It is not an easy question to answer, since the adequacy of the soluble sugar intake is measured as a percentage of the total calories and, moreover, it does not take into account the distinction between discretionary table granular sugar, recipe sugar - also industrial - and natural food sugar.
The Italian Society of Human Nutrition (SINU), in 2014 established that, in a balanced diet for a healthy adult subject, the consumption of simple and soluble sugars should remain below 15% of total calories; in a regime of 2000 kcal / day, for example, no more than 80 g. The World Health Organization (WHO) has recommended, for a few years now, not to exceed 10%. This is because a contribution of more than 25% is statistically correlated with an increase in the incidence for the aforementioned pathologies.
Can sugar constitute a balanced diet?
However, to an inexperienced eye, these are just numbers without practical feedback. So let's take a small example. Let's consider again the case of an adult who has a normocaloric requirement of 2000 kcal / day and a maximum sugar ration of 80 g / day. Table granulated sugar is not the only source of simple and soluble carbohydrates since these are also contained in foods, both natural and processed. We are talking about milk lactose, fruit and vegetable fructose, maltose from rusks and bread, and fructose / glucose and sucrose from jam or honey. In total, respecting the adequacy of the portions, we reach over 95 g of simple soluble sugars; 15 g more than the maximum recommended by SINU and 40 g more than suggested by the WHO.
In practice, to maintain a balanced diet, granular table sugar should be totally eliminated. Then there are those who argue that, in the count of total daily sugars, the lactose and fructose naturally contained in food may not be counted. However, it is a conjecture without foundation and which, at the moment, has no statistical value.
Kitchen
Important characteristics of sugar in the kitchen
Sugar, basically understood as sucrose, is a widely used ingredient in the kitchen - the use of dextrose and fructose is, by comparison, very limited. Its chemical and physical properties greatly affect the organoleptic and taste characteristics of foods and the success of various recipes.
Did you know that ...
Fructose, in its natural state, at room temperature has a liquid consistency. Only after adequate industrial processing is it crystallized to become white table granulated sugar.
The first characteristic of the sugar that affects the kitchen is the sweetening or sweetening power, or the ability to stimulate the sweet taste. The one with the highest value is fructose, followed by sucrose, honey and gradually - by flowing various non-available carbohydrates - up to glucose.
The second characteristic of sugar is very important in gastronomy is the taste. In fact, granular table sugar can have different organoleptic facets. The white one is the most refined or neutral, even if between sucrose and fructose are not perceptible many differences. Dark sugars, on the other hand, which contain a part of molasses, have a characteristic taste. Furthermore, when cooked, the sugars take on a different flavor. Later we will understand better why.
The third characteristic of sugar is color. The refined one is from transparent to white, while the less manipulated is light or dark brown. Even the color can change drastically when cooked.
The fourth characteristic is the granulometry, which modifies the tactile perception. The most subtle of all is icing sugar. The "raw" sugars, like the brown one, have a granulometry higher than the refined whites. The integrals are quite different from each other and vary depending on the product.
The fifth characteristic is solubility - water solubility. Depending on the chemistry and grain size - at 20 ° C the sucrose 211.5 g / 100 mL (two kg per liter, but up to 5 kg if the temperature rises to 100 ° C), while the fructose has solubility of 3760 g / L - therefore higher. The icing sugar, which is the thinnest but contains small amounts of starch, is used in recipes that do not require very prolonged dough or mixing actions, which contain little water, or which are processed at low temperature - for example, chantilly .
The sixth characteristic is the melting temperature. It is lower in fructose (100 ° C) than sucrose, which melts almost twice as hot (180 ° C).
The fifth and sixth characteristics have a great influence on culinary preparations. To produce a highly concentrated syrup, for example, it is necessary to boil water and sugar together, bringing the latter to melting temperature. In a liter of water, for example, bringing the temperature from 18 to 100 ° C we can dilute from 2 to 5 kg of sucrose.
Sugar and Maillard reaction
The sugar, subjected to heating, first increases in solubility, then melts and finally meets the Maillard reactions.
These non-enzymatic processes modify the chemical-physical structure of the food. At 160 ° C the sucrose begins to liquefy. At 170 ° C the caramelization process begins, that is a further dehydration that recombines the oxygen atoms of the sugar and promotes a molecular re-arrangement producing numerous compounds, simple or complex, volatile and non-volatile. Caramel has the typical hints of burnt sugar and contains glucosanes, aldehydes, ketones, etc., but also toxic and carcinogenic compounds such as hydroxymethylfurfural (HMF) and acrylamide.
For this reason, the caramel must not be returned to ordinary human consumption. It is also always a good idea:
- Increase the temperature slowly because, even if the fire is immediately turned off, the caramelization process continues based on the temperature reached by the sugar
- Stir repeatedly
- Use a thermometer.
It is also possible to add a small amount of water, although this depends a lot on the type of caramel to be made. Compared to a liquid caramel, the solid cannot obviously contain liquids and therefore it must take into account how much water can evaporate during cooking.
Chemistry
Carbohydrate chemistry
Carbohydrates - or glycides or carbohydrates or carbon hydrates or simply sugars - are ternary chemical compounds formed by carbon, hydrogen and oxygen, with a generally exosa or, more rarely, pentose structure; the brute formula of hexose glucides is C6H12O6, while that of pentoses has only 5 carbon atoms.
In addition to the criterion of the number of carbon atoms, glycides can be classified in various ways. The most widespread is based on their molecular complexity. A single glucide-monomer constitutes a monosaccharide; the most important monosaccharides in human nutrition are three: glucose, fructose and galactose.
Through a covalent chemical bond, each monomer can be linked to others forming linear polymers or, interacting laterally, also with other polymers by drawing a branched structure. The union of a few monosaccharides gives rise to an oligosaccharide; when there are two, one speaks of disaccharides. The most important disaccharides in human nutrition are mainly three: maltose (glucose + glucose), sucrose (glucose + fructose) and lactose (glucose + galactose).
These covalent bonds are of the glycosidic type and, among the carbon hydrates, determine a condensation - elimination of a water molecule - which leaves as a "connection" only one oxygen atom (O-glycosidic bond). In other chemical structures, glycosidic bonds can affect nitrogen (N-glycosidic) and sulfur (S-glycosidic). Hydrolysis, or the addition of a water molecule, must take place to break down chemical bonds.
The O-glycosidic bonds are not all the same. They can differ according to the conformation of the first sugar, alpha (α) or beta (β), or to the position of the carbon atoms concerned: first position of the first molecule and second position of the second (1, 2), first position of the first molecule and fourth position of the second (1, 4), first position of the first molecule and sixth position of the second (1, 6).
In nutrition, these chemical bonds are very important. This is because in the intestine only molecules of a certain size are absorbed; in the case of carbohydrates, only monosaccharides. On the other hand, foods do not only contain monosaccharide glycides, but also oligo and polysaccharides; this requires that the relative glycosidic bonds are split during digestion. Like all covalents, glycosidic bonds can also be broken down chemically and / or physically or by means of biological catalysts. The presence of water, pH, temperature increase, mechanical breakage, addition of other substances, etc. they are chemical and physical factors - they come into play, for example, during the processing of ingredients and cooking. However, they are not sufficient to completely hydrolyse the complex molecules. This is why the human digestive system is provided with specific enzymes that are able to separate some of these bonds; in particular the α-glycosidic ones.
The β instead, are those that combine non-digestible oligo and polysaccharides, typically contained in "not available" carbohydrates and in some molecules forming part of dietary fiber. They too play a particular nutritional function, which is not energy-caloric - like the available carbohydrates - but prebiotic for the bacterial flora, plastic for faeces - regulating their volumes, consistency, etc. - and modulator for the intestine - increases or changes peristalsis, slows down or hinders absorption, etc.
Sucrose chemistry
Granular table sugar is mainly composed of the sucrose disaccharide; exception is the granulated fructose - which contains exclusively the homonymous monosaccharide - according to the level of consumption among the general population.
Sucrose is a soluble, disaccharide glucide formed by the union - with α-1, 2-glycosidic bond - of two monosaccharides: α-D-glucose and β-D-fructose; the bond is interposed between the anomeric carbon 1 of glucose and the anomeric carbon 2 of fructose.
Although composed of two units, equivalent to an oligosaccharide, sucrose is normally defined as a "simple" sugar, therefore not "complex". This is a criterion of differentiation which, on a practical level, separates two large macrogroups of carbohydrates, respectively those characterized by high water solubility and those that do not interact equally with water.
However, even if it dissolves easily in water, a specific enzyme is required to digest sucrose. Placed on the intestinal microvilli - tract of the small bowel - this highly specific biological catalyst is called saccharase or invertase. It is obviously not exclusive to the human being; on the contrary, it is quite widespread both in other mammals - such as the bear - and in microorganisms such as yeasts - Saccharomyces cerevisiae . His intervention is necessary to reduce the disaccharide to glucose + fructose.
If table granulated sugar is composed of fructose, no enzyme is required.
