Acetobacters: these are microorganisms present in nature prevalently in fruits such as grapes. Their function is to activate acetic bioxidation. These single-cell plant microorganisms are visible only using a microscope with at least 1000 magnifications. Obligate aerobes are able to fix oxygen in quantities up to 500 times their own weight. With reference to balsamic vinegars, they are the agents responsible for the bioxidation of ethyl alcohol (present in the cooked must since it is produced by yeasts) into acetic acid according to the oxidation: C2H5OH (ethyl alcohol) + 20 (oxygen) –> CH3COOH (acetic acid) + H2O (water). The yield of transformation of the alcohol contained in the solution is usually 80-90%. In order to live, multiply and produce acetic acid, acetobacters need not only alcohol but also oxygen: a minimum of 236 litres of air for every 100 g of ethyl alcohol contained in the solution to be acetified and an optimum temperature of 25-30°C. There are different species, the most common of which are acetobacter aceti and Xylinum, which produces cellulose. The varieties or strains that particularly concern balsamic vinegar are listed below: acetobacter aceti, acetobacter xylinum, acetobacter mesoxydans, acetobacter lovaniese, acetobacter racens, acetobacter ascendens, acetobacter peroxidans, acetobacter paradoxum, acetobacter oxydans. Most acetobacters contain the glucose oxidase enzyme which can oxidise glucose into gluconic acid (1 g of glucose gives 0.2b of gluconic acid. This process does not affect the fructose. For this reason, in balsamic vinegar, the percentage of fructose is higher than that of glucose; this does not happen in grapes and must, where the parts of the two components are more or less the same.
Acetic acid: primary product of the bioxidation of ethyl alcohol by acetobacters. Since this reaction requires a lot of energy, the activity of the acetobacters is highly conditioned by the ambient temperature, the optimum value of which is around 25-30°C.
Acetic bioxidation: chemical transformation generated by acetobacters, which transform ethyl alcohol into acetic acid in the presence of oxygen. The chemical reaction is: C2H5OH (ethanol) + O2 (oxygen) → CH3COOH (acetic acid) + H2O (water).
The acetobacters also give rise to a series of secondary products: lactic acid, ethyl acetate, methyl acetate, formic acid, propionic acid, gluconic acid, etc.
Acidity (A): this is the amount of acid present in 100 ml or in 100 g of product. For this reason, depending on the type, it is classified as acidity in volume (grams of acetic acid per 100 ml of product) or as acidity in weight (grams of acetic acid per 100 grams of product). The acidity measured always refers only to acetic acid, even though its composition consists of many more acids dissolved in the product in small quantities that are negligible in comparison with acetic acid. For this reason it is more correct to speak of fixed acidity, which is given by the natural organic acids found in the grapes (tartaric, malic, citric acid, etc.) and by others that originate from fermentation (lactic, butyric, succinic acid, etc.) and of volatile acidity: the total acidity is the sum of the fixed and the volatile acidity. The total acidity is normally attributed to the acetic acid, derived from young grape musts that are acetifying. The volatile acidity can be sensorially assessed by the presence of acetic acid, of aldehydes and, to a lesser extent, of other volatile acids that appear during fermentation.
Ageing: series of physico-chemical transformations that take place in the barrels in the battery with the smallest capacity and during which the taste and olfactory properties of the balsamic vinegar are strengthened and refined. This phase may be prolonged over time indefinitely with the practice of decanting, obtaining more and more satisfactory results.
Alcoholic fermentation: chemical transformation generated by yeasts, which transform sugar and glucose into ethyl alcohol in the absence of oxygen. The chemical reaction is: C6H12O6 (glucose) -> 2C2H5OH (ethyl alcohol) + 2C02 (carbon dioxide) + 24 calories. This is a carbonic degradation: from one molecule of sugar with six carbon atoms (C6H12O6,) an alcohol is obtained having one molecule with two carbon atoms (C2H5OH). Higher alcohols are also formed in the fermentation phase that derive from amino acids which, combining with the acids generated by the acetobacters, give origin to esters.
Alzavino: in Modena dialect “saz” (from “saggio”, meaning taste). A glass instrument used in wine production, cylindrical with a small constriction and a thin hole, with a section suitable for the density of balsamic vinegar. Used for extracting small amounts from the barrels.
Aroma: natural or chemical odorous substance that determines a pleasing olfactory impression perceived at the back of the nose. The aromas perceived in “balsamic vinegar” are classified as tertiary to distinguish them from the primary aromas coming from the must and the secondary ones produced by fermentation.
Balsamic: term used to characterise the product of the transformation of grape must, cooked and reduced over a direct flame without a lid and poured into barrels made of different types of wood, with different capacities. Human intervention and prolonged storage in the barrels have always allowed it to be compared to “balsams”, natural products of plant origin characterised by fragrant, exquisite and unmatched perfumes and flavours, a kaleidoscope of small and great suggestions in the slow, but productive, passing of time. In the Middle Ages it was also used as a soothing medication.
Balsamic vinegar components:
Carbohydrates: glucose, fructose, polysaccharides
Acids: tartaric, citric, malic, lactic, butyric, ascorbic, glutamic, succinic, gluconic, saccharic, formic, propionic, acetic
Other compounds: methyl acetate, ethyl acetate, ethanol, higher alcohols, polyvalent alcohols, 2,3-butylene glycol, acetyl methyl carbinol, diacetyl, ethers, aldehydes, ketones and esters with low molecular weight, polyterpenes, etc.
Metals and mineral salts: manganese, iron, cobalt, copper, zinc, sodium, potassium, magnesium, sulphates and phosphates
Water: its presence is not easy to quantify. Indicatively it may be around 30% of the whole, but it depends on many factors that cannot always be statistically controlled.
Barrique or badessa: this is a large barrel with a capacity of 225 litres, generally known as a barrique. It is usually made of oak and its task is to hold the acetifying cooked must before it is used to top up the battery. The barrel also allows the graft present to thicken and acetify. The term “mother barrel” used to be used for the 200-250 litre barrique, because it was often used for grafting acetobacters with the fermented must, and because it contained the “mother” of the vinegar.
Battery: this is a set of at least five barrels made of different types of wood and with different capacities. The purpose of the different capacity is to concentrate the product by natural evaporation and physico-chemical transformation. The decreasing number of barrels always goes from the largest to the smallest. Their capacity varies on average from ten to eighty litres, while the choice of the types of wood depends mainly on the manufacturer’s preferences.
Barrel: this is a wood barrel that is mainly cylindrical and ovalised in shape, which allows the physico-chemical transformations of the product as an effect of the exchange of oxygen with the outside through the pores in the wood. There are barrels made of different types of wood such as oak, chestnut, cherry, black locust, ash, juniper and others, all with different characteristics of hardness, porosity and fragrance. These characteristics, along with the tannins in the wood, are transmitted in a more or less accentuated way to the product, during the time that it remains in the barrel. Each barrel is made with different techniques: first the wood is normalised, possibly in a natural environment and not in artificial dryers; it is then hand-crafted by the cooper, shaping the staves that are used to make the barrel. The staves may be bent using different techniques: these may be by direct heat, by steam, or they may be made one by one from solid wood. The staves are held together by hoops, which may be made of iron, galvanised, or stainless steel. Their function is to avoid loss of the product, which nevertheless, with ageing and thickening, occasionally tends to leak out of the barrel drop by drop.
Bouquet: this is the characteristic and complex, penetrating perfume, with an evident but pleasing and harmonic acidity.
Bung hole: hole made across the whole width of one or more staves of the barrel, at the point corresponding to the maximum diameter. It facilitates the operations carried out on the barrels and allows greater oxygenation of the product. It is used to fill or empty the barrel; to draw off some product periodically, for decanting and topping up, for internal inspections and for cleaning operations. Generally square or rectangular in shape, it is made with sufficient dimensions to allow a hand to be inserted.
Calastra: this term indicates each of the two shaped supporting beams on which the barrels rest. In general it represents all the single or multiple supports, made of wood or metal, on which the barrels in the battery are arranged close together in sequence.
Colour: this is the impression that the light produces in the eye of the taster. The colour of balsamic vinegar is by definition “full glossy dark brown” and as such it cannot be attributed to any extractable chemical substance. Any attempts to isolate coloured components or colourings have so far given a negative result. The colour is due both to the secondary products that appear during fermentation and bioxidation, and to the group of compounds that are formed during maturing and ageing. The colour tone may indicate the state of evolution of the balsamic vinegar.
Decanting: this is the operation with which the product is decanted from one barrel to another in each battery. Decanting is performed once a year, starting from the largest barrel in the battery and decanting the product into the barrel of the next size.
Density (B): this is the weight/volume ratio and corresponds to the weight of 10 g of sugar (contained in the grapes) for every kg of must. This measurement is known as the degree Babo. However, for densities higher than that of must, typical of Eufonico® Balsamic Vinegar, the degree Brix is used, which measures the weight of the solid substances, therefore mainly sugars, dissolved in 100 grams of product. The specific weight may also be used to measure the density of Eufonico® Balsamic Vinegar: there is a technical table for converting between degrees Babo, degrees Brix and specific weight. The density visually indicates the state of consistency and viscosity of the balsamic vinegar: it is expressed and recognised through the persistence of the liquid that adheres to the wall of the flask when subjected to a rotating movement.
Dregs: deposit that forms as time passes on the bottom of the barrel. It consists mainly of salts and tartrates, but also of precious substances that make up the humus of the balsamic vinegar. Every 10-15 years it should be removed, adequately filtered, and the filtrate should be returned to the barrels from which the liquid necessary to carry out the operation was taken.
Electronic titrator: electronically measures the pH and the fixed acidity in weight of the balsamic vinegar. The acidity % refers in particular to the principal acid present in the product, which is acetic acid.
Enocyanin: colouring substance contained in the skin of black grapes. It belongs to the group of anthocyanins which, during cooking of the must, cause it to turn brown irreversibly. Through polymerisation and condensation, anthocyanins and catechins give rise to so-called noble tannins.
Enzyme: specific catalyst of a biological nature (it is a protein) consisting of a chemical substance of an organic nature and of vegetable, animal or microbial origin. It has the property of provoking or accelerating a chemical reaction without being modified or consumed and without entering the final products of the reaction. The enzyme and the substrate that must react must be perfectly adaptable to each other, just as a key must match its lock. The enzymes released by autolysis of the cell of yeasts and of acetobacters post mortem are particularly important for the genesis of balsamic vinegar. They become responsible for the maturing phase and make a decisive contribution to the formation of aromas and flavours.
Esters: combination of an alcohol with an acid. They are recognised as natural flavourings. Present in many essential oils and in fruit extracts, they are also in balsamic vinegar to contribute to the formation of its complex fragrances.
Ethers: name of a group of substances obtained from the reaction of two alcohols, on the nomenclature of which the name of the compound considered depends. They are represented by two radical alcohols connected with an atom of oxygen. Possessing strong volatility and a pleasant smell, they contribute to the formation of the bouquet of the balsamic vinegar.
Ethyl Alcohol: intermediate product of the transformation of part of the cooked must reduced to acetic acid. It derives from the alcoholic fermentation of the sugar in the must by the yeasts Saccharomyces and Zygosaccharomyces; the latter are able to remain active even in an environment with a high sugar concentration, such as very reduced cooked musts. Carbon dioxide is obtained as a secondary product, as well as energy in the form of heat. It is characteristic of balsamic vinegar that the alcohol fermentation takes place at the same time as the acetic bioxidation. However, part of the alcohol may be combined with some acids present in the balsamic vinegar to create esters, highly volatile products, also responsible for perfumes, as happens for some polyalcohols of fermentative origin, for example glycerine.
Finesse: it is conceived as a property able to evaluate not only the overall result but also the quality of the typical aromas of the balsamic vinegar at high perception levels. It is delicate and difficult to evaluate. It therefore becomes necessary to memorise experiences on highly prized samples as opposed to others of poor quality value.
Flask: Blown glass container with the spherical shape of a bottle with a long neck and a cork cap, with a capacity of 100 cc, used for the organoleptic examination. It is used for the sensory evaluation of the product over a candle flame, which enhances its visual, olfactory and taste characteristics, as well as imbuing the environment with an air of ritual.
Flavour: this property is closely linked to the immediate feeling of pleasure that is sensed when tasting the balsamic vinegar with the taste buds.
Frankness: this property is to be interpreted as the total absence of interference in identifying the aromas, that is as the lack of defects that could be attributed to shortcomings of the product. A balsamic vinegar is defined as frank when it releases its perfume and reveals its bouquet clearly and immediately.
Fructose: monosaccharide also known as laevulose because it makes the plane of polarised light rotate to the left, also called fruit sugar since it is contained in many sweet fruits. It is an isomer of glucose with which it is nearly always associated. Obtained by hydrolysis from sucrose, it is sweeter than ordinary sugar. It crystallises with difficulty and melts at 95°C. Together with glucose, it is subjected to alcoholic fermentation by yeasts.
Fullness: this is interpreted as the combination of the richness of all the components that contribute to the formation of the extracted substances and it is produced by the complexity of all the fixed acids, the mineral salts and the tannins connected with the sugars present in the liquid.
Glucose: this is the most important sugar in the series of monosaccharides, known also as grape sugar or dextrose to distinguish it from laevulose or its isomer, fructose. Contained in nature in many fruits, it crystallises with difficulty and melts at 146°C. From 1 g of glucose, by fermentation, 0.480 g of carbon dioxide and 0.31 calories are obtained.
Grape must: Basic element for the production of Eufonico® Balsamic Vinegar. It may be subdivided into:
- Uncooked must. Juice obtained from the soft pressing of overripe Trebbiana or Lambrusco DOC grapes, after removal of the stalks, skins and pips;
- Cooked must. Raw juice heated over a direct flame without a lid for a more or less prolonged period of time. It undergoes many transformations, not the least of which is the concentration of the sugar fraction by evaporation of the water that it contains. Cooking is interrupted when the desired degree of concentration is reached.
- Certified cooked must for A.B.T.M. Raw juice obtained only from A.B.T.M. certified grapes (Trebbiano di Spagna, Trebbiano di Castelvetro, Lambrusco di Sorbara and Grasparossa, and other minor autochthonous grapes of the province of Modena). The raw juice undergoes traditional cooking without a lid over a low heat and at a constant temperature of 88-90°C until the desired sugar concentration of the product is reached.
Harmony: defines the optimum result of the balance that must exist among all the components of the balsamic vinegar, with particular reference to the sugars and acids, that is to the sweet and sour ratio.
Harmonic ratio (R): this is the ratio between density and acidity in volume. It measures the sweet and sour equilibrium between the sugar content of the product and the acetic content.
R is ideally between a maximum value of 12 and a minimum value of 3: the maximum value obtained from the ratio between the admissible maximum density and minimum acidity, that is Rmax=Bmax/Amin. The maximum density is 72 Brix, beyond which recent studies believe sugar crystallisation phenomena may be triggered, leading to the progressive solidification of the product. The minimum acidity in volume is 6% by law, the value which determines the classification of a product as vinegar. This means that Rmax = 72/6 = 12.
Instead the minimum value of R is obtained from the ratio between the admissible minimum density and maximum acidity, that is Rmin=Bmin/Amax. The minimum density is 30 Brix, consisting of mixtures of acetified cooked must and simple cooked must. The maximum acidity in volume is 10%, which represents the maximum value of acetification of the must, cooked at 40 Brix. It should be noted that, if the must is cooked at more than 40 Brix, it is no longer possible to acetify the product due to the excessive increase of the sugar content which inhibits the physico-chemical transformations. Therefore, Rmin = 30/10 = 3.
Ideally, the harmonic ratio, which is a linear function of the battery, has a range between 3<R<12.
At year zero from the start, Eufonico® Balsamic Vinegar is obtained starting from mixtures of more or less acetified cooked must, controlled and certified for A.B.T.M.
The position of the harmonic ratio R of the whole range of Matildis Eufonico® Balsamic Vinegars is always between the maximum and minimum values. It tends to be in the range 6<R<8 for a product with more acid characteristics and in the range 8<R<10 for a product with sweeter characteristics. The optimum value of R may vary according to the ageing of the product, the barrel to which it refers and the surrounding climate.
However, it must be said that the final harmony is obtained only with time, with the natural and balanced ageing that “softens” the fixed acidity, “dampens” the volatile acidity, and exalts the balsamic aromas.
Intensity: this is the force and vigour with which the aromas and flavour of the balsamic vinegar are expressed.
Limpidity: the term is synonymous with the transparency to rays of light, it is related to the degree of light absorption by the liquid and the suspended particles. Balsamic vinegar is limpid if it allows the light of a candle to be clearly seen through the flask.
Maturing: transformation phase of the balsamic vinegar during which modifications of a mainly enzymatic type take place.
“Mother” of the balsamic vinegar: a solid, organic and gelatinous compound which forms in the presence of high concentrations of acidity in the product, typical of wine vinegar, especially where there is not sufficient alcohol derived from yeast fermentation. A kind of acetobacter, called acetobacter xylinum, then transforms the acetic acid into cellulose which, if dried in the sun, is called paper. In the past, the “mother” of the vinegar was used to trigger acetification phenomena, but always in large barrels, called barriques. It is known that, if the cellulose is left to develop in small barrels, the product gradually tends to solidify, becoming completely stratified.
More precisely, the natural aggregation of acetobacters grouped in colonies is defined as the “mother” of the balsamic vinegar. It is generally found on the surface of alcoholic liquids in the form of a veil or film, with different characteristics connected to the species of acetobacters that generate it and to the composition of the medium. This is primarily due to the fact that the acetobacters rise to the surface of the liquid in search of oxygen, since they are aerobe-dependent. The “mother” may be smooth or rough, opaque or glossy, thin or thick, fragile or resistant. It can rise up the inside walls of the barrel, remain suspended in the liquid or fall to the bottom; it may also remain compact or crumble. Although it is important because it is rich in acetobacters, great attention must also be paid to the way in which it is presented and developed. Sometimes the film is composed of a fairly consistent gelatinous mass which lives at the expense of the liquid contained in the barrel, to such an extent that the liquid deteriorates severely and irreversibly. In this case it also damages the submerged part which continues to breathe, and therefore to live, at the expense of the oxygen dissolved in the medium and of the acetic acid produced previously. It must therefore by closely monitored and removed when it reaches large dimensions or produces unpleasant smells. This may occur particularly if there is a prevalent presence of the acetobacter xylinium in the barrel.
There are mainly two different types of mother, which may generally be:
- whitish or grey with a thickness of 1-2 mm produced by the acetobacter aceti (in this case it should not be considered dangerous but rather an indicator of the physico-chemical transformations in progress);
- mucilaginous or brownish with a thickness of several mm, tending to reproduce easily and at considerable speed, produced by the acetobacter xylinum (dangerous for the formation of balsamic vinegar).
Palio: yearly competition for the best balsamic vinegar. There are three of these competitions: the Palio of San Giovanni at Spilamberto in the province of Modena, the Palio of the Ghirlandina in Modena and the Palio Matildico at Scandiano in the province of Reggio Emilia. Each Palio envisages the participation of between 50 and 1500 competitors from only the province of Modena, of Reggio Emilia, or from both as in the case of the Palio Matildico.
Persistence: the time that the aromas remain on the olfactory mucosa of the taster.
Refractometer: instrument for measuring the density of the product by measuring the refraction index of solid or liquid transparent substances. It is made of two prismatic lenses and a graduated eyepiece. When a drop of sugar solution (must or balsamic vinegar) is placed between the two prisms, it produces a refraction of the light with a different intensity depending on the type and characteristics of the solution used. A graduated scale allows the sugar percentage present in the solution to be read with a fair approximation. The refractometer most used is the Brix. Today there are more modern and precise electronic models on the market.
Sugar crystallisation: this is a recently discovered phenomenon according to which the uncontrolled increase of the density of the product in the battery leads to a progressive crystallisation of the sugars, particularly of glucose. If this phenomenon is not suitably controlled, it leads to the progressive solidification of the product, which in the long run becomes unusable. For this reason the maximum limit of the product density is 72 Brix.
Tannins: compounds widely found in nature, belonging to the aromatic series (phenols and polyphenols). They are found in tree bark, in wood, in leaves, in plant roots and in some fruits. With regard to grapes, we have to consider the “vegetable” tannin contained in the still unripe grapes, the “rough” tannin that comes from the pips and the stalk, and the “bitter” tannin that comes from grapes with poor acidity. These types of tannins generally provoke acid, bitter and astringent sensations. However, there are also so-called “noble” tannins contained mainly in the wood of the barrels. These provide a positive contribution to characterising the balsamic vinegar from the organoleptic point of view.
Topping up: this is the operation with which the biggest barrel in the battery is filled with a new graft of raw material, consisting of more or less fermented and acetified cooked must or of mixtures of older product in the case of batteries containing products that have already aged. Topping up is performed once a year.
Tragno: also called “Tragn” in Modena or Reggio dialect, this is a typical container with centuries of tradition; it has a wide belly and a more or less narrow neck of terracotta. With or without ears (two or four), it is often still present in old vinegar cellars, ready to hold the “balsamic vinegar” for everyday use. Its shape calls to mind the image of “pilgrim’s flasks” with loop-shaped handles for passing a cord through, or the bowls known as “zuccotti” that had no handles.
Vasello: this term was used to indicate the wood container made for producing “balsamic vinegar””. It is synonymous with barrel or cask. Nowadays it indicates the small 50 ml or 100 ml bottles that hold the balsamic vinegar drawn off each year.
Yeasts: these are single-cell microorganisms of different types, spherical or elliptical in shape, naturally present in grape must. The most frequent is the species Saccharomyces cerevisiae, commonly known as “brewer’s yeast”. Their task is to trigger the alcoholic fermentation of the cooked grape must. There are also Zygosaccharomyces which are osmophilic yeasts able to develop up to a 50% concentration of sugar and sometimes more: the most common are bailii, bisporus, rouxii. Saccharomyces have the property of demolishing the sugar molecule in medium concentrated cooked musts; Zygosaccharomyces (osmophilic yeasts) develop also in these sugar-saturated yeasts (up to 50% and sometimes even higher values). As occurs for acetobacters, when inhibited by the medium their function and their life cycle cease. Then, by autolysis, they release their numerous precious enzymes in the medium to encourage the transformations that characterise the maturing phase of the balsamic vinegar. The yeasts can be seen only using a microscope with at least 1000 magnifications and they belong to the fungi family. They manifest precise nutritious and environmental requirements and produce different effects:
- In the presence of oxygen (breathing phase) they transform the sugars contained in the cooked must into water, carbon dioxide and a lot of energy (C6H12O6 + 602 –> 6CO2 + 6H20 + 673 calories).
- In the absence of oxygen (fermentation phase) they transform the sugars into alcohol, carbon dioxide and a little energy (C6H12O6 –> 2C2H5OH + 2C02 + 24 calories).
From 100 g of glucose, 51 g of ethyl alcohol are obtained (theoretical yield allowing both for the sugar assimilated by the cells and for the part transformed into secondary substances).
Their life conditions and activity depend on various factors:
- on the environment temperature (optimum between 20 and 30°C, above 35 and below 10 they tend to stop all activity);
b. on the sugar concentration of the cooked must (above 50% their work of demolishing the sugar molecule becomes considerably difficult);
- on the alcohol produced. As it increases, its action is inhibited, as is that of acetic acid.
Weakening: loss of strength seen in the decrease of the fixed acidity. The phenomenon generally occurs in barrels with a larger capacity (where fermentation takes place) in the moment when the bacterium aceti attacks the acetic acid produced to transform it into water and carbon dioxide according to the equation:
CH3COOH (acetic acid) + 202 (oxygen) = 2H2O (water) + 2CO2 (carbon dioxide).
The problem is generally eliminated by adding an adequate quantity of must with a high alcohol content to the barrels.
Withdrawal: this is the operation with which the product is taken from the smallest barrel for consumption. The operation is performed once a year withdrawing only the product on the surface, to avoid mixing the dregs that result from the physico-chemical transformations of the product. The maximum percentage withdrawn depends on the battery’s capacity to compensate not only the withdrawal, but also the natural yearly decrease and the yearly decanting. The withdrawal quantity varies along with the variation of the product parameters to maintain a balanced ratio R. The withdrawal limit is normally fixed by the fact that all the barrels in the battery must never go down by more than 50% of the product that they contain.