History of Modena Balsamic Vinegar
Traditional Balsamic Vinegar (or Aceto Balsamico Tradizionale) is a type of balsamic vinegar produced in Modena and the wider Emilia Romagna region of Italy. Unlike inexpensive "Balsamic Vinegar of Modena" (BVM), Traditional Balsamic Vinegar (TBV) is produced from cooked grape must, aged at least 12 years, and protected under the European Protected Designation of Origin (PDO) system, fetching higher prices (BVM has lesser protection under the European Protected Geographical Indication (PGI) system.) Although the names are similar, TBV and the inexpensive imitation BVM are very different.
A comprehensive study of the original production procedures, the aging conditions, and the sensory profile is not available. This and the few and often-confusing documents make the reconstruction of the true history of TBV a challenge. The term balsamico derives from the Latin word “balsamum” and from the Greek word “βάλσαμον”, in the sense of "restorative" or "curative". The art of cooking the must of grapes dates back to the ancient Romans: it was used both as a medicine and in the kitchen as a sweetener and condiment. The first generally accepted document referring to a precious vinegar produced in the area of Modena and Reggio Emilia is the poem written in the 12th century by the monk Donizo of Canossa, although the word "balsamic" is never mentioned. The first testimonies clearly speaking about "balsamic vinegar", as well as of recipes and making procedure, appear from the 19th century even if little is known about the original recipes and related production practices. The adjective "balsamic" has been used to designate any kind of generically aromatic vinegar and products not just obtained from the fermentation of grape must alone. As far as the aging method is concerned, it is very similar to the Solera system used in Spain after the Napoleonic Wars which spread abroad after the second half of the 19th century.
The oldest and most detailed description of the method and techniques for the production of balsamic vinegar is reported in a letter written in 1862 by Francesco Aggazzotti to his friend Pio Fabriani, in which he describes the secrets of his family's "acetaia" (the vinegar-cellar where balsamic vinegar is made).
The entire production process of ABT begins with the pressing of the grapes and ends with the taste-olfactory evaluation of the aged product. The production steps are well defined, from the cooking of the grape must, to the alcoholic fermentation, from the acetic bio-oxidation by acetobacteria to the slow aging in wooden barrels.
The basic ingredient is cooked grape must. The grapes used are Trebbiani (from Spain, Castelvetro ...), Lambrusco (in all their varieties), Ancellotta, Sauvignon, Sgavetta, Berzemino, Occhio di Gatta and in general the grapes from the vineyards registered with the DOC of the provinces. of Modena and Reggio Emilia. The maximum yield of allowed grapes is limited to 160 quintals / hectare.
The grapes must necessarily be grown in the provincial territories of reference, characterized by a slight calcareous content and the presence of macro and micro elements. The entire production process must also take place within the same geographical area, characterized by harsh winters and decidedly hot summers, which make possible the unique and particular processes necessary for the correct development of the product.
Cooking of grape must
The cooking (jargon called "cotta") of the grape must of at least 15 saccharometric degrees (° Bx), without any additive, takes place at natural pressure, over direct heat and in open containers for about 12-24 hours at a temperature minimum of 30 ° C, until the reduction to about 2/3 of the total mass. For ABTM, unlike the provisions of the ABTRE specification which provides for a minimum concentration of 30 ° Bx, there is no minimum concentration of sugars, and indeed the minimum cooking time is defined as 30 minutes. However, this time is not in the least sufficient to produce those profound physical and chemical modifications that must necessarily connote the final product. On the contrary, cooking temperatures that are too high, perhaps associated with long boiling times, could lead to unwanted crystallization of sugars, slowdowns in alcoholic fermentation and the production of furan compounds such as 5-hydroxymethylfurfural (HMC) , therefore the most recent scientific trend is that of cooking between 75-90 ° C, for no more than 14 hours, with a reduction of the must up to a maximum of 28-30 ° Bx .
Cooking stops all enzymatic reactions that are rapidly initiated by catechol oxidase, and causes discoloration of the wort with the heat-induced deactivation of the proteins. At the same time, the browning of the must is due to non-enzymatic chemical reactions due to the conversion of sugars and the formation of high molecular weight melanoidins , and more generally to the effect of the Maillard reaction. Evaporation induces the degradation of sugars (in particular fructose), as a result of their dehydration in an acidic environment (which also persists during the long years of aging of the ABT, of caramelization and of the Maillard reaction itself. Finally, evaporation it induces the concentration of the sugars themselves, of the organic acids, of the polyphenols, with the consequent increase of the density, of the viscosity, of the refractive index, while the pH value is lowered.
Image of Saccharomyces cerevisiae obtained with an interferential contrast microscope
The fermentation of sugars, in the presence of not too high sugar concentrations, starts immediately, and continues in the winter months. It is due to yeasts of the saccharomyces genus, mainly saccharomyces cerevisiae, and of the zygosaccharomyces genus (osmophilic and fructosphilic yeasts), in particular zygosaccharomyces bailii. The former are more appreciated for the aromas they give to the product, while the latter (which proliferate in environments with a higher sugar density or high acidity) should not be prevalent. This type of fermentation is almost identical to that which occurs for raw must, as are the yeasts mainly involved, and in fact the yield of ethanol is equal to 0.6 degrees of ethyl alcohol per 1 degree of sugar, similarly to what happens for wine.
In the past there was the belief of a commensalistic interaction between saccharomycetes and acetobacteria, for which alcoholic fermentation and acetic bioxidation would take place simultaneously. Recent studies have shown that in reality a concentration of acetic acid higher than 3% of the total volume prevents the life of even the most resistant zygosaccharomycetes , and for this reason the most recent trend is to manage the alcoholic fermentation phase separately from the rest of the cycle, with containers (vats, demijohns or barrels) separated from the actual "battery".
Maturation and Aging
Once fermented and acetified, the product begins the maturation and aging phase, two phases characterized by the effect of the enzymes dispersed in the liquid by the autolysis of microorganisms (enzymes and acetobacteria). Enzymes catalyze chemical-physical processes that originate increasingly complex flavors and aromas, without however being involved in the reactions themselves (so at their end they will be "ready" to catalyze new ones). At the end of this phase of maturation, called "enzymatic", with the drastic reduction of the reactions catalyzed by enzymes, oxidation and redox processes are triggered which give rise to further modifications of the chemical-physical properties of the vinegar, leading to the formation of acids humic, and achieving a balance between the fixed and volatile substances (what tasters call the "mature and amalgamated harmony" of the product).
In addition to this, during the years of maturation and aging, traditional balsamic vinegar undergoes a continuous concentration, due to the loss of aqueous volume through evaporation. Generally, the "annual decrease" is around 8-15% for the larger barrels, called "head", increasing up to 12-25% for the smaller ("tail") barrels.
Aging is primarily linked to the time that the vinegar spends inside the various barrels (the so-called "battery") defined as "age" or "residence time", but also to all the time-dependent changes that occur in the chemical, physical and sensory properties of traditional balsamic vinegar ("physical ripening time") .
The maturation phase lasts approximately ten years: added to the approximately 2 years necessary for the fermentation and acetification of the starting product, this justifies the 12 years required as a minimum requirement for the definition of ABT. The 25 years required for the extra old product are instead defined in an arbitrary way, since the enzymatic and oxidative processes have practically no end, lasting uninterruptedly for centuries.
To allow these continuous exchanges of oxygen, water vapor and volatile substances, it is essential that the ABT is stored and aged in substantially open containers: the availability of barrels for the transport of wine to isolated country inns (generally of modest capacity), and the accumulation of a wealth of experiences and traditions has probably led to the use of small wooden barrels for the maturation and conservation of the product, instead of other forms of containers (glass demijohns, amphorae ...). And in fact the wood guarantees exchanges with the external environment not only through the opening bung, but also through its porosity, during all the life stages of the traditional balsamic vinegar. The battery must necessarily be placed in a place that is affected by temperature variations between day and night, but even more between summer and winter: the acetification process, in fact, requires an ambient temperature above 20-22 ° C, below which the acetobacteria remain in a quiescent state. Conversely, the winter cold is necessary to slow down the evaporative process and to make the mucilaginous substances and the corpuscular parts of the liquid settle on the bottom, as well as to guarantee a decisive activity of the odorous parts. And in fact, even today the barrels are placed in the attics of the houses, in order to expose the aging vinegar to both the harsh winters and the sultry Emilian summers. The large vinegar cellars, with dozens if not hundreds of batteries, are often located in old converted barns, or in modern warehouses designed specifically to guarantee the effect of the seasons.
Information source: Wikipedia