To chill or not to chill, the natural stabilization of grappa
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“Natural” or “mechanical” stabilization? “Chill filtered” or “Not chill filtered”? Marolo has recently launched Nivis, the first grappa made through natural stabilization and not chill filtered, on the market. But what does “stabilization” exactly mean and why does grappa usually undergo mechanical chill filtering before it is put on the market?
Let’s admit it: just like the other spirits, grappa takes pride in its outward appearance. Would anyone drink a murky grappa, one that is not perfectly clear, which acquires an unpleasant milky look with the cold? Thus, stabilization and filtration are necessary to the grappa’s appearance, increasing its pleasantness.
The “fatty part”
Grappas, once distilled, are still a “raw” product. In fact, they have a “fatty part” mainly composed of oils and other insoluble substances from the skins of marcs that, especially after a sudden drop in temperature, cause the murkiness of their appearance. That’s not all. Some of these substances have a foul smell that, with time, could make the spirit stink or turn rancid.
Stabilization: what it is and its use
To avoid changes in colour and smell, grappas undergo stabilization. “Stabilization” consists in endowing a product with unvaried characteristics: this means preventing the variation of its composition over time, preserving its traits up until the packaging stage.
There are two ways to stabilize grappa:
1 – Through the process of decantation: it aims at separating the coarser impurities of the distillate thanks to their specific weight, waiting for them to sink on the bottom or rise to the surface.
2- Through mechanical and thermal techniques: this method is widely used by those who produce spirits for the consumer market – it allows a faster stabilization, very efficient and thorough, effectively separating the “fatty part” of the grappa.
Almost regularly, after dilution (>>> read our post on this subject) and before bottling, grappas are refrigerated at temperatures below 0° C. This is done in order to facilitate the separation of the “liquid part” from the “fatty” one, and to ensure the grappa’s clarity even at low temperatures, which could risk condensing the oils and giving it a milky appearance that nobody would like to see.
Question. Why do we talk about mechanical refrigeration? Why can some grappas, notably Nivis, be defined as «not chill filtered»?
“Chill filtered”, technically speaking, means “filtering while cold”, insinuating the term «mechanically». Let’s make this clear. The refrigeration process does not occur naturally, but it is generated by machines that drastically reduce the temperature, usually a set of refrigerants that can lower the temperature between -4 and -15° C.
By doing this, the distillate’s density increases and, along with it, that of the insoluble oils. It is at this point – once it is «chilled» – that the grappa can be filtered. Particular absorbent filters “trap” the oils of the grappa which, now completely clear, can then be bottled.
Does mechanical refrigeration tarnish the grappa?
The answer is no. This method, strictly industrial, has been developed for aesthetic reasons and – at least in theory – it does not reduce the organoleptic characteristics.
In theory. Because some experts note an impoverishment of the final product that has undergone chill filtering. For example, with distillates marked by their aroma quality, mechanical refrigeration and filtration may trap and remove, along with the oils, part of those delicate components (terpenes, acids and aldehydes) that are responsible for the richness and pleasantness of the bouquet.
NIVIS, the first grappa made through natural stabilization and “not chill filtered”
In order to avoid such inconvenience, Marolo has chosen to stabilize the grappa Nivis.
Nivis is made from marcs of the 2006 vintage, one of exceptional quality, which deserves particular attention. However, in order to attain better results, the barrels containing Nivis have been voluntarily exposed to the winter weather. Rain, wind, frost and snow have made the stabilization process quite long and very delicate, letting the fatty part of the grappa, which have been manually removed afterwards – with an estimated loss of about 15% of the total product – to rise to the surface.
Nivis is a precious grappa, naturally stabilized by the cold winter season for 3 months, which can boast the title “not chill filtered””.