Producing Extra-Dry Asti Spumante
"Aste nitet mundo Sancto custode Secundo" ("Asti shines in the world thanks to its patron saint Secundus")—this motto is on the coat of arms of the municipality of Asti); in particular, with Google Earth you can admire the verdant splendor of the Asti vineyards, in which the iconic Asti Spumante is produced. This Demonstration examines the complex process that transforms a wine into a sparkling wine .[more]
The process begins with the addition of the "liqueur de tirage," a sugar solution added to selected yeasts with ingredients protected by trade secrets. Invertase is an enzyme that catalyzes the hydrolysis (breakdown) of sucrose into fructose and glucose, which are naturally present in wine [2, 3].
When this reaction takes place in an acidic environment, the kinetics can be determined by analyzing the order of reaction. The species involved in the reaction are optically active. The reaction was determined to follow pseudo first-order kinetics by following the variation of the optical rotatory power with a polarimeter as a function of time. The fructose and glucose produced in this way trigger a second fermentation that, in addition to increasing the alcohol content, produces carbon dioxide inside the bottle, developing the classic pressure of 4–6 atm, typical of all sparkling wines.
Contrary to what happens using the Martinotti–Charmat method, with the champenoise method, the second fermentation takes place in a folkloric way inside the bottles, with their inclination gradually increased with a periodic rotation ("remuage") around the axes of the bottles in characteristic shelves ("pupitre"), and the solid residue formed due to fermentation slides slowly in the neck. The neck of the bottle is then frozen by immersion in a solution at ° C.
Finally, the sediment surrounding the dead cells is removed by means of a quick disgorgement ("dégorgement"). The pressure will be regenerated when chemical balance is reestablished.
The addition of the "liqueur d'expedition" also makes it possible to standardize the level of the sparkling wine inside all the bottles. The "reaction kinetics" options show the various reaction stages. The "processing steps" option shows the bottling steps. Use "time" to follow their temporal evolution.
This work is dedicated to all those who want to make wine, especially people from Asti—Asti in Italy and in California. Enjoy and drink. Cheers![less]
Snapshot 1: fast stage of the reaction mechanism: ion attachment with catalyst
Snapshot 2: bottleneck (not because it happens in the bottle!):
Snapshot 3: fast stage: water attachment:
Snapshot 4: fast stage: ion detachment (catalyst):
Snapshot 5: "remauge": the sediments (yeasts) produced by the second fermentation are made to slide in the neck of the bottle by means of a gradual increase from the horizontal position to the "sur pointe" position, all associated with small rotations of the bottle; the result is a perfectly clear liquid
Snapshot 6: "dégorgement à la glace": with a quick opening of the cap, the internal pressure will expel the ice cylinder; the operation can be carried out either manually or mechanically
Snapshot 7: after adding and mixing the "liqueur d'éxpedition" and after the insertion of the "muselet," the bottles are returned to the cellar for a rest period
Snapshots 8: a flûte is a suitable glass for tasting dry sparkling wines: the rising bubbles and aromas in confined spaces prolong the effervescence of the sparkling wine while maintaining the classic "perlage" for longer; the traditional cup, coppa Asti, is used only for Asti Spumante dolce
 Wikipedia. "Asti Wine." (Dec 22, 2020) en.wikipedia.org/wiki/Asti_wine.
 R. T. Morrison and R. N. Boyd, Organic Chemistry, 3rd ed., Boston: Allyn and Bacon, 1973.
 "Reazione di idrolisi del saccarosio.doc." (Dec 15, 2020) puccini.chimica.uniba.it/didattica/corsi/labchimfis2/polarimetria.pdf.