• University
  • Research
  • Permeabilty Study
  • Factor of Choice
University
Scientific Partner
University of Udine
All the different tasting effected up to now, following a precise procedure decided by the University of Udine, revealed a clear preference towards the products bottled with KORKED™ closures; such preference is due to the fact that the wines are always agreeable and, above all, do not reveal reduction problems or defections at all. The wines employing the closures KORKED™ present very stable values of sulphurous anhydride and carbonic dioxide, even after certain months since bottling.
The results of the tasting and the chemical analysis led the University of Udine to the following conclusion: ...omissis... “The elaboration of the results obtained evidences that the average permeability values are different according to the typology of stoppers and that it is not possible to include all synthetic closure in one single group. On the other hand natural corks often determine great differences within the same parcel of product. Conclusions: the sensorial tests confirm that the wines bottled with the closures KORKED™ present the same evolution degree as the ones using natural corks. At the same time, all the defection traditionally associated with natural corks are avoided. On considering the productive standards the performances of the closures KORKED™ are comparable to those of high quality natural cork”.
R. Zironi, Professor of Oenology
University of Udine
Food Science Department
Research Colorimetric Method In 2001 the University of Udine used, for the first time in Italy, the colorimetric method to measure the permeability to oxygen of different wine closures. The same method had already been used by the Oenology Faculty of the University of Bordeaux, in France. The bottles are filled up with an indigo-carmine solution, extremely sensible to oxygen. At the beginning the solution is yellow but, on adding some chemical reagents properly calibrated, it turns to green and afterwards to dark blue. The quantity of oxygen that permeates the closure in each unite of time is measured by means of a spectrophotometer of precision. The picture shows how more is the concentration of oxygen present, more the solution turns to blue:
  • Colour a: absence of oxygen
  • Colour from b to d: progressive oxidation
  • Colour e: 100% oxidation of the liquid
Colorimetric Method










This method has already been used to test and to measure the permeability with more than 40.000 bottles stoppered with all different closures actually available on the market and using plenty different membrane produced by KORKED™ and subjected to various storage conditions. Ruthenium fluorescence method Since 2006 Korked and the University of Udine have decided to support the method of fluorescence of the ruthenium to the colorimetric method.
In various bottlings have been stoppered bottles, filled with demineralized water with nitrogen, with statistically representative quantities of different types of closures (natural cork, micro-agglomerated, synthetic stoppers, screw caps). The method is based on the excitation, through a specific impulse of the blue range, of the sensor containing ruthenium previously inserted inside the bottles. The ruthenium content in the sensor emits in reaction a fluorescent signal in the range of red with a delay, than at the time of excitation, which varies from 1 to 5 milli-seconds. The delay measurement signal, which is a direct function of the amount of oxygen contained in the bottle, determines in scientific way the permeability of the closure with which the bottle was corked.
Results The values measured with the colorimetric method and with the method of fluorescence of the ruthenium at monthly / quarterly periods till 36 months, processed and converted into data by the University of measurement of permeability of the closure, have allowed Korked after years of study to determine the permeability of the several closures existing in the wine market. A particular study has been dedicated to natural cork monopiece and how vary their permeability as a function of the density of cork that composes them.
Tabella Permeabilità

These studies have allowed Korked to identify the minimum, medium and maximum permeability of natural cork and to implemented in collaboration with the Politecnico di Milano membranes that replicate scientifically without any defects what nature has created. At the same time were conducted chemical and sensory analysis of wines bottled with different closures to verify their evolutionary status and to determine for each type of wine the membrane that determines the best aging in bottle from the organoleptic point of view. Studies managed have allowed to realize the synthetic stopper KORKED™ PRO (medium permeability) and KORKED™ BLUE (low permeability) and screw caps KORKED™ SPIN- (minus) (low permeability), KORKED™ SPIN (medium permeability) and KORKED™ SPIN+ (plus) (high permeability).
The KORKED closures are patented in all most important states in the world from the oenological point of view.
Permeabilty Study The object of micro-controlled oxygenation is to obtain a wine more stable and with better features, both from the chemical point of view that sensorial one; to use closure systems with micro-permeability appropriated to the wine bottled allows to exalt its organoleptic properties.
The role of the closure is very important for a correct maintenance and refinement of wine in bottle and to avoid that:
  • Be established an environment extremely reducing;
  • There are reactions of oxidation and premature aging of the product;
  • There are unpleasant releases of substances




The closure systems actually presented in the market offer to producer a permeability that can’t be chosen from the winery according to the specific needs of the bottled wine: the permeability of the closure is sustained.
The closure system KORKED™ is the first screw cap that through a membrane allows to pre-determine the desired permeability to gases
In the chart below is highlighted, in relation to the permeability, the positioning of the closures KORKED™ in the areas of aging and maintenance compared to the main closures present in the market.

Tabella Permeabilità
The main factors to determine the correct permeability The closures KORKED™ allow to the oenologist to choose between different levels of permeability, choosing the type of stopper which exalt the organoleptic characteristics of its own bottled wine.
But what are the major aspects to analyze for determining the correct permeability of KORKED™ SPIN screw cap to use?
Factors to consider when choosing are essentially four:
  • Structure of the wine
    A delicate structure requires an adding of oxygen extremely low, while a more structured wine needs much more oxygen for its refinement. Examples: An aromatic white wine such as Riesling requires a low adding of oxygen, while a structured red wine with a high presence of tannins (antioxidants) and anthocyanins (astringents), such as cabernet, needs a higher quantity of oxygen.
  • Processing Method
    The wine is in contact, in very variable quantities, with oxygen in all its phases of production in relation to the structures and the production technique used by the winery. The same wine produced in steel tanks or refined in barrique will require, during aging in bottle, of closures with different permeability. Examples: Brunello of Montalcino, after 24/36 months in barrique, having already absorbed enough oxygen, must be obligatorily stoppered with a closure with low permeability.
  • Shelf Life
    As for all the foods, also for the wine its own evolution and life are highly correlated to the contribution of oxygen. The purpose is to manage the permanence of the wine in the bottle so that it can reach its highest sensorial expression at the time of consumption. Examples: a sangiovese which will be drunk after 12 months from bottling, for expressing its best own characteristics and fragrance should be stoppered with a closure with medium-high permeability; the same wine which will be drunk after 60 months will require a closure with medium-low permeability
  • Style
    At the end, is the winemaker that has to decide the identity to give to its product. For each wine he chooses if it would be better to preserve the wine’s features as bottled or if it would be better to research an ageing in the bottle to reach the correct refinement.

  • From 2009 KORKED™ SPIN screw caps are used by the all major wineries from very important stated from the oenological point of view (Italy, France, Spain, Germany, Hungary, South Africa) with excellent results. In each case it was suggested to the winery the correct permeability according to its wine features and according to its specific needs.
    Consult us to define what is the optimal closure to refine your wine.

    Barrique

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