Hot instability of red wines

Luigi Sanarica, Enolife

The world of wine has undergone profound changes over the past decades facing the challenges of a modern and globalized market that does not allow for approximations, One of the consequences of the enlargement of the markets themselves and in particular of global warming lies in a potential increase in the thermal stress to which wines are subjected, which can cause the presence of deposits in the bottle, which are not well accepted by the consumer.

Specifically, heat stress cloudiness is an indication of protein instability in white and rosé wines. Red wines, due to their chemical composition, generally do not show instability following these tests, but recent studies have shown that this statement is not entirely correct. The phenomenon of hot instability in red wines is very complex, and in some specific cases the use of negatively charged adjuvants such as bentonites, which are effective in the case of white and rosé wines, does not prove effective.
This very particular phenomenon, at the preliminary stage is not solved by using adjuvants or oenological additives, but by carrying out a cold treatment for 48 hours.
This technique is extremely expensive and poses limitations in view of a modern oenology, so the development of an additive technique is necessary.

In the present study, wines with different characteristics are analyzed in a structured manner. In particular, a positive correlation is found between, polyphenol content, resistant pigments, absorbance at 420 nm and heat test instability.

Different oenological aids such as different kinds of bentonites, decolorizing carbons, stabilizers, chitosan and different proteins, both animal and vegetable, were tested on red wines characterized by different heat instability.

In conclusion, the results obtained show that it was possible to develop REDGEL an innovative protein capable of stabilizing such wines and indicate a protocol such that total stabilization of red wines can be guaranteed in hot weather.

A necessary “evolution”

Chiara Pisarra, Enolife

Color stabilization has always found its faithful ally in wood, whether in the form of barrels or chips its help is now proven.
It is already known in the literature that the mechanisms and molecules involved in the evolution of color are anthocyanins, tannins, and ethanal, which, on the one hand, allows the formation of ethyl bridges between anthocyanins and tannins and, on the other hand, stabilizes anthocyanins by cycloaddition. For this to occur, the contribution of oxygen is needed.
Thus, microoxygenation plays a key role in influencing the balance between free forms of anthocyanins and those combined with tannins by increasing the percentage value of the latter within wines.
The current climate change implies a change in the chemical and physical parameters of grapes, which combined with the new globalized and dynamic market implies an acceleration of wine preparation time.
These conditions inevitably imply the reshaping of treatments that have so far proved effective.
This is the case with color evolution, a process that for certain wines to date is very complex to the point that the Enolife R&D department’s attention is focused on this issue.

Research and the constant desire to give solutions in step with the times and customers’ problems led to a systematic study of the effect of different toastings and types of oak fragments on color stability. It was therefore possible to develop WINELIFE EVOLUTION, a new product in the Enolife alternative wood range that, thanks to its special chemical and physical characteristics and thanks to its innovative production process, is targeted for the rapid color stabilization of the most complex wines.

New technologies for modulating color characteristics and volatile fraction of red wines

Vito Michele Paradiso, Department of Biological and Environmental Sciences and Technologies, University of Salento

Color stabilization and modulation of sensory characteristics are two fundamental objectives in the management of red wines.
An experimental trial was conducted to evaluate the effect of using an innovative dynamic chip extractor, followed by passive micro-oxygenation in PET, possibly combined with the addition of oenological tannins, on the color characteristics and volatile profile of a wine from Primitivo grapes.
The wine, in 50 hL aliquots, was subjected to treatments of different durations with a dynamic extractor operating at room temperature (< 20 °C) and low overpressure (< 1 bar). The resulting wines were subsequently stored for 4 months in PET bottles in both the presence and absence of enological tannin.

The results obtained show that dynamic extraction from the chips, in combination with passive micro-oxygenation and in the presence of oenological tannins, promotes color stabilization, with values of the index of resistant pigments almost double those of the starting wine.
Moreover, the use of enological tannins ensured the highest levels of intensity and aromatic quality in the wines.

The results obtained showed that the use of the dynamic extractor can be considered not only as an expedient to reduce process time in wine handling, but as a flexible tool to modulate the sensory and chemical profile of a wine by balancing its different components. In combination with passive micro-oxygenation and the use of enological tannin, it can provide a platform for an integrated approach to color stabilization.