The temperature at which a wine is served represents a critical element for the correct perception and development of its organoleptic characteristics. The right temperature of service can in fact improve the pleasingness of a wine as well as drastically change its real nature. For this reason, temperature is the best friend of any sommelier, whom - in order to ensure the best possible condition of tasting - use it according to the sensorial qualities of wine to be attenuated or emphasized. In other words, the accurate choice of the temperature of service can be proficiently used to hide certain faults as well as emphasizing specific qualities. A mediocre wine, therefore, can taste better than what it really is; likewise, an excellent wine can be worsened when served to the wrong temperature.

 It must however be said temperature is not capable of making astonishing sensorial miracles: a bad quality wine can be slightly improved according to the temperature at which it is being tasted, it will however keep its real quality. The temperature at which a beverage or food is tasted has the property of changing the sensorial perception, including tactile stimuli. A food or beverage tasted at different temperatures will have, not only different tastes and aromas, but also different tactile profiles, by drastically affecting its organoleptic perception. For example, we could consider the difference in tasting a cold beverage - even the simple water will do - with the very same beverage tasted at a quite higher temperature. Its sensorial profile, as well as the psychological approach towards the beverage, will be different.

 It could be considered, for example, the tasting of a cold beverage in summer: psychologically speaking, the low temperature anticipates the pleasure it can give in terms of wellness to contrast the hot temperature. The same beverage, served cold in winter, will give a completely different psychological effect, by wishing a higher temperature or even hot. The pleasingness of a beverage - and wine, of course, is no exception - is strongly determined by the temperature of service which can be properly used according to room temperature and season in order to improve its enjoyability. Not only from a tactile point of view - a very important sensorial characteristic - but also, and in particular, for the improvement of the perception of aromas, flavors and tastes.

 The effects of temperature on the sensorial perception of a food or beverage are - or, better said, should be - well known to wine tasters. Every taster knows that tasting a wine at a wrong temperature can significantly affect the reliability of his or her job. Like already said in the past, wine quality is expressed in function of the absence of faults, or - at least - to their minimum possible presence and minimum impact. The temperature at which a wine is tasted can in fact hide the presence of faults or, better said, strongly attenuates their perception. This is true both for the perception or wine aromas as well as for its taste. Tasting a wine at a very low temperature, means strongly flattening its sensorial profile, as well as significantly attenuating the impact and the intensity of any possible fault.

Sensorial tasting of white wines is done at a temperature higher than the one used in service

 As for the temperature of tasting - that is the critical and analytic operation having the goal of determining the quality and characteristics of a wine - it follows principles different from the ones used for service. The temperature of service, that is the one used for the best expression of a wine's pleasingness and used in ordinary consumption, it is in fact based on rules allowing the reaching of this goal. In the ordinary service of wine, temperature is used in order to emphasize certain wine qualities and the attenuation of any possible fault. On the other hand, in sensorial tasting the goal is to favor conditions such to proficiently perceive any possible presence of faults and, therefore, the temperature is determined according different criteria. On this context, therefore, it is favored the expression of faults.

 Among the worst pitfalls of sensorial tasting there is low temperature. If it is true - we will see later - a high temperature can favor and emphasize the perception of certain wine qualities, also negative ones, low temperature has the property of attenuating most of the stimuli. For this reason, in choosing the temperature of sensorial tasting of wines, it is usually favored a temperature slightly higher than the common ones and used for the service of wine. The reason is essentially associated to the best development of the organoleptic sensations - good and bad ones - although this could also favor the excessive development of the ones sensitive to heat. It is - in any case - an acceptable compromise in order to favor the perception of the worst enemies of quality: faults.

 Let's understand the effects of temperature on the many sensorial aspects during the evaluation of a wine. The only sensorial characteristic not affected by temperature is appearance. If it is true temperature however affects the appearance of wine, this effect is the result of a slow process taking place within months or years. In the evaluation of appearance during sensorial tasting, temperature is therefore a negligible factor as the change to which the wine is subjected is very short. We will see later, temperature has evident effects both on the development of aromas as well as of taste, even completely changing - with an excessively wrong use - the profile of a wine.

 In the olfactory evaluation of a wine, the first aspect to be analyzed - always - is the presence of faults, sometimes being evident and macroscopic, sometimes light and weak, as to be completely ignored by a careless nose. As for the development and the perception of aromas, temperature plays a fundamental role and according to the volatility of odorous substances. As the temperature goes down, the perception of aromas will be attenuated and completely disappear, whereas high temperatures favor their development, including the violent ethereal character of ethyl alcohol. Temperatures lower than 5 °C (40 °F) will significantly attenuate the development of any aroma, whereas the ones higher than 20 °C (68 °F) will excessively emphasize the ethereal character of alcohol, while making all the other aromas smell as rough.

 On this regard, it can be done a simple experiment. Let's take a wine and pour the same quantity in two tasting glasses, then let's seal both with a cellophane film. One glass will be kept in the freezer of your fridge, whereas the other will be left at room temperature. After one hour, remove the cellophane film from both glasses and smell the two wines: the cold one will be almost mute and with no aromas, whereas the other one will develop more intense aromas and it will be possible to smell - in particular in summer - the ethereal and volatile character of ethyl alcohol. Another experiment which can be done is about a wine having an evident fault, such as - for example - the infamous cork taint. After having cooled down the wine in a freezer for one hour, the disgusting fault will seem to be disappeared, more precisely, its perception will be strongly attenuated. The same wine, as the temperature goes up, will seem to accentuate this unpleasing smell.

 Temperature substantially affects the perception of taste and of tactile stimuli of a wine. The sensations generally defined as round - sweetness, the impact of alcohol and roundness - are emphasized with high temperatures and, on the other hand, are attenuated by low ones. Some gustatory sensations defined as hard, have an opposite behavior, in particular astringency and the perception of bitter flavor. On this regard, we should notice the sensation produced by astringency is to be considered as a tactile stimulus, produced by the interaction of tannins with the mucosa of oral cavity and, in particular, with its property of bonding with proteins. Astringency in wine also produces a bitter flavor, which nature and intensity depend on the type of polyphenols found in a wine and on their ripeness at the moment of tasting.

 Astringency increases the intensity of its tactile stimulus as the temperature goes down, whereas tends to get rounder as the temperature goes up. The perception of bitter flavor follows - in general terms - the same type of pattern: a low temperature accentuates its perception. On this regard it should be said the perception of a bitter flavor is also in function of round substances found in wine that, in this case, work a contrasting action. The perception of round substances - including sugar - is stronger as the temperature goes up, therefore, in this case, the contrasting action to the bitter flavor will be more effective. Carbon dioxide - responsible of effervescence in sparkling wines - changes its development according to temperature. Low temperatures significantly slow its release, therefore prolonging the show of bubbles in the glass.

 According to an organoleptic point of view, carbon dioxide has a basically acidic taste, a gustatory sensation which perception remains unaltered with temperature changes. Acidity is well perceptible at any temperature, we should however notice its pleasingness is better at low temperatures. In sensorial tasting, white wines are usually evaluated at a temperature of 12-14 °C (52-57 °F) and according to their evolution, whereas reds are evaluated at a temperature of about 18 °C (64 °F). Sparkling wines are never evaluated at the canonical temperature of 8-10 °C (46-50 °F) because the perception of aromas and faults would be attenuated, therefore it is used a higher temperature instead. In any case, the temperature for tasting wines is never higher than 20 °C (68 °F), as this temperature would make alcohol volatility too aggressive and the finesse of aromas would be compromised. In sensorial tasting, it should be noticed the main goal is the evaluation of wine quality and the correspondence to its type. Temperature is one of the factors favoring - when correctly used - the conditions for a better analysis and, as such, it must be determined according to the type of wine.