Wine Faults and Flaws. Keith Grainger

CO₂ from the alcoholic fermentation. In the case of still wines, a brief observation of the size and quantity of bubbles should be made. The bubbles may appear on the tasting glass surface, in which case they are likely to be large, on the rim, or in the heart of the wine.

       Sparkling Wines

      The quality of the mousse is considered to be an essential part of the overall quality of sparkling wines. The size, quantity, and consistency of the bubbles should be noted. The bubbles may rise from the base of the cup or a seemingly random point in the heart of the wine. Generally speaking, small bubbles are indicative of a desirable cool, slow second fermentation, especially when this has taken place in the bottle as in Champagne and other high‐quality sparkling wines made by the traditional method. The character and volume of bubbles will vary somewhat according to the type and washing of the tasting glass. Of course, a lack of bubbles in ‘sparkling’ wine is a physical fault, almost certainly indicating failure of the cork or other closure. Such a wine will almost certainly show other faults resulting from oxygen ingress, including oxidation.

      2.5.5.2 Legs

      One of the most misunderstood visual aspects of wine tasting is the presence or otherwise of legs, often referred to as tears. The wine should be swirled in the glass, held to eye‐level and, after waiting for several seconds, viewed horizontally and observed as to how the swirled wine runs back down the glass. If the liquid congeals into little tears, arches, or rivers running down the glass, these are called legs. The legs may be broad or narrow (thin), short or long, and run slowly or more quickly down the glass. Wines that contain a high degree of alcohol will normally show broad legs, formed by the difference in surface tension between water and alcohol and the differential evaporation of alcohol, influenced by sugar and glycol. Several authors and critics claim that legs are purely a sign of high‐alcohol, glycerol or very high residual sugar. This is refuted by examples of their presence in high‐quality wines which are relatively light in alcohol, for example, fine Riesling Kabinetts from the Mosel region in Germany. The amount of dry extract also contributes to legs. Further, the amount and type of legs, if any, can be very dependent on the condition, and particularly the washing and drying of the tasting glass.

      2.5.5.3 Deposits

Any deposits in the glass should be noted. These may comprise tannin sediments (which are simply the coagulation of phenolic substances) in the case of red wines or tartrate crystals in either reds or whites. Phenolic sediments naturally occur in fine red wines following bottle maturation, and such wines should be decanted before service. Although some might disagree, tartrate crystals should not be regarded as a wine fault, and are often visible in wines of the very highest quality. Thick deposits in red wines may also be tannin‐stained tartrate deposits (especially in low pH wines). However, in white wines, they can look alarmingly like pieces of broken glass and worry the consumer, but they are completely harmless. The crystals are most likely a precipitate of potassium bitartrate (KC₄H₅O₆) or occasionally calcium tartrate (C₄H₄CaO₆). They are often found in bottles of German or other wines that have a high level of tartaric acid. They may precipitate if the wine is subjected to cold conditions – perhaps in a cold cellar or refrigerator. Many winemakers go to great lengths to try to ensure that the crystals do not appear in the bottle. This topic is discussed in detail in Chapter 15. The money and time spent by the industry on such treatments might be better invested in consumer wine education.

      Grey or pale brown deposits are certainly a warning sign – they are most likely to be dead yeast cells or bacteria. Whilst it is possible that these are a consequence of inadequate racking and filtration, they are more likely an indication that the wine has undergone an alcoholic or MLF in the bottle, as discussed in Chapter 9. In any event, the aroma and flavour profiles together with the texture, will have been modified.

2.6 Nose

      The second stage in a tasting assessment is to nose the wine. The olfactory epithelium, situated at the top of the nasal cavity, is a very sensitive organ. The tongue reveals only a very limited number of tastes, and most of the ‘taste’ sensations are detected by the receptor cells of the olfactory epithelium, received either via the nasal or retro‐nasal passage. The information is turned into electrical signals and sent via the olfactory bulb to the olfactory cortex in the brain. There is a difference between the impressions of aromas obtained nasally and retro‐nasally, and the sensations transmitted via the retro‐nasal passage will be discussed later in this chapter. There is no doubt that repeated and overexposure to particular smells reduces sensitivity to them, and this can be an issue for winemakers who are regularly exposed to odours such as sulfur dioxide (SO₂), or whose cellars are contaminated with haloanisoles (see Chapter 3).

      When nosing a wine, we are smelling the headspace in the glass, above the surface of the liquid. There must be plenty of headspace for the aromas, the volatile compounds in the wine, to develop. The inwards tapering bowl of a well‐designed tasting glass (narrower at the top than the bottom) enables aromas to be retained in the headspace.

      The nose of the wine should be assessed in the following stages:

       Condition;

       Intensity;

       Aroma characteristics;

       Development.

As discussed below, the wine should be first nosed without swirling, then swirled around the glass to vaporise the volatile compounds, and then given a comprehensive nosing.

      2.6.1 Condition

      The initial nosing of the wine will assess the condition: is the wine clean, or does it show a fault? The wine should not be swirled before this, and just one or two short sniffs are all that is required. Long and deep sniffs of a wine affected by 2,4,6‐trichloroanisole (TCA) or 2,4,6‐tribromoanisole (2,4,6‐TBA), or possessing high volatile acidity, would result in the taster's nose being desensitised for some time! Basically, at this point, the light nosing is to check if we want to go any further in the tasting procedure. Most faults and flaws are detectable upon the nose to a trained and experienced taster. Depending on the nature and severity of any fault revealed, a decision has to be made whether to proceed with the wine tasting or not. A nose that is free from faults is described as clean. It should be borne in mind that on occasions wines, particularly after some years in bottle, may smell somewhat unclean when first opened, a phenomenon sometimes referred to as ‘bottle stink’. This should dissipate after aeration. If there is doubt on this matter, the wine should be nosed again, having being swirled around the glass and allowed to ‘breathe’ for a few minutes.

Faults that are or may be detectable on the nose are shown in Table 2.2. This list is not exhaustive.

Table 2.2 Faults detectable on nose of wine.

Olfactory indicator	Possible fault	Refer to:
Damp sack, wet cardboard, dusty, musty. Muted fruit	Chloroanisoles or Bromoanisoles	Chapter 3
Earthy, beetroot	Geosmin	Chapter 14
BAND‐AID® stables, faecal, animal, smoky, spicy	Brettanomyces related faults	Скачать книгу В начало < 20 21 22 23 24 25 26 27 28 29 > В конец