In Sensory

This has often been slurred after one to many glasses of Chardonnay has been gulped down or heard whilst serving a guest who for the fifth time has not heard you explain that you’ve served them a 2011 Syrah. It may seem like one of those completely obvious questions with the answer simply being: you are smelling wine. It still remains a standing joke in lecture halls when we have our tasting practicals for someone to pipe up that it seems to in fact be white wine in the glass in front of us.

For those who like to dive deeper into the glass and deeper into thought the answer is for more fantastical and complex.

First let’s look at some biology and how the sense of smell works (this is a Crip notes version by an oenology student not a biologist). Flavour molecules slowly evaporate off the exposed area of the wine; these molecules are then inhaled when you sniff the wine. Inside your nose are receptor sites which the molecules are ‘bound’ to. The receptor then sends off an electrical signal that is received by the olfactory bulb and translated and sent off to the olfactory cortex which then interprets the smell of the compounds.

Never be upset when the more advanced taster finds more flavour’s than you in the wine. The more practice you get the more you will be able to differentiate between the different molecules and the more your olfactory cortex will be able to remember that this smell is elderflower rather than just a floral aroma.

The flavours we taste in wine are broken into primary, secondary and tertiary. Primary flavours are derived straight from the grape, some are precursors to flavonoids that evolve during fermentation and others are evident in the final product. These would include your berries and grassy/green notes. Secondary flavours are developed during fermentation; the primary precursors are bound with other ions and evolve into complex aroma characteristics such as volatile thiols and terpenes. These would be the tropical fruit aromas you can identify. Tertiary flavours are developed during maturation in the bottle, on the lees or in the barrel, allowing for smoother wines, cooked fruit, wooden flavours and rising bread.

Let’s go on a journey to illuminate the vastly unknown territory of flavour compounds:

Floral varietals such as Muscat, Gewürztraminer and Riesling contain monoterpenes such as linalool which can be perceived as orange blossom or lavender.

Fruity aromas that can be identified in most young wines are given off by esters. Esters are present in two different forms: Ethyl esters and acetate esters. Ethyl esters are formed during the enzymatic reaction between alcohol and acetic acid. An example of an ethyl ester is ethyl hexonate that gives rise to aroma characteristics such as stone fruit, strawberry, liquorice and green apple. Acetate esters are formed during amino acid metabolism and containing an acid group and a higher alcohol group. South Africa’s very own cultivar Pinotage can sometimes be guilty of having an over baring concentration of the acetate ester: Isoamyl acetate which gives off that infamous banana flavour.


Green and grassy aromas that you either love or love to hate in Sauvignon blanc, Cabernet sauvignon, Cabernet franc and many other cultivars. These can be given off by compounds called methoxypyrazines. Methoxypyrazines are secondary products of amino acid metabolism and are nitrogen containing compounds.  There are three major methoxypyrazines that have been identified: Isobutyl-Methoxypyrazines which give off bell pepper and cape goose-berry flavours, Isopropyl-methoxypyrazines which gives some Sauvignon blancs and semillions that cooked/pickled asparagus flavour, and secbutyl-methoxyoyrazines which also gives off green aromas.


Mouth-watering tropical fruit that make wines a bit too easy drinking are formed by volatile thiols. The three most predominant and evident in wines are 3-MH, 3-MHA and 4MMP, they are formed during fermentation by binding precursors to sulphur molecules. Aromas such as granadilla, guava, grapefruit, boxwood and gooseberry are given off by these molecules. They are very evident in Sauvignon blanc, Chenin blanc and Chardonnay.


Now that we have more of an understanding of what we smell it’s important to remember some simple tips to improve your tasting profile. Firstly, a sip or two is more than enough per wine in order to taste it, judge it and see if you love it. Secondly spitting is not gross, it is necessary in order to be able to taste every wine and remain a good level of sobriety toward the end of the tasting. Thirdly, have a designated tasting notes book, it may be hard to recall a specific wine from that tasting at that place that one time, so it’s great to have a reference. Lastly if you would like to expand your taste buds, don’t simply refer to the red fruit you smell in the pinot noir, elaborate: Is it fresh, cooked or cured? Is it a sour cherry or a sweet strawberry? Try and be as specific and elaborate as possible, it will also make it easier to identify a wine you have tasted before.

Happy tasting!

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