What causes petrol aromas in Riesling?

Quick answer

Petrol aromas in Riesling are mainly associated with TDN, short for 1,1,6-trimethyl-1,2-dihydronaphthalene. This volatile compound develops from grape-derived precursors, many of them linked to carotenoid breakdown, as the wine develops and ages.

The precursors are largely non-volatile in fresh grapes and juice. During winemaking and bottle ageing, chemical changes can release or form TDN. The result may remind you of petrol, kerosene, petroleum, plastic or mineral oil.

That description is an analogy, not evidence that petrol has entered the wine. TDN is a recognised part of Riesling’s developed aroma profile. It can add complexity at moderate levels, although a strong concentration may dominate the wine or hide its fruit.

How does the aroma develop?

A useful, simplified chain is:

grape compounds → non-volatile precursors → wine development and ageing → TDN → petrol or kerosene aroma

The grape-derived precursors are associated primarily with carotenoid metabolism. Some are attached to sugar molecules, which makes them less aromatic. Over time, wine acidity and other chemical reactions can help transform this precursor reservoir into TDN.

Bottle age commonly makes TDN more noticeable, but age is not a guarantee. Some young Rieslings show the character, while some mature wines remain mainly floral, citrusy, honeyed or toasty.

What influences petrol aromas?

Several factors can contribute, and they interact rather than acting as simple on/off switches.

Sunlight and berry temperature are among the better-supported vineyard influences. More sun exposure can increase the grape’s potential to form TDN-related compounds. Warm conditions may also encourage earlier or stronger expression in some wines.

Grape maturity and fruit composition matter because TDN precursors can increase as Riesling grapes ripen. But “late harvest causes petrol aroma” is too definite: ripeness is only one part of a larger system involving canopy, climate, vineyard conditions and the fruit itself.

Storage temperature can affect development. Research cited by the Australian Wine Research Institute found greater TDN increases in wine stored at 30°C than at 15°C. This does not mean a short period in an ordinary warm car explains every petrol-scented bottle.

Acidity, winemaking choices, yeast, closure and oxygen exposure can also affect formation, transformation or retention. Their influence is less universal. For example, a closure may affect how much TDN remains in the wine; it does not necessarily create the aroma.

Is petrol aroma a fault?

Not by itself. A Riesling with a clean petrol or kerosene note, lively acidity and fresh fruit may simply be showing a developed varietal character. Some people enjoy that complexity; others find it distracting.

Assess the wine as a whole. Is it fresh and balanced, or does the aroma overwhelm everything? Oxidation may bring bruised apple, stale, nutty, brown-fruit or sherry-like characters. Cork taint may smell mouldy, damp or like wet cardboard. Reduction may show struck match, sulphur or rotten-egg aromas. These are different issues from TDN.

A single descriptor cannot diagnose a particular bottle.

Why do some people notice it more?

Tasters differ in sensitivity, recognition and preference. One person may immediately smell kerosene while another notices only citrus or flowers in the same wine. Other compounds in the wine can also mask or strengthen TDN’s impression.

That is why a measured concentration does not perfectly predict whether a wine will smell strongly petrol-like—or whether someone will enjoy it.

Australian Riesling context

Australian Riesling can develop petrol or kerosene aromas, including in mature examples. An Australian Wine Research Institute survey found TDN across samples from Adelaide Hills, Eden Valley, Clare Valley, Tasmania and Victoria, with wide variation rather than one uniform regional pattern.

The survey linked higher TDN, in general, with bottle age and warmer conditions, but the relationships were not clear-cut. It is not accurate to say that Australian Riesling is uniquely prone to petrol character, or that a particular region guarantees it.

Frequently asked questions

Does every Riesling develop petrol aromas?

No. Wines begin with different precursor levels and experience different vineyard, winemaking and storage conditions. Tasters also vary in sensitivity.

Does petrol aroma prove that a Riesling is old?

No. Age often makes TDN more noticeable, but some young wines show it and some older wines do not.

Should I avoid a Riesling that smells like petrol?

Not automatically. Decide whether the aroma is balanced by freshness and fruit, and whether you enjoy it. If it comes with obvious stale, mouldy or sulphurous characters, a separate fault may be involved.