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Robyn Mackenzie

The question

I left a fairly expensive bottle of shiraz (a gift for my boss) in the back seat of my car for three hours at 35-38 C in the middle of summer here in Northern Australia and found there was a bit of liquid around the screwcap. I had no choice but to give it to him as I did not have the time to buy another. Now I am sweating bullets about giving him cooked wine. Will it continue to leak, and how long will it last?

The answer

There's only one way to tell, by opening and tasting. Unfortunately your boss will be the one doing the judging.

My suspicion is that he's got a slightly mulled shiraz on his hands. The wine will likely taste cooked or have the bruised, nutty-tang quality of Madeira. If outside temperatures reached 38 degrees, most likely your car's passenger compartment got even hotter with the greenhouse effect, assuming your windows were rolled up. That's one of the prices you pay for living in gorgeous Northern Australia, I'm afraid.

The leaky screwcap is the smoking gun. It suggests the wine got so hot that it pushed through the plastic liner under the cap and likely even deformed the metal. (Liquids expand faster than glass, which is why the wine had nowhere to go but up and out.)

It might interest you to note that one of the bad raps against kosher wine in the distant past had to do with heat. Wines labelled "mevushal" – which constitute only a minority of kosher offerings – must be pasteurized for the sake of purification. I think it's fair to say that most, until recently, tasted pretty cooked. But today's quality-minded producers rely on extremely short, flash-pasteurization techniques that do little harm to flavour.

If the screwcap on your pricey shiraz indeed became deformed, the wine will have a much shorter shelf life than usual – probably measured in months rather than years. That said, good-quality Australian shiraz is a forgiving beast. It's concentrated and tannic and can withstand heat and oxygen exposure better than most wines. I've sampled 20-to-30-year-old shirazes bottled under cork that had lost quite a bit of volume to evaporation (a phenomenon called ullage) and some were splendid. But I'm pretty certain none of them had been left in a boiling-hot car in their youth.

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