The Auswine Forum

So far this summer, I've returned four bottles of various wines for replacement and all were under screwcap and had the same fault verified by the wineries or representatives: Heat damage.
The wines typically tasted flat and acidic, the reds most niticeably had a bitter chemical finish.

Interesting.

This is not how I remember the taste of heat damaged wines under cork. Under heat the wine usually expand, pushing the cork out a little and will have a slight cooked flavour but stil drinkable. Sometimes they look very forward but still good.

Under screwcap in a completely airtight space it must be a different chemical reaction.

Our warm climate and the carry trucks I often see standing for a long time with cartons of wine exposed to the sun in the back of liquor stores makes me wonder if there are many more bad bottles to come...

Personally I think that screwcapped wines can't take heat damage.
This could escalate into a huge problem with transportation in the summer months.

Cheers,
Attila

I wouldn't of thought the increasing sealing ability of the screwcap would change the chemical reaction. May change the rate though? Perhaps the difference in how the wine was prepared for bottling i.e. sulfur addition may create the difference?

I think an experiment is in order

Find a wine that is bottled under both and cook them (as well as having controls and maybe the cork sample should be two cooked and uncooked to allow for potential bottle variation/cork taint)

cheers

Carl

"I wouldn't of thought the increasing sealing ability of the screwcap would change the chemical reaction."

Actually, an incerase in pressure cuases an increase in a chemial reaction.

The screw cap, by the sounds of it, will hold in place and therefore the pressure in the top of the bottle is greater compared to the equivalent cork, which will slide out under the same pressure, hence a lower pressure in the neck.

Make sense?

Paullie wrote:"I wouldn't of thought the increasing sealing ability of the screwcap would change the chemical reaction."

Actually, an incerase in pressure cuases an increase in a chemial reaction.

The screw cap, by the sounds of it, will hold in place and therefore the pressure in the top of the bottle is greater compared to the equivalent cork, which will slide out under the same pressure, hence a lower pressure in the neck.

Make sense?

Erm.....try not to selectively quote. If you read the sentence after you should see that you didn't understand what I said.

If its any help the reaction rate is the correct vernacular to stop this sort of confusion I guess.

cheers

Carl

griff wrote:I think an experiment is in order

Find a wine that is bottled under both and cook them

As I said, it's been done. I had "cooked" wine in both variants although not of the same but the screwcap version was always affected to the level of undrinkability.
Sun cooked that is.
Cheers,
Attila

griff wrote:

Paullie wrote:"I wouldn't of thought the increasing sealing ability of the screwcap would change the chemical reaction."

Actually, an incerase in pressure cuases an increase in a chemial reaction.

The screw cap, by the sounds of it, will hold in place and therefore the pressure in the top of the bottle is greater compared to the equivalent cork, which will slide out under the same pressure, hence a lower pressure in the neck.

Make sense?

Erm.....try not to selectively quote. If you read the sentence after you should see that you didn't understand what I said.

If its any help the reaction rate is the correct vernacular to stop this sort of confusion I guess.

cheers

Carl

Agreed, doesn't change the chemical reaction, only the rate at which it occurs.

Attila wrote:

griff wrote:I think an experiment is in order

Find a wine that is bottled under both and cook them

As I said, it's been done. I had "cooked" wine in both variants although not of the same but the screwcap version was always affected to the level of undrinkability.
Sun cooked that is.
Cheers,
Attila

Fair enough. But I would like it to be more scientific and have a control. Did you have a replacement of the same wine that wasn't cooked and did that taste fine? That would be a de facto control.

cheers

Carl

Paullie wrote:
Agreed, doesn't change the chemical reaction, only the rate at which it occurs.

Chemical equation for working that out is: PV = nRT

Whoa, first year chem all again.. eeeep!

Experiment as suggested sounds fantastic! Use inexpensive wines!!!!

Daniel Jess wrote:Experiment as suggested sounds fantastic! Use inexpensive wines!!!!

The trick is to find some cheap plonk available from the same place bottled under both natural cork and screwcap - a few years ago that might have been easier when some wineries and retailers were hedging their bets.

After seeing first hand the 7cm fill level drop of a bottle of 2002 Riesling that had been sitting on a retailer's shelf five years, I finally decided to cook a couple of cleanskin reds to evaluate the results (with a couple of control bottles for comparison). Unfortunately for the purposes this thread, they're all under screwcap.

Cheers,
Ian

n4sir wrote:

Daniel Jess wrote:Experiment as suggested sounds fantastic! Use inexpensive wines!!!!

The trick is to find some cheap plonk available from the same place bottled under both natural cork and screwcap - a few years ago that might have been easier when some wineries and retailers were hedging their bets.

After seeing first hand the 7cm fill level drop of a bottle of 2002 Riesling that had been sitting on a retailer's shelf five years, I finally decided to cook a couple of cleanskin reds to evaluate the results (with a couple of control bottles for comparison). Unfortunately for the purposes this thread, they're all under screwcap.

Cheers,
Ian

Agreed. I have been half seriously been looking around to try to find wine for the experiment but can't find any. I think the Jacob's Creek Reserve range might have bottled under both recently so will have a look out for those next time I'm in a wine store.

cheers

Carl

I think Red Knot is under screwcap & zork if that helps.

griff wrote:

n4sir wrote:

Daniel Jess wrote:Experiment as suggested sounds fantastic! Use inexpensive wines!!!!

The trick is to find some cheap plonk available from the same place bottled under both natural cork and screwcap - a few years ago that might have been easier when some wineries and retailers were hedging their bets.

After seeing first hand the 7cm fill level drop of a bottle of 2002 Riesling that had been sitting on a retailer's shelf five years, I finally decided to cook a couple of cleanskin reds to evaluate the results (with a couple of control bottles for comparison). Unfortunately for the purposes this thread, they're all under screwcap.

Cheers,
Ian

Agreed. I have been half seriously been looking around to try to find wine for the experiment but can't find any. I think the Jacob's Creek Reserve range might have bottled under both recently so will have a look out for those next time I'm in a wine store.

cheers

Carl

I should have thought of that one - it was only a couple of months ago I saw bottles of the 2004 Shiraz under screwcap and cork at the grocer over the road from work, and picked up a bottle of the screwed version and was quite disappointed - ironic as I thought it would be more tolerant of the shop storage/display.

I went back there tonight with no luck - they still had a couple of 2004 Shiraz under cork, but all the screwcapped wines were 2005.

Ps. If someone does try this experiment, what exactly are the parameters going to be - ie. how long are the wines going to be cooked for (say in a tin shed or on a window ledge at 35+ degrees for three days) and then opened after, and will there be controls with regularly cellared wines, and wines cooked and then returned to the cellar (to try and duplicate Roger Pike's 'Lazarus' experience as noted on Attila's duplicate thread on the other forum).

Cheers,
Ian

2004 Philip is available under cork and screwcap - if you look about.
GW

Maybe someone with the cork lobby may want to test this theory properly and commission testing with the AWRI. Maybe one of the few flaws for screwcaps. And with global warming will it only be more of a problem?

Attila wrote:So far this summer, I've returned four bottles of various wines for replacement and all were under screwcap and had the same fault verified by the wineries or representatives: Heat damage.
The wines typically tasted flat and acidic, the reds most niticeably had a bitter chemical finish.

Interesting.

This is not how I remember the taste of heat damaged wines under cork. Under heat the wine usually expand, pushing the cork out a little and will have a slight cooked flavour but stil drinkable. Sometimes they look very forward but still good.

Under screwcap in a completely airtight space it must be a different chemical reaction.

Our warm climate and the carry trucks I often see standing for a long time with cartons of wine exposed to the sun in the back of liquor stores makes me wonder if there are many more bad bottles to come...

Personally I think that screwcapped wines can't take heat damage.
This could escalate into a huge problem with transportation in the summer months.

Cheers,
Attila

Interestingly I heard a story about a problem with a well regarded 2005 Pinot Noir bottled under DIAM over the weekend.

The owner of the store said they had opened three bottles and struck two duds - the dud wines were bitter and short, and left a strange silver spoon sensation on the back palate.

Some of their wine storage isn't the best, and I had asked whether the wines in question had been heat affected under the lights - it was old stock and he said it may be a possiblity, although there weren't any obvious 'cooked' fruit characters either.

I get the feeling we're going to hear more about these nasty surprises - that said the closures themselves aren't the fault, it's the stupid way they're being stored.

Cheers,
Ian

We struck several dud bottles of wines sealed with screwcaps at wineries in Victoria, in each case the next bottle opened was not faulty. These were not the (too common) reductive problem, but examples of wines which exhibited stripped fruit, disjointed palate and sour/metallic finish.

The first was at Bests, where the first bottle of Bin 1 Shiraz 2005 was showing these unpleasant characteristics and the next bottle (probably from the same box) was bright and vibrant and balanced as expected.

One possible explanation offered (by another winemaker) is that even where a pack of bottles is freshly opened from shrink wrap at bottling time, they are separated in the pack with layers of masonite and there may be some dust contamination (or other contmaination) that isn't removed by simple rinsing.

It may be significant that Bests has invested in a new bottling line that thoroughly rinses each bottle with sterile-filtered water dosed with a small amount of sulphur prior to filling.

Blame the winemaker and the bottling process, not the seal.

Liebichwein have a couple of reds which they do under screwcap & cork