Grape juice has more antioxidants than wine?

I came across this interesting blurb during one of my usual Concord browsing sessions and thought I'd put this up for general discussion.

Fruit of the vine

The folks at Welch's want you to know that you can enjoy the health benefits of red wine without the alcohol by buying their product, grape juice.

Concord grape juice works similarly to red wine in keeping blood flowing freely through your arteries, and grape juice has more antioxidants than wine, according to studies cited by Welch's.

Antioxidants decrease disease risk and delay age-related conditions. So why has red wine gotten more press coverage than grape juice as a healthy beverage? Probably because wine is more fun.

Now, we all know that Concord grapes are great for you, and most will correctly assume that this good news is great news for a labrusca fan like me. Having said that, I have always thought that wine per se had more antioxidants "locked in" due to the anaerobic nature of the fermentation process, and that what antioxidants are present in grape juice (or must, arguably) are subject to eventual oxidation.

What could be true but not explicitly mentioned is the chance that Concord grapes as such have more antioxidants than typical (i.e. vinifera) wine grapes, but which grapes in particular is, again, not mentioned, and I think that even among the viniferas, antioxidant levels vary.

This article from the CNN archives, on the other hand, seems to posit that grape juice has more antioxidant activity because alcohol is itself an oxidant; therefore, with the alcohol not being a factor in juice, those antioxidants function for a longer time in the body.

Interesting questions remain:

• Are all grapes equal in antioxidant capacity? (Probably not.)
• How does processing of juice and wine affect the availability of antioxidants?
• To what extent does the anaerobic process of alcoholic fermentation "lock in" the antioxidants, and is the effective bioavailability of those antioxidants greater in wine - despite the mediating influence of ethanol - than for juice?
• Finally, what kind of time curves are involved in the breakdown of bioavailable antioxidants in grape juice?

Hi Paul,

As a plant biochemist I can answer some of your questions about antioxidants. The main antioxidant in red or purple grapes are anthocyanins. These are pigments that give the grapes their characteristic colour. When you evaluate a red wine, the depth of the colour will give you a very good indication of its antioxidant concentration. The darker the wine the more antioxidants it contains. Other compounds found in wine and grape juice are also antioxidants such as revertrol, but they are generally at much lower concentrations than the pigments. So, a variety like pinot noir that tends to have less pigments and makes lighter coloured wines will have a lower antioxidant concentration than a cabernet sauvignon or syrah which have much darker in hues. Processing the grapes for fermentation will definitely affect the antioxidant concentration since the pigments are in the skins. The longer you leave the skins in contact with the wine up to a certain point, the darker it will be, and the higher antioxidant concentration the resulting wine will have. Anaerobic conditions are important for preserving the antioxidants in the wine because as you expose it to oxygen the antioxidants get oxidized and are no longer strong antioxidants as their double bonds get broken down in the process. Oxidation also causes the pigments to lose their colour, a process of chemical bleaching by the oxygen.

Many thanks, Tom.

I guess that would mean that wines like Foch and Norton - both extremely inky and pigmented - should be loaded with all the good stuff.

Hi Paul,

As a plant biochemist I can answer some of your questions about antioxidants. The main antioxidant in red or purple grapes are anthocyanins. These are pigments that give the grapes their characteristic colour. When you evaluate a red wine, the depth of the colour will give you a very good indication of its antioxidant concentration. The darker the wine the more antioxidants it contains. Other compounds found in wine and grape juice are also antioxidants such as revertrol, but they are generally at much lower concentrations than the pigments. So, a variety like pinot noir that tends to have less pigments and makes lighter coloured wines will have a lower antioxidant concentration than a cabernet sauvignon or syrah which have much darker in hues. Processing the grapes for fermentation will definitely affect the antioxidant concentration since the pigments are in the skins. The longer you leave the skins in contact with the wine up to a certain point, the darker it will be, and the higher antioxidant concentration the resulting wine will have. Anaerobic conditions are important for preserving the antioxidants in the wine because as you expose it to oxygen the antioxidants get oxidized and are no longer strong antioxidants as their double bonds get broken down in the process. Oxidation also causes the pigments to lose their colour, a process of chemical bleaching by the oxygen.

I'll add a few additional points to your post. Firstly, the alcohol of fermenting wine is an important factor in the amount of antioxidants leached out of the skins. As I understand it, that's the justification for chaptalization in France (to get more extraction). Secondly, alcohol is most decidedly not an oxidant; it's not much of an anti-oxidant (reducing agent) either, but classing it as an oxidant is just plain wrong. Thirdly, as you said, the more the juice/wine is exposed to oxygen, the less antioxidant capacity it'll have. Fourthly, Welch's claims are a tad disingenuous: while it's true that they're rich in antioxidants, it's not true that they contain any significant amouts of resveratrol and quercetin, the two components of red wine that have been mostly closely linked with health benefits. Intriguingly, the amounts of resveratrol and quercetin aren't linked to the amount of anthocyanins, either: Finger Lakes Pinot Noir has more than California Cabernet Sauvignon, for instance.


Mark Lipton

Mark, that was extremely helpful - thanks.

And I did forget to factor resveratrol and quercetin into the equation - very true.

Perhaps the reason why NY Pinot would have more of the healthful compounds is that the vines have to produce them to live in what is a decidedly harsher climate. That, in turn, probably translates into more bioavailable antioxidants for the happy consumers - us!

Mark, that was extremely helpful - thanks.

And I did forget to factor resveratrol and quercetin into the equation - very true.

Perhaps the reason why NY Pinot would have more of the healthful compounds is that the vines have to produce them to live in what is a decidedly harsher climate. That, in turn, probably translates into more bioavailable antioxidants for the happy consumers - us!

I think that the link is that cold climate grapes have thicker skins, and therefore more of the stuff that comes from the skins. You'd think that would also make them more tannic, but I'm not sure that that's the case. Oh, BTW, a recent Nature paper makes the claim that the cardioprotective benefits of red wine are more likely attributable to the tannins than resveratrol, but that's only one component of resveratrol's health benefits.

Mark Lipton

I'll add a few additional points to your post. Firstly, the alcohol of fermenting wine is an important factor in the amount of antioxidants leached out of the skins. As I understand it, that's the justification for chaptalization in France (to get more extraction). Secondly, alcohol is most decidedly not an oxidant; it's not much of an anti-oxidant (reducing agent) either, but classing it as an oxidant is just plain wrong. Thirdly, as you said, the more the juice/wine is exposed to oxygen, the less antioxidant capacity it'll have. Fourthly, Welch's claims are a tad disingenuous: while it's true that they're rich in antioxidants, it's not true that they contain any significant amouts of resveratrol and quercetin, the two components of red wine that have been mostly closely linked with health benefits. Intriguingly, the amounts of resveratrol and quercetin aren't linked to the amount of anthocyanins, either: Finger Lakes Pinot Noir has more than California Cabernet Sauvignon, for instance.
Mark Lipton

Mark,
I think I agree...if only I was smart enough to understand this chemistry stuff and what I was agreeing with.

I think I agree...if only I was smart enough to understand this chemistry stuff and what I was agreeing with.

That's all right, 'winger. You just keep showing up with a bottle of Jamet in tow and I'll be happy to discourse at length about all this crap-o-la.

Mark Lipton