Whey proteins for reducing astringency: If it works for tea…

Important note: The following story should NOT lead you to conclude that you need to stop drinking wine if you generally avoid dairy. Please see the comments at the bottom of this post, this post on wine allergies (and why you probably don’t have them), and this post on gluten in wine.

Short: The main protein in whey, a voluminous byproduct of cheesemaking, might be a good (and cheap) fining agent for reducing astringency in red wine, but it’s going to need a lot more testing, and I’m (very) suspicious.

Longer:

Many people* add milk to black tea because it softens the harsh edges of what is so often an unfortunate cup of broken orange pekoe. The combination works because a milk protein, β-lactoglobulin, binds tannins. This was news a few years back because adding milk reduces astringency, but not nutrition value (unless you’re fine-filtering your tea after adding milk, and I can’t imagine you are). Whey protein-bound tannins won’t bind to your salivary proteins to dry out your mouth, but still work as antioxidants in your body.

Adding β-lactoglobulin from whey protein might for essentially the same reasons be useful to decrease the astringency of red wine. Casein, another milk-derived protein, is routinely used for wine fining. The benefit of making the switch is cost. Casein ends up in cheese. β-lactoglobulin ends up in the whey left over after making cheese. Ergo, the cheese-eating world has more β-lactoglobulin sitting around than casein, body-builders’ post-workout protein shakes and the occasional bottled whey beverage notwithstanding.

This is one of those so obvious and sensible-sounding ideas that I’d be inclined to think: surely someone’s already tried this and found that it doesn’t work or everyone would be doing it already. Still, a quick search of the scholarly literature suggests that no one has, publicly, though this study from 2007 found that β-lactoglobulin binds well to resveratrol.**

The chemists behind this just-published study found that β-lactoglobulin reduced astringency about as well as gelatin, gram for gram, at least for the random cheap French merlot they tested. Even better, β-lactoglobulin worked about as well as a combination of β-lactoglobulin and casein.

If you’re waiting for the catch(es), here they are:

  • β-lactoglobulin shouldn’t work as well as gelatin on the basis of established knowledge about tannin-protein interactions. Tannins bind best to big, loosely folded proteins with lots of an amino acid called proline. Tannins bind less well to small, balled-up proteins. Gelatin (and some major salivary proteins, coincidentally) are loosely folded and proline rich. β-lactoglobulin is small and balled up. The authors make a gesture toward figuring out why β-lactoglobulin still works by quantifying the concentration of total protein-precipitable tannins and a few specific, important tannin molecules in the wines before and after treatment with gelatin, β-lactoglobulin, or the β-lactoglobulin-casein combination. Those tests confirmed that β-lactoglobulin is binding tannin molecules, but also that they’re binding weakly.
  • This weak binding seems to involve groups of tannin molecules strung together. β-lactoglobulin doesn’t do a good job of binding to individual tannin units (monomers) hanging out in the wine on their own.
  • These authors only tested whey protein with one red wine (the random French merlot), and only measured astringency by chemical approximations, not with real swirling and spitting tasters. So I’m suspicious. Surely, the idea of using whey protein for wine fining has occurred to at least one food processing house or winemaking supply company with the resources to test the theory out on their own, on many different wines, with their in-house sensory panels doing the tasting. If it worked, whey protein would be on the market. If it didn’t, they might well not broadcast the news. And – forgive me this, because excellent research can come from unlikely places – the authors are from the University of Reading in the UK and the National University of Rosario in Argentina, neither of which is a hot bed of groundbreaking wine research. That’s not to say the researchers aren’t good, but it is to say that they might not have ideal access to the accumulated wisdom of the field.

An interesting idea. Unlikely to be the next wine chemistry success story, but an interesting idea.

 

*I add milk to black tea on rainy days because the aroma evokes England and memories of a childhood I never actually had of drippy days shut up inside with endless tea and books in a British country house. I can tell you this because it has rained here every day for more than a week.

**I think that at least the general idea that β-lactoglobulin binds to wine tannins might be buried in this 2011 masters thesis conducted at Massey University in New Zealand, but I’ll be honest: I didn’t have the patience to read the whole thing carefully enough to find out.