rayg

Recipes 

From: "Acute Effect of Tea, Wine, Beer, and Polyphenols on
ecto-Alkaline Phosphatase Activity in Human Vascular Smooth
Muscle Cells"MARIA R. NEGRA÷O,et.al.
J. Agric. Food Chem. 2006, 54, 4982-4988



Beverage Polyphenols mg/L
green tea 937
black tea 654
red wine 1673
white wine 222
lager-type beer 446
stout beer 987

Ray

__________________
Zymotechnia Fundamentalis
Ask not for whom the beer twangs; it twangs for thee.

pcollins

Recipes 

But then there's this quote from the abstract:

"Teas, wines, and beers also inhibited ecto-ALP activity, largely according to their polyphenol content. All tested compounds and beverages improved or did not change AALTR cell viability. Stout beer was an exception to the described behavior."

Linked from here:

http://www.ncbi.nlm.nih.gov/pubmed/16819906

Just wondering what all that means. In the abstract are they saying that stout conformed to the behaviour according to polyphenol numbers or went against the behaviour? So the fact that stout has higher numbers is good, better or not so good?

rayg

Recipes 

More from that paper:

"All tested beverages significantly inhibited ecto-ALP activity
in AALTR cells...Concerning
beers, lager type beer, unexpectedly, had a stronger inhibitory
effect on ALP activity than stout type beer. Theoretically, stout
type beer has a higher antioxidant content than lager type beer
(57). We confirmed that the total polyphenol content of the stout
beer used in the study was higher than that of lager type beer.
Therefore, the beer polyphenol content does not seem to be
determinant of these beverages effects on ecto-ALP activity.
In this context, it must be stressed that polyphenolic compounds
present in beers are generally very different from polyphenols
of other beverages. None of the beverages tested diminished
cell viability, with the exception of stout beer."

So they were testing two things, and stout was good for
one and not the other. They were using a beer from
Portugal called SuperBock Stout.

Ray

__________________
Zymotechnia Fundamentalis
Ask not for whom the beer twangs; it twangs for thee.

emjay

Recipes 

And by polyphenols, they mean tannins? I suppose it could mean other things too since polyphenols are a group of chemicals, although they're hardly desirable considering that there are even finings agents focused on precipitating polyphenols...

ODaniel

Recipes 

Can someone post a link to the full text that doesn't require a login or other credentials?

rayg

Recipes 

I posted this in another thread yesterday:

From: "Effects of Protein-Polyphenol Interactions on Beverage Haze,
Stabilization, and Analysis" Siebert, K.J.
J. Agric. Food Chem., Vol. 47, 1999 353-362


"Protein-polyphenol interaction is important not just
in beverage haze. Dietary tannins (defined as water
soluble plant phenolic materials with molecular weight
>500 Daltons and the ability to precipitate
gelatin and other proteins from aqueous solution) have
an antinutritional effect (Mehansho et al., 1987; Baxter
et al., 1997). Tannins depress the growth rate of rodents
and chicks and decrease protein utilization in humans.
Hamsters are particularly sensitive to tannins, which
can be lethal to them in as little as 3 days."

So tannins aren't just polyphenols, they are large polyphenols.

From: "Polyphenols, Astringency and Proline-Rich Proteins
Luck, G. et. al. Phytochemistry 1994, 37, 357-371.

"Polyphenols (tannins) have a harsh astringent taste and
produce in the palate a feeling of roughness, dryness and
constriction [l]. According to Bate-Smith, and later
Swain and others [2,3] the primary reaction whereby
astringency develops is via precipitation of proteins and
mucopolysaccharides in the mucous secretions. Following
the classic experiments of Feeny [4,5] on the deleterious
effects of dietary tannins on the feeding of the larvae
of the winter moth (Operophtera brumatn) on oak the view
was formulated that tannins are uniquely a quantitative
defence. They repel predators by virtue of their strongly
astringent taste and because of their anti-nutritional
characteristics once ingested. Bate-Smith
[6] elegantly summarized their role in plant chemical
defence: “From the biological point of view the importance
of tannins in plants lies in their effectiveness as
repellents to predators, whether animal or microbial. In
either case the relevant property is astringency rendering
the tissues unpalatable by precipitating proteins or by
immobilizing enzymes, impeding invasion of the host by
the parasite.”

This paper also details the mode of binding of tannins to
proteins if you are interested.

Rayg

__________________
Zymotechnia Fundamentalis
Ask not for whom the beer twangs; it twangs for thee.