Phenolics vs. Esters

More goodies from the Beer Judge Certification Program.

Steve Peek wrote:

I think when people take a sip of wine or mead and say "phenolic," they usually have noticed bitterness or astringency in the taste. Tannins are a type of phenolic compound and can come from grape skin, seeds, and oak.

Fruity smells are associated with esters, which can be be present in the original must or be created during fermentation.

I can't help much if you're interested in the details of the chemistry, though.

Erroll

Steve Peek replied:

First, it is important to note that ignorance is the constant state of all life forms. So I should not have been embarrassed by my ignorance. My answer to the question was:

"As fermentation temperatures decrease fruity esters increase and as condition fermentation temperatures increase earthy increase. While I can not adequately describe earthy esters, I know the previous sentence is true. The only description I can conjure up about phenolics is they are tastes that don't belong there unless the guidelines say they should be there."

So I probably should have asked "Other than the cloves, bananas, and vanilla of Hefe-Weizen and Belgian yeasts, how do you know a phenolic when you meet one?"

Dick

I have taken it that Esters are fruity flavours produced by: (a) particular strains of yeast where the particular estery flavour is desirable such as wheat beers. (b) where particular strains of yeast produces unacceptable fruity flavours that are not supposed be present by fermenting at higher temperatures than is recommended. Fruitiness in lagers for example are generally not acceptable.

I have taken Phenolics to be tannins, an undesirable sensation of dryness and astringency that is not acceptable in any beer style. I understand that chlorine in the brewing water can bond with the phenols in the beer to form chlorophenols but, I have not experienced this, I think it's a somewhat rare fault.

Steve W (in Aus)

It is hard to describe a flavor or aroma in words. Fortunately, many esters and phenols have flavors that strongly resemble foods or substances that most people are already familiar with. For instance:

ISOAMYL ACETATE is an ester that smells like bananas or pears ETHYL ACETATE is an ester that smells generally fruity, or in higher concentrations like nail polish remover (because it is one) PHENYLETHYL ACETATE is an ester reminiscient of roses or honey

These are common ones in beer, but there are others that generally tend toward fruity, solventy, or even cheesy/sweaty. In my experience the esters become much more apparent the warmer the beer gets.

Phenolics also can be related to other substances. Phenolics are a very broad group of compounds--but I believe that when the word is used commonly to describe tastes in beer, though, it's usually meant to refer to phenolic compounds that create spicy or medicinal flavors:

4-VINYL-GUIACOL tastes like cloves or similar spices 4-VINYL-PHENOL can also be spicy CHLOROPHENOLS taste medicinal (to me almost mouth-numbing)

General flavors in this group are spicy, peppery, smoky, or medicinal.

One way to learn these flavors is by tasting beers known to have them. Of course fresh German hefeweizens are known for their banana esters and clove phenols. Some readily available beers that are estery without being phenolic are Fullers ESB or Youngs Special London Ale (make sure they are fresh or the esters may be diminished). Beers that are phenolic without being estery may be harder to come by. Some witbiers may fit the bill, as will old German Hefeweizens that have lost their banana esters. To me De Konnick is also pretty phenolic when found on tap in the US, without lots of esters.

Hope that helps.

Baums

Seems to me that one of the problems here is the dfference is judgement between beer-makers and wine-makers.

Esters are important to winemakers in that these include fermentation created compounds that can be desirably fruity - or undesirably fruity. I have no idea what, if any, role esters play in the tastes and aromatics of beer.

But with phenols, winemaking and beermaking seem to diverge. Just the other day I heard a beermaker, in a brew supply store, ranting to a winemaking customer about how undesirable phenolics were. Beer makers seem to wish to avoid the dry, astringent characteristics that ar associated with certain of the phenol compounds. But winemakers need certain phenolics - many of the armomatics, tannins, and flavanoid compounds that we desire fall under the broader characterization of "phenolics".

No. Both can be evident in aroma and flavor. In fact I personally tend to notice phenols more readily in the aroma than in the flavor.