Malt Monday: Striking Gold

22 February 2010
By Richard Pliny

Ithaca Beer Company Excelsior! White Gold


Style:“Rustic Pale Wheat Ale”
Color: Pale to Amber
ABV: 8%
Price Point: $10 for 750 mL
Technical Notes:
From the Ithaca Beer website: “A Belgo-American Ale brewed with domestic barley and French wheat malts, the finest Continental and U.S. grown hops, and fermented with Belgian, English and Wild yeasts.” Bottle-conditioned.

Hedonic Notes:
The beer pours dark gold and opaque with thick white foam.  Very effervescent with bubbles rising through the glass throughout the tasting.  There is a good amount of yeast at the bottom of the bottle, as one would expect from a bottle-conditioned wheat beer.

Lemon zest and citrus notes dominate the aroma with a slight bit of funk almost akin to {Brettanomyces} horse blanket.  A slight earthy, hoppy smell is present along with a traditional Belgian clove taste.

Citrus pervades the palate to start, reinforced by a wheaty maltiness.  Initial flavors subside to a faint lingering sour taste.  The finish is drier than expected for a wheat beer.  A slight acidity may be perceived initially, possibly due to the high carbonation.  Also, this beer surprisingly lacks any solvent-like taste despite being 8% alcohol. Its dry mouthfeel with a great deal of carbonation creates a Champagne-like texture.

This beer is fairly palatable overall, with no single flavor overwhelming.  That said, the balance almost makes this beer boring.  Though the label says English yeast it’s not easily discernible, with any sweetness being dominated by the clear Belgian presence.  Belgian yeast flavors (fruity ester and spice) dominate the first flavors while lingering flavors are almost sour in composition. 

Rating: corkcorkcorknocorknocork 3 out of 5 corks . With regard to other wheat beers, White Gold sets itself apart, almost reminding one of a Berliner Weisse.


Science!

Wheat beers are traditionally left cloudy and have a thicker mouthfeel.  This is due in large part to high protein content, but also to elevated beta-glucan levels.  Glucose monomers may be linked together between the 1 and 4 carbons in one of two conformations (α-1,4-glycosidic linkage).  As seen below, alpha conformations are formed when the oxygen atom attached to the number 1 carbon pointing downward, beta conformations see this same bond pointing upward.

Beta glucans

The difference may look subtle, but the beta connection is the reason cows need 4 stomachs to digest grass, while starch begins breaking down in plain old saliva.

Polymers of beta-glucans are akin to cellulose, while alpha-glucans include starch.  Barley malt contains a very high proportion of alpha-glucans, while wheat contains a large fraction of beta-glucans.  The primary difference of concern for beer brewers is the ability to break down these sugar structures.  Amylase enzymes (to be discussed in more detail in a future post) are able to break only alpha glycosidic bonds.

Being more easily broken down, alpha-glucans yield simple and highly soluble sugars that may be metabolized easily by the yeast.  By contrast, beta-glucans can not be broken down by the barley enzymes that enable the mashing process, resulting in complex sugar structures in the wort.  These sugars help to contribute to the often sweeter final taste, relatively high final gravity, and increased viscosity prior to fermentation.

These sugar structures also have consequences for the beer production process.  Studies have shown that increased beta-glucan concentration and molecular weight result in increased viscosity of the fluid.  Even in low concentration ranges, there is a noticeable increase in viscosity.  This change in viscosity may make it more difficult to drain the wort from the grains in the lautering or sparging process.

Further Reading:
Jin, Yu-Lai; Speers, Alex; Paulson, Allen T. and Stewart, Robert J.  “Effects of Beta-Glucans and Environmental Factors on the Viscosities of Wort and Beer.”  Journal of the Institute of Brewing. 2004.

Daniels, Ray.  Designing Great Beers.  Brewer’s Publications: Boulder, CO.  2000.

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2 Responses to Malt Monday: Striking Gold

  1. Tom Mansell on 22 February 2010 at 4:34 pm

    Good stuff, Richard.

    On a side note, hydrolysis of Beta-glucans like cellulose is also important in the biofuel industry, and lots of money is spent on production and engineering of cellulases, enzymes that can break beta-glycosidic bonds to create sugars for ethanol biofuel fermentation.

  2. Malt Monday: The Warrior | Ithacork on 23 May 2010 at 10:20 am

    [...] amylase has the ability to break nonreducing alpha 1,4-glycosidic linkages.  Thus beta amylase yields maltose (dimmers) or maltotriose (trimers).  Yeast are not able to [...]

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