Fermentability Of Large Sugars

[Benchish]

I am currently studying brewing and i have yet to find a professional/scientific reference to the fermentability of maltotetraose with lager yeast, only distillers yeast.

I have come across many home-brew books that mention that only lager yeast can utilise maltotetriose.
Similarly i have found reference to wine/mead yeasts being unable to process maltotriose (less important but interesting).

This raises the question is this another example of home-brew lore or have i missed a reference somewhere?

 

[Nick JD]

Typically maltose is the most abundant sugar in wort.
Sugars in a 12% wort, in g/100 ml, were glucose + fructose, 0.9-1.2; sucrose, 0.4-0.5;
maltose, 5.6-5.9; and maltotriose, 1.4-1.7; total 8.3-9.3 (Evans et al., 2002). Some
yeasts only attack maltotriose (4.5) to a limited extent, while other `super-attenuating'
strains may also utilize maltotetraose (4.6) and dextrins.

Of the carbohydrates present in
wort, glucose (4.1), fructose (4.2), sucrose (4.3), maltose (4.4) and maltotriose (4.5) will
usually be fermented. Under-attenuating yeast strains will not ferment maltotriose while
super-attenuating strains will partly ferment maltotetraose...

 

[Benchish]

Cheers on the quick reply,

would you happen to have a reference for that info?

 

[Nick JD]

Cheers on the quick reply,

would you happen to have a reference for that info?

Brewing Science and Practice
Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and
Roger Stevens. 2004

EDIT: I can't find any reference to maltotetraose and lager yeasts ... but where it's mentioned, there's a much lower level of maltotetraose in Lagers than Ales in general - even though Lager yeasts aren't necessarily super-attenuative.

I'd say a Saison yeast can eat maltotetraose - so it might not be as cut and dried as to say that the one Sacc can and the other can't. Looks like most lager yeasts eat some, and most ale yeasts don't - but some do.

 

[hefevice]

Gregory J. Noonan, New Brewing Lager Beer, pp 31

"Trisaccharides are three molecule sugars. In malt, they are maltotriose, glucodifructose, and fructisant; raffinose, which is present in barley, disappears during malting. Maltotriose (three molecules of glucose) is slowly fermentable by most strains of brewing yeast. It is the only the only significant trisaccharide in brewing, accounting for up to 15 percent of wort solids."

The sugar that can be fermented by lager yeasts, and not ale yeasts is Melobiose, not Maltotriose. References as follows:

Noonan, pp 30

"Other disaccharides present in malt are sucrose (one molecule each of glucose and fructose), lactose (an isomer of sucrose) and melibiose. Sucrose is readily fermentable, lactose is unfermentable, and melibiose is fermentable only by Saccharomyces uvarum."

Note, Saccharomyces uvarum is the lager species, and now called Saccharomyces pastorianus.

Another reference that deals with the difference in fermentation ability between ale and lager yeasts:

Chris White and Jamil Zainasheff, Yeast the Practical Guide to Beer Fermentation, pp 50

"Besides the ability to ferment melibiose, what are the differences between ale and lager yeast?"


pp 254

"Lager yeast can ferment the carbohydrate melibiose and ale yeast cannot. Many brewers speak of this as the ability to ferment raffinose, which is a sugar composed of melibiose and fructose."

Hope these references meet your criteria; Noonan is a little old, but in this case I think it is accurate, White and Zainasheff was published last year.

[Edit - sentence order]