Agents of Fermentation

Source: Here

Scientists Make New Beer Yeast

“You can now produce lager yeasts that are very different from one another,” Gibson says. All the resulting hybrids outperformed their parents, producing alcohol faster and at higher concentrations and turning out tastier products, as documented in a paper published in the Journal of Industrial Microbiology & Biotechnology. In particular, they made 4-vinylguaiacol, which resulted in flavors more characteristic of Belgian wheat beers. “The beers have a clovey aroma,” Gibson says. “It's actually quite nice but maybe something we don't always want. The idea is to have a whole range of strains, and you just pick and choose.” The hunt has now turned to finding new yeast unions that gobble up sugar more effectively, potentially creating lower-calorie beers.

Source: Here

Genetics, Molecular and Cell Biology of Yeast - Roger Schneiter

"The most well-known and commercially significant yeasts are the related
species and strains of Saccharomyces cerevisiae. These organisms have long been
utilized to ferment the sugars of rice, wheat, barley, and corn to produce alcoholic
beverages and in the baking industry to expand, or raise, dough. Saccharomyces
cerevisiae is commonly used as baker's yeast and for some types of fermentation.
Yeast is often taken as a vitamin supplement because it is 50 percent protein and is a
rich source of B vitamins, niacin, and folic acid.

In brewing, Saccharomyces carlsbergensis, named after the Carlsberg
Brewery in Copenhagen, where it was first isolated in pure culture by Dr. Emile
Christian Hansen around 1888, is used in the production of several types of beers
including lagers. S. carlsbergensis is used for bottom fermentation. S. cerevisiae used
for the production of ales and conducts top fermentation, in which the yeast rise to the
surface of the brewing vessel. In modern brewing many of the original top
fermentation strains have been modified to be bottom fermenters. Currently the S.
carlsbergensis designation is not used, the S. cerevisiae classification is used instead."

- Roger Schneiter, 2004

To read the entire publication click here

Debunking the Myth of Yeast Respiration and Putting Oxygen in Its Proper Place

Originally Published by Tracy Aquilla in Brewing Techniques (Volume 5, Number 2)

"Through it flies in the face of popular wisdom, yeast does not go through a respiration phase in the early stages of fermentation. A careful look at yeast metabolism and reproduction reveals a common misunderstanding and points the way to more sophisticated applications of oxygen in the brewery.

Fermentation is perhaps the most interesting and exciting part of brewing beer. There is something fascinating about watching yeast in action, and being close to the process contributes immensely to my enjoyment of my beer. No matter how well we do our part in preparing bitter wort for fermentation, it is the yeast that turns it into beer. For this reason alone, it is important to understand and appreciate what these microorganisms are really doing inside our fermentors. Most of the popular brewing literature, however, fosters a misconception about yeast and fermentation. This articles sets the record straight.

Most of the brewing literature indicates that brewers’ yeast (Saccharomyces cerevisiae and S. uvarum) required dissolved oxygen for a brief period of time after pitching so the cells can respire and grow, implying that yeast needs oxygen to bud and must respire before it can ferment wort. It is true that aerating or oxygenating wort is generally beneficial to fermentation, but it is untrue to say that yeast requires oxygen to reproduce or that yeast uses oxygen to respire during fermentation. The misunderstanding may be subtle, but it is a misunderstanding nonetheless. Gaining a clear understanding of the truth about how yeast works not only sets us on sound technical foundations, but has practical applications as well. This article briefly discusses yeast metabolism, clarifies the role of oxygen, and suggests some practical applications of this more refined understanding of fermentation processes."

Read the rest of the article: Here

Yeast under the Microscope x1000

Fermentation Tests for Starter and Air Access Experiments

Source: Here

Workhorse Beer Yeast Equivalent Chart (Wyeast/White Labs/Fermentis)

The goal was to create a yeast chart for common beer styles using three major beer yeast producers.  These yeasts may not be exactly equivalent but are comparable and referenced to use for the given beer style.  Experience is expected to vary with the combination of water, malt, hop, yeast, temperature and technique.

Printable chart here

	Smack Pack	Pure Pitch	Dry Yeast
Common Name	Wyeast	White Labs	Fermentis	Floculation	Attenuation	Temperature	Origin Similarity
American Ale	1056	WLP-001	US-05	Medium	73-77%	60-72°	Sierra Nevada
English Ale	1098	WLP-007	S-04	High	73-75%	64-72°	Fullers/Whitbread
German Ale	1338	WLP-011	K-97	Medium	65-70%	65-70°	Wisenschaftliche
German Lager	2124	WLP-830	W-34/70	Medium	73-77%	45-68°	Weihenstephan – 34/70
Kolsch	2565	WLP-003	S-23	Low	73-77%	56-70°	Weihenstephan – 165
Bavarian Weizen	3333	WLP-380	WB-06	High	73-77%	63-75°	Weihenstephan – 66
Belgian Saison	3724	WLP-565	T-58	Medium	65-75%	68-75°	Brasserie Dupont
Trappist Ale	3787	WLP-530	BE-256	Low	74-78%	64-78°	Westmalle

Genetic History of Yeast

Yeast Evolutionary Ecology and Domestication

"The beginning of agriculture and the domestication of plants and animals are among the most decisive events in the past 13,000 years of human history. Archaeological and biomolecular evidence indicates that rice wine was produced as far back as 7,000 BC in China. In Zagros mountains in Iran, wine was produced 5,000 BC and the domestication of barley in the Fertile Crescent led to the emergence of the forebear of modern beer in Sumeria 4,000 BC. Furthermore, yeast cells were detected in Egyptian leavened bread dough dated 3,000 BC and molecular evidence for the presence of Saccharomyces cerevisiae in wine fermentation has been obtained from pottery jars of the same period." - José Paulo Sampaio

 

"Rather than one or two domestication events leading to the extant baker's yeasts, the population structure of S. cerevisiae consists of a few well-defined, geographically isolated lineages and many different mosaics of these lineages, supporting the idea that human influence provided the opportunity for cross-breeding and production of new combinations of pre-existing variations." - Liti G, et al.

Original Research: Population genomics of domestic and wild yeasts.

Nature [2009, 458(7236):337-341]

Here It Is, the Genetic Family Tree of Beer

"The genetics research was led by Kevin Verstrepen, a yeast biologist at the Flanders Institute for Biotechnology and the University of Leuven, in Belgium. Verstrepen and his colleagues genetically sequenced more than 150 yeasts for the project. Most are brewers yeasts, with some wine, sake, bread, and biofuel-making yeasts thrown in to boot. Verstrepen notes that today's family tree focuses heavily on the yeast behind ales, and that his team is currently working on the genetic linage of the yeasts behind crisper, lighter lagers." - By William Herkewitz, Sep 8, 2016 

"By comparing the genetic makeup of modern yeasts the world over, Verstrepen found that the first linage of domesticated brewing yeasts (called Beer 1) formed around this time, the turn of the 17th century. This linage of yeasts started in breweries around Germany and Belgium. As brewers shared tips, tools, and yeast sediment, those yeast spread to breweries in the U.K., and then branched off into American breweries. Most of the yeasts used in brewing today fall under this Beer 1 linage."

Original Research: CELL: Volume 166, Issue 6, p1397–1410.e16, 8 September 2016

Lager yeast father (Saccharomyces eubayanus):

PNAS August 30, 2011 vol. 108 no. 35 

3D Yeast Model

Scientific American:
Why would a biochemist make three-dimensional prints of budding yeast cells?

Your Home Yeast Lab Made Easy

Great You Tube Channel from Sui Generis Brewing for learning about setting up a Yeast bank.

Probotic Beer Recipe

Here is a great article and story about the profession of pharmacy and beer brewing working together with the yeast: Saccharomyces boulardii.

Saccharomyces boulardii is a tropical species of yeast first isolated from lychee and mangosteen fruit in 1923 by French scientist Henri Boulard.  Numerous randomized, double-blind, placebo-controlled studies show the efficacy of S. boulardii in the treatment and prevention of gastrointestinal disorders.

Scientists Make the First New Lager Yeasts in Centuries

"Lagers are boring. When you pop a can of lager beer, you taste the product of closely related strains of Saccharomyces pastorianus. Their genetic variety pales in comparison to the small but diverse group of yeasts used for making ale and wine, which pump out vastly different metabolic by-products and a wide range of flavors. In fact, lagers have looked and tasted much the same for hundreds of years because breeding strains with new brewing characteristics and flavors has proved difficult; the hybrids were effectively sterile. But that is about to change."

Saccharomyces eubayanus

See Scientific American Article for the rest on "Lager lovers can now officially raise a toast because Gibson and his colleagues recently logged the success of re-creating the ancient fling between S. cerevisiae and S. eubayanus."

Yeast Cells Budding - Beer Yeast Life Cycle

Beer Yeast Life Cycle
Strange Brews: The Genes of Craft Beer