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Yeast Biology

Uncover the essence of yeast, a vital component in biology, as we delve into its cellular structure, functions, and reproductive methods. Learn how yeast, a single-celled organism, plays a crucial role in brewing chemistry, from fermenting alcohol to bread-making. Discover the intricacies of yeast cell components like the nucleus, cytoplasm, and organelles, and explore the diverse species of brewing yeasts. Delve into the realm of brewing chemistry, microorganisms, and the significance of culturing microbes for optimal fermentation. Enhance your understanding of yeast biology and its impact on various industries.

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Yeast Biology

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  1. Yeast Biology

  2. General Biology Living Organism Classification- Taxonomy 3 Domain System5 Kingdom System

  3. What is a CELL? Cells are the “basic unit of life” Cells can live on their own, reproduce and do all the processes living things do Single cell organisms, like: bacteria and yeast Multicellular organisms, like: plants and animals

  4. What is a CELL? What are the 3 main parts of a cell? 1. Cell membrane 2. Nucleus 3. Cytoplasm

  5. What is a CELL? Cell (plasma) membrane The cell wrapper made of mostly lipids (fats) This wrapper has control over many important functions, including what goes in and out of the cell [bacteria + yeast]

  6. What is a CELL? Nucleus Primarily made of DNA/chromosomes/genes-- the so-called “genetic material” The genetic material is essentially the ‘recipe’ to make other cell parts, cell products (like esters or phenols), and entire cells, for that matter nucleus

  7. What is a CELL? Cytoplasm The water part of the cell Also contains organelles -- structures that have specific functions The fermentation chemical reactions occur our here

  8. What is a CELL? Cytoplasm Organelles -- structures that have specific functions Rough endoplasmic reticulum (ER): site of protein production. Smooth ER: site of lipid or fat production. Mitochondrion: site of energy production. Vacuoles: sacks of any kind of product or water.

  9. What is a CELL? Smooth ER Rough ER Mitochondrion

  10. What is a CELL? Cell Wall An additional structure, external to the cell membrane Most bacteria have cell walls All yeast have cell walls. (Animals like us and dogs, do not have cell walls.) Cell walls give the cell extra protection and structure- like an external skeletal system. Chemicals can go in and out of cell walls.

  11. Cell Reproduction- 2 types • Asexual • Only 1 • Goal • Fast • Simple • However, . . . • Sexual • Takes 2 • More lengthy in time • More complicated • More potential problems • Goal • However, . . .

  12. Cell Reproduction- 2 types • Asexual • Bacteria • Brewing/Distilling Yeast • Some Protists • Sexual • Plants • Fungi (wild yeasts) • Animals • Some Protists

  13. What is a yeast cell? Single cell organism Member of Fungus Kingdom Some yeasts cause human/animal diseases Yeasts are used to ferment alcohol: wine, liquor and BEER! Yeast can also be used to bake– the CO2 causes bread to rise

  14. What is a yeast cell?

  15. The 2 basic brewing yeast types: Ale Yeasts and Lager Yeasts Ale yeast species is Sacchromyces cerevisiae Lager yeast species is Sacchromycespastorianus Sacchromyces, literally means, “sugar fungus”

  16. The 2 basic brewing yeast types: Ale Yeasts and Lager Yeasts Ale yeast species is Sacchromyces cerevisiae Classic, ‘natural’ brewing yeast Ferment at higher temperatures Produce more complex flavor compounds -esters -phenols Lager yeast species is Sacchromycespastorianus Developed in lab at Carlsberg Brewery in 1883 (Saccharomyces carlsbergensis) Ferment at lower temperatures Produce less complex flavor compounds

  17. Yeast REPRODUCTION Brewing yeast reproduce asexually: they essentially make an exact copy of themselves…called BUDDING Yeast will start reproducing after being ‘pitched’ into the wort. There is not enough yeast to eat up all the s-sugars, so . . . They need to reproduce so they can eat up all the simple sugars to produce as much ethanol as possible Bud (new ‘baby’ yeast cell) Parent yeast cell

  18. BRETTANOMYCES (BRETT) • In the yeast Family- Saccharomycetaceae • Brettanomyces lives on the skins of fruit • Brettanomyces is most associated with barrel aged red wine • Brett is typically a contaminant; off-flavors • Certain traditional Belgian ales-- appreciated and encouraged.  • Lambic • Queuze • Saison/Farmhouse ales • Oud Bruin • Flanders Red Ale • Pitched or in inoculated/wine barrels • Read “Brettanomyces” Yeast book, p.58+

  19. BRETTANOMYCES (BRETT) • Flavor Profile/4 key by-products • 1. Volatile organic acids • a. Acetic acid- vinegar/sour • b. Fatty acids • 2. Esterases • a. Ethyl acetate- fruity, pear • 3. Tetrahydopyridines- mousy flavors • 4. Volatile phenols • a. 4-ethylphenol– band-aid • b. 4-ethylguaiacol- burnt wood • c. Others- spicy cinnamon, peppery, barnyard, horsey • *GROWS WELL IN O2 (over-oxygenated wort)

  20. BREWING CHEMISTRY C6H1206→ C2H5O + CO2 WHY WE ADD O2 BEFORE FERMENTING ENERGYFORREPRODUCTION

  21. BREWING CHEMISTRY TO CHILLEDWORT WHEN (EXACTLY) DO WE ADD O2 BEFORE FERMENTING?

  22. BREWING CHEMISTRY • Definition- • Microbes- (5 types) MICROBIOLOGY

  23. BREWING CHEMISTRY • CULTURING MICROBES • 1. Why? • 2. Theory– ideal conditions • 3. Culture medium • a. Agar • b. Broth • 4. Technique • (Swabbing/Tank Sampling p. 219, YEAST ) • 5. PCR microbe identification • Polymerase Chain Reaction • https://www.youtube.com/watch?v=bRadiLXkqoU MICROBIOLOGY

  24. BREWING CHEMISTRY MICROBIOLOGY

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