FERMENTATION By Jeff Louella

Why Understand Fermentation? Understanding the science behind fermentation can greatly affect the quality of beer made. There are some great products on the market to help home brewers excel. Brewers make wort, Yeast make beer. So be nice to your yeast.

Agenda Designing a Beer’s Fermentability Yeast Nutrition Yeast Pitching Controlling Fermentation Fermentation Phases

Designing a Beer’s Fermentability Dry vs Sweet

Fermentability - Dry All-Grain Mashing Mash at a lower temperature range. Many dry beers mash between 148° - 151° Use fermentable adjuncts Sugar, Honey, Maple & Rice Syrup, and Most Fruit will ferment out dry

Fermentability - Sweet All-Grain Mashing Mash at a higher temperature range. Many full mouth feel and sweeter beers mash between 154° - 160° Extract Brewing Liquid Malt Extract tends to have an average fermentability. Tough for big beers to ferment out fully. Adjuncts Brews with a lot of adjuncts, such as roasted barley, will not ferment out as much.

Yeast Nutrition Carbohydrates Nitrogen Vitamins Minerals Zinc Oxygen

Nutrition - Carbohydrates Sugars in order of concentration Maltose Maltotriose Glucose Sucrose Fructose

Nutrition - Nitrogen Amino Acids Amino acids collectively referred to as "free amino nitrogen (FAN)," are the principal nitrogen source in wort and are an essential component of yeast nutrition. It is the amino acids that the yeast cells use to synthesize more amino acids and, in turn, to synthesize proteins. Peptides Ammonium Salts

Nutrition - Vitamins Biotin Biotin deficiencies will result in yeast with high death rates. Panthotenic Acid Thiamin Inositol

Nutrition - Minerals Phosphate Phosphate is involved in energy conservation, is necessary for rapid yeast growth, and is part of many organic compounds in the yeast cell. Potassium Potassium ions are necessary for the uptake of phosphate. Calcium Magnesium Sulfur Trace Elements

Nutrition - Zinc The most important trace element is zinc, and at least 0.10 to 0.15 mg/l should be present in the wort. Zinc assists in protein synthesis in yeast cells and controls their nucleic acid and carbohydrate metabolism. Fermentations are accelerated by adding zinc chloride (0.2-0.3 mg/l) to the wort.

Nutrition - Products Complete Nutrients White Labs - Servomyces Wyeast - Nutrient Blend Nitrogen Fermaid K DAP

Nutrition - Oxygen Oxygen is an essential nutrient for yeast growth. Too low a level of dissolved oxygen can lead to insufficient yeast growth and, therefore, sticking fermentations. Too much oxygen can lead to excessive production of yeast.

Oxygenation Methods Shaking Carboy Aquarium Pump with Stone Pure O2 with Stone

Yeast Pitching Strain Pitching Rates Viability

Yeast Strain Specifications Attenuation Attenuation is the percentage of sugars that the yeast consume during fermentation. If the fermentation went to 1.000 gravity, that would be 100% attenuation. Understanding the different attenuation ranges of each strain will help determine the terminal gravity of the beer. Ex. 1.050 OG to 1.012 FG = 75% Attenuation Flocculation Flocculation refers to the clumping of yeast cells at the end of fermentation. Strains are separated into three main degrees of flocculation- High, Medium, and Low. An example of a highly flocculent strain would be an English Ale yeast, which will settle at the bottom of the fermentation tank. An example of a low flocculent strain would be a Hefeweizen yeast.

Pitching Rates 1 million cells of viable yeast, for every milliliter of wort, for every degree plato. 1.050 OG - 5 Gallons Wort - 91% Viability 175 Billion Cells - 1.9 Vials or Smack Packs 1.080 OG - 5 Gallons Wort - 91% Viability 273 Billion Cells - 3 Vials or Smack Packs Pitching Rate Calculator www.mrmalty.com/calc/calc.html

Controlling Fermentation Fermentation temperature control is one of the most important thing you can do that will make the most dramatic improvements in your beer. High Esters, Fruitiness, and Fusel Alcohols (too warm) Incomplete Fermentation (too cold or temp drop) Too Low Esters for Style (too cold)

Controlling Fermentation Ways to Control Temperature Temperature Methods Refrigerator or Freezer Fermwrap or Brew Belt Temperature Control Units Analog and Digital Controller Dual Stage Controller

Fermentation Phases Aerobic / Lag Fermentation Stabilization

Secondary Fermentation? True secondary fermentation happens when more sugars are added. What most home brewers consider secondary fermentation is basically the Stabilization phase. For most brews, there is no need to move beer into a secondary vessel.

Questions?

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