Utilizes existing microorganisms

Is how all food fermentations began

Add desired microorganism.

Previously natural fermentations can now be controlled

A controlled lactic acid fermentation

Streptococcus thermophilus and Lactobacillus delbrueckii bulgaricus

1. Add ST and LB cultures
2. Inoculate (40-45C)
3. Fill in containers
4. Ferment to pH 4.3-4.5
5. Cool

• Grow first
• Reduce Oxygen level, pH, Eh
• Produce lactic acid and galactose from lactose
• Produces some CO2 and formic acid
• acid-sensitive

• Grow second
• use CO2 and formic acid
• Hydrolyze milk proteins, providing essential amino acids for ST
• produces lactic acid and galactose from lactose

• LB and ST produce exopolysaccharides, which serve as stabilizers
• Acetaldehyde is produced (green apple flavor)
• Defect of wheying-off (over acidification)
• Problems with bacteriophage to ST (viruses that infect and kill)

1. Malting
2. Mashing
3. Boiling wort and hops
4. fermentation
5. ageing
6. finishing

1. barley grains are soaked in water and held at 16-21C for 5-7 days
2. Dry to stop sprout development
3. Can roast to generate flavors and colors (the sugar maltose)
4. Primary role: source of amylases and proteinases

1. Crushed malt and malt adjuncts added to water and temp increase slowly to 75C
2. results in production of wort
3. Primary role: solubilize components of the malt and adjuncts; will provide food for yeast

1. Add hops to wort, boil for 2.5 hrs and filter
2. Primary role: Extract hops, concentrate and sterilize wort (essential oils)

1. Add saccharomyces cerevisia (Ales) or Saccharomyces carlsburgensis (Lagers)
2. Incubate for 8-10 days at 18-21C for Ales, incubate at 4-7C for lagers
3. Primary role: Produce ethanol, CO2, and flavor

1. Stored (lagered) at 0C for months
2. Primary role: precipitation of yeast and proteins; mature the flavor

1. CO2 produced during fermentation is added and then beer is packaged
2. Primary role: Carbonate and package

1. Standardize the milk
2. Pasteurize the milk
3. Add starter culture (lactococcus lactis)
4. add Chymosin
5. Cut curd and drain whey
6. Cheddar
7. Mill and salt
8. Press into block
9. Ripening

• Lactococcus lactis-
• added with multiple strains incase pH is off a lil
• Rate and extent of acidification is critical
• Converts lactose to L-lactic acid
• Control acid production with temp and salt
• Ihibition by bacteriophage is major concern (use different cultures during week)

• virus that infects bacteria
• made up of DNA and protein
• inactive- but viable
• survives pasteurization
• 1/1000 the size of bacteria cell
• pH tolerant
• repicate quickly
• 1--> 200 every 20 mins.

Lactic acid bacteria

Contaminants that grow during ripening to high cell numbers

Impact flavor, can be positive or negative

Lactobacillus casei most common

• Tons of metabolically active bacteria in every gram of cheese during ripening, with some dying and releasing cell contents into cheese matrix
• Enzymes and metabolites from these cells can serve as metabolites for other microbes, whose emergence may be good or bad for the flavor

1. Shred Cabbage (decompartmentalization=food for bugs)
2. Add salt, mix
3. Pack, cover, seal (anaerobes)
4. Incubate 21-24C (mesophiles produce acid)
5. Cool or Can. Cooling stops bugs from producing more acid, canning kills them to make sterile

• grows first in sauerkraut
• Reduces oxygen, pH, Eh
• produces acetic acid and lactic acid from glucose
• Converts fructose to mannitol (sugar alcohol)
• pH limits its growth

• Grows second in sauerkraut
• needs conditions provided by LM, is acid tolerant
• Produces lactic acid from glucose

Controlled mold fermentation

1. Soybeans soaked, hull removed, boiled
2. Add Rhizopus oligosporus, Mix
3. Incubate at 32C
4. Refrigerate

product: soy beans held together by mycelium.

benefits of fermentation:

• destroys trypsin inhibitor (allows it to be nutritious)
• eliminate bean flavor
• reduce cooking time from 6hrs to 10 mins
• longer shelf life