Food Fermentations Now and Then Biotechnology and Society January 14, 2005

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Food Fermentations Now and ThenBiotechnology
and SocietyJanuary 14, 2005

• Gülhan Ü. Yüksel, Assistant Professor
• Dept. of Food Science and Toxicology
• University of Idaho

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UI Snack Bar
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Food Fermentations

• Major events in food fermentation and
  preservation through the years Figure 1

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Food Fermentations Definitions

• Gentle bubbling or boiling action
• Production of CO2
• Pasteur life in the absence of oxygen
• Gay-Lussac
• alcoholic fermentation
• 1 mole glucose2 moles alcohol 2 moles CO2
• Controlled degradation of a food product

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Food Fermentations Definitions

• Anaerobic breakdown of an organic substrate by an
  enzyme system in which the final hydrogen
  acceptor is an organic compound
• Example
• NADH2 NAD
• Pyruvic acid Lactic acid
• (CH3-CO-COOH) (CH3-CHOH-COOH)
• Biological processes that occur in the dark and
  that do not involve respiratory chains with
  oxygen or nitrate as electron acceptors

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Food Fermentations Biochemistry

• Sugars Acids Alcohols, Aldehydes
• Proteins Amino acids Alcohols, Aldehydes
• Lipids Free fatty acids Ketones

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Why Do We Ferment Foods?

• Food preservation
• Inhibit pathogens
• Inhibit spoilage organisms
• Change in organoleptic characteristics
• Flavor
• Texture
• Odor

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Controlled vs. Natural Fermentation

• Natural fermentation
• Create conditions to inhibit undesirable
  fermentation yet allow desirable fermentation
• Examples
• Lambic fermentation
• Beer-like beverage
• Brussels, Belgium
• Vegetable fermentations
• Vegetables salt

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Controlled vs. Natural Fermentation

• Controlled fermentation
• Deliberately add microorganisms to ensure desired
  fermentation
• Example fermented dairy products
• Lactose Lactic acid
• Starter culture
• Lactics or Lactic starter or Lactic acid bacteria
  (LAB)

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Controlled vs. Natural Fermentation

• Secondary fermentation
• Microorganisms other than starters (secondary
  flora)
• Example fermented dairy products
• Non starter lactic acid bacteria (NSLAB)
• Enhance organoleptic properties of product

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Which Microorganisms Dominate?

• Food related factors
• Nutrients
• pH
• Water activity
• Environmental factors
• Temperature
• Atmosphere
• Relative humidity

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Microorganisms Used in Food Fermentations

• Lactic acid producing bacteria
• Homofermentative LAB
• Heterofermentative LAB
• Ethanol producing yeast
• Saccharomyces cerevisiae
• Flavor producing microorganisms
• Bacteria, yeasts, molds
• Acetic acid producing bacteria
• Acetobacter

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Homofermentative LAB

• Anaerobic glycolysis for glucose utilization
• Glucose 2 Pyruvate 2 Lactate
• Actual yield of 1.8 mole lactate per mole glucose
  (90 conversion)
• Net energy yield 2 mole ATP/mole glucose
• Lactococcus, Streptococcus, Pediococcus,
  Lactobacillus (some)

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Heterofermentative LAB

• Hexose monophosphate or pentose phosphate pathway
• Glucose Lactic acid (50) Ethanol CO2
• Can also form acetate
• Net energy yield 1 mole ATP/mole glucose
• Leuconostoc, Lactobacillus (some)
• Some heterofermentative Lactobacillus
• Additional biochemical pathways to obtain energy
• Arginine fermentation
• Proton motive force

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Saccharomyces

• Saccharomyces
• Sugar fungus
• saccharo sugar
• myces fungi
• Found naturally on grapes and other fruits
• Many strains are commercially available
• Aerobic or anaerobic metabolism
• Alcohol is produced anaerobically
• Glucose Ethanol CO2

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Flavor Producing Microorganisms

• Bacteria
• Limburger Brevibacterium linens
• Swiss Propionibacterium freundenreichii
• Molds
• Camembert Penicillium camemberti
• Roquefort Penicillium roqueforti
• Tempeh Rhizopus oligosporus

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Fermented Dairy Products

• Products
• Cheese
• Fermented milks
• Yogurt
• Acidophilus milk
• Sour cream
• Cultured buttermilk
• Kefir
• Koumiss

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Fermented Dairy Products

• Microorganisms
• Lactococcus
• Leuconostoc
• Lactobacillus
• Others
• Preservation
• Lactic acid production

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General Cheesemaking Steps

• Pasteurization
• Add starter
• Lactose Lactic acid
• Form a clot
• Rennet curd or acid curd or acid-heat curd
• Cut curd
• Heat curd whey
• Remove whey
• Salting-Hooping-Pressing
• Curing-ripening

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Quality Changes During Processing/Aging

• Buttery flavor
• Citrate Diacetyl
• Some LAB
• Eye formation
• CO2 production
• Propionibacterium shermanii
• Blue veins
• Penicillium roqueforti

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Cheese

• Cottage cheese
• Roquefort
• Stilton
• Blue cheese
• Gorgonzola
• Camembert
• Brie
• Swiss
• Baby Swiss
• Gouda
• Edam

• Limburger
• Traditional brick cheese
• Cheddar
• Colby
• Sweet Brick
• Muenster
• Havarti
• Mozzarella
• Provolone
• Parmesan
• Romano

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Alcoholic Beverages

• Products
• Beers
• Wines
• Distilled beverages

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Alcoholic Beverages

• Microorganisms
• Yeast
• Saccharomyces cerevisiae
• Lactic acid bacteria
• Desirable or undesirable depending on the product

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Alcoholic Beverages

• Preservation
• High acidity/low pH (wine)
• Ethanol (all alcoholic beverages)
• Sulfites (wine)

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Wines

• Natural wines
• Dry
• Slightly sweet
• Sparkling
• Desert and appetizer wines
• Flavored specialty wines (e.g. Vermut)
• Sherry
• Sweet wines

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Winemaking

• Crushing grapes to obtain the juice called Must
  
• Addition of SO2 (depends on wine)
• Anti-browning agent
• Inhibits growth of undesirable organisms
• Fermentation
• Inoculate with active yeast culture (1-5)
• Incubate at 70-85oC
• Racking/Aging/Filtering/Bottling

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Fermented Vegetable Products

• Sauerkraut (cabbage)
• Pickles (cucumber)
• Olives
• Other vegetables

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Fermented Meat Products

• Semi-dry sausages
• Summer sausage
• Lebonon bologna
• Dry sausages
• Genoa salami
• Hard salami
• Pepperoni

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Asian Fermented Foods

• Soy sauce- fermented soybean souce
• Miso (Japan)-fermented soybean paste
• Tempeh (Indonesia)-fermented soybean
• Sufu (China)-fermented soybean curd
• Natto (Japan)-
• Lao chao (China)-fermented rice
• Tape ketan (Indonesia)-fermented rice
• Ang-kak (Korea)-fermented rice
• Ontjam (Indonesia)-fermented peanut press cake

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Fermented Cereal Products

• Breads
• Crackers
• Pretzels

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Vinegar

• Microorganisms
• Acetobacter and Gluconobacter
• Ethanol Acetic acid
• Preservation
• Acetic acid

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Chocolate

• Seeds of cacao trees
• Naturally occurring microbes
• Yeasts
• Bacteria
• Lactobacillus
• Acetobacter

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Food Fermentations

• Other examples of fermented foods Table 1

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Thank you!

• Questions?