Fermentation

• Fermentation


  A process in which microorganisms, in the absence of oxygen, generate energy by oxidizing carbohydrates and related compounds
• Fermentation


  • It will preserve the food, and it will also enhance the taste, aroma, texture and nutritional value of the product
  • The preservation effect is the result of synthesis of lactic acid and heterofermentation – also, acetic acid and sometimes, antimicrobial substances
• Fermentation Processes


  • Spontaneous fermentation
  • Back-slopping
  • Addition of starter cultures
• Spontaneous fermentation


  The raw material and its initial treatment, will encourage the growth of an indigenous flora. For most spontaneous fermentation, a microbial succession takes place
• Back-slopping


  A part of a previous batch of a fermented product is used to inoculate the new batch
• Addition of starter cultures

  Most often used when it is possible to inactivate the indigenous flora by heat treatment of the raw material, permitting the growth of only the added starter microorganisms
• Metabolism, Activity, and Reliability

  • Anaerobic alcoholic fermentation
  • Lactic fermentation
  • Aerobic acetic fermentation

  
• Main end products


  Alcohol and organic acids
• Biopreservation


  • A general preservation effect is obtained by most food fermentation from the accumulation of organic acids and alcohols concomitantly with the reduction in free sugar levels, depletion of oxygen, and lowering the pH
• Probiotic effects


  Live microorganisms, which when consume in adequate amounts, confer a health effect on the host
• Bacterial Starter Cultures


  • Saccharomyces cerevisiae
  • Lactococcus lactis
  • Streptococcus thermophilus
  • Lactobacillus delbrueckii
  • Lactobacillus acidophilus
• Lactic acid bacteria (LAB)

  • Gram-positive rods or cocci, non-spore formers, catalase negative, obligatory fermentative, microaerophilic, usually nonmotile bacteria having extensive growth requirements
  • They produce mainly lactic acid from glucose fermentation
  • Homofermentative LAB mainly make lactic acid as their final product, whereas heterofermentative LAB make equal amounts of lactic acid, acetic acid, and CO2
• Fermented Milk Products


  • Cheese
  • Yogurt
  • Cultured Milk
  • Acidophilus Milk
  • Kefir

  
• Cheese


  Concentrated form of 2 major milk components- milk protein (casein) and milk fat. Besides milk, it contains a selected strain of bacteria, a milk clotting agent and sodium chloride
• Types of Cheese


  • Soft cheese
  • Semi-soft cheese
  • Hard cheese
  • Semi-hard cheese
  • Fresh cheese
  • Blue cheese
  • Processed cheese

  
• Types of Organism used in Cheese Production

  • Saccharomyces cerevisiae
  • Lactococcus lactis
  • Streptococcus thermophilus
  • Lactobacillus delbrueckii
  • Lactobacillus acidophilus

  
• Yogurt


  Produced by the controlled fermentation of milk by 2 species of bacteria Lactobacillus bulgaricus and Lactococcus thermophilus

  
• Types of Yogurt


  • Set yogurt
  • Stirred yogurt
  • Drinking yogurt
  • Flavored yogurt
  • Concentrated/Greek yogurt
  • Frozen yogurt

  
• Cultured Buttermilk


  The fluid remaining after ripened or sour cream is churned into butter using mesophilic starters
• Organisms used in Cultured Buttermilk

  • Streptococcus cremoris
  • Streptococcus lactis
  • Leuconostoc cremoris
  • Leuconostoc citrovorum

  
• Acidophilus Milk


  Whole or skimmed milk is fermented with Lactobacillus acidophilus which is said to have therapeutic benefits in the gastrointestinal tract
• Kefir


  A beverage produced by the action of lactic acid bacteria, yeast and acetic acid bacteria on milk, which produces a distinctive fermented milk product with unique properties

  
• Yeast as Starter Cultures

  • Brewing Yeast
  • Baker's Yeast
  • Winery Yeasts and Yeasts Used for the Production of Distilled Alcohols