Fermentation lecture 1 intro

give the historic , biochemical and simple  definition for fermentation

Historical definition (Pasteur, 1822-1895) 
● “La fermentation c'est la vie sans l'air” 
● Based on studies of alcoholic fermentation using yeast 
● Etymology: Fervere (Lat.) = to boil, to leaven 

 
2. Biochemical, bioenergetic definition (Kluyver 1924*): 
A process that derives metabolic energy from the oxidation of 
organic compounds (mostly carbohydrates) and uses an 
endogenous electron acceptor (usually also an organic compound) 

Bioprocess driven by microorgansims yielding a product with desirable properties. 

does fermentation mean spoilage

no

• In a well conducted fermentation process, desirable microorganisms 
  (“the good”) are abundant/dominant 

• A spoiled/rotten food product is dominated by undesirable 
  microorganisms (“the bad” en “the ugly”) 

Historic preservation techniques

-Drying of food 
- Heating > smoking 
-Salting – brining 
- Storage in leaves/skins > fermentation 

benefits of fermentation

• prevents spoilage, 
• increases the microbial safety, 
• improves digestibility, 
• adds taste and aroma, 
• improves textural properties, 
• & adds nutritional value. 
and also because... 
• fermented foods are abundant in human diet! 
• it is a sustainable and natural processing technology 

Ways to start fermentation process 

Ways to start fermentation process 

1.Spontaneous fermentation: 
 Raw material not sterile 
 Depends on “contaminating” resident microbiota 

 
2. Back-slopping procedure: 
 addition of sample previous batch 

 
3. Starter cultures: 
 undefined mixed culture 
 defined mixed culture 
 defined single strain starter 

describe Spontaneous fermentation

 Raw material not sterile 
 Depends on “contaminating” resident microbiota 

Spontaneous fermentation advantages and disadvantages

Problems: 

Contamination with: 
 Pathogenic micro-organisms – safety issue 
 Spoilage-causing micro-organisms – quality issue 

 
Fermentation rate (speed): 
 Unpredictable 
 Conditions not constant: Quality, composition & safety 
of final product not guaranteed 

describe Starter cultures advantages and disadvantages

what are the workhouses

• Lactic acid bacteria LAB 

• Yeast  

• Moulds 

lab products 

yeast

moulds

What is meant by natural fermentation?

Microorganisms responsible for fermentation are present in raw materials.

advanatges and disadvanatges for natural fermentation

Natural fermentation: Microorganisms responsible for fermentation are present in raw materials. 

Disadvantages of natural fermentation are irregular reaction course, potential spoilage and possible survival of pathogens 

disadvantage of starter cultures

Disadvantages of the use of defined fermentation starters are that these require more complex and expensive techniques.Furthermore, working under sterile circumstances is necessary when defined fermentation starters are used.