Introduction to Fermentation Process

What is Fermentation?

 

Fermentation is the process in which the chemical transformation of organic substances into simpler compounds carried out by the action of bio-catalysts (enzymes) produced by microorganisms like bacteria, molds or yeasts.

The enzymes act by hydrolysis, a process of predigesting or breaking down of composite organic molecules into smaller units or more easily digestible stuffs in case of foods

For example…

1. The enzyme carbohydratases act on carbohydrates. For an instance, enzyme  amylase act on starch and  convert it them into simple sugars which can be utilized easily by the microorganisms
   

2. The enzyme proteases act on various proteins. For an instance,  enzyme protease breaks down huge protein molecules initially into polypeptides and peptides and then into numerous amino acids, which can be readily and easily taken up by the microorganisms
   

3. The enzyme lipases on various lipids. For an instance, the enzyme lipase hydrolyzes complex fat molecules into simpler free fatty acids and glycerol making them available to the organisms
   

The end products of any fermentation process depend on the process aimed. It can be any of the following end product.

1. The cell itself.  i.e. Biomass production. (for e.g. Single cell proteins)
   
2. Primary or secondary metabolites of microorganisms itself. This can be produce by naturally isolated organisms (wild type) or can also be produce by  genetically improved strain. See Table 1.
   
3. The products foreign to the microorganisms. This can be produced by genetically engineered organisms by the help of recombinant DNA technology . See Table 2.
   

Definitions of  Fermentation

The term “fermentation” can describe in various ways. Following are some definitions  of fermentation which explain of fermentation  from origin to till date

• “The bubbling observed when sugar and starchy materials underwent a transformation to yield alcoholic beverages”  (Original definition of fermentation)

• “The process in which alcohol was formed from sugar, regardless of whether the causative agent was or was not biological” (Anonymous)

• “Those anaerobic reactions through which microorganisms obtained energy for growth in the absence of oxygen” (Fermentation term defined by Louis Pasteur)

• “It applies to both the aerobic and the anaerobic metabolic activities of microorganisms in which specific chemical changes are brought about in an organic substrate” (Anonymous)

•  “Almost any process mediated by or involving microorganisms in which a product of economic value produced” (From an industrial microbiology point of view)

A Brief History of Fermentation 

• The invention of the compound microscope in the late 1500s, a simple instrument  which revolutionized man's knowledge of invisible tiny microbial world can be considered as the origins of microbiology

• A scientific discovery, which electrified the scientific world of the time, was done by the greatest of the early microscopists, Anton van Leeuwenhoek, in 1675. He saw and reported one-celled organisms, which he called "animacules" (Today they are called "protozoa.")

• Lavoisier, in the late 1700s showed  the process of transforming sugar to alcohol and carbon dioxide

• In 1810 J.L. Guy-Lussac,  on the basis of detailed analyses, specified ethanol and CO₂ as the principal products of the decomposition of sugar summarizing with the  well-known equation: C₆H₁₂O₆ –> 2C₂H₅OH + 2CO₂ (an ex post facto formulation)

• The first concrete evidence of the living nature of yeast came out between 1837 and 1838. One of the important feature of the yeast that “yeast was a living organism that reproduced by budding” was explain by  Cagniard-Latour (1837) in France, and Schwann (1837) and Kutzing (1837) in Germany, independently

• Louis Pasteur (1850s and 1860), proved conclusively in a series investigations that fermentation was initiate by living organisms

• Louis Pasteur (1857) explained that living organisms are responsible for  lactic acid fermentation

• Louis Pasteur (1860) demonstrated that bacteria cause souring in milk and later on the role of microorganisms in food spoilage show the way to the process of pasteurization

• In 1877, Pasteur published his famous paper on fermentation, titled “Etudes sur la Biere”, English meaning “Studies on Fermentation”. He defined fermentation incorrectly as "Life without air," but correctly showed specific types of microorganisms carry out  specific types of fermentation processes and produce specific end products

• The term "microbiology" was first used in English in 1885, long after Pasteur's major discoveries

References

• Principles of Fermentation Technology

             (2^nd  edition,  by Peter F. Stanbury, Allan Whitaker and Stephen J. Hall, Butterworth-Heinemann, An  imprint of Elsevier Science.)

• Industrial Microbiology

          (By Casida L. E.New Age international (P) ltd publications)

• A Text Book of Industrial Microbiology

               (2^nd edition By Wulf Crueger & Anneliese Crueger)

• Biotechnology: Food Fermentation Microbiology, Biochemistry & Technology Vol. 1 & 2

           (By V.K. Joshi & Ashok Pandey)

• Manual of Industrial Microbiology and Biotechnology

(2^nd Edition by Arnold L. Demain and Julian E. Davies, Ronald M. Atlas, Gerald Cohen, Charles L. Hershberger, Wei-Shou Hu, David H.   Sherman, Richard C. Willson and J. H. David Wu)

• Industrial Microbiology-An introduction

(By Michael J. Waites, Neil L. Morgan, John S. Rockey and Gary Higton)

• Comprehensive Biotechnology-The Principles, Applications and Rugulations of Biotechnology in Industry, Agriculture and Medicine

(By Mrray Moo Young)

• Fermentation Technology : Up Stream Fermentation Technology- Vol-I

(By H. A. Modi-Pointer Publications)

• Fermentation Technology : Down Stream Fermentation Technology- Vol-II

(By H. A. Modi-Pointer Publications)

• Industrial Microbiology by Prescott and Dunn's

(4^th edition, edited by Gerald Reed, CBR publications)

• Fermentation Technology