CT: The word “fermentation” has undergone many changes in meaning during the past hundred years. According to the derivation of the term, it signifies merely a gentle bubbling or boiling condition. The term was first applied when the only known reaction of this kind was the production of wine, the bubbling, of course, being caused by the production of carbon dioxide.
It was not until Gay-Lussac studied the chemical aspects of the process that the meaning was changed to signify the breakdown of sugar into ethanol and carbon dioxide (316). It was Pasteur, however, who marked the birth of chemical microbiology with his association of microbes with fermentation in 1857. He used the terms “cell” and “ferment” interchangeably in referring to the microbe. The term “fermentation” thus became associated with the idea of cells, gas production, and the production of organic byproducts.
The evolution of gas and the presence of whole cells were invalidated as criteria for defining fermentation when it was discovered that in some fermentations, such as the production of lactic acid, no gas is liberated. Moreover, other fermentation processes could be obtained with cell-free extracts indicating that the whole cell may not be necessary.
S: SD – https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/fermentation (last access: 28 January 2021)
N: 1. Late 14c., in alchemy, with a broad sense; modern scientific sense is from c. 1600; from Late Latin fermentationem (nominative fermentatio), noun of action from past-participle stem of Latin fermentare “to ferment” (see ferment (v.)). Figurative use attested from 1650s.
2. Fermentation, chemical process by which molecules such as glucose are broken down anaerobically. More broadly, fermentation is the foaming that occurs during the manufacture of wine and beer, a process at least 10,000 years old. The frothing results from the evolution of carbon dioxide gas, though this was not recognized until the 17th century. French chemist and microbiologist Louis Pasteur in the 19th century used the term fermentation in a narrow sense to describe the changes brought about by yeasts and other microorganisms growing in the absence of air (anaerobically); he also recognized that ethyl alcohol and carbon dioxide are not the only products of fermentation.
3. Raw materials containing sugars or be transformed into sugars can be used as fermentation substrates. The fermentable raw materials can be grouped as directly fermentable sugary materials, starchy, lignocellulosic materials and industrial wastes. Sugar containing materials require the least costly pretreatment, where starchy, lignocellulosic materials and urban wastes needed costly pretreatment, to convert into fermentable substrates.
4. Conventional crops such as corn and sugarcane are unable to meet the global demand of bioethanol production due to their primary value of food and feed. Therefore, lignocellulosic substances such as agricultural wastes are attractive feedstocks for bioethanol production. Agricultural wastes are cost effective, renewable and abundant. Bioethanol from agricultural waste could be a promising technology though the process has several challenges and limitations such as biomass transport and handling, and efficient pretreatment methods for total delignification of lignocellulosic. Proper pretreatment methods can increase concentrations of fermentable sugars after enzymatic saccharification, thereby improving the efficiency of the whole process. Conversion of glucose as well as xylose to ethanol needs some new fermentation technologies, to make the whole process cost effective. Goals of an effective pretreatment process are:
(i) formation of sugars directly or subsequently by hydrolysis
(ii) to avoid loss and/or degradation of sugars formed
(iii) to limit formation of inhibitory products
(iv) to reduce energy demands
(v) to minimize costs.
S: 1. OED – https://www.etymonline.com/search?q=fermentation&ref=searchbar_searchhint (last access: 28 January 2021). 2. EncBrit – https://www.britannica.com/science/fermentation (last access: 28 January 2021). 3&4. EUBIA – https://www.eubia.org/cms/wiki-biomass/fermentation/ (last access: 28 January 2021).