Author Topic: food fermentation  (Read 6762 times)

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food fermentation
« on: December 09, 2008, 03:40:45 pm »

the following is from
"Fermentation is the process of deriving energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. This is in contrast to cellular respiration, where electrons are donated to an exogenous electron acceptor, such as oxygen, via an electron transport chain. Fermentation does not necessarily have to be carried out in an anaerobic environment, however. For example, even in the presence of abundant oxygen, yeast cells greatly prefer fermentation to oxidative phosphorylation, as long as sugars are readily available for consumption.

"Sugars are the most common substrate of fermentation, and typical examples of fermentation products are ethanol, lactic acid, and hydrogen. However, more exotic compounds can be produced by fermentation, such as butyric acid and acetone. Yeast carries out fermentation in the production of ethanol in beers, wines and other alcoholic drinks, along with the production of large quantities of carbon dioxide. Fermentation occurs in mammalian muscle during periods of intense exercise where oxygen supply becomes limited, resulting in the creation of lactic acid.

"Fermentation products contain chemical energy (they are not fully oxidized) but are considered waste products, since they cannot be metabolized further without the use of oxygen (or other more highly-oxidized electron acceptors). A consequence is that the production of adenosine triphosphate (ATP) by fermentation is less efficient than oxidative phosphorylation, whereby pyruvate is fully oxidized to carbon dioxide.

"Lactic acid fermentation breaks down the pyruvate into lactic acid. It occurs in the muscles of animals when they need energy faster than the blood can supply oxygen. It also occurs in some bacteria and some fungi. It is this type of bacteria that converts lactose into lactic acid in yogurt, giving it its sour taste."

the following is from
"Fermentation in food processing typically refers to the conversion of sugar to alcohol using yeast under anaerobic conditions. A more general definition of fermentation is the chemical conversion of carbohydrates into alcohols or acids. When fermentation stops prior to complete conversion of sugar to alcohol, a stuck fermentation is said to have occurred. The science of fermentation is known as zymology.

"Fermentation usually implies that the action of the microorganisms is desirable, and the process is used to produce alcoholic beverages such as wine, beer, and cider. Fermentation is also employed in preservation to create lactic acid in sour foods such as pickled cucumbers, kimchi and yogurt.

"The primary benefit of fermentation is the conversion of sugars and other carbohydrates, e.g., converting juice into wine, grains into beer, carbohydrates into carbon dioxide to leaven bread, and sugars in vegetables into preservative organic acids.

"Food fermentation has been said to serve five main purposes:
~ enrichment of the diet through development of a diversity of flavors, aromas, and textures in food substrates
~ preservation of substantial amounts of food through lactic acid, alcohol, acetic acid, and alkaline fermentations
~ biological enrichment of food substrates with {added} protein, essential amino acids, essential fatty acids, and vitamins {see steinkraus}
~ detoxification during food-fermentation processing
~ a decrease in cooking times and fuel requirements

"Fermentation has some uses exclusive to foods. Fermentation can produce important nutrients or eliminate antinutrients. Food can be preserved by fermentation, since fermentation uses up food energy and can make conditions unsuitable for undesirable microorganisms. For example, in pickling the acid produced by the dominant bacteria inhibit the growth of all other microorganisms. Depending on the type of fermentation, some products (e.g., fusel alcohol) can be harmful to people's health.

"A stuck fermentation is where a fermentation has stopped before completion; i.e., before the anticipated percentage of sugars has been converted by yeast into alcohol or carbohydrates into carbon dioxide.
"Typically, a stuck fermentation may be caused by: 1) insufficient or incomplete nutrients required to allow the yeast to complete fermentation; 2) low temperatures, or temperature changes which have caused the yeast to stop working early; or 3) a percentage of alcohol which has grown too high for the particular yeast chosen for the fermentation.
"Corrections to stuck fermentations may include: 1) repitching a different yeast 2) incorporation of nutrients in conjunction with the repitched yeast; 3) restoration of accommodative temperatures for the given yeast.

"Alaska, despite its small population, has witnessed a steady increase of cases of botulism since 1985. It has more cases of botulism than anywhere else in the United States of America. This is caused by the traditional Eskimo practice of allowing animal products such as whole fish, fish heads, walrus, sea lion and whale flippers, beaver tails, seal oil, birds, etc., to ferment for an extended period of time before being consumed. The risk is exacerbated when a plastic container is used for this purpose instead of the old-fashioned method, a grass-lined hole, as the botulinum bacteria thrive in the anaerobic conditions created by the plastic."

see also

the following is from steinkraus (1995, 1996, 1997):
(note that this author does not consider meat fermentations; i think meat fermentation may be included in the lactic acid category, but i may be wrong; yet seinkraus does refer, see below, to protein rich foods such as nuts)

"Early {humans} very likely consumed fruits, leaves, berries, seeds, nuts probably tubers foraging from place to place as apes do today. Their bodily wastes, as well as their bodies at death, were recycled by microorganisms. There was a relatively large potential food supply and relatively few humans. Excess food supplies, fruits, berries, fell on the ground and the seeds either germinated or the carbohydrates, proteins, fats, and so on, were consumed by microorganisms using enzymes that converted fermentable carbohydrates to alcohol or acids and finally to water and carbon dioxide. Seeds and nuts and other protein-containing components were converted to their essential amino acids, peptides and finally to ammonia and water and a wide variety of chemical products. All of these reactions occurred (as recycling) for a billion years before {humans} arrived or evolved on earth.

"Foods invaded by bacteria producing toxins or by fungi producing mycotoxins are dangerous to {humans}. If the products of invasion are ill-smelling, off-flavored or toxic, human consumers try to avoid them and the foods are described as spoiled. If the microbial products are pleasantly flavored, have attractive aromas and textures and are nontoxic, the human consumer accepts them and they are designated as fermented foods.

"Food fermentations that improve food safety are as follows:
1. Food substrates rapidly overgrown by edible microorganisms leading to desirable flavors, aromas and free of toxins are resistant to development of spoilage, food poisoning or toxin-producing organisms.
2. Food fermentations involving lactic acid production
3. Food fermentations involving ethanol production
4. Food fermentations involving acetic acid production
5. Food fermentations involving highly alkaline conditions with liberation of free ammonia
6. Food fermentations carried out in the presence of high salt concentrations (above 13% w/w) are generally safe."

Offline TylerDurden

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Re: food fermentation
« Reply #1 on: December 09, 2008, 09:04:35 pm »
The trouble with the above notion is that fermenting meats doesn't produce alcohol. Wild animals also, I should add, love to consume fermented fruit as well as fermented meats. Given numerous studies which claim that a little alcohol, such as red wine etc., prolongs longgevity in humans, there may be something to those practices(I'm thinking of hormesis, in this case).

. Also, it should be noted, that due to survival of the fittest, if consuming fermented foods really were that dangerous, then those wild animals which went in for that practice would quickly die out, thus eliminating this practice altogether. However, it seems to be going strong among a wide number of species, indicating that it is a successful characteristic which promotes survival.

As regards food-poisoning, it's striking how it barely affects RAFers, with minimal effects if it does, while food-poisoning hits those on partially-raw or mostly-cooked diets with ease.
"During the last campaign I knew what was happening. You know, they mocked me for my foreign policy and they laughed at my monetary policy. No more. No more.
" Ron Paul.


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fermentation proteolysis lipolysis
« Reply #2 on: December 10, 2008, 02:53:10 am »

fermentation (carbs) - proteolysis (proteins) - lipolysis (lipids) = 3 different, albeit related, events

the following is from
"Fermentation has many important uses in industry. Though the word fermentation can have stricter definitions, when speaking of it in industrial fermentation it more loosely refers to the breakdown of organic substances and re-assembly into other substances. Somewhat paradoxically, fermenter culture in industrial capacity often refers to highly oxygenated and aerobic growth conditions, whereas fermentation in the biochemical context is a strictly anaerobic process. A very old method is ABE fermentation.

"There are 5 major groups of commercially important fermentation:
   1.   Microbial cells or biomass as the product, e.g. single cell protein, bakers yeast, lactobacillus, etc.
   2.   Microbial enzymes: catalase, amylase, protease, pectinase, glucose isomerase, cellulase, hemicellulase, lipase, lactase, streptokinase, etc.
   3.   Microbial metabolites :
   a.   Primary metabolites – ethanol, citric acid, glutamic acid, lysine, vitamins, polysaccharides etc.
   b.   Secondary metabolites: all antibiotic fermentation
   4.   Recombinant products: insulin, HBV, interferon, GCSF, streptokinase
   5.   Biotransformations: phenyl acetyl carbinol, steroid biotransformation, etc.

"Growth media are required for industrial fermentation, since any microbe requires water, oxygen, an energy source, a carbon source, a nitrogen source, and micronutrients for growth.
Carbon & energy source + nitrogen source + O2 + other requirements ? Biomass + Product + byproducts + CO2 + H2O + heat


the following is from
"Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion.

"Proteolysis is used by the cell for several purposes. They include:
~ Removal of N-terminal methionine residues after translation.
~ Removal of the signal sequence of peptides after their transport through a membrane
~ Separation of viral proteins that were translated from a polycistronic mRNA
~ Digestion of proteins from foods as a source of amino acids
~ Conversion of predecessor-proteins (proenzymes, zymogens, prehormones) into their final structures.
~ Degradation of cyclins at different stages of the cell cycle."


the following is from
"Lipolysis is the breakdown of fat stored in fat cells. During this process, free fatty acids are released into the bloodstream and circulate throughout the body. Ketones are produced, and are found in large quantities in ketosis (a state in metabolism occurring when the liver converts fat into fatty acids and ketone bodies which can be used by the body for energy.). Lipolysis testing strips such as Ketostix are used to recognize ketosis.

"The following hormones induce lipolysis: epinephrine, norepinephrine, glucagon and adrenocorticotropic hormone. These trigger 7TM receptors, which activate adenylate cyclase. This results in increased production of cAMP, which activates protein kinase A, which subsequently activate lipases found in adipose tissue.

"Triglycerides undergo lipolysis (hydrolysis by lipases) and are broken down into glycerol and fatty acids. Once released into the blood, the relatively hydrophobic free fatty acids bind to serum albumin for transport to tissues that require energy. The glycerol also enters the bloodstream and is absorbed by the liver or kidney where it is converted to glycerol 3-phosphate by the enzyme glycerol kinase. Hepatic glycerol 3-phosphate is mostly converted into dihydroxyacetonephosphate (DHAP) and then glyceraldehyde 3-phosphate (G3P) to rejoin the glycolysis and gluconeogenesis pathway."


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Re: food fermentation
« Reply #3 on: December 10, 2008, 02:58:55 am »

incidentally, i did not mean to say that the fermentation of carbs is necessarily bad or deleterious or poisonous

i was merely trying to clarify the meaning of the word "rotten", when used to describe high meat, which was left undefined in another thread

also, from reading the 1st post in this thread i get the impression that the production of alcohol is only 1 of all possible carb fermentation processes

« Last Edit: December 10, 2008, 03:02:46 am by coconinoz »


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what is rotten?
« Reply #4 on: December 10, 2008, 03:25:04 am »

when it comes to food, or other things some people pop in their mouth, "rotten" may mean 1-3 things:

fermentation (carbs) - proteolysis (proteins) - lipolysis (lipids) = 3 different, albeit related, events

Offline mel

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Re: food fermentation
« Reply #5 on: July 23, 2009, 08:00:09 pm »
i read a book called Wild Fermentation and it seems it gives so many enzymes it's superraw
Anyway the book is good because you don't need starter cultures :)


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