Autolyzed Yeast Extract

<a href="http://en.wikipedia.org/wiki/Autolysis_(biology)" title="Autolysis (biology)" >Autolyzed</a> yeast (containing the cell walls) or autolyzed yeast extract consists of concentrations of <a href="http://en.wikipedia.org/wiki/Yeast" title="Yeast" >yeast</a> cells that are allowed to die and break up, so that the yeasts’ endogenous <a href="http://en.wikipedia.org/wiki/Digestion" title="Digestion" >digestive</a> enzymes break their <a href="http://en.wikipedia.org/wiki/Protein" title="Protein" >proteins</a> down into simpler compounds (<a href="http://en.wikipedia.org/wiki/Amino_acids" title="Amino acids" class="mw-redirect" >amino acids</a> and <a href="http://en.wikipedia.org/wiki/Peptides" title="Peptides" class="mw-redirect" >peptides</a>).

Yeast autolysates are used in <a href="http://en.wikipedia.org/wiki/Vegemite" title="Vegemite" >Vegemite</a> (<a href="http://en.wikipedia.org/wiki/Australia" title="Australia" >Australia</a>), <a href="http://en.wikipedia.org/wiki/Marmite" title="Marmite" >Marmite</a>, <a href="http://en.wikipedia.org/wiki/Promite" title="Promite" >Promite</a>, <a href="http://en.wikipedia.org/wiki/Oxo_(food)" title="Oxo (food)" >Oxo</a> (<a href="http://en.wikipedia.org/wiki/New_Zealand" title="New Zealand" >New Zealand</a>, <a href="http://en.wikipedia.org/wiki/South_Africa" title="South Africa" >South Africa</a>, <a href="http://en.wikipedia.org/wiki/United_Kingdom" title="United Kingdom" >United Kingdom</a>, and <a href="http://en.wikipedia.org/wiki/Republic_of_Ireland" title="Republic of Ireland" >Republic of Ireland</a>),<a href="http://en.wikipedia.org/wiki/Cenovis" title="Cenovis" >Cenovis</a> (<a href="http://en.wikipedia.org/wiki/Switzerland" title="Switzerland" >Switzerland</a>) and Vitam-R (<a href="http://en.wikipedia.org/wiki/Germany" title="Germany" >Germany</a>). <a href="http://en.wikipedia.org/wiki/Bovril" title="Bovril" >Bovril</a> (<a href="http://en.wikipedia.org/wiki/United_Kingdom" title="United Kingdom" >United Kingdom</a> and <a href="http://en.wikipedia.org/wiki/Republic_of_Ireland" title="Republic of Ireland" >Republic of Ireland</a>) switched from beef extract to yeast extract for 2005 and most of 2006, but later switched back.

The general method for making yeast extract for food products such as <a href="http://en.wikipedia.org/wiki/Vegemite" title="Vegemite" >Vegemite</a> and <a href="http://en.wikipedia.org/wiki/Marmite" title="Marmite" >Marmite</a> on a commercial scale is to add <a href="http://en.wikipedia.org/wiki/Sodium_chloride" title="Sodium chloride" >sodium chloride</a> (salt) to a suspension of yeast, making the solution <a href="http://en.wikipedia.org/wiki/Hypertonic" title="Hypertonic" class="mw-redirect" >hypertonic</a>, which leads to the cells shrivelling up; this triggers <a href="http://en.wikipedia.org/wiki/Autolysis" title="Autolysis" class="mw-redirect" >autolysis</a>, in which the yeast self-destructs. The dying yeast cells are then heated to complete their breakdown, after which the husks (yeast with thick cell walls) are separated. Removing the cell walls concentrates the flavors and changes the texture.

One common commercial use of yeast extract is as a flavor enhancer in processed food products, including vegetarian and vegan foods.

Since <a href="http://en.wikipedia.org/wiki/Glutamates" title="Glutamates" class="mw-redirect" >glutamates</a> are important <a href="http://en.wikipedia.org/wiki/Neurotransmitters" title="Neurotransmitters" class="mw-redirect" >neurotransmitters</a> in the human brain, playing a key element in learning and memory, there is ongoing study by <a href="http://en.wikipedia.org/wiki/Neurologists" title="Neurologists" class="mw-redirect" >neurologists</a> about possible side-effects of MSG in food but no conclusive studies drawing any connections.<a href="http://en.wikipedia.org/wiki/Monosodium_glutamate#cite_note-twsNovK8d-27" >[28]</a>

Monosodium glutamate (MSG) is one of several forms of glutamic acid found in foods, in large part because glutamic acid, being an amino acid, is pervasive in nature.

Glutamic acid and its salts can also be present in a wide variety of other additives, including <a href="http://en.wikipedia.org/wiki/Hydrolyzed_vegetable_protein" title="Hydrolyzed vegetable protein" class="mw-redirect" >hydrolyzed vegetable protein</a>, <a href="http://en.wikipedia.org/wiki/Autolyzed_yeast" title="Autolyzed yeast" class="mw-redirect" >autolyzed yeast</a>, <a href="http://en.wikipedia.org/wiki/Hydrolyzed_yeast" title="Hydrolyzed yeast" class="mw-redirect" >hydrolyzed yeast</a>, <a href="http://en.wikipedia.org/wiki/Yeast_extract" title="Yeast extract" >yeast extract</a>, <a href="http://en.wikipedia.org/wiki/Soy" title="Soy" class="mw-redirect" >soy</a> extracts, and protein isolate, which must be labeled with these common and usual names. Since 1998, MSG cannot be included in the term "spices and flavorings".

The food additives <a href="http://en.wikipedia.org/wiki/Disodium_inosinate" title="Disodium inosinate" >disodium inosinate</a> and <a href="http://en.wikipedia.org/wiki/Disodium_guanylate" title="Disodium guanylate" >disodium guanylate</a>,

which are <a href="http://en.wikipedia.org/wiki/Ribonucleotides" title="Ribonucleotides" class="mw-redirect" >ribonucleotides</a>, are usually used in synergy with monosodium glutamate-containing ingredients.

However, the term "natural flavor" is now used by the food industry when using glutamic acid (which is similar to MSG, lacking only the sodium ions)[<a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" >citation needed</a>].

Due to lack of FDA regulation, it is impossible to determine what percentage of "natural flavor" is actually glutamic acid[<a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" >citation needed</a>].

The FDA considers labels such as "No MSG" or "No Added MSG" to be misleading if the food contains ingredients that are sources of free glutamate, such as hydrolyzed protein.

In 1993, the FDA proposed adding the phrase "(contains glutamate)" to the common or usual names of certain protein hydrolysates that contain substantial amounts of glutamate.