What are some flavor compounds from yeast activity found in beer?!

Question: What are some flavor compounds from yeast activity found in beer!?
What is produced!?Www@FoodAQ@Com


In case you want just the specific I will cut a paste!.
Okay, that did not work so well so I give the below information!.

The Basics:

CHARACTERISTICS: Acetaldehyde has the flavor and aroma of green apples!. It can also taste and smell acetic/cidery!.

CHARACTERISTICS: Skunk odor; unmistakable and generally not desirable in beer!.
CHEMISTRY: Light will degrade hop iso-alpha acids which then combine with sulphur compounds in the beer to produce 3-methyl-2-butene-1-thiol, or prenyl mercaptan!. Other sulphur compounds also contribute to the overall lightstruck character!.

CHARACTERISTICS: A hospital-medicine chest flavor and aroma, usually detected by its aroma components!. Some phenolic tastes are desired depending on the style!. Other descriptions include Band-Aid-like, plastic-like, smoky and clovelike!.

CARBONATION (Carbonic Acid)
CHARACTERISTICS: The presence of carbonic acid in beer gives the head and bubbles when the bottle is opened and pressure released!. Gives head characteristic!. Taste is tart and acidic, increasing with the carbonation!. This is especially noticeable on overcarbonated brews!. An overall prickly or stimulating mouth feel!. Small bubbles are desired, as these will retain both the head and the carbonation for a longer period!.
CAUSES: CO2 is dissolved in beer during the
fermentation process!.

CHARACTERISTICS: An acetone-like, lacquer-thinnerlike, pungent, acrid aroma which is followed up by a harsh, burning sensation on the tongue and possibly the back of the throat!. Not desired in any beer style!.
CHEMISTRY: Ethyl acetate in larger quantities (>33 ppm) is the primary cause, either by wild yeast or the yeast strain used!. Other compounds may also be present!.

CHARACTERISTICS: Another of the basic taste
sensations, sourness is perceived on the sides of the tongue towards the back of the mouth!. At higher levels it can be felt in the throat!. Generally in beer this is perceived as a sour aroma and a tartness or vinegarlike aroma!. Sourness from bacterial contamination can also be perceived as spoilage or putrefaction!.
CHEMISTRY: Caused by lactobacillus, pediococcus, acetobacter and some yeast strains!.

CHARACTERISTICS: Strong sulfuric aroma and taste reminiscent of rotten eggs (hydrogen sulfide), sulfur dioxide, or yeast!. Other descriptions include garlic, burnt rubber, shrimp-like, meaty!.
CHEMISTRY: Formed by amino acids methionine and cysteine in the malt and by certain yeast strains and bacteria, notably Zymononas, Pectinatus, and Megasphaera!. also formed by yeast autolysis!.Www@FoodAQ@Com

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