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Constituent of butter and produced by many microorganisms [DFC] Acetoin is a colorless or pale yellow to green yellow liquid with a pleasant, buttery odor. Acetoin is used as an external energy store by a number of fermentive bacteria. Acetoin, along with diacetyl, is one of the compounds giving butter its characteristic flavor. Acetoin is used as a food flavoring (in baked goods) and a fragrance. It can be found in apples, butter, yogurt, asparagus, black currants, blackberry, wheat, broccoli, brussels sprouts, cantaloupe. [Wikipedia].

A methyl ketone that is butan-2-one substituted by a hydroxy group at position 3." []

A dioxane with oxygen atoms at positions 1 and 4." []

A hydroxyaldehyde that is isobutyraldehyde carrying a single hydroxy substituent at position 2." []

Isobutyric acid is a carboxylic or short chain fatty acid with characteristic sweat-like smell. Small amount of isobutyrate is generated via microbial (gut) metabolism. Small amounts may also be found in certain foods or fermented beverages. There is anosmia (genetic inability to smell) for the odor of isobutyric acid with a frequency of about 2.5%. (OMIM 207000). Isobutyric acid is slightly soluble in water but much more soluble in ethanol, ether and organic solvents. Isobutyric acid can affect people if breathed in and may be absorbed through the skin. Contact can irritate and burn the skin and eyes. Breathing Isobutyric acid can irritate the nose, throat and lungs causing coughing, wheezing and/or shortness of breath.

Acetoin, also known as dimethylketol or 2,3-butanolone, belongs to the class of organic compounds known as acyloins. These are organic compounds containing an alpha hydroxy ketone. Acyloins are formally derived from reductive coupling of carboxylic acyl groups. Thus, acetoin is considered to be an oxygenated hydrocarbon lipid molecule. Acetoin is used as an external energy store by a number of fermentive bacteria. Acetoin, along with diacetyl, is one of the compounds giving butter its characteristic flavor. Acetoin is a very hydrophobic molecule, practically insoluble in water, and relatively neutral. Acetoin is used as a food flavoring (in baked goods) and a fragrance. Acetoin is a sweet, buttery, and creamy tasting compound. Outside of the human body, Acetoin has been detected, but not quantified in several different foods, such as cocoa and cocoa products, evergreen blackberries, orange bell peppers, tortilla chips, and pomes. This could make acetoin a potential biomarker for the consumption of these foods. Constituent of beer, wine, fresh or cooked apple, fresh or cooked leak, corn, honey, cocoa, butter, cheeses, roasted coffee and other foodstuffs. Acetoin, with regard to humans, has been found to be associated with several diseases such as eosinophilic esophagitis and ulcerative colitis; acetoin has also been linked to the inborn metabolic disorder celiac disease. Acetoin is a colorless or pale yellow to green yellow liquid with a pleasant, buttery odor. It can be found in apples, butter, yogurt, asparagus, black currants, blackberry, wheat, broccoli, brussels sprouts, cantaloupe.

Butyric acid is a short-chain fatty acid (SCFA) formed in the mammalian colon by bacterial fermentation of carbohydrates (including dietary fibre). It is a straight-chain alkyl carboxylic acid that appears as an oily, colorless liquid with an unpleasant (rancid butter) odor. The name butyric acid comes from the Greek word for "butter", the substance in which it was first found. Triglycerides of butyric acid constitute 3–4% of butter. When butter goes rancid, butyric acid is liberated from the short-chain triglycerides via hydrolysis. Butyric acid is a widely distributed SCFA and is found in all organisms ranging from bacteria to plants to animals. It is present in animal fat and plant oils, bovine milk, breast milk, butter, parmesan cheese, body odor and vomit. While butyric acid has an unpleasant odor, it does have a pleasant buttery taste. As a result, butyric acid is used as a flavoring agent in food manufacturing. Low-molecular-weight esters of butyric acid, such as methyl butyrate, also have very pleasant aromas or tastes. As a result, several butyrate esters are used as food and perfume additives. Butyrate is naturally produced by fermentation processes performed by obligate anaerobic bacteria found in the mammalian gut. It is a metabolite of several bacterial genera including Anaerostipes, Coprococcus, Eubacterium, Faecalibacterium and Roseburia (PMID: 12324374; PMID: 27446020). Highly-fermentable fiber residues, such as those from resistant starch, oat bran, pectin, and guar can be transformed by colonic bacteria into butyrate. One study found that resistant starch consistently produces more butyrate than other types of dietary fibre (PMID: 14747692). The production of butyrate from fibres in ruminant animals such as cattle is responsible for the butyrate content of milk and butter. Butyrate has a number of important biological functions and binds to several specific receptors. In humans, butyric acid is one of two primary endogenous agonists of human hydroxycarboxylic acid receptor 2 (HCA2), a G protein-coupled receptor. Like other SCFAs, butyrate is also an agonist at the free fatty acid receptors FFAR2 and FFAR3, which function as nutrient sensors that facilitate the homeostatic control of energy balance. Butyrate is essential to host immune homeostasis (PMID: 25875123). Butyrate's effects on the immune system are mediated through the inhibition of class I histone deacetylases (specifically, HDAC1, HDAC2, HDAC3, and HDAC8) and activation of its G-protein coupled receptor targets including HCA2, FFAR2 and FFAR3. Among the short-chain fatty acids, butyrate is the most potent promoter of intestinal regulatory T cells in vitro and the only SCFA that is an HCA2 ligand (PMID: 25741338). Butyrate has been shown to be a critical mediator of the colonic inflammatory response. It possesses both preventive and therapeutic potential to counteract inflammation-mediated ulcerative colitis and colorectal cancer. As a short-chain fatty acid, butyrate is metabolized by mitochondria as an energy source through fatty acid metabolism. In particular, it is an important energy source for cells lining the mammalian colon (colonocytes). Without butyrate, colon cells undergo autophagy (i.e., self-digestion) and die.

Ethyl acetate, also known as 1-acetoxyethane or acetic ester, belongs to the class of organic compounds known as carboxylic acid esters. These are carboxylic acid derivatives in which the carbon atom from the carbonyl group is attached to an alkyl or an aryl moiety through an oxygen atom (forming an ester group). Ethyl acetate exists in all eukaryotes, ranging from yeast to humans. Ethyl acetate is a sweet, anise, and balsam tasting compound. Ethyl acetate is found, on average, in the highest concentration within a few different foods, such as milk (cow), pineapples, and sweet oranges and in a lower concentration in safflowers. Ethyl acetate has also been detected, but not quantified, in several different foods, such as alcoholic beverages, oxheart cabbages, agaves, chervils, ryes, and peach. It is used in artificial fruit essences. In the field of entomology, ethyl acetate is an effective asphyxiant for use in insect collecting and study. Because it is not hygroscopic, ethyl acetate also keeps the insect soft enough to allow proper mounting suitable for a collection. In a killing jar charged with ethyl acetate, the vapors will kill the collected (usually adult) insect quickly without destroying it. In organic and in natural products chemistry ethyl acetate is often used as a solvent for reactions or extractions. Ethyl acetate is a potentially toxic compound. Ethyl acetate, with regard to humans, has been found to be associated with several diseases such as perillyl alcohol administration for cancer treatment, crohn's disease, nonalcoholic fatty liver disease, and pervasive developmental disorder not otherwise specified; ethyl acetate has also been linked to the inborn metabolic disorder celiac disease.

Methyl propionate is a flavouring ingredient. It belongs to the family of carboxylic acid esters. These are carboxylic acid derivatives in which the carbo atom from the carbonyl group is attached to an alkyl or oaryl moiety through an oxygen atom (forming an ester group).

1-Hydroxy-2-butanone is found in coffee and coffee products. 1-Hydroxy-2-butanone is a constituent of coffee and various edible mushrooms. 1-Hydroxy-2-butanone is a flavouring ingredient

Propyl formate is found in apple. Propyl formate is a flavouring ingredient.

Isopropyl formate is found in alcoholic beverages. Isopropyl formate is a constituent of coffee, plum brandy, various mushrooms and dwarf quince (Chaenomeles japonica).

A hydroxyaldehyde that is isobutyraldehyde carrying a single hydroxy substituent at position 2." []

A primary alpha-hydroxy ketone that is butane-1,2-diol in which the hydroxy group at position 2 has been formally oxidised to give the corresponding ketone." []

Any member of the class of dioxanes that is a cyclohexane in which two carbon atoms are replaced by oxygen atoms." []