Bitter oxidized fatty acid

This analysis measures the amount of free acid, and is used to reflect the level of FFA in the sample. Free fatty acids are significant for the quality of the oil because they increase the oil s susceptibility to oxidation, can contribute bitter/soapy flavors, and can cause a decrease in the oil s smoke and flash points. 

Many bioactives have an undesirable taste and odour. Peptides are known for their bitter taste, mineral salts for their metaUic tastes and marine oils rich in omega-3 fatty acids for fishy taste and odour. Further, the addition of soluble iron salts to foods catalyses the oxidation of fats and amino acids and imparts undesirable metallic tastes to foods (Zimmermann 2004 Yang and Lawless 2006). A variety of added ingredients (e.g., sugar, flavours) have been used to mask these tastes, but with limited success. 

This enzyme oxidizes linoleic and linolenic acids rapidly in whole flour or milling products containing wheat germ or bran mixed with water. The initial hydroperoxides formed by lipoxygenases in stored wheat bran are converted to secondary products, mono- and trihydroxy fatty acids. These oxidation products causing bitter and rancid flavors are formed in higher concentrations in hydrated products than in dry raw materials. Rancid flavors develop rapidly on hydration. 

The primary aromatic substances in beer are derived from raw materials (barley or hops) that confer the beer s typical odour and taste. Bitter acids of hops have a bitter taste (see Section 8.3.5.1.3), but hop cones also contain 0.3-1% m/m of terpenoids (60-80% of hop essential oil), which have a considerable influence on the smell of beer. The main components of aromatic hop oils are sesquiterpenic hydrocarbons in which a-humulene, P-caryophyllene and famesene dominate. The major monoter-penic hydrocarbon is myrcene. For example, the essential oil content of fine aromatic varieties, such as Saaz, is 0.8% m/m, of which 23% is myrcene, 20.5% a-humulene, 14% famesene 6% and P-caryophyUene. Significant components of the hop aroma in beer are mainly isomeric terpenoid monoepoxides resulting from autoxidation and diepoxides of a-humulene and fS-caryophyUene, but also other terpenoids. Important components of hops odour are also various alcohols (such as geraniol and hnalool), esters (ethyl 2-methylpropanoate, methyl 2-methylbutanoate, propyl 2-methylbutanoate and esters of terpenic alcohols, such as geranyl isobutanoate), hydrocarbons, aldehydes and ketones formed by oxidation of fatty acids, such as (3E,5Z)-undeca-l,3,5-triene, (Z)-hex-3-enal, nonanal, (Z)-octa-l,5-dien-3-one, their epoxides, such as ( )-4,5-epoxydec-2-enal and sulfur compounds. Other important components of hops are so-called polyphenols (condensed tannins) that influence the beer s taste and have antioxidant effects. Less important compounds are waxes and other hpids. Hop products, such as powder, pellets and extracts (by extraction with carbon... 

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