Off-Flavors, Food Taints

6-Trichloroanisole (IV) with an extremely low odor threshold (mouldy-like 3.10 5 pg/kg, water) is an example of an off-flavor substance (cf. 20.2.7) which is produced by fungal degradation and methylation of pentachlorophenol fungicides. 

To a certain extent, unwanted aroma substances are concealed by typical ones. Therefore, the threshold above which an off-flavor becomes noticeable can increase considerably in food compared to water as carrier, e. g., up to 0.2 pg/kg 2,4,6-trichloroanisole in dried fruits. 

Photooxidation of methionine to methional (with riboflavin as a sensitizer) 

The level of O3 in air too high ozonolyis of 8,15- and 9,15-isolinoleic acid to 6-trans-nonenal 

Autoxidation of pentaene- and hexaene fatty aeids to octa-l,cis-5-dien-3-one Faulty fermentation by Streptococcus lactis, van maltigenes formation of phenylacetaldehyde and 2-phenylethanol from phenylalanine Saturated and unsaturated aldehydes, octa-3,5-dien-2-one, 3-alkyl-2-methoxypyrazines, hexanal 

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