Compounds responsible for earthy and/or musty aromas in various food systems, including drinking water, are discussed. Major emphasis is given to the compounds geosmin, 2‐methyl‐isoborneal, and various pyrazines as contributors to both desirable and undesirable aromas. Occurrences, formation pathways, their sensory properties, and methods of analysis are discussed.

Musty/earthy aromas.

To identify absorption sites of earthy-flavor in rainbow trout (Salmo gairdneri), we placed the geosmin-producing algae Symploca muscorum on four locations We showed that the most rapid absorption

Sites of Uptake of Geosmin, a Cause of Earthy-Flavor, in Rainbow Trout (Salmo gairdneri)

The concentration of geosmin (1,10-trans-dimethyl-trans-9-decaol) in fresh tilapia were analyzed by applying high-vacuum distillation, extraction and gas chromatography techniques. The distribution of geosmin in the fish was determined by examining tissues from various parts of tilapia, along with the rates of geosmin absorption and purging. Analysis showed that when geosmin was added to fish flesh at concentrations ranging from 2.8 to 390 μg per kg of flesh, the rate of recovery was 51 to 89%. Sensory evaluation detected muddy flavor in freshwater tilapia with geosmin content ranging from 7.55 to 9.85 μg/kg of fish flesh. However, panelists failed to detect muddy flavor in brackish water tilapia that contained geosmin only in the range of 1.5 to 2.6 μg/kg. Among various tissues of the fish, the intestines contained the highest geosmin concentration, and appeared in descending order in the abdominal, skin and muscle tissues. After holding for 2 h in water with 5 and 50 μg/l geosmin, tilapia absor...

Geosmin and Off-Flavor in Nile Tilapia (Oreochromis niloticus)

Uptake and release of environmentally occurring odorous compounds by fish. A review

The concentration of geosmin was determined in freshly dredged and 2-wk relayed rangia clam (Rangia cuneata) samples in different seasons of the year. Vacuum distillation/solvent extraction using an internal standard was followed by multiple-level standard addition gas chromatography/selective ion monitoring mass spectrometry. Most coefficients of variation were lower than 10%. On a dry-weight basis, the geosmin level in dredged clams was highest (343 ng/g) in August and averaged 51.6 ng/g in other months. A 52% reduction of geosmin was found after two week relaying during the period of May-June. However, only 1% reduction of geosmin was observed during February-March.

Methodology for Quantification of Geosmin and Levels in Rangia Clam (Rangia cuneata)

Studies were conducted to determine the length of time required to purge a muddy–earthy flavor taint from pond cultured rainbow trout (Salmo gairdneri) transferred to two different clear water environments. Sensory data from trained judges show that this required 5 days for fish transferred to a rapidly changing purified artificial water environment and 16 days for fish transferred to a relatively static natural water environment to reduce this taint to or below threshold levels of recognition.

R. K. York

Papers

Purging a Muddy–Earthy Flavor Taint from Rainbow Trout (Salmo gairdneri) by Transferring to Artificial and Natural Holding Environments