Off-flavors in aquaculture are primarily due to the production and subsequent absorption of one or more metabolic by-products of cyanobacteria (blue green algae) by the fish. The fish may absorb these compounds through their gills and/or skin, or by ingestion during feeding (Schrader and Rimando, 2003) .
What is meant by off flavor in fishes?
Off-flavors are undesirable flavors in fish and shellfish that render them permanently or temporarily unmarketable. Two reports state that off-flavors are responsible for 25 to 54 percent of fish harvesting delays, so off-flavor is a critical problem for the aquaculture industry.
Does fish feed contribute to off Flavour and Odour in fish?
The results suggest that fish feed may contribute to fish malodor. Most of these off-flavors were linked to lipid source (fish oil or plant/lard alternatives), unsaturated fatty acids contents, and protein type (plant-based or fishmeal-based sources) in the feed.
How do you remove Geosmin from fish?
Off-flavors are typically removed by depurating the fish in clean water. Unfortunately, this often takes from days to weeks, and can lead even to significant economic losses due to delays of harvest and high consumption of clean water (Burr et al. 2012).
What are the most common causes for off Flavours in high fat products?
Unsaturated aldehydes and ketones are most responsible for off-flavors because of their low threshold. For example, the metallic taint in oxidized butter has been attributed to 1-octen-3-one (Stark and Forst, 1962). Trace metals (copper, iron, cobalt) and high temperature hasten lipid oxidation.
Why does catfish taste so bad?
Off-Flavor tastes in catfish are derived from certain types of algae and bacteria that occur in nutrient rich, densely stocked catfish production ponds. The flavors are varied, but are often described as musty, muddy, woody, sewage, rotten or diesel tasting.
What does Geosmin smell like?
Geosmin typically produces an earthy or musty odor as is found in the odor of overturned rich soils, and is present in some foods such as beets, spinach, and mushrooms. Why do we smell it? The human nose is extremely sensitive to geosmin.
What is oxidation rancidity?
Oxidative rancidity is a chemical reaction catalyzed by heat, ultraviolet light, heavy metals and oxygen. Many of these factors are obviously present during the extrusion process. Oxidative rancidity is best controlled by the addition of antioxidants and ‘oxygen scavengers’.