Animal foods generally contain fishy substances, especially in aquatic products, where the odor is prominent. It intensifies as the freshness of the food decreases. These off-flavor substances not only cause nausea but can also be harmful to human health after consumption. There are many methods to remove the fishy taste during cooking; depending on the degree of off-flavor in the ingredients, a combination of measures can be adopted to achieve the goal of deodorizing.
Neutralization to remove fishiness:
Animal food ingredients contain large amounts of nutrients such as proteins, amino acids, and lecithin. Due to the action of bacteria from the environment and the ingredients themselves, various fishy substances are produced, such as ammonia, trimethylamine, methyl mercaptan, hydrogen sulfide, indole, and nitrogen-containing heterocyclic compounds. The aforementioned fishy and odorous substances are all alkaline compounds (pH greater than 7.25). During cooking, adding an appropriate amount of vinegar to neutralize them, forming acetates, can significantly reduce the fishy and odorous smell. Furthermore, tomato sauce contains organic acids such as citric acid and malic acid, which also have a neutralizing and deodorizing effect. Of course, directly cooking fish and meat with tomatoes also has a deodorizing effect.
Alcohol to remove fishiness:
When some low-boiling, non-alkaline fishy substances cannot be removed by neutralization, the solubility and volatility of alcohol (ethanol) for these substances can be utilized. Aldehydes, ketones, and sulfur-containing compounds in fish and meat are first dissolved by the alcohol, and then volatilized and removed together upon heating. At the same time, ethanol can react with aldehydes in the ingredients to form aromatic substances—acetals. It can also combine with organic acids to form esters. The combined effect of these two reactions can deodorize the dish and enhance its aroma. Therefore, to achieve a fresh and savory taste in fish and meat, cooking wine and vinegar are indispensable.
Spices to remove fishiness:
China boasts a wide variety of spices, which can be selected appropriately according to the specific situation. For example, scallions contain volatile oils and allicin; ginger contains gingerol, gingerene, and shogaol; Sichuan pepper and black pepper contain sanshools; star anise contains anethole and anisole; and cassia bark contains volatile oils and organic acids. The substances mentioned above can cause aldehydes, ketones, and other fishy components to undergo oxidation, acetalization, or esterification reactions, thereby weakening the off-flavor and enhancing the aroma. This effect is particularly significant when used in animal ingredients with a strong muttony or fishy smell.
Heating to remove fishiness:
Low-boiling fishy substances such as methyl mercaptan and ethyl mercaptan can be removed by heating. Some higher-boiling fishy substances can also be removed by prolonged heating methods like stewing, braising, roasting, or grilling, or by allowing them to volatilize in hot oil. Most fishy substances are water-soluble to some extent. During cooking, methods like blanching or scalding can be used first to remove water-soluble fishy substances such as urea, amines, and low-molecular-weight acids before proceeding with the main cooking process.