Not all sardines are created equal. The season of catch, preparation process, size of the fish, and cooking methods all directly impact the final product. Typically, you can determine the size of sardines from the label, which often indicates the quantity per can, ranging from 3-4 to 16-20 sardines. Larger fish tend to have softer flesh and a richer flavor. The best processors prepare sardines by hand, removing the heads and guts, washing them with saltwater, and air-drying them before cooking. Sardines can be fried or steamed, depending on the producer's preference, but the quality of the end product largely depends on the raw materials, cooking techniques, and the knowledge and experience of the processor.
The medium used to preserve sardines has the most direct impact on their flavor; olive oil has been widely used (the tight packaging of sardines is because this oil used to be more expensive than fish), but opinions vary on whether extra virgin olive oil is better than milder oils, or if it may overpower the fish's flavor. Other sauces are also commonly used, with tomato sauce or mustard being most prevalent, and chili-infused oils being popular for seasoning. Some may suspect that these sauces are used to mask the taste of inferior fish.
Time is also a factor for connoisseurs. A technical manager from a well-known brand told me that if she had her way, newly packaged sardine cans would rest for at least a year before being sold, ensuring that their taste and texture are optimal. Unfortunately, commercial demands often mean sardines are delivered to customers without this resting period. Some fully believe in the benefits of aging canned sardines and age them at home, much like aging fine wines to bring out the best flavors. Stories abound of sardines aged for decades, during which they absorb rich olive oil, fully integrating the subtle fishy taste.
