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Salt Causes Food to Release Water

When salt comes into contact with the surface of food, it creates a concentration difference between the inside and outside of the cells. To balance this concentration, water from inside the food is drawn out through osmosis. Therefore, after sprinkling salt, home cooks may notice the surface of the ingredients becoming wetter due to water release.

In cooking, experienced home cooks often utilize this water-removing property of salt to enhance the flavor of dishes. For example, when making vegetable salads, sprinkling salt before cooking helps to remove excess water and reduce the bitterness and astringency of the food. In traditional pickled vegetables, sprinkling salt also helps vegetables release water, creating a natural fermentation environment that makes the dish crispy, delicious, and preserves it longer.

However, it's important to note that adding salt too early can sometimes alter the texture of the dish. When stir-frying green vegetables, adding salt at the beginning often causes them to release water quickly, reducing the heat of the pan and making the vegetables soft and less crispy.  Similarly, when stir-frying shrimp or meat, salting them too early can cause the meat to release water. This reduces the conditions for the Maillard reaction to occur, the reaction that creates browning and aroma when food is exposed to high temperatures.

Sugar helps retain moisture and tenderize ingredients.

Unlike salt, sugar has the ability to bind with water in food and slow down the dehydration process during cooking. When used in moderation during marination, sugar helps meat fibers retain moisture better, resulting in a softer and juicier texture after cooking.

In addition to its moisture-retaining properties, sugar also plays a crucial role in the caramelization reaction. When exposed to high temperatures, sugar turns brown and creates a distinctive aroma. Therefore, grilled, braised, or stewed dishes often have an attractive amber color and richer flavor if a suitable amount of sugar is used from the start.

In many familiar dishes such as braised meat, braised ribs, grilled meat, and stewed meat, home cooks often add a little sugar during marination. Sugar not only helps balance the saltiness of the fish sauce and salt but also contributes to a glossy and more fragrant surface after cooking.

Everyday Kitchen Applications

Based on the principle of "salt separates, sugar retains," many experienced chefs and home cooks adjust the timing of seasoning to enhance the flavor of their dishes. When stir-frying green vegetables, salt should be added near the end to prevent the vegetables from releasing too much water. For pan-fried or stir-fried meat dishes, seasoning should only be added after the meat is cooked through.

Conversely, when marinating meat for grilling or braising, a small amount of sugar helps tenderize the meat and create a beautiful color when cooked. However, this principle shouldn't always be applied rigidly. The effectiveness depends on the type of ingredients, the amount of seasoning, and the cooking temperature.

 Understanding the different effects of salt and sugar helps cooks proactively adjust seasonings, thereby maintaining the crispness of vegetables, the juiciness of meat, and the harmonious flavor of the dish. This is also why the timing and quantity of these two familiar seasonings are always carefully considered in many cooking techniques.