Salts and Minerals.
A pinch of salt changes flavour. A few percent changes structure: minced meat binds, cabbage wilts, and tofu sets with a calcium salt.
Salt — sodium chloride — dissolves into sodium and chloride ions, and ions change how proteins and cell walls behave. At about 2–3 % in minced meat, salt draws the muscle protein myosin out of the fibres into a sticky solution; heated, that solution sets and glues the mince together. It is why sausages, meatballs and 丸子 are salted and worked before cooking, and why a burger salted early in the mixing turns springy and dense.
Other minerals matter too. Calcium ions bridge between pectin chains (V.4) and between protein molecules: they firm pickles and canned tomatoes, curdle soy milk into tofu (XX.9) and help milk curdle into cheese (XIV.6). The workshop shows, in a teaching model, how much myosin salt extracts from minced meat.
Below: the share of myosin drawn into solution and the binding of minced meat against salt concentration (a teaching curve with the threshold near 2 % that published work describes), and the salt in a typical sausage.
- Explain how salt dissolves muscle proteins.
- Choose a salt level for binding mince.
- Name the roles of calcium in firming.
- Distinguish seasoning from structural uses of salt.
Seasoning and structure
At 1 % salt — ordinary seasoning — the model extracts little myosin (index 0.09); at 1.8 %, 0.50; at 2.5 %, 0.88. Sausage makers work in the 1.5–2.5 % range for this reason, and knead the salted meat until it turns tacky and stringy. For a burger you want the opposite — loose and tender — so salt only the outside just before cooking.
Salt also draws water out of vegetables by osmosis (III.8), which is how 泡菜, sauerkraut and salted cucumbers begin (XIV.4), and in brines it lets meat hold more water as it cooks (XVIII.4). Calcium firms: calcium chloride in pickles and canned tomatoes, calcium sulphate (石膏) or magnesium chloride (卤水) to set tofu. Phosphates, found in some processed meats and baking powders, raise water-holding and act as leavening acids (XXV.1).
Divide 300 g of minced pork in two. Mix one half with 1 % salt and the other with 2 %, and knead each for a minute. Form small balls and poach them. The 2 % balls are springy and hold together; the 1 % ones are crumbly.
Terms
- Myosin extraction
- Dissolving muscle protein from minced meat with salt and work, so it binds when heated.
- Binding
- The gluing of minced meat into a coherent mass by set protein.
- Calcium bridging
- Calcium ions linking pectin or protein chains, firming foods.
- Coagulant
- A salt or acid that sets a protein solution, as in tofu making.
Sources
- A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.
- H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, 2nd ed., Scribner, 2004.