In the process of preservation by salting method, salt is an important factor that should get attention. The purity of the salt used will affect the quality of the salted fish as the final product produced. The salt used in the process of preserving the fishery product is preferably pure salt which is a salt having a large NaCl composition (95%) and contains few other elements such as MgCl2, CaCl2, MgSO4, CaSO4, mud and other impurities.
Types of salt can be divided into several categories such as; very good category, good and medium. It is said to be excellent if it contains NaCl> 95%, good if NaCl content is 90-95%, and moderate if NaCl content is between 80-90%.
Figure 1. Salt
The non-NaCl salt element has several disadvantages, including:
a. Salt containing Ca and Mg slowly penetrates deeply into the meat of fish, allowing the process of decomposition to continue during the process of salting. In addition, salted fish products produced are hygroscopic.
b. Salt containing 0.5% – 1%, CaSO4 produces stiff and pale (white) products.
c. Salt containing magnesium sulfate or magnesium chloride causes salted fish products rather bitter.
d. Iron and copper salts cause brown fish, brown, and yellow.
e. Salt contains CaCl2 causes salted fish is white, hard and fragile.
The process of making a simple salt is to evaporate seawater so that the minerals in it settles. It’s just that the salt produced to a minimum may contain minerals that are less desirable.
Calcium and magnesium as a substantial element conceived in seawater other than NaCl need to be precipitated to increase the obtained NaCl content. Calcium and magnesium can be deposited in the form of sulfate, carbonate and oxalate salts. In the process of precipitation or crystallization of precipitated salts of carbonate and oxalate, following the sulfate salt, the last form of the chloride salt.
Figure 2. Traditional process of salt production