Characteristics of spinach and boiled water with added various cooking salt

Abstract

[Purpose] There are various types of salt to which anti-caking agents or organic acids are added, and some of them change the pH of boiled water when used for cooking. Therefore, we selected representative salts that change the pH of boiled water from among commercially available salts and verified the characteristics of spinach boiled with 1% added salt and boiled water.

[Methods] Spinach samples were purchased several times at a supermarket in Tokyo, and four types of salt were used: “Pure Salt (special grade refined salt)”, “Tsukemonoen (pickling salt)”, “Cooking Salt (smooth type salt)”, and “Yukisio (powder salt)”. After boiling in water 10 times the sample weight or 1% salt water for 2 minutes, the spinach was dipped twice (for a total of 5 minutes) in the same amount of water as the boiling water and pressed by hand with “makisu (bamboo sushi mat)” so that the weights before and after heating were the same. The water after boiling was measured for pH, salinity, and color change (delta E*ab) before and after heating at normal temperature, and leaves ware measured for ascorbic acid (AsA) and nitrate (nitrate ion) using a reflectance spectrophotometer.

[Results] The pH of 1% brine varied with the type of salt (pH 4-10). The pH of boiling water was lower (pH 4-5.5) for Tsukemonoen and higher (pH 8-9) for Yukisio compared to no addition before and after heating. There was no change in pH for Pure Salt (pH 6). For some types of salt, boiling with added salt resulted in a darker water color and greater loss of components than boiling in water.