What is Used to Prevent Browning in Potatoes?

After potatoes are peeled, a reaction occurs between the orthodiphenol species and some forms of iron present within them.

The phenomenon of potato browning can be explained as follows:

When peeled potatoes are exposed to air, oxidation occurs as the iron ions within the potato react with orthodiphenols and ferric compounds, resulting in a dark color. Chemically, this process can be likened to corrosion. This is why potatoes turn brown.

To prevent browning on potatoes, the iron ions within them must be sequestered. Treating potatoes with solutions of Sodium Acid Pyrophosphate and EDTA prevents free iron ions from undergoing corrosion, thus reducing browning.

In short, once the iron is no longer in its free ionic form, it cannot react to form the pigment that causes browning on potatoes.

What is a Sequestrant?

Sequestrants have chelating effects on both heat-treated and untreated foods. Sodium Acid Pyrophosphate and Sodium EDTA are food additives used to maintain quality and stabilize foods.

Sequestrant agents work by converting high-valence metal ions (such as copper, iron, and nickel) found in food into complex compounds.

Because they bind with these metal ions and remove them from the solution, they are also referred to as metal chelating agents.

Trace elements (metals) naturally present in food can act as oxidation catalysts, leading to discoloration.

Sequestrants must have an appropriate electronic configuration and steric compatibility with the metal they are complexing. For this reason, sequestrant agents like Sodium Acid Pyrophosphate are used to prevent metal ions in many foods from being converted into undesirable substances.

To prevent potato browning, Sodium Metabisulfite can be used in conjunction with Sodium Acid Pyrophosphate. Sodium Metabisulfite is effective at preventing browning in potatoes. In practice, a sodium metabisulfite solution is prepared in a container. Peeled and sliced potatoes are then dipped into this solution, coating them with the preservative agent.

Another Method to Prevent Browning in Potatoes

There is another method to prevent browning in peeled potatoes. This method is often preferred over the use of sulfites. To inhibit enzymatic browning, the potatoes are dipped into a Sodium Erythorbate solution (an organic acid) at 45-50 °C. Afterwards, the potato surface is neutralized with a salt like trisodium citrate.

How Does Trisodium Citrate Affect Browning?

Trisodium citrate prevents potatoes from browning by inhibiting or slowing enzymatic reactions. Its ability to regulate acidity can reduce the effectiveness of these reactions by altering the pH level. Additionally, trisodium citrate can prevent the browning reaction by blocking oxygen from reaching the potato's surface.