Water conservation and water injection of food are two different concepts. Water injection is illegally used by some unscrupulous businesses for the benefit of interests, while sodium tripolyphosphate is a water retaining agent and one of the food additives, which is safe and guaranteed when used in accordance with the requirements of national standards.

In fact, we should know from the name that water retention can increase the water content of food by 10% - 60% without damaging the taste, and increase the water content of food cells without damaging them.

However, water injection is simply to inject water into muscle tissue. The free water, which is still in a free state, will be lost from muscle tissue by slight processing (heat treatment or freezing treatment), which will not only improve the appearance and taste of meat, but also affect the later consumption.

The use of water retention agent for different foods is also different. Sodium tripolyphosphate is a commonly used water retention agent in phosphate, which is mainly used for processing meat and aquatic products to enhance their water stability and high water retention. The addition of sodium tripolyphosphate can improve the stability of the product, maintain the internal water retention of the food, and improve the shape, flavor, color, etc. of the food.

Water retention mechanism of sodium tripolyphosphate in food processing:

1. Adjust the PH value of meat to make it higher than the isoelectric point of meat protein (pH5.5), so as to improve the water retention performance of meat and ensure the freshness of meat;

2. Increase the ionic strength, which is conducive to the dissolution of myofibrin, and form a network structure with sarcoplasmic protein in cooperation with salt, so that water can gather in the network structure;

3. It can chelate Ca²⁺, Mg²⁺, Fe²⁺ and other metal ions, improve the water retention performance, and improve the antioxidant effect, because the metal ions are the activator of fat oxidation and rancidity. After adding sodium tripolyphosphate, the calcium and magnesium ions originally combined with muscle are chelated by polyphosphate, and the carboxyl groups in muscle protein are released. Due to the electrostatic repulsion between the carboxyl groups, the protein structure is relaxed and can absorb more water, So as to improve the water retention of meat.

Sodium tripolyphosphate in China is widely used in food water-retaining agents, such as meat products processing, aquatic products processing, frozen and conditioned food processing. It can be used alone or in combination with sodium pyrophosphate, sodium hexametaphosphate and other phosphate food additives. The correct use of sodium tripolyphosphate can not only improve the water yield and structure of the product, but also increase the brittleness, extend the shelf life and ultimately save costs.