Phosphate is said to give a whiter and thicker fish (Thorarinsdottir et al. 2010) and the water holding capacity increases. Furthermore, it is said that the phosphate-treated fish is juicier and have better texture than other salted fish. Knowledge of the use of phosphate in the production of salted fish is largely based on trials and experiences carried out by producers and is very little documented and reported in controlled, scientific trials.
Some of the main challenges in the production of salted fish is blood in the raw material, the fish becomes yellow (discoloration) during production and storage, and that the fish loses varying amounts of liquids out into cardboard boxes during storage, transport and sale.
Through Møre Research´s work with the use of phosphate in salted fish in the fall of 2010, a review of the literature in this area have shown that very few experiments have been carried out. It is therefore a significant need for more work to examine the effects phosphates on salted fish. Different types of phosphates have different properties that can help to resolve or reduce the main problems listed above.
Some phosphates can bind iron (blood) and other metals that could potentially cause the fish to oxidize during storage, as well as the blood may be able to be extracted from the raw material during salting. Both of these effects will potentially give whiter salted fish. Moreover, phosphates could increase the WHC in salted fish. This can be used (but also abused) to increase the yield, but the yields/water content will largely be determined by what is acceptable in the various markets. By increasing the WHC may result in that fish releases smaller amounts of liquid during storage, and one trial has indicated this (Bjørkevoll, 2004). It will be beneficial both to save weight, but also to avoid the brine from leaking out into the environment during storage, transport and sale. Phosphates can also affect the sensory characteristics such as texture and juiciness because the water binding properties are affected (cooking loss is reduced).
Based on a theoretical approach, there is a significant potential for phosphates having several positive effects on seafood and phosphates can help increase the quality of some of these products. To clarify whether these conditions are also applicable for salted fish, the must be conducted controlled experiments in both small-scale and industrial scale.
The objective with this project has been to document which effect phosphates have on light salted and cured fish during processing and storage. This knowledge was achieved through the following targets:
Target 1: To document how phosphates affect blood amount in the raw material and salted products
Target 2: To map how phosphates affect the development in color during production and storage
Target 3: Investigate how the storage stability of the products concerning liquid drop and yield are affected by phosphates
Value for the industries
Whiteness of the salt fish is a very important quality parameter in most markets. To improve the whiteness and achieve higher dividends, some competitors to Norwegian salted fish use phosphate as process aid or additive. A bright white color of salted fish can today best be achieved by proper handling of raw materials. Most salt fish producers, however, have difficulty in obtaining such a raw material. The option, then, is to improve the color of the fish raw material available. By using additives or techniques to improve the color, one is likely to be able to achieve improvements of whiteness, especially in the surface of the muscle. It will be difficult to remove bad color in the muscle altogether, but it could be that the color can be improved, for example, by removal of blood. Another positive effect of phosphates may be to prevent unfortunate discoloration due to blood residues in fish muscles.
By producing whiter salted fish, can salt fish producers expect increased price, increased turnover of the products and any access to well-paid market segment. Salted fish on dried and salted cod production can also get a better color, and to provide a quality termination of the product dried and salted cod. When it comes to light salted fillets, it's essential to be competitive in the market that the phosphates used to achieve the right color, prevent drip loss and achieve appropriate sensory properties. Provided the examined types of phosphates work and are not too costly, improved whiteness, stable dividend and reduced yellowing will improve profitability for salt fish producers. Optimal whiteness and a good dividend is a precondition for being able to compete with other salt fish producers.
The project has been led by Møre Research Marine by a project manager, Researcher II, Ingebrigt Bjørkevoll. Moreover, scientists Trygg Barnung, Margareth Kjerstad, Ann Helen Hellevik and Gretel Hansen Aas will participate from Møre Research. The second project participant is Nofima Marin where Sjurdur Joensen will be responsible and other project participants appointed if necessary. ANFACO-CECOPESCA researchers Rodrigo G. Reboredo and Lorena Formoso coordinate the analytical part of the project regarding phosphate and mineral residuals, product oxidation and sensorial testing. It will also assist with information related to the Spanish and Portuguese legislation, market and practice.