Seafood quality improvement by phosphates

ALEX AUGUSTO GONÇALVES1 & JOSÉ LUIS DUARTE RIBEIRO2

Abstract: Phosphates are natural components of almost all foods and are also used as functional food additives in food processing. In the seafood industry, phosphates have a wide application and are providing many functional uses. Consumers should be able to acquire seafood with as little loss of content and quality as possible. An appropriate treatment of the seafood with phosphates should be chosen carefully, based on the seafood species, product type and according to the consumer's expectations and international legislations. Moreover, phosphates cannot substitute an inadequate handling and cannot improve the quality of a poor product. The conditions of the product and its quality should be evident and documented during the whole processing.Key words: Seafood, phosphates, quality, legislation.

Industrial Relevance 

This review intend to show for researchers and seafood industrials the potential use of additive phosphate in industrial applications; showing the importance of legislation and limit use. The phosphates application in seafood is shown promising, but it has to be used with criterion. The incorrect or abusive use will lead to sensorial failures and besides that, it can characterize economic frauds.Introduction Seafood is very popular in the world, with high nutritional value, what explains the high demands on the part of the consumers. Besides, the growing costs of these products generate higher quality expectations. Consumers should be able to obtain “seafood products” of high quality, best appearance and little weight loss, mainly the frozen products.

Shortly after the capture, a series of complex alterations (biochemical and microbiological) occurs on the surface and inside the edible portion of all seafood, resulting in a decrease of its quality. Water is the most abundant component in its muscle, considering weight as well as volume (70-80%). As a main component,it influences the seafood sensorial attributes, its shelf life and quality. However, a part of this water is lost during transportation, from its capture to its processing and posterior comercialization, through drip, evaporation and/or cooking.Thus, the seafood processing companies have a great concern in retaining this water, first for economic reasons (seafood is sold by weight)and secondly, for the quality of the final product(Toldrá 2003). On the other hand, an excessive loss of water can generate a great dissatisfaction on the part of the consumers for the following reasons: (a) the drip of the fish generates an undesirable appearance; (b) cooking reduces thesize of the fish; (c) and mainly, the loss of the sensorial attributes (juice, texture and color) makes the seafood less attractive.

Use of phosphates in seafood

Aware of the loss of water during the capture and processing, the commercial practices have been involving the control, addition (hydration)and retention of the moisture of the fish during the capture, processing, distribution, storage and preparation. The treatment of the fishwith phosphates, to guarantee its quality, has been used for many years. However, excessive addition of water can lead to adulteration resulting in economic fraud, while a limit of water and loss of water can endanger the quality, the shelf life and the acceptance of the product by the consumer (Schnee 2004; Garrido & Otwell2004).Among the functional properties changed by the addition of phosphates in seafood and its products are: (a) the retention of the moisture and natural flavor, inhibiting the loss of fluids during the distribution and the comercialization, (b) the emulsifying (mainly in sausage products), (c) the inhibition of the process of lipid oxidation (by the quelation of metallic ions),(d) the stabilization of the color, and (e) the cryoprotection which contributes to the extension of its shelf life (Neto & Nakamura, 2003; Schnee2004; Ünal et al. 2004).Recently, the use of phosphates in some segments of the fishing industry has been object of meticulous exam of the governmental institutions in several countries, including Brazil. When used inadequately, the excessive absorption of moisture can lead to economic fraud accusation. However,when applied criteriously, the phosphates retain the natural moisture resulting in softer and succulent products. It is important to highlight that the polyphosphates should never be used to mask aninferior or deteriorated quality product (Aitken2001; Neto & Nakamura 2003).Classification and nomenclature The phosphates are obtained by the refine of the calcium phosphates that occur naturally in the mineral rocks. Through total or partial neutralization of the phosphoric acid with alkaline metallic ions(sodium, potassium or calcium), two phosphate classes are formed: orthophosphates and pyrophosphates (Dziezak 1990; Lampila 1992; Neto& Nakamura 2003; WFM 2004).The basic structures for the salts of phosphate are the orthophosphoric acids. The salts formed by the reaction with a base, as the sodium hydroxide, are for that reason referred to as orthophosphates, besides other salts of sodium which are also presented on Table 1, with the common nomenclatures in the literature, as well as the code International Number System for Food Additives - INS (Marujo 1988; Dziezak1990; Teicher 1999; Neto & Nakamura 2003; WFM2004). 

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