Surimi technology

Abstract

Review Surimi -minced and washed fish meat -has primarily been produced from white-muscled fish species, since the desir-able odor, light color and gel-forming characteristics of the resultant surimi are very important to enable further process-ing to heat-induced gel products such as crab leg analog. The production of lowfat surimi with desirable gelJorming characteristics from sardine and mackerel by conventional processing methods has had only limited success; however, recent developments have opened the way to the utilization of red-meat fish for surimi production. During surimi process-ing, the loss of water-soluble proteins into the wash water leads not only to the waste of certain valuable nutrients but also to pollution of the water; new methods for the recovery of water-soluble proteins from the wash water are described. The role of cryoprotectants in improving frozen surimi storage is explained by the glass lransition concept. Originally the term 'surimi referred to minced and water-washed llsh muscle tissues. while it has now also been accepted to refer to crab leg analogs, a surimi-based product, in Europe and in Nonh America. [n this review. 'surimi' will be used to refer to minced and water-washed Iish muscle tissues; its frozen products will be denoted 'frozen surimi'. Although Alaska pollock (The ragra chalco gramma) has been the most utilized raw material for surimi pro-cessing, its muscle tissues are not necessarily suitable for use in other lish products. They are too soft to handle during processing and are very susceptible to quality deterioration. Once the muscle tissue has been frozen and subsequently stored at a low temp€rature' the thawed muscles tend to be spongyr and, therefore. its value as merchandise is drastically reduced. These undesirable changes in the frozen musclc tissues are believed to be due to the formation of formaldehydesr and to the accumulation of peroxidized lipids' in the muscle tissues during relatively long periods of frozen storage. Thus, up to the time when a nearly completed surirn-i technology was commercialized in thc 1960s (Refs 4-6), there was little use of Alaska polkrk muscle tissues as food and foodstuffs. except in the no(hern regions of Japan where these fish species are readilv available. Reoeated washing o[ the minced ms5cls 1i":'tlss u ith fresh water is the most characterrstic and indispensable ,irna of trtiri processing: this treatment is effective in remoring cenain factorr lhat accelerate proteln Janu,uru,ion-into the waste water and in improving J.-.,uUif,ty of the gel-forming characteristics of surimi ;;-ri;-f;." storale. New divelopments in the use of Ioshiali Olxhima, Toru Suzuti and Chirli (oizumi are al lhP Depd'lmenl of fJ S.i"n." and T".hnology, The TokYo Universily oi tisheries' Konin 4' Minato'k!, Tokyo I08, ,apan. cryoprotectants to protect the minced and washed 6sh muscle tissues against protein denaturation during sub-sequent frozen storage mean that surimi, developed pri-marily in Japan, is now produced and consumcd as a foodstuff all over the world. The ready availahility of Alaska pollock in the Nonh Pacific may have conrib-uted to the recent increase in the output of surirni'. Fuflhermore. the high level of quclily rutrienl\ in \urimi and its products matches that of land-animal meats. lndeed, the overall amino acid score of surimi is that of a high-quality protein. and is sirnilar to those of beef and turkey&n (Table I). Modern surimi processing The oyerall process of modern surimi production is summarized in Fig. l. Alaska pollock is caught by mid-water and bottom trawlers. Thc lish should be handled carefully since tish fieshness affects the quality ol the surimi; fresher fish results in higher-quality products. The body tcmperature of the hsh should bc kcpt just above the freezing point prior to processinS. stored in crushed ice or in refrigerated sea water. tn addition, the