Microstructure of suwari and kamaboko sardine surimi gels

In a previous work it was suggested that the texture of kamaboko (set and c ooked) gels made from sardine surimi under varying setting conditions was p redetermined by the specific matrix forming in each suwari (set) gel. This paper describes the microstructure of the networks formed in suwari and kam aboko gels set at 25, 35 and 40 degrees C for 30 or 60min as examined by sc anning electron microscopy (SEM). Cooking conditions for kamaboko gels were fixed at 90 degrees C for 30min; other preparation conditions were invaria ble. At low magnification (less than or equal to x500) the gel matrixes wer e compact, with practically no differences among lots. At higher magnificat ion (x20000), the suwari gel matrixes formed at low temperature consisted o f globules. At higher temperatures the globules joined up to form fibrillar structures (fibres) and zones of disordered globule aggregation (coagula); at longer setting times, lateral bonding of the fibres became apparent. Ka maboko gels produced from unstructured globular matrixes exhibited only a f ew fibrillar zones and large areas of coagula. Where there was already an i ncipient fibrous formation, these developed into individual fibres or bundl es of fibres that correlated with the best texture characteristics. Suwari gels with extensive lateral bonded fibres gave rise to kamaboko gels with a highly compact appearance under SEM; this correlated with a decline in tex ture values. These different structures suggest that the protein-protein bo nds in the suwari networks have different levels of stability to heat, and these levels determine whether or not the proteins can subsequently be reor ganised when the kamaboko gel forms. (C) 1999 Society of Chemical Industry.