Effect of kappa-carrageenan on the gelation of horse mackerel (T-murphyi) raw paste surimi-type

摘要

Gelation of fresh (unfrozen) raw surimi-type paste (RS paste) from horse mackerel (T murphyi) was studied in the presence Of kappa-carrageenan (0.5, 1, 2% Ckappa) and KCl (0.5-2%) as a substitute for NaCl. Gelation was traced by measuring the storage modulus (G') during heating-cooling cycles. Variations in G' during the heating stage of the mixed system RS-Ckappa characterised the presence of a phase separation in this stage due to Ckappa solubilitation (at about 50degreesC) as well as to RS gelation (35-80degreesC) in the mixture. It was also observed that when Ckappa was added as a single ingredient. it inhibited RS gelation as a function of its concentration (>2%). Nevertheless, during the cooling stage, the final G' value for the RS-2% Ckappa mixed system was greatly increased. This reinforcing would be caused by further (cold) Ckappa gelation in the mixture. It is theorised that Ckappa might act by forming 'packed' microgels within the RS protein gel network, which is favoured upon application of a moderate (40degreesC, 60 min) thermal treatment rather than when an extreme (90degreesC, 20 min) treatment is applied. On the other hand, although KCl enhanced gelation of the 2% Ckappa solution, addition of this salt to the RS-2% Ckappa mixture did not improve its gelation. Rheological information was complemented with observation of the resulting structures by scanning electronic microscopy (SEM).