evaluation the effect of hydrogen peroxide and ph on colour and microsturcture of common carp (cyprinus carpio) fillets and its resultant

the preferred colour for surimi is white, but surimi prepared from light fillets of common carp (cyprinus carpio) is slightly pink. hydrogen peroxide (h2o2; 1-3% v/v) with and without sodium tri-polyphosphate (stp; 1-2% w/v) was added to a sodium carbonate bath (ph 7.0-11.5) resulting in a final ph range of 4.4 to 10.1 which was injected into carp fillets. after soaking and tumbling for 30 min at 4-10ºc, the fillets were evaluated for colour and water holding capacity (whc). fillets tumbled with treatment solution at different ph levels (7.0-11.5) without h2o2, had improved colour with significantly (p 0.05) within the ph levels (7.0-11.5) trialled. with increasing h2o2 levels (1-3%), fillets became lighter and δe increased significantly (p < 0.05), especially with a 3% h2o2 treatment at ph of 10.5. the whiteness (l*-3b*) of surimi produced from treated (3% h2o2, ph 10.5) common carp fillets was compatible with that of alaska pollock and significantly (p < 0.05) higher than that of surimi from threadfin bream. on the contrary, whc of treated fillets and its resultant kamabok gel significantly decreased in comparision with other samples. this was investigated by scanning electorn microscopy (sem) technique. it was concluded that application of 3% h2o2 has possibly denatured the myofibrillar proteins which caused lower number of polygonal structure at the gel matrix of kamaboko prepared from treated fillets. it is recommended to improve the colour of common carp surimi while keeping the myofibrillar proteins intact by application of lower concentration of h2o2 on either chopped fillets or mince.