Characterization of fresh muscle pigments in channel catfish and their influence by chilling stress.

摘要

Color and color components are important quality attributes for fresh channel catfish muscle. The objective of the present research was to obtain inside understanding regarding color distribution, color component stability and the pre-slaughter conditions influence on color and color components and other quality attributes. Catfish fillets were rendered to be paler and redder on iced storage; and paler, less red and less yellow by ice-water chilling process. Visual classified "reddish" catfish fillets had higher heme-protein content than "white" fillets and these pigments were derived mainly from hemoglobin. Pre-slaughter live fish chilling in ice water and bleeding at slaughter also slightly affected muscle color and total heme-protein content, but they were not the main factors for the "reddish" color on catfish muscle. Catfish hemoglobin autoxidation rate was similar at room and at refrigeration temperature. Myoglobin gene and hemoglobin beta gene were cloned and expressed in Escherichia coli cells in insoluble form. The myoglobin gene had an open reading frame of 444 nucleotides and translated into 147 amino acids with molecular weight of 16,909 and pI of 9.43. The myoglobin gene in vivo expression in white muscle was not affected by pre-slaughter chilling. Pre-slaughter chilling is a stressor to channel catfish and shortens the pre-rigor time postmortem; thus, it is not recommended in catfish processing.