Effects of chopping and salting on the properties of pre-rigor silver carp muscle: Metabolic process, protein...

Chopping and salting are two important processing steps in emulsified meat products. Effects of chopping and salting on metabolic process, protein functionality, and ultrastructure of pre-rigor silver carp muscle, and how these three aspects changed during rigor transformation were explored. Chopping caused an accelerated loss of adenosine triphosphate (ATP) from 1.16 μmol/g to 0.16 μmol/g, and salt addition inhibited accumulation of hypoxanthine nucleoside (HxR) and hypoxanthine (Hx). Similarly, chopping led to faster decrease of glycogen from 4.59 mg/g to 1.50 mg/g and increase in lactic acid from 0.52 mmol/g protein to 0.82 mmol/g protein, and salt exerted an inhibition effect. In agreement with ATP and glycogen breakdown, metabolic profiling revealed that chopping and salting altered the metabolism in fatty acids and amino acids during rigor transformation. After rigor transformation, chopping with salt led to significant reduction in radical scavenging ability, accompanied by greater loss of sulfhydryl groups. Salt also promoted protein denaturation, evidenced by increased surface hydrophobicity and decreased intrinsic fluorescence. The ultrastructure of fish muscle after chopping or chopping with salt was similar between pre- and post-rigor stages. The abovementioned findings can provide valuable insight into the production of fish products.