Underlying chemical mechanisms of the contradictory effects of NaCl reduction on the redox-state of meat proteins in fermented sausages

• NaCl-reduction inhibits tryptophan oxidation in fermented sausages.
• NaCl-reduction led to an increased proteolysis and protein carbonylation.
• The formation of cross-links via carbonylation may increase hardness.
• The redox state of proteins is affected by ionic-driven effects and proteolysis.

NaCl reduction remains a significant challenge for the food industry. The influence of NaCl reduction on the oxidative damage to meat proteins during processing of experimental fermented sausages was studied. Sausages with low (0.55%, LS), medium (1.1%, MS) and high (2.2%, HS) NaCl concentrations were produced and analyzed at fix times (days 1, 18, 42 and 54 of processing) for proteolysis, protein oxidation, volatiles and texture. NaCl reduction led to a 30% lower oxidation of TRP but promoted proteolysis (from 19.5 to 26.7 mg free amino acids/g sample in HS and LS, respectively at day 54), protein carbonylation (from 0.62 to 1.18 nmol carbonyl/mg protein in HS and LS, respectively at day 42) and formation of Schiff bases (from 119 to 179 fluorescence units in HS and LS, respectively at day 54). NaCl reduction led to a significantly lower detection of Strecker aldehydes (from 8.8 to 28.6 area units in LS and HS, respectively at day 42) and a significant increase of hardness (from 117 to 143 N in HS and LS, respectively at day 54) in fermented sausages. The redox state of proteins is affected by ionic-driven effects and proteolysis with this having consequences on relevant quality traits.