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Hydrophilic interaction chromatography has been used to investigate the retention characteristics of a group of polar compounds typically present in meat like carnosine (Car), anserine (Ans), creatine (Cr), creatinine (Cn), glutathione oxidised (GSSG), glutathione reduced (GSH) and nicotinamide adenine dinucleotide (NADH). These compounds were separated using four polar stationary phases composed by bare silica, amide and zwitterionic groups bound to porous silica and zwitterionic groups attached to a polymeric bead. Ammonium acetate salt used in the mobile phase was found to provide the best results in selectivity and reproducibility. The effect of salt concentration together with pH and acetonitrile (ACN) content of the eluent on the retention of the different polar stationary phases was also studied. A linear gradient of ACN from 80% to 30% with 10 mM ammonium acetate at neutral pH values (pH 6.0 and pH 7.8) offered retention factors k ≤ 10 while keeping a resolution higher than 1.5 for all the assayed compounds in bare silica and amide columns. The separation of NADH from GSSG was not possible under the studied conditions at any salt concentration using zwitterionic columns.

This study is focused on the effect of sodium chloride alternative salts (KCl, MgCl2 and CaCl2) on porcine muscle proteases (cathepsins, dipeptidylpeptidases and aminopeptidases). In general, KCl exerted a very similar effect to NaCl for all the studied enzymes, while the effect of divalent salts (CaCl2 and MgCl2) was more pronounced. Cathepsins, dipeptidyl peptidase III, dipeptidyl peptidase IV and alanyl aminopeptidase activities were strongly inhibited by all the chloride salts especially by divalent ones. Dipeptidyl peptidase II and leucyl aminopeptidase were little affected and methionyl aminopeptidase was only inhibited by divalent salts. Dipeptidyl peptidase I was strongly activated by low concentrations of the chloride salts except NaCl. Arginyl aminopeptidase was activated by NaCl and KCl and low amounts of MgCl2, while CaCl2 showed a strong inhibitory effect. This is very important as these enzymes play important roles in dry-cured meats and their activity is, in general, regulated by sodium chloride. Thus, reductions in the sodium concentration with subsequent increases of other alternative cations may have relevant consequences on enzyme activity that should be taken into account when processing dry-cured meats.

The simultaneous brine thawing/salting operation has been proposed as an effective alternative for the accelerated processing of frozen cured hams. The aim of the present study was to study the effect of this new technology on the lipolytic and proteolytic enzymes responsible for the generation of flavour precursors during the salting and post-salting stages of the manufacturing of Spanish dry-cured ham. The effect of the frozen and thawed process produced a higher proteolytic and lipolytic activity than in the fresh traditional salted hams (FPS) that was detected by a higher concentration in free amino acids and free fatty acids. On the other hand, the brine thawed/salted treatments, at atmospheric pressure (BTS) and with vacuum impregnation (BTS-TP), produced an acceleration of the myofibrillar degradation that occurred in the BTS and BTS-TP hams in comparison to FPS. However, the lipolysis was affected by the frozen treatment but not by the brine thawed treatments, as few differences in free fatty acids and lipase activity were detected among the frozen and brine thawed hams at the end of post-salting stage.