Gelation and microstructural properties of fish myofibrillar protein gels with the incorporation of l-lysine and l-arginine at low ionic strength

BACKGROUND The solubility limitation and poor gelation properties of myofibrillar proteins at low ionic strength are the most challenging obstacle to limit salt reduction in meat products. In the present study, five amino acids with different concentrations of 5, 10 15, and 20 mmol L-1, l-lysine (Lys), l-arginine (Arg), l-histidine (His), l-proline (Pro) and l-glycine (Gly), were introduced into myofibrillar protein (MP) suspensions at low ionic strength to improve solubility and gelation properties. RESULTS The dynamic rheological analysis showed that the MPs at 100 mmol L-1 NaCl containing 15/20 mmol L-1 Lys/Arg exhibited similar gelling behaviors to MPs at 600 mmol L-1 NaCl. Similarly, 15/20 mmol L-1 Lys/Arg significantly increased the solubility of MPs and the water holding capacity (WHC) and gel strength of MP gels, which was comparable to those of MPs at 600 mmol L-1 NaCl. Furthermore, Lys and Arg promoted the formation of aggregation-type gel with a dense and compact structure observed by scanning electron microscopy. The gels containing 15/20 mmol L-1 Lys/Arg exhibited a significant increase in the proportion of immobilized water (P-21). CONCLUSION The enhancement of WHC, gel strength, and P-21 was closely associated with the increased solubility and the dense microstructure induced by Lys and Arg with high concentrations of 15 and 20 mmol L-1. The knowledge obtained from this study may be useful for the improvement of gelation properties of MPs at low ionic strength using l-lysine and l-arginine. (c) 2021 Society of Chemical Industry.

Automated summary

The introduction of different concentrations of five amino acids improved the solubility and gelation properties of myofibrillar proteins at low ionic strength. High concentrations of Lys and Arg significantly increased solubility and gel strength, leading to a dense microstructure.