Vacuum impregnation in Merluccius hubbsi hake fillets brining. Effect on mass transfer kinetics, texture and colour

Brining is a preliminary process for the development of many traditional and innovative fish products. We analysed the use of vacuum impregnation (VI) in hake fillets brining (10 g NaCl/100 mL solution, 4 +/- 2 degrees C). VI brining (p1 = 10000 Pa, t1 = 5 min, restoring atmospheric pressure for 25-415 min) was compared with brining at atmospheric pressure (control). VI had a significant effect on mass transfer kinetics, yielding a higher Total Mass Change (Delta M) and salt content, which implied shorter brining times as well as higher product yield. Brined fillets presented lower L*, a* and b* values compared to fresh samples. VI did not affect colour when comparing with control. Likewise, texture varied with brining time, but not due to VI. Principal Component Analysis indicated that unbrined fresh hake and samples brined for 240 min (either VI or control) were different in their Delta M, NaCl content, colour and elasticity. Peleg equation accurately modeled salt and water contents behavior during brining, predicting a 75% processing time reduction by the use of vacuum impregnation.