Treatments: F2 — frozen at 1 day post mortem and stored for 2 weeks (non-aged control), A3F2 — ageing for 3 weeks and then frozen-stored for 2 weeks, A4F2 — ageing for 4 weeks and then frozen-stored for 2 weeks, and A4 — ageing for 4 weeks (non-frozen control). All frozen loins were thawed overnight at 3 °C prior to being removed from the vacuum package for further analyses.
2
Freezing rate: the beef samples assigned to Fast freezing were placed in a calcium chloride immersion tank operated at − 17 to − 18 °C, while the samples assigned to Slow freezing were placed in a conventional air freezer (− 18 °C).
3
No significant interaction between ageing period and freezing rate was observed (P > 0.05).
4
SED: standard errors of difference between means.