2. Materials and methods
2.1. Raw materials preparation
The M. longissimus lumborum (LL, the anterior 12th rib to the last
lumbar vertebrae) were randomly extracted from four fattened steers
at a commercial abattoir in Jilin province. Carcasses were conventionally
chilled in a chilling room at 2–4 °C for 72 h. Both the left and right loins
were obtained, then vacuum packaged, and kept frozen at −20 °C according
to the process of production until transported to the laboratory.
The fattened cattle were a cross of Bos Japanese Black Cattle and
Bos Yanbian Yellow cattle, aged 32 to 37 months old, and raised on
the same farm. Carcasses weighted 392 to 423 kg and the rib eye
area was 50.1 ± 1.5 cm2 (mean ± SD), and subcutaneous fat thickness
(6–7th rib) was 2.8 ± 0.2 cm (mean ± SD).