title: Effects of aging and freezing/thawing sequence on quality attributes of bovineMm. gluteus mediusandbiceps femoris.
abstract: OBJECTIVE
  The effects of aging and freezing/thawing sequence on color, physicochemical, and enzymatic characteristics of two beef muscles (Mm. gluteus medius, GM andbiceps femoris, BF) were evaluated.
  
  
  METHODS
  Beef muscles at 3 d postmortem were assigned to four different combinations of aging and freezing/thawing sequence as follows; aging at 2°C for 3 wk (A3, never-frozen control), freezing at -28°C for 2 wk then thawing (F2, frozen/thawed-only), aging at 2°C for 3 wk, freezing at -28°C for 2 wk then thawing (A3F2), and freezing at -28°C for 2 wk, thawing then further aging at 2°C for 3 wk (F2A3).
  
  
  RESULTS
  No significant interactions between different aging/freezing/thawing treatments and muscle type on all measurements were found. Postmortem aging, regardless of aging/freezing/thawing sequence, had no impact on color stability of frozen/thawed beef muscles (p<0.05). F2A3 resulted in higher purge loss than F2 and A3F2 treatments (p<0.05). A3F2 and F2A3 treatments resulted in lower shear force of beef muscles compared to F2 (p<0.05). Although there was no significant difference in glutathione peroxidase (GSH-Px) activity, F2A3 had the highest β-N-acetyl glucominidase (BNAG) activity in purge, but the lowest BNAG activity in muscle (p<0.05). GM muscle exhibited higher total color changes and purge loss, and lower GSH-Px activity than BF muscle.
  
  
  CONCLUSIONS
  The results from this present study indicate that different combinations of aging/freezing/thawing sequence would result in considerable impacts on meat quality attributes, particularly thaw/purge loss and tenderness. Developing a novel freezing strategy combined with postmortem aging will be beneficial for the food/meat industry to maximize its positive impacts on tenderness, while minimizing thaw/purge loss of frozen/thawed meat.
authors.affiliation: Meat Science and Muscle Biology Laboratory, Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Hyun-Wook
authors.initials: HW
authors.lastname: Kim
authors.affiliation: Meat Science and Muscle Biology Laboratory, Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Yuan H
authors.initials: YH
authors.lastname: Brad Kim
keywords: Aging; Freezing; Glutathione Peroxidase; Purge; Thawing