Farmer wants a life – sheep research open day

Keeping up appearances – why meat colour matters

Honor Calnan & Maddison Corlett,Murdoch University

Why does meat colour matter?

  • consumers demand that fresh lamb meat has a bright red colour
  • consumers associate dark, pale or browned lamb meat with reduced meat quality and imminent spoilage, so will avoid purchasing this meat
  • lamb meat browns much faster than beef, after only 2-3 days of overwrapped display
  • lamb meat turns brown due to myoglobin oxidation long before any discolouration due to microbial growth, meaning brown lamb meat can still be of premium quality
  • lamb meat browning results in substantial economic losses for the industry.

Lamb meat colour in Australia

  • The Sheep CRC Information nucleus flock experiment assessed the initial bloomed colour of loin meat and its rate of browning over a three day simulated retail display in >5000 lambs:
  • all bloomed loins were adequately red, however only 60% of loins met the consumer acceptance threshold for lightness, meaning 40% of loins were too dark
  • 55% of lamb loins were too brown for consumer acceptance after only 48 hours on display
  • 75% of loins were too brown for consumer acceptance at 72 hours display.

Factors influencing the display colour of lamb meat

  • Bloomed meat colour –increasing myoglobin concentration and pH reduce meat lightness, while marbling increases meat lightness and selection for lean meat yield has little impact.
  • Meat browning on retail display –high muscle oxidative capacity, marbling and particularly pH increase the rate of lamb meat browning, while selection for muscling and particularly high muscle vitamin E reduce meat browning on display.

Packaging solutions for lamb meat colour

  • Modified atmosphere packaging (MAP) can reduce lamb meat browning for up to 10 days on retail display. However, the high oxygen concentration (typically 75%) used in MAP can negatively impact the eating quality of meat, particularly tenderness.
  • Vacuum packaging can extend shelf life beyond high oxygen MAP and allows for continual tenderisation. The disadvantage is that fluid accumulates and the zero oxygen environment means the meat retains its dark purple colour.
  • Vacuum skin packaging may be a more saleable product as a thin upper film is applied to the product under low vacuum pressure, thus preventing the formation of exudates.