Consumer Perceptions Towards Lamb Meat Colour and Eating Quality

Maddison T Corlett

Meat colour and eating quality of sheepmeat are crucial factors impacting consumer satisfaction and purchasing decisions. Therefore, this thesis explored how these traits are affected by storage time under vacuum, display time and different cuts of meat, quantifying these effects using colour instruments and untrained consumers. In addition, the effect of various packaging types on colour and eating quality were also investigated. These included overwrap packaging, vacuum skin packaging and modified atmosphere packaging (MAP) which is an alternative packaging type that can extend the retail shelf life of meat. Modified atmosphere packaging typically contains 80% oxygen and 20% carbon dioxide (MAP80) which promotes desirable red meat colour for 9 days, compared to 2-3 days for overwrap packaging. However, the widely used MAP80 mixture has known detrimental effects on subsequent eating quality, particularly tenderness, and therefore different gas mixtures were also explored. The first experiment compared the redness of meat on display scored by untrained consumers (n = 879) to HunterLab instrument measured oxymyoglobin to metmyoglobin ratio (reflectance of light at wavelengths 630nm and 580nm). This study compared lamb (n = 79) meat redness on the M. longissimus lumborum (loin) and M. semimembranosus (topside), stored for short (5 – 7 days), medium (33 – 35 days), and long periods (110 – 112 days) and a retail display time of 1 to 4 days. Results showed consumer colour scores remained similar for loin samples across the three storage periods, in contrast to the topside declined in redness following the longer storage periods. Furthermore, there was a weak correlation between consumer colour scores and oxymyoglobin to metmyoglobin ratio. The second experiment examined the impact of MAP containing varying levels of oxygen (0, 20, 40, 60 and 80% oxygen) on meat colour, measured by a HunterLab a* (indicator of redness) and oxymyoglobin to metmyoglobin ratio. Loin and topsides were collected from 50 lambs and stored for 5 or 20 days before being re-packaged into the allocated MAP gas mixture and placed under retail display for 2, 6 or 10 days. MAP oxygen levels as low as 40% demonstrated similar meat redness as MAP80 for loin samples for the entire retail display period. Whereas, topside samples under 40% oxygen MAP were less red than MAP80 at day 2 and 6 of retail display, but then similar in redness to MAP80 at day 10. Furthermore, increasing the storage period of samples prior to re-packaging in MAP appeared to extend the duration that samples retained their redness under subsequent retail display. Additional analysis revealed that the bacteria and lipid oxidation levels were all acceptably low, and did not vary between MAP oxygen concentration treatments, meat cuts, storage periods or display times. After identifying 40% oxygen MAP produced similar bright red meat colour to the widely used MAP80, a follow-on study compared MAP containing 40% oxygen to MAP80 on the subsequent eating quality. This experiment involved testing the sensory responses of untrained consumers (n = 960) on loin and topside samples under different packaging types including vacuum skin packaging, a MAP mixture containing 40% oxygen, 20% carbon dioxide and 40% nitrogen, a high carbon dioxide MAP mixture containing 40% oxygen and 60% carbon dioxide and MAP80 following retail display for 3 or 8 days. In general, vacuum skin packaging reported the highest sensory scores, followed by MAP containing 40% oxygen, 20% carbon dioxide and 40% nitrogen which was higher than MAP80. In addition, the high carbon dioxide MAP mixture containing 40% oxygen and 60% carbon dioxide recorded similar scores to MAP80 which received the lowest sensory scores as assessed by consumers. These results suggest a MAP mixture containing 40% oxygen, 20% carbon dioxide and 40% nitrogen should replace the widely used MAP80 as it minimised the detrimental impact on eating quality and would likely improve consumer satisfaction. As shown by the previous experiment, vacuum packaging resulted in the highest sensory scores and was thus selected for the next experiment. Therefore, the final component investigated the effect of sheepmeat derived from grain versus grass-fed diets and storage times of either 5, 21 or 45 days under vacuum packaging on sensory scores. This experiment involved testing the sensory responses of US consumers in 12 grill (n = 720) and 4 roast (n = 240) sessions. Overall, the grain and grass-fed diets resulted in similar sensory scores regardless of meat cut, cooking method and storage period. Predominantly within a cut and diet treatment, higher sensory scores were observed by increasing storage time from 5 to 21 days, while no further eating quality improvements were observed between 21 to 45 days. This finding debunked anecdotal evidence that suggested US consumers would prefer grain-fed over grass-fed samples, as well as samples under shorter storage periods. These are beneficial findings for the Australian sheepmeat industry as large portions of lamb exported to the US is grass-fed and aged for extended periods in chilled shipping freight. Overall, results demonstrated a complex variety of factors influencing consumer perceptions of lamb meat colour and eating quality. Key findings identified a lower oxygen MAP mixture promoted bright red coloured meat under retail display with higher eating quality compared to the standard MAP80 mixture. In addition, results were critical to debunking misconceptions held by US consumers towards Australian sheepmeat derived from grass-fed diets and longer storage periods affecting eating quality.

Consumer Perceptions Towards Lamb Meat Colour and Eating Quality

Files and links (1)

Abstract

Details

UN Sustainable Development Goals (SDGs)

Metrics