Australian consumers are more responsive to intramuscular fat than American or Chinese consumers
Rachel O’Reilly, Liselotte Pannier, Graham Gardner and David Pethick, Murdoch University Western Australia; Robin Jacob, DAFWA
Corresponding author: R.Oreilly@murdoch.edu.au
*This project was undertaken with collaborators at Texas Tech University, Lubbock United States of America (USA) and China Agricultural University, Beijing China.
The USA and China are Australia’s most valuable export markets for chilled and frozen sheepmeat products, yet international consumer perceptions of Australian sheepmeat are poorly understood.
Previous work in beef has demonstrated that perceptions of eating quality differ between Australian and Korean consumers. This may stem from greater sensitivity to intramuscular fat (IMF) among Australian consumers, whose palatability scores for tenderness, juiciness, liking of flavour and overall liking have been shown to be particularly responsive to changes in IMF. Additionally, Japanese consumers respond negatively to branched chain fatty acids, which would off-set the positive relationship between IMF and eating quality traits.
Extrapolating these Asian results to Chinese consumers, we hypothesise that their eating quality scores would be less responsive to changes in IMF than the eating quality scores of Australian consumers or the similarly Westernised palates of American consumers.
Materials and methods
Lambs and yearlings (n=328) were from the Kirby Meat and Livestock Australia genetic resource flock and consisted of maternal, terminal and merino sire types.
Animals were slaughtered in two kill groups, and the longissimus lumborum (loin) muscle was collected and aged for 10 days prior to frozen transport to the USA, China and within Australia.
Untrained consumers tasted and scored six grilled samples for eating quality traits of tenderness, juiciness, liking of flavour, and overall liking on a scale of 1 to 100. A total of 720 consumers were surveyed in each country.
Each animal was represented by a loin cut in two different countries at the same time. Each cut was sampled ten times. IMF and Warner Bratzler shear force (WBSF), both good indicators of eating quality for Australian consumers, were measured on loin samples.
Eating quality data was analysed using linear mixed effects models in SAS with fixed effects of country, muscle type, sire-type within age class, sex within age class, and kill group. Random terms included sire, tasting session within country, and animal identification.
Results and discussion
The level of IMF in the loin had a significant positive association with all sensory traits, across all countries (P<0.001). As IMF increased from 2.5% to 9%, consumer sensory scores increased for tenderness (by 7.9 eating quality scores), juiciness (5.8), liking of flavour (7.2) and overall liking (6.7).
The increase in consumer sensory scores with increasing IMF levels highlights IMF as a strong driver of eating quality. In agreement with our hypothesis, Australian consumers demonstrated a stronger response to changes in IMF% compared to Chinese consumers, yet contrary to our hypothesis the American consumers were similar to the Chinese.
For overall liking, the Australian consumer scores increased by 1.8 scores per 1% increase in IMF (Figure 2). The increase was 0.8 scores or less for Americans and Chinese consumers (P<0.05).
Shear force (N) is a measure of the force required to chew a meat sample. Higher shear force levels of the loin had a negative association with the sensory traits, across all countries (P<0.001). As shear force increased from 15 to 95 N, consumer sensory scores reduced for tenderness (by 17.6 eating quality scores), juiciness (8.6), liking of flavour (5.5) and overall liking (8.9).
In contrast to the results for IMF, the size of this effect was consistent across all countries (Figure 3). Given that there was no variation in the response to WBSF between countries, the variation observed for IMF between countries may be a reflection of the inherent correlation between consumer scores with liking of flavour most strongly linked to IMF changes. This would support the assertion that Asian consumers are more sensitive to branched chain fatty acids.
Conclusion
Increasing IMF showed a positive impact on all eating quality traits regardless of cultural background; however, Australian consumers demonstrated the greatest sensitivity towards IMF changes. Results indicate sheepmeat producers supplying the Australian domestic market would yield the greatest improvements in eating quality by breeding for higher IMF, where other factors along with IMF likely contribute to perceived eating quality for American and Chinese consumers.
Acknowledgements
The authors would like to thank the Cooperative Research Centre for Sheep Industry Innovation (Sheep CRC), Meat and Livestock Australia and associated organisations for funding, and data collection support.