Liselotte Pannier

The USA and China are Australia’ s strongest sheep meat export markets , however insights into consumer perceptions of Australian sheep meat are limited . IMF and shear force are good indicators of eating quality for Australian consumers however the relationship for American and Chinese consumers is unknown. Eating quality scores (tenderness, juiciness, liking of flavour, and overall liking) were obtained from American, Australian, and Chinese consumers for Longissimus lumborum and semimembranosus muscles collected from Australian sheep (n=328). Shear force was negatively associated with all sensory traits, consistent for all countries. Whereas, increasing IMF levels had a positive impact on all eating quality scores for all countries, however the most significant change was observed for Australian consumers indicating their higher sensitivity towards IMF differences.

This study tested the palatability of lamb meat derived from pasture versus grain finishing systems. The loin and topside muscles from 105 lambs were collected. Sensory scores were generated using untrained consumers who tasted 5 day aged grilled steaks, scoring tenderness, juiciness, flavour and overall liking. Consumer scores did not differ in female lambs fed grain or pasture diets. However in wether lambs palatability scores for overall liking, tenderness and juiciness were higher for those on grain compared to those on pasture. Correcting for intramuscular fat accounted for most of these differences. These results confirm that Australian consumers do prefer grain-fed lamb meat, but only in wether lambs.

Genetic parameters were estimated for 5 sensory (overall liking, tenderness, juiciness, flavour and liking of odour) and 2 objective eating quality (EQ) traits (intramuscular fat, IMF, and shear force, SF), measured on loin and topside meat cuts (except IMF) produced by progeny from the Information Nucleus of the CRC for Sheep Industry Innovation. Heritabilities for sensory traits were low to moderate for loin and moderate to high for topside cuts. Loin IMF was highly heritable while SF was moderately heritable in both cuts. Genetic correlations among the sensory EQ traits were all positive and high (0.72-1.00). Genetic correlations between loin IMF and sensory traits were moderately positive and lowly positive for loin and topside respectively. SF had stronger, negative correlations with sensory EQ traits in the topside than in the loin. Overall liking may be improved more so through selection on IMF in the loin and SF in the topside.

In addition to nutritional attributes and lean meat, eating quality is a key driver influencing the consumer demand for sheep meat. It is generally believed that meat from older animals reduces the overall consumer acceptance of meat products, however there are limited sensory studies available to define these differences within untrained consumers, or to identify factors that affect them. A lamb versus hogget comparison study was conducted, which was part of a larger sens01y experiment within the Information Nucleus program of the CRC for Sheep Industry Innovation. This study tested genetic and non-genetic factors, and objective meat quality traits on sensory scores. We hypothesised that hogget meat will have lower sensory scores compared to lamb meat. Sensory scores were generated on the longissimus thoracis et lumborum (loin) and semimembranosus (topside) muscle from 189 Merino lambs, average age 355 days, and 209 Merino hoggets, average age 685 days. Five day aged grilled steaks were tasted and scored (1-100 score) by untrained consumers for tenderness, juiciness, flavour and overall liking. The difference in magnitude of sensory scores of the topside was greater than for the loin. Lamb topside had 8.4, 7.0, 3.3 and 5.8 more sensory scores for tenderness, overall liking, juiciness and flavour than hogget topside samples, whereas the lamb loin had only 4.7, 2.7, 1.6 and 2.2 more sensory scores for tenderness, overall liking, juiciness and flavour than hogget loin samples (P<0.01). Within each age group loins were more acceptable than topsides. In support of our hypothesis, older sheep had reduced sensory scores however these differences were minimal for the loin. These preliminary results highlight the better eating quality of lambs but show an acceptable eating quality of hogget meat, particularly for the loin, which opens the possibility of developing a high quality hogget product.

Sensory enjoyment is one of the key drivers that influences the consumer demand for lamb in Australia. One of the key factors that determines consumer satisfaction of lamb is intramuscular fat (IMF). Yet the challenge is to balance this against the industry aim of selecting for lean meat yield using Australian Sheep Breeding values for post-weaning eye muscle depth (PEMD) and subcutaneous fat depth at the c-site (PFAT), as these have been shown to decrease IMF levels. Hence, we hypothesised that selection for reduced PFAT and increased PEMD will reduce the sensory scores of lamb and that this relationship is driven through reduced LMF levels. Sensory scores were generated on both the longissimus thoracis et lumborum (loin) and semimembranosus (topside) muscle from 1,434 lambs. Five day aged grilled steaks were tasted by untrained consumers who scored (1-100 score) the samples for tenderness, juiciness, flavour, odour and overall liking. Increasing PEMD was associated with 5.3, 3.6 and 3.1 lower sensory scores for tenderness, overall liking and flavour for both the loin and topside samples. Decreasing PFAT was associated with a 3.1 score reduction for tenderness within the loin samples only All sensory scores increased with higher IMF levels, most strongly for juiciness and flavour, however in this analysis variation in IME levels did not appear to explain the impact of either PEMD or PFAT. This illustrates that the associations seen between PEMD and PFAT with the sensory scores are not solely driven through the phenotypic impact of IMF, in contrast to our initial hypothesis. Yet in support of our hypothesis, selection for more muscular and leaner animals did reduce the sensory score, confirming our growing concerns that selecting for lean meat yield would reduce consumer eating quality. This highlights the need for careful monitoring of selection programs to maintain the eating quality of lamb.