National sampling and gross composition of Australian retail pork cuts 2005/2006.

After consideration of five potential sampling designs, 13 retail pork cuts were purchased from randomly selected supermarkets and butchers' stores in urban areas across the socioeconomic scale in three States of Australia in late 2005 and early 2006. They were analysed, raw and cooked, for gross composition (fat, lean, bone and gristle). Gross composition varied considerably within cut associated with large divergences in interpretation of standard pork cuts by butchers. There were no notable differences in gross composition across States, across the socioeconomic range of suburbs of purchase or between outlet types (butcher vs supermarket). Cuts tended to be larger and leaner than those in similar studies in the 80s and 90s. Due to increasing uniformity in breeding and feeding of pigs in Australia, sampling designs in future surveys could be simplified.

The effects of finishing diet and postmortem ageing on the eating quality of the M. longissimus thoracis of electrically stimulated Brahman steer carcasses.

Beef from cattle finished on grass will be of similar quality to that from cattle finished on grain when their carcasses are processed using best practice protocols. To test this hypothesis, carcasses of twenty Brahman steers, finished to 400 kg live weight on either Buffel grass pasture (n=10) or grain (n=10), were electrically stimulated with 400 V for 50 s 45 min postmortem, and their beef quality assessed 1 and 14 days postmortem. Hot weight, rump subcutaneous fat thickness and animal rate of growth in the 205 days preceding slaughter were recorded for each carcass as potential influences on beef quality. Quality of the M. longissimus thoracis (LT) at 1 and 14 days postmortem was evaluated using peak Warner-Bratzler shear force, compression, pH, cooking loss and taste panel acceptability, as well as by moisture and crude fat contents measured at 1 day postmortem. Results showed that steers finished on pasture grew the slowest and had the least subcutaneous fat at the same carcass weight. LT from carcasses of steers finished on pasture also had the shortest mean sarcomere lengths, suggesting these muscles may have been cold-affected, but there was no effect of diet on peak shear force. LT from carcasses of steers finished on pasture had the highest mean compression value, possibly because of increased collagen cross-linking associated with slow growth or increased exercise. Ageing significantly decreased LT peak shear force and compression values and increased cooking loss, L (∗), a (∗) and b (∗) values. Taste panellists rated the aged, grass-finished beef the most tender and the best quality; however, the taste panel in this study may have favoured LT from grass-finished steers because it was significantly juicier than LT from the grain-finished steer carcasses. These results indicated that carcass composition and processing conditions interact to exert a greater effect on LT toughness and sensory acceptability than finishing diet. Ageing LT from steers finished on grass improved its colour, and thus may enhance its consumer acceptability.

Partial least squares (PLS) regression for the analysis of instrument measurements and sensory meat quality data.

The partial least squares (PLS) regression technique was used to examine meat quality data derived from instruments (including Warner-Bratzler shear force and Instron Compression) and sensory panels. The data related to beef longissimus dorsi muscles collected during trials to study the effect of hot boning on meat quality. The univariate analysis of tenderness showed that over 60% of the variation in sensory tenderness, and almost 60% of the variation in sensory acceptability, could be explained from instrument variables and a consideration of boning and ageing time. Graphical displays from the analysis indicated that hot boning (either at 1 or 4 h) had little effect on meat quality. Graphical displays demonstrated a possible important effect of vacuum-pack ageing on acceptability. For this data set, it appears that samples of approximately equivalent tenderness differ in acceptability, depending on whether the samples have been aged for 1 or 4 weeks. This finding may have practical importance in attempts to predict eating quality (acceptability) from instrument measurements. Separate equations are necessary for products aged for different periods. ©