I. L. Larsen

Establishment of consumer thresholds for beef quality attributes

Acceptability threshold values for Warner-Bratzler shear (WBS) and trained sensory panel attributes were determined through regression analyses against consumer scores for overall tenderness, juiciness, flavour desirability and overall palatability for both the longissimus lumborum (LL) and semimembranosus (SM) muscles. Although consumers were not as sensitive to changes in tenderness as trained panellists, the relationship between consumer scores and trained panellist scores was moderate (r value = 0.64; P = 0.001). Based on the 50% confidence levels for WBS (7.85 and 8.15 kg for the LL and SM, respectively), 20% of LL steaks and 28% of SM roasts collected from commercial abattoirs and aged 6 d exceeded these thresholds. When assessed on the basis of subjective sensory panel scores for overall tenderness, 25.3% of LL steaks and 39.9% of SM roasts exceeded the 50% confidence level. Clearly, without intervention strategies beyond 6 d of aging, there was a significant portion of beef steaks and roasts which...

Extended ageing time and temperature effects on quality of sub-primal cuts of boxed beef

Most of the information indicating ageing improves tenderness has been collected on the loin and rib-eye muscles over relatively short ageing times, assuming that all muscles will react similarly. In the present study, the effect of extended ageing times on instrumental texture (56 d) and sensory characteristics (42 d) of six different beef sub-primals [striploin (SL), inside round (IR), outside round (OR), eye of round (ER), blade eye (BE) and chuck tender (CT)] was studied. The effects of two ageing temperatures (1 and 5°C) were also compared. In general, ageing increased tenderness (P   0.05) and resulted in a decrease in tenderness of OR (P < 0.05) until day 35, with a later increase after 42 d of ageing. Increasing ageing temperature (5°C) had limited effect on tenderness, but ageing time and temperature increases led to lower flavour and higher...

Enhancing pork loin quality attributes through genotype, chilling method and ageing time.

The experiment was conducted to examine opportunities for enhancing pork quality through the use of post-mortem ageing when combined with different chilling regimes. Large White (LW, n=24) and Duroc×Large White (Duroc, n=24) barrows were slaughtered and alternate carcass sides were either conventionally or blast-chilled. The longissimus thoracis et lumborum muscle was dissected from the carcass sides (24h post-mortem) and trimmed of cover fat. Three sections (15cm length) were vacuum packaged and assigned to 2, 7 or 14days of ageing (2°C) randomized within muscle location. Blast-chilled meat had lower purge (P=0.009) and drip (P=0.0009) losses and higher hue (P=0.02) than conventionally chilled meat. However chilling by conventional or blast-chilling methods had no effect on sensory characteristics (P>0.1). When breeds were compared, meat from Duroc barrows had lower moisture (P<0.0001) and higher intramuscular fat content (P<0.0001), L∗ (P=0.0003) and hue (P=0.007) values than LW. Overall tenderness (P=0.005), juiciness (P=0.0007) and palatability (P<0.0001), as well as flavour intensity (P<0.0001) and desirability (P<0.0001) values were higher and undesirable flavours were lower (P<0.0001) for meat from Duroc pigs, when compared with LW. Ageing increased purge loss (P<0.0001), L∗ (P<0.0001), hue (P<0.0001), chroma (P<0.0001) and content of protein (P=0.002), with corresponding decreases (P<0.0001) in drip loss and moisture content. Instrumental (P<0.0001) and sensory (initial, P<0.0001 and overall, P<0.0001) tenderness increased from day 2 to 14. Therefore independent of chilling method, ageing improved quality of pork loins. Moreover ageing had greater effect on tenderness, while breed had greater effect on flavour which may be related to differences in intramuscular fat content.

Contribution of myofibrillar and connective tissue components to the Warner–Bratzler shear force of cooked beef

Myofibrillar (MF-SF) and connective tissue (CT-SF) peak shear forces were interpolated from Warner-Bratzler shear force (SF) deformation curves of cooked bovine M. gluteus medius (GM) and M. semitendinosus (ST) from 112 crossbred steers in a 2×2×2 factorial experiment examining the interactions between slaughter age, growth promotants and breed cross (British versus Continental). Mixed model analyses, Pearson correlations and stepwise multiple regression identified relationships between shear forces, meat quality measurements and production treatments. Connective tissue contribution to SF increased with slaughter age and implantation in the ST and with slaughter age only in the GM. Myofibrillar contribution to SF increased with slaughter age for the ST and with Continental genetics for the GM. Variation in ST SF and MF-SF was best described by muscle weight, which increased with animal age, while GM SF and MF-SF variation was best described by cooking loss, indicating that ST and GM SF were most affected by connective and myofibrillar proteins, respectively.

The impact of ultimate pH on muscle characteristics and sensory attributes of the longissimus thoracis within the dark cutting (Canada B4) beef carcass grade

Canada B4 beef carcasses are penalized because the longissimus thoracis (LT) at the grade site (12-13th ribs) is darker than the color threshold for normal bright cherry-red beef. Previous studies have shown that not all B4 carcasses have pH>6.0; therefore, the relationship between LT pH and meat quality was investigated by collecting thirty half-carcasses comprised of the following: ten Canada AA (AA, control), ten B4 with LT pH>6.0 (CL, classic), and ten B4 with LT pH<6.0 (AT, atypical). LT from CL carcasses had the lowest mean lactate level, lowest glucidic potential and highest mean pH value. LT muscle from CL and AT carcasses was dark and had decreased purge, drip loss and cooking loss. Warner-Bratzler shear force values and sensory panel results showed that AT beef was toughest (P<0.0001), substantiating economic penalty. Causal mechanisms for AT carcasses may be inconsistent with traditional DFD theory because of close to normal final muscle pH.

A within-animal examination of postmortem ageing for up to 21 d on tenderness in the bovine longissimus thoracis and semimembranosus muscles

The present research shows an interesting example of ageing up to 21 d having a differential effect on tenderness in the longissimus thoracis (LT) and semimembranosus (SM) muscles. When compared to 1 d postmortem, Warner - Bratzler shear (WBS) progressively decreased over time postmortem in the LT (12.05 kg at 1 d vs. 8.08 kg at 6 d, 6.95 kg at 14 d, and 5.52 kg at 21 d) but not in the SM (9.81 kg at 1 d vs. 8.19 kg at 6d, 8.43 kg at 14 d, and 9.30 kg at 21 d). Introduction of muscle-specific ageing times in industry could reduce tenderness variation and reduce refrigeration costs. Key words: Beef, ageing, tenderness, longissimus thoracis, semimembranosus

Effects of dry-ageing on pork quality characteristics in different genotypes

Presumably, dry-ageing enhances flavour attributes of meat by surface desiccation to increase and modify fatty acid content and other organoleptic molecules. However information regarding dry-ageing of fresh pork is limited. To examine the effects of dry-ageing on pork quality, Large White (LW, n = 24) and Large White × Duroc (Duroc, n = 24) barrows were slaughtered and three longissimus thoracis et lumborum sections from each side of the carcass were wet or dry-aged for 2, 7 or 14 d. Dry-aged meat had lower (P < 0.001) moisture and higher (P < 0.001) protein content due to higher purge losses (P < 0.001) when compared with wet aged meat. However no dry-ageing effect (P > 0.05) was observed on sensory characteristics. The increase in the duration of ageing decreased moisture content and drip loss and increased (P < 0.001) protein content, purge loss and L*, chroma and hue values. These changes were more accentuated in dry-aged meat (P < 0.01). Days of ageing dependent increases (P < 0.001) were observed for instrumental and sensory tenderness and juiciness in both ageing types. Moreover, meat from Duroc barrows had lower (P < 0.001) moisture and protein content, and higher (P < 0.01) fat content, L* and hue values. Instrumental and sensory tenderness, juiciness and flavour were higher (P < 0.01) in meat from Duroc than LW barrows. Increases (P < 0.01) in flavour intensity and decreases in off-flavour of meat from LW barrows were greater (P < 0.05) in d 7 than in d 14. Therefore the duration of ageing affected most quality and sensory characteristics, while the changes to quality attributes of dry versus wet-aged pork were attributable to the differences in shrink losses in the present study.

The effects of modified carcass chilling on beef carcass grade and quality of several muscles

To determine the effect of modified carcass chilling on beef carcass grade and meat quality, paired sides were assigned to modified (5°C for 24 h then 0–2°C until 48 h post-mortem) or control chilling (0–2°C for 24 h). After grading at the completion of respective chilling treatments, the longissimus lumborum (LL), longissimus thoracis (LT), semimembranosus (SM), semitendinosus (ST), and infraspinatus (IS) were removed and evaluated immediately or aged for 7, 15, 21, or 29 d prior to evaluation. Estimated cutability was not affected by chill treatment. Modified chilled sides tended (P = 0.15) to have greater marbling scores than control with ~65% having scores 10–110 units greater than control. In ~15% of paired sides, this difference was sufficient to result in upgrading from Canada AA to Canada AAA. Modified chilling reduced mean shear value across all muscles, with these early effects persisting throughout ageing in the LL and LT and represented a savings of at least 7 d of refrigerated ageing time. Ne...

Practical dietary levels of canola oil and tallow have differing effects on gilt and barrow performance and carcass composition

Previously we demonstrated that barrows produced leaner carcasses when fed 5% versus 2% canola oil. The present trial was conducted to determine if the same would be true for gilts or when feeding beef tallow (a source of saturated fatty acids). Four diets were fed (2 or 5% canola oil or digestible energy equivalents of tallow), and 27 gilts and 27 barrows were fed each diet. Experimental diets were fed from 49.4 to 113.5 kg body weight. Barrows fed 2% canola oil had similar average daily gains (ADG) relative to gilts (P > 0.05) fed any diet, but grew slower than barrows fed 5% canola oil (0.99 vs. 1.08 kg d-1; P < 0.05) and tended to have lower ADG relative to barrows fed diets containing tallow (P < 0.10). Barrows fed 2% canola oil had poorer feed conversion efficiency (kg feed kg-1 gain) relative to animals fed any other diet (P < 0.05). For barrows, feeding the 2% canola oil resulted in more subcutaneous fat relative to feeding 2.16% tallow (+18 g kg-1 lean cuts; P < 0.05), but the anticipated decreas...

Rapid discrimination of enhanced quality pork by visible and near infrared spectroscopy

This study tested the ability of visible and near infrared spectroscopy (Vis-NIRS) to discriminate enhanced quality pork. Vis-NIR spectra were collected on intact chops from 148 pork carcasses using a portable LabSpec®4 spectrometer (350-2500 nm). Partial least squares discriminant analyses based on Vis-NIR spectra correctly classified 94, 95 and 100% of the 2d, and 95, 98 and 100% of the 14 d aged pork samples within Lacombe, Duroc and Iberian pig breeds, respectively. Moreover, Vis-NIRS correctly classified 97 and 99% of the moisture enhanced (ME) and Non-ME pork samples aged for 2d, and 94 and 95% of those aged for 14 d, as well as 94 and 97% of the 2 and 14 d aged pork samples, respectively. Conversely, Vis-NIRS technology could not differentiate pork samples based on pre-slaughter diet or post-slaughter carcass chilling process. Vis-NIRS can segregate enhanced quality pork according to production factors and post-mortem strategies such as pig breed, moisture enhancing and ageing period.