Remy van de Ven

Effect of pulsed electric field on the proteolysis of cold boned beef M. Longissimus lumborum and M. Semimembranosus.

The effects of pulsed electric field (PEF) and ageing (3, 7, 14 and 21days) on the shear force, protein profile, and post-mortem proteolysis of beef loins (M. Longissimus lumborum, LL) and topsides (M. Semimembranosus, SM) were investigated using a range of pulsed electric field treatments [voltages (5 and 10kV) and frequencies (20, 50, and 90Hz)]. PEF treatment decreased the shear force of beef LL and SM muscles by up to 19%. The reduction in the shear force in the LL was not affected by the treatment intensity whereas the reduction in the SM was dependent on PEF frequency. PEF treated beef loins showed increased proteolysis, both early post-mortem and during subsequent post-mortem storage reflected by increased degradation of troponin-T and desmin. The most prominent troponin-T degradation was found in samples treated with 5kV-90Hz, 10kV-20Hz at day 3 and day 7 post-treatment in addition to 10kV-50Hz in subsequent post-treatment times. The degradation of desmin in PEF treated beef loins increased with ageing time.

Raman Spectroscopy compared against traditional predictors of shear force in lamb m. longissimus lumborum

A Raman spectroscopic hand held device was used to predict shear force (SF) of 80 fresh lamb m. longissimus lumborum (LL) at 1 and 5days post mortem (PM). Traditional predictors of SF including sarcomere length (SL), particle size (PS), cooking loss (CL), percentage myofibrillar breaks and pH were also measured. SF values were regressed against Raman spectra using partial least squares regression and against the traditional predictors using linear regression. The best prediction of shear force values used spectra at 1day PM to predict shear force at 1day which gave a root mean square error of prediction (RMSEP) of 13.6 (Null=14.0) and the R(2) between observed and cross validated predicted values was 0.06 (R(2)cv). Overall, for fresh LL, the predictability SF, by either the Raman hand held probe or traditional predictors was low.

Using instrumental (CIE and reflectance) measures to predict consumers' acceptance of beef colour

We aimed to establish colorimetric thresholds based upon the capacity for instrumental measures to predict consumer satisfaction with beef colour. A web-based survey was used to distribute standardised photographs of beef M. longissimus lumborum with known colorimetrics (L*, a*, b*, hue, chroma, ratio of reflectance at 630nm and 580nm, and estimated deoxymyoglobin, oxymyoglobin and metmyoglobin concentrations) for scrutiny. Consumer demographics and perceived importance of colour to beef value were also evaluated. It was found that a* provided the most simple and robust prediction of beef colour acceptability. Beef colour was considered acceptable (with 95% acceptance) when a* values were equal to or above 14.5. Demographic effects on this threshold were negligible, but consumer nationality and gender did contribute to variation in the relative importance of colour to beef value. These results provide future beef colour studies with context to interpret objective colour measures in terms of consumer acceptance and market appeal.

Effect of pulsed electric field treatment on hot-boned muscles of different potential tenderness

In this study, the effect of pulsed electric field (PEF) treatment and ageing on the quality of beef M. longissimus lumborum (LL) and M. semimembranosus (SM) muscles was evaluated, including the tenderness, water loss and post-mortem proteolysis. Muscles were obtained from 12 steers (6 steers for each muscle), removed from the carcasses 4 hour postmortem and were treated with pulsed electric field within 2h. Six different pulsed electric field intensities (voltages of 5 and 10 kV × frequencies of 20, 50 and 90 Hz) plus a control were applied to each muscle to determine the optimum treatment conditions. Beef LL was found to get tougher with increasing treatment frequency whereas beef SM muscle was found to have up to 21.6% reduction in the shear force with pulsed electric field treatment. Post-mortem proteolysis showed an increase in both troponin and desmin degradation in beef LL treated with low intensity PEF treatment (20 Hz) compared to non-treated control samples.

SmartStretch™ technology. IV. The impact on the meat quality of hot-boned beef rostbiff (m. gluteus medius)

The impacts on traits of the m. gluteus medius hot-boned from young cattle were assessed after stretching (SmartStretch™) and ageing (0 or 8 days ageing). Tenderness, as reflected in reduced shear force measurement, was significantly (P<0.05) improved in 0 day aged stretched samples over the un-stretched control. After 8 days ageing there was no longer a difference in the tenderness between stretch treatments. Meat aged for 8 days was significantly more tender than 0 day aged meat irrespective of treatment. Sarcomere length was significantly (P<0.05) increased by stretching. There was a significant (P<0.05) negative relationship between sarcomere length and shear force. Presentation traits, such as purge loss and fresh colour, were unaffected by the stretch treatment, while cooking loss was significantly (P<0.05) reduced by stretching in the 0 day aged samples.

Effect of repeated pulsed electric field treatment on the quality of hot-boned beef loins and topsides

The effects of repeated (1×, 2×, 3×) pulsed electric field (PEF) treatment (10 kV, 90 Hz, 20 μs) on the quality of beef loins and topsides were evaluated, including the tenderness, purge loss, cooking loss, myofibrillar protein profile and post-mortem proteolysis. Both muscle types were obtained from each of 12 steers and were processed within 6h. After PEF treatment samples of both muscle types were subjected to 3, 7, 14 and 21 days ageing. The 1× and 2× PEF treatments had no effect on the tenderisation of hot-boned beef Musculus longissimus lumborum muscle for all ageing treatment times, while the 3× treatment reduced the tenderness. The opposite effect was observed in hot-boned beef Musculus semimembranosus muscles where the 3× treatment produced meat with lowest shear force at 3 days post-treatment time, but this beneficial effect disappeared with longer ageing times. An increase in proteolysis of troponin T was seen to the largest extent with 1× PEF treatment and decreased with every extra application of treatment.

The effect of forage type on lamb carcass traits, meat quality and sensory traits.

The aim of this study was to evaluate the effect of different forage-types on lamb carcass, meat quality and sensory attributes. Sixty-two, White Dorper lambs finished on bladder clover, brassica, chicory+arrowleaf clover, lucerne+phalaris or lucerne, were slaughtered at a commercial abattoir. At 24h post-mortem, the m. longissimus thoracis et lumborum (LL) was removed from the left side and sliced into three equal sub-samples, vacuum packaged and randomly assigned to ageing periods (5, 12 or 40days) and the right side was aged for 5days. The m. semimembranosus and m. adductor femoris were removed and, the former was then aged for 40days. Lambs fed chicory+arrowleaf clover or lucerne had a higher dressing percentage and fat depth. Bladder clover gave the highest level of glycogen in the LL. No sensory or other meat quality trait differences were found between the treatments. In general, no treatments showed any unfavourable effect on the traits examined.

Post-mortem modelling of pH and temperature in related lamb carcases

Exponential decay models have been used to model pH and temperature decline in lamb carcases post mortem. Such models, once fitted to carcase data, can then be used to predict a carcases pH at a temperature of 18°C and its temperature when the pH equals 6. Unfortunately, these models frequently fail when fitted to limited pH/temperature data, because of either insufficient data or inappropriateness of the exponential decay model. To overcome these problems an alternative though similar modelling approach is proposed. This alternative approach replaces the exponential decay model with a more flexible spline modelling approach for the average trend and includes in the model, as random effects, individual deviations from average trend. Including the individual deviations from average trend as random effects in the model allows information on individual carcases to be shared across carcases.

Lamb meat colour values (HunterLab CIE and reflectance) are influenced by aperture size (5 mm v. 25 mm)

The effect of aperture size on the assessment of lamb meat colour values (L*, a*, b* and R630/580) was investigated. Two experiments using 2 HunterLab MiniScan colorimeters (large [25mm] and small [5mm] apertures) were conducted: 1) coloured tiles were measured and 2) unaged lamb (n=65) m. longissimus lumborum (LL) and m. semimembranosus (SM) muscles were measured over 2.5d under simulated retail display. For Experiment three, 2 different colorimeters were used on lamb (n=36) LL aged for 6weeks before measurement over 4d on simulated retail display. Coloured tile a* and b* values were unaffected by aperture size, but L* values and the R630/580 ratio were influenced by aperture size. The effect of aperture size on lamb meat colour measurements varied with display time and muscle type. The large aperture size generally provided the highest colorimetric values, and is recommended for measuring lamb meat colour.

Predicting tenderness of fresh ovine semimembranosus using Raman spectroscopy

A hand held Raman probe was used to predict shear force (SF) of fresh lamb m. semimembranosus (topside). Eighty muscles were measured at 1 day PM and after a further 4 days ageing (5 days PM). At 1 day PM sarcomere length (SL) and particle size (PS) were measured and at 5 days PM, SF, PS, cooking loss (CL) and pH were also measured. SF values were regressed against Raman spectra using partial least squares regression and against traditional predictors (e.g. SL) using linear regression. The best prediction of SF used spectra at 1 day PM which gave a root mean square error of prediction (RMSEP) of 11.5 N (Null = 13.2) and the squared correlation between observed and cross validated predicted values (R(2)cv) was 0.27. Prediction of SF based on the traditional predictors had smaller R(2) values than using Raman spectra justifying further study on Raman spectroscopy.