Effects of medium-voltage electrical stimulation on postmortem changes in fat-tailed sheep

Electrical stimulation and wet ageing effects on the carcass and meat quality of Australian rangeland goats

Medium voltage electrical stimulation and wet ageing periods effects on the carcasses and meat quality of Australian rangeland goats were investigated. 64 rangeland goats were slaughtered as 2 equal consignments, wherein half were exposed to post-dressing electrical stimulation (300 V, 500 ms pulse width, 45 s) and half were not (control). Carcass and pH decline parameters and glycogen concentration were recorded. At 24 h post-mortem, fresh colour was measured and longissimus lumborum muscles (LL) removed. Within carcass, paired LL were halved and allocated to each of 4 ageing periods (1, 2, 4, or 21 d). There were no significant effects from electric stimulation on LL pH at 18 °C, LL temperature at pH 6, LL pH at 24 h post-mortem, semitendinosus pH at 24 h post-mortem, and LL glycogen concentration. There were no significant interactions between stimulation and ageing period on cooking loss, particle size, purge loss, sarcomere length, shear force, and ultimate pH. Independent to stimulation, shear force, particle size, and cooking values declined as ageing period increased. Purge loss was highest after 21 d of ageing. Colour stability was unaffected by ageing, although all CIE colour coordinates varied across the 74 h total retail display period. There were negative linear relationships found between LL glycogen concentrations and LL temperature at pH 6, ultimate pH, and sarcomere length. These findings suggest there to be little benefit to post-dressing electrical stimulation of rangeland goat carcasses, when applied independent to or in combination with ageing.

The effect of shower time, electrolyte treatment, and electrical stimulation on meat quality of cattle longissimus thoracis muscle in cold weather

The effects of three treatments (two levels each), namely shower time (ST), electrolyte treatment (ET), and electrical stimulation (ES), on meat quality were investigated using 112 cattle which were randomly allocated to different combinations of each treatment level. ST2, compared with ST1, increased ultimate pH from 6.05 to 6.23 and blood adrenaline levels while deteriorating beef color. ST2 also improved the water-holding capacity (WHC), exhibiting more immobilized water and less free water. Finally, it promoted protein unfolding and the conversion of α-helix to random coil, thus producing tenderer beef. In contrast, results indicated that ET either decreased pH_u in ST1 groups or relieved pre-slaughter stress in ST2 groups. ES accelerated pH₁ drop with maximum efficiency in an ST1-ET combination, but it did not alter pH_u. In addition, ES decreased WHC with an enlarged relaxation time for bound water while causing beef tenderization through protein unfolding. ST1-ET(-ES/NES) maximized pH_u reduction and provided an alternative for dark-cutting prevention in cold weather.

Effect of Dietary Bacillus coagulans and Different Forms of Zinc on Performance, Intestinal Microbiota, Carcass and Meat Quality of Broiler Chickens

A total of 288-day-old male broilers were allocated to six dietary treatments to evaluate the effects of zinc source and Bacillus coagulans supplements and their interaction on growth, intestinal microbial population, carcass traits and meat quality in broiler chickens. Three levels of dietary supplemental Zn source (100 mg/kg of DM diet zinc oxide, 25 and 50 mg/kg of diet zinc oxide nanoparticles (Zn-nan)) and two levels of B. coagulans (0 and 100 mg/kg of diet) were combined as a completely randomised design with a 3 × 2 factorial arrangement. B. coagulans increased the body weight gain, body weight and feed conversion ratio. The lactic acid producing bactereia of ileal were increased by B. coagulans supplementation, and its coliform count was decreased by Zn-nan in a dose-dependent manner. The B. coagulans increased the relative weights of legs and proventriculus and reduced weights of livers, abdominal fat and meat thiobarbituric acid (TBA) value. Likewise, dietary B. coagulans increased pH, yellowness and lightness values of leg muscles. Birds fed Zn-nan50 had lower liver weight, TBA and cooking loss and higher yellowness values than chicks fed ZnO-100. In conclusion, the dietary supplementation with B. coagulans improved broiler performance, microbial population and meat quality. The Zn-nan in lower dose could be a good substitution in mineral premix instead of zinc oxide. In addition, the Zn-nan improved intestinal microbial population, carcass characteristics and oxidative stability of chicken meat; however, the combination of two levels of Zn-nan with B. coagulans did not vary the measured parameters.

Endogenous Proteolytic Systems and Meat Tenderness: Influence of Post-Mortem Storage and Processing

Meat proteolytic systems play a crucial role in meat tenderisation. Understanding the effects of processing technologies and post-mortem storage conditions on these systems is important due to their crucial role in determining the quality characteristics of meat and meat products. It has recently been proposed that tenderisation occurs due to the synergistic action of numerous endogenous proteolytic systems. There is strong evidence suggesting the importance of μ-calpain during the initial post-mortem aging phase, while m-calpain may have a role during long-term aging. The caspase proteolytic system is also a candidate for cell degradation in the initial stages of conversion of muscle to meat. The role of cathepsins, which are found in the lysosomes, in post-mortem aging is controversial. Lysosomes need to be ruptured, through aging, or other forms of processing to release cathepsins into the cytosol for participation in proteolysis. A combination of optimum storage conditions along with suitable processing may accelerate protease activity within meat, which can potentially lead to improved meat tenderness. Processing technologies such as high pressure, ultrasound, and shockwave processing have been reported to disrupt muscle structure, which can facilitate proteolysis and potentially enhance the aging process. This paper reviews the recent literature on the impacts of processing technologies along with post-mortem storage conditions on the activities of endogenous proteases in meat. The information provided in the review may be helpful in selecting optimum post-mortem meat storage and processing conditions to achieve improved muscle tenderness within shorter aging and cooking times.

Volatile Flavor Components as a Function of Electrical Stimulation and Chiller Aging for m. longissimus and biceps femoris of Hanwoo Beef

The aim of the study was to evaluate the effect of an early post-mortem low voltage electrical stimulation (ES) to localized part of carcasses [m.longissimus lumborum (LL) and m.biceps femoris (BF)] and determined the tenderness and flavor compounds of Hanwoo steers (n=16). Carcasses were stimulated within 30 min post-mortem for 60s using 60 volts and muscles aged 2 and 14 d. Degradation of Troponin-T were accelerated by ES and degraded little faster in BF muscle than LL. Level of free amino acid content of stimulated and aged muscles was significantly (p<0.05) greater than control for both muscles. Totally 63 volatile compounds were identified by using SPME-GC. The ES treatment significantly (p<0.05) affected the level of 20 volatile compounds of LL as well 15 volatiles in BF muscle along with total amounts of ketones, sulfur containing, pyrazines and furans. Low voltage ES could be applied to reduce the aging time and improve volatile flavor development by increasing important desirable volatile compounds such as 2-methylpyrazine, 2,5-dimethylpyrazines and 2-acetylthiazole etc. due to released free amino acids from protein degradation.

Use of electrical stimulation and chilling to enhance meat tenderness of heavy lambs

Pouliot, E., Gariépy, C., Thériault, M. and Castonguay, F. W. 2014. Use of electrical stimulation and chilling to enhance meat tenderness of heavy lambs. Can. J. Anim. Sci. 94: 627–637. The aim of this study was to determine if electrical stimulation and chilling can modulate pre-rigor pH–temperature dynamics in order to enhance meat tenderness of heavy lambs produced in Quebec and determine if there is an optimum carcass temperature window to reach pH 6.0. A total of 128 heavy lambs (fasted body weight between 38 and 52 kg) were selected at the abattoir over 8 slaughter days (16 lambs d–1) and assigned to four processing treatments in a 2×2 factorial design: electrical stimulation (ES) or not (NES) and normal (NC) or slow (SC) chilling. Slow-chilled carcasses stayed warmer during the first 12 h postmortem (P<0.001), but reached the same temperature as NC ones thereafter. They also had a lower pH between 2 and 12 h (P<0.05). Stimulated carcasses had a lower pH than NES throughout the first 24 h postmortem (P<0.001), while ultimate pH was similar (P=0.738). Shear force values were improved (P<0.001) by both ES and aging as expected, although chilling had no effect (P=0.400). Stimulation×aging interactions for shear force values (P=0.019) and myofibrillar fragmentation index (P=0.097) indicate that aging began earlier following ES. Sarcomeres were longer for ES compared with NES carcasses (P<0.001) indicating that the latter were subject to cold shortening. Meat from NES carcasses was more prone to be tough, although an important part of NES carcasses provided tender meat. This illustrates the importance of individual variations on tenderness and the multiplicity of factors involved in its development. No optimal window was observed for temperature at pH 6.0.