EFFECT OF DIFFERENT ELECTRICAL STUNNING METHODS ON MEAT QUALITY OF MARMARA KIVIRCIK BREED LAMB IN TURKEY REPUBLIC

The effects of head-only electrical stunning method were compared with the effects of headtoback electrical stunning method. A total of 90 kivircik breed lambs were randomly allocated immediately prior to slaughter to one of three stunning treatments: control group (C), head only group (HO; 1.0 AAC for 3 s at a frequency of 50 Hz), head to back group (HB; 1,0 AAC for 3 s at a frequency of 50 Hz) electrical stunning. Meat quality was assessed by examining pH, colour as L, a, b values, water holding capacity (WHC) and shear force. The effect on meat quality was assessed in head-only electrically stunned, head to back electrically stunned and non-stunned lambs. Shear forces were not significantly different between treatments. However colour (L*,a*,b*), water holding capacity (WHC) and muscle ultimate pH were found to be significantly higher (P<0.05) between the groups.

ultimate pH of meat Š2¹.Electric stunning is the most common commercially used method in the EU.There are several methods used to apply the electrodes used with electrical stunning apparatus like head-only, head-to-brisket and head-toback Š7¹.
Electrical stunning methods are effective and produce instantaneous insensibility by the induction of epileptiform activity in the brain Š8¹.The few studies on sheep examine the effect of the type of stunning on bleeding efficiency Š9¹, petechial haemorrhages Š6¹, blood pressure and muscular activity Š16¹, final pH Š14¹, meat quality parameters such as colour, tenderness, juiciness Š20¹ and meat quality parameters, the presence of haemorrhages and the bone fractures Š18¹ but not different electrical stunning methods effects on meat quality parameters.

Animals / @ivotinje
Ninety male lambs of the Kivircik breed from the flock of the Experimental Farm of Istanbul University were slaughtered at 5 months of age.Animals were separated into three group (n = 30 each) for pre-slaughter handling.In the first group, the lambs were slaughtered without previous stunning.The second group was electrically stunned by the head only method at 1 A for 3 s.The other group was electrically stunned by the head to back method at 1 A for 3 s.Immediately after stunning, the lambs were slaughtered using conventional procedures.The carcasses were chilled at 6 o C for 24 h in a conventional chiller.
Twenty-four hours post mortem, the M. longissimmus dorsi was removed from the carcass after measuring pH24, and cut into four equal portions.One portion packed in a plastic tray over-wrapped with permeable gas film and stored at 3 o C prior to analysis for initial meat quality.Twenty-four hours post mortem water holding capacity (WHC) and colour (as L, a, b values), 72 hours post mortem shear force (SF) were determined.
The rest of the samples were vacuum packed in Cryovac barrier bags.Samples were taken, as required at 24h, 48h and 72h.During this time the bags were stored at 3 o C.
The samples were analysed for pH, colour, WHC as percentage free water Š20¹.SF was evaluated using an Instron Texture Analyser (model 1140)

Materials and methods / Materijal i metode ispitivanja
equipped with a kremear shear head.Samples were read at 500 kg load cell and 50 range.

Data Analysis / Analiza podataka
The data of the meat quality variables were analysed by the SPSS Š17¹, using the analysis of variance (ANOVA).
Results of the effect of pre slaughter handling (PSH) during ageing on the meat parameters are presented in Tables 1-4.

pH / pH
The values of pH 45 were similar to those found by Paulick et al.Š14¹.During the first 72 hours post mortem except pH 0, pre-slaughter handling affects the decrease in pH (Table 1).However other studies in lambs Š19¹ showed no significant differences in the pH 0, pH 45 and pH 24 with the stunning method.Headonly electrical stunning method had an effect on the final pH of the muscle.From 45 minutes onwards significant differences between the different pre-slaughter handling groups were found in pH values.In the control group the lowest value was reached at 24 hours post mortem.On the other hand in the other two groups the lowest value was reached at 18 hours post mortem.Our results agree with those of Vergara and Gallego Š20¹ and Paulick et al.Š14¹, pH decreases more rapidly, and ageing starts earlier.Petersen and Blackmore Š15¹ found that the increased muscle activity in animals stunned electrically is probably responsible for their more rapid post-mortem pH decline.

Meat colour / Boja mesa
Meat of the non stunned lambs was brighter (higher L* values) than that of electrically stunned groups and the difference between the groups was significant statistically.Also pre slaughter handling affected a* and b* values (Table 2).In similar, studies on domestic birds show that electrically stunned turkeys Š5¹ and broilers Š11¹ have redder meat (higher a* values) than those stunned with CO 2 .
Water holding capacity / Kapacitet zadr`avanja vode Significant differences were found between the pre slaughter handling groups in WHC values except on days 5 (Table 3).In all groups (C, HO and HB), WHC decreased (more water expelled) with storage (14.10 ± 0.241, 13.83 ± 0.233 and 13.80 ± 0.174% at 24 h post mortem to 20.46 ± 0.355, 23.50 ± 0.292, 23.57± 0.301 at 8 days post slaughter, for C, HO and HB, respectively).This agrees with the study of Koohmaraie, Whipple and Crouse Š10¹, Moore and Young Š12¹ and Vergara and Gallego Š20¹.In the C group the highest percentage of water expelled was at 11 days postmortem and 3 days earlier in the HO and HB groups.The tendency to release more water in the C group after 8 days post mortem suggests their initial juiciness could be greater.

Shear force / Meko}a mesa
The meat from stunned animals appeared more tender than that of the non-stunned animals, although the differences were not significant (Table 4).The differences in pH (Table 1) may be the cause of the higher values of shear force in meat of the non-stunned animals group, due to decreased activity of calpain Š3¹.Another study suggests the activity of calpain depends not only on the amount of enzyme present, but also on the muscle pH Š13¹.Vergara and Gallego Š20¹ did not find any differences between the stunned and non-stunned lamb meat shear force value.
The effect on meat quality was assessed in head-only electrically stunned, head-to-back electrically stunned and non-stunned lambs.Shear forces were not significantly different between treatments.However colour (L*,a*,b*), WHC, muscle ultimate pH were found to be significantly higher (P<0.05) between the groups.It is concluded that some of the meat quality parameters are affected by electrical stunning methods.

Table 1 .
Effect of pre-slaughter handling and ageing on the pH of meat in Marmara Kivircik lambs / Tabela 1. Efekat rukovanja pre klanja i zrenja na pH mesa kod Marmara Kivircik jagnjadi Biyikinal and B. Nazli: Effect of different electrical stunning methods on meat quality of marmara kivircik breed lamb in Turkey...