Nurdeng Deuraseha: Director of Halalan Thayyiban Research Centre of Universiti Islam Sultan Sharif Ali (UNISSA) Brunei Darussalam
Zeiad Amjad Abdulrazzak Aghwan : Lecturer, Universiti Islam Sultan Sharif Ali (UNISSA), Brunei Darussalam
Slaughter is probably the most important operation in the transformation of an animal into pieces fit for human consumption. This crucial moment of killing is governed by strict regulations related to food hygiene and safety, working conditions and animal welfare.
This study was conducted to evaluate the bleeding efficiency and meat drip loss of halal, non halal and decapitation slaughtered broiler chickens. To achieve this, a total of 30 broiler chickens of six weeks old with body weight between 2.2 kg and 2.5 kg were obtained from a commercial farm. The chickens were divided into three groups of 10 chickens each and subjected to either halal slaughter, non halal slaughter, or decapitation. It was found that halal slaughter method showed a high potential to improve bleeding efficiency and meat drip loss than those non halal and decapitation methods. Further research is needed to investigate the impact of halal slaughter method on meat quality parameters during post mortem aging period.
Slaughter is probably the most important operation in the transformation of an animal into pieces fit for human consumption. This crucial moment of killing is governed by strict regulations related to food hygiene and safety, working conditions and animal welfare (BergeaudBlackler, 2007). Poultry processing is a complex combination of biology, chemistry, engineering, marketing, and economics. Poultry production and processing involve a series of interrelated steps designed to convert domestic birds into ready-to-cook whole carcasses, cut-up carcass parts, or various forms of deboned meat products (Alan, 2001). Accepting that animals are to be slaughtered, then how this should be carried out? The methods used have varied between cultures and faiths worldwide. In our study, three manual slaughtering methods will be used that they are halal, non-halal and decapitation. The Islamic method requires the use of sharp knife, which according to Prophet Muhmmad (peace be upon him) relieves the animal of any suffering (Sahih Muslim). Maximum drainage of blood is required. In the Holy Quran blood consumption has been forbidden by Muslims. Halal slaughtering process of animal involves restraining and severing of trachea (halqum), esophagus (mari’) and both the carotid arteries and jugular veins (wadajain) (Department of Islamic Malaysian Development. (2011); Department of Standards Malaysia (2009). MS1500: 2009).
Chicken meat is a good source of nicotinic acid, which helps fighting against cancer (Ali et al., 2011). It also have,trace amounts of mineral like selenium, which helps to make the hair strong and healthy. Other important Bcomplex vitamins like B6 and its co-ordinate function with nicotinic acid helps to convert the available food sources like carbohydrates, fats and pertains into energy sources and also important to maintain the cardiovascular health.
Eating is considered as a matter of worshiping God for Muslim. Islamic law prescribes a set of dietary rule, called “Halal” (legal, permitted by Allah) which lists the permitted food and prohibits the consumption of meat not obtained according to Islamic rules, covering livestock handling before and during slaughter (Regenstein et al., 2003; Bonne and Verbeke, 2008).
“Halal” is also refers to the aspects of reliable, food quality, wholesome, hygiene and safety. Muslims must make an effort to obtain halal food of good quality. For non-Muslim consumers, halal foods are often perceived as specially selected and processed to achieve the halal standards of quality (Sams, 2001; Bonne, K. and Verbeke, W. (2008). Nowadays, consumers demand convenience, health, safety, taste, uniformity, nutritive value, good appearance and variety of meat and meat products (Ademeyi and Sazili, 2014). From the Muslim’s point of view, decision to choose one food over the other depends on its halal status (Nakyinsinge et al., 2012).
Thus, this study aims to determine whether halal slaughtering is comparable to non halal and decapitation slaughtering of broiler chickens in terms of bleeding efficiency and meat drip loss for five days aging
2. Literature review
To optimize bleed out at slaughter and reduce carcass and meat defects is a major goal of the meat processing industry, as improved bleeding can improve the quality of the meat during storage (Ali et al., 2007; Department of Veterinary Service Malaysia. (2012). Inefficient and improper bleeding may cause more blood to be retained in the meat. Blood favors multiplication of spoilage microorganisms and acts as a carrier for food borne pathogens (Lerner, 2009).
Additionally, residual blood in the meat equates to retention of more haemoglobin. Haemoglobin is a powerful promoter of lipid oxidation (Everse and Hsia, 1997; Alvarado et al., 2007). Lipid oxidation constitutes a major cause of non-microbial meat spoilage, especially under pro-oxidative conditions such as storage and cooking. It can also occur during refrigeration and frozen storage (Soyer et al., 2010).
The halal method has been thought to provide considerable bleeding when the heart is still beating, which might be beneficial for shelf-life extension or meat quality maintenance (Addeen et al., 2014). Although some investigations have been conducted on the efficacy of different slaughter methods on bleeding efficiency and meat keeping quality, most information originates from research in conventional slaughter methods with limited comparison to specifically halal slaughter method. This was due to the limited access to religious slaughter without stunning in most developed countries due to legal andwelfare reasons (Nakyinsige et al., 2013; Grandin, T. and Regenstain, J. M. 1994).
The ability of fresh meat to retain its own water during storage is referred to as water holding capacity (WHC), and it is one of the significant factors that can affect yield and quality of raw products (Huff-Lonergan & Lonergan, 2005). Fresh meat after slaughter contains approximately 75% water, and this amount is subject to increase due to the gains during processing or reduction through the losses because of drip, evaporation or cooking (Offer & Trinick, 1983). Water in the muscle cell is found within the myofibrils, between the myofibrils and cell membrane, between muscle cells, and between muscle bundles (Offer & Cousins, 1992). Water in the muscle cell is closely bound to protein. Fennema (1985) indicated that there are three types of water in the muscle, and each fraction differs on its mobility. The bound water exists next to proteins and has reduced mobility as well as strong resistance to freezing. During post mortem, the amount of bound water in the muscle does not change or may change very little (Offer & Knight, 1988). The bound water accounts for less than 10% of the total water in muscle (Huff-Lonergan & Lonergan, 2005). The immobilized or entrapped water is another fraction of water, which accounts for up to 85% of the total water that exists in the meat (Pearce et al., 2011). This water is held within the structure of muscle either by steric (space) effects and/or by attraction to the bound water. This type of water is not bound to protein and can easily convert to ice during freezing. Offer & Knight (1988) documented that immobilized water is most affected by the post mortem process, and dropping the pH makes this water drip as purge. The manipulation of the net charge of myofibrillar proteins and the structure of the muscle cell and its components as well as the amount of extracellular space within the muscle can maintain the retention of immobilized water (Huff-Lonergan & Lonergan, 2005). the third type of water present in the muscle is known as free water which is readily seen in pre rigor meat. Weak surface forces mostly hold the free water, and its outpouring from the tissue is unimpeded (Fennema, 1985).
Many hypotheses have been presented to explain the improvement of meat WHC with aging. Offer and Trinick (1983) suggested that the swelling or shrinkage of myofibrils as a result of the expansion or shrinkage of the filament lattice clarify the gain or loss of water in meat. The “leaking out” theory by Joo et al. (1999) and Van Moeseke & De Smet (1999) explain that the loss of water during early post mortem in the form of evaporation or drip resulting in fewer water being lost at a later time post mortem, and hence enhance WHC.
As suggested by Kristensen & Purslow (2001) the degradation of the cytoskeletal proteins during post mortem gradually eliminates the linkage between the lateral shrinkage of myofibrils and shrinkage of whole muscle, thus eliminating the force that causes flow into the extracellular space and enabling the inflow of previously expelled water, thus improving WHC. This theory was supported by the findings of Zhang et al. (2006) that reduced drip loss in fresh pork was related with the degradation of integrin and desmin. More recently, the “sponge effect” is reported by Farouk et al. (2012) who explained that the improvement of meat WHC with long term aging may be due to the disruption of channels through which water is lost as a result of muscle structural breakdown and the formation of a “sponge effect” which slows the flow of the drip to the cut surface of meat.
Drip loss represents an important quality characteristic for both retailers and consumers. Product weight losses as a result of purge can range from 1- 3% when meat is cut into chops, and can be up to 10% in PSE products (Offer & Knight, 1988). Moreover, drip loss causes significant loss of proteins (Offer & Knight, 1988). Higher drip loss has been shown to occur during early post mortem storage and gradually decrease as ageing continues (Kristensen & Purslow, 2001). During the conversion of muscle to meat during the post mortem period, the mobilization of tissue water is related to physical processes, such as alteration of structural protein and cell membrane as well as longitudinal and lateral contraction of muscle fiber (Pearce et al., 2011). This pressure can cause a move of water from the intercellular to the extracellular space and then on to the meat surface (Kadim & Mahgoub, 2012).
Numerous shared interacting factors of both ante and post mortem can affect drip loss during conversion from muscle to meat; animal growth rate, pre slaughter handling, slaughter age, chilling rate, aging time, temperature and muscle fiber type (Pearce et al., 2011).
The objective of this study was to evaluate the bleeding efficiency and meat drip loss of halal, non halal and decapitation slaughtered broiler chickens. 4. Materials And Methods A total of 30 broiler chickens of six weeks old with body weight between 2.2 kg and 2.5 kg were obtained from a commercial farm. The chickens were divided into three groups of 10 chickens each and subjected to either halal slaughter, non halal slaughter, or decapitation. The slaughter procedure was conducted at the Department of Animal Science research abattoir, Faculty of Agriculture, Universiti Putra Malaysia. In the halal method, the animals were humanely slaughtered by a licensed slaughter man according to halal slaughter procedure as outlined in the Malaysian Standard; MS1500: 2009 (Department of Standard Malaysia, 2009). The procedure involved severing the carotid artery, jugular vein, trachea and oesophagus. In the non halal procedure, groups of ten chickens were slaughtered by a skilled slaughterer. The procedure involved severing the carotid artery, jugular vein without cutting trachea and oesophagus. Furthermore, the third group of chickens were slaughtered following decapitation method. In the procedure, the head and the posterior legs of the animal are stretched out on the opposite direction. The chicken is beheading from the backbone side with a single stroke of sharp knife which
causes sudden death.
5. Determination of blood loss
The amount of blood loss of individual birds during 90 sec bleeding period was estimated as the difference
between pre-slaughter weight and post-slaughter weight (Velarde et al., 2003) as follows: Blood loss (%) = [(W1-W2)/ W1] x100 Where:
W1 (kg) = weight before slaughter.
W2 (kg) = weight after slaughter.
6. Carcass sampling
Samples from Pectoralis major muscle (approximately 20g) of 0 d post mortem were labelled, vacuum packaged and transferred to the 4°C chiller for drip loss determination. Drip loss of fresh meat samples from pectoralis major muscle was determined as weight loss percentage of differences of initial weight at day 0 and sample weight after 5 d conditioning in a chiller at 4°C divided by sample initial weight (Honikel, 1998).Drip loss (%) = [(initial weight- final weight) ÷ initial weight] × 100.
7. Data analysis
The data of meat quality was statistically analysed using the general liner model (GLM) procedure of Statistical
Analysis System (SAS) package and the statistical significance will set at p< 0.05. Data of studied parameters were subjected to one-way analysis of variance (ANOVA) using a model that included treatment and animal as
possible sources of variation. Duncan multiple range testwas used to test the significance of variance between the
means of the studied parameters.
8. Results and Discussion
8.1 Bleeding efficiency Optimizing bleed out at slaughter and reducing carcass andmeat defects is a major goal of the me shelf life.
The consumption of blood is forbidden (Nakyinsige et al.,2012). Therefore, religious slaughter aims at draining as much blood as possible out of the carcass. In Europe and North America, modern slaughter practices are also based on traditions which require that animals killed for food should be properly bled before consumption. Normally,
this is achieved through a bilateral or a unilateral neck cut to sever the carotid arteries and jugular veins. Factors
influencing bleeding efficiency at sticking include;
i) blood vessels that are severed,
ii) size and patency of the sticking wound,
iii) cardiac arrest at stunning,
iv) orientation of the carcass – positioned horizontally or vertically,
v) vasodilation or vasoconstriction in the capillary bed,
vi) tonic muscle contractions squeezing blood capillaries and
vii) clonic activity causing movement of blood towards the sticking wound (Gregory, 2005). Poor bleeding efficiency can negatively affect colour of the meat and is considered to be a major quality defect, which can even cause undesirable discoloration and short shelf life (Griffiths and Nairn, 1984). Residual blood has also been associated with meat flavours. Greater blood loss during halal slaughtering can be due to the fact that when animals are bled, the greatest percentage of blood loss (between 75% and 85%) occurs while the heart is still bleeding.
Inefficient and improper bleeding may cause more blood (haemoglobin) to be retained in the meat. Haemoglobin is a
powerful promoter of lipid oxidation and may decrease the shelf life of meat products. Residual blood is also important in promoting microbiological deterioration of carcasses (Warriss, 2000; Alvarado et al., 2007; Lerner, 2009). In addition to accelerating multiplication of spoilage microorganisms, blood acts as a carrier for food borne pathogens (Lerner, 2009).
Bleeding efficiency of chickens subjected to halal slaughter was significantly higher (p<0.05) than those subjected to non halal and decapitation slaughter, and therefore reduce the blood content in their meat and eventually reduce meat spoilage and increase the shelf life.
8.2 Drip loss
During the conversion of muscle to meat, the ability of fresh meat to hold moisture is probably one of the main
quality features of fresh yields. In addition to loss of weight (Huff-Lonergan & Lonergan, 2005), poor meat WHC also causes loss of an important amount of protein (Offer & Knight, 1988).
The results for drip loss are shown in Figure 2. The slaughter method had a significant effect on cooking loss,
with halal slaughter exhibiting a lower drip loss than non halal and decapitation. Water holding capacity is influenced by muscle pH decline and temperature postmortem. In our study, pH decline in the pectoralis majormuscle was faster during post mortem in the chickensslaughtered with halal method than those slaughtered with non halal and decapitation methods.
Drip loss in chickens subjected to halal slaughter was significantly lower (p<0.05) than those subjected to non halal and decapitation slaughter, and therefore the loss ofweight will be lower. Additionally, higher meat drip loss also causes the loss of an important amount of protein.
From the findings of the current study, it is probable to conclude that halal slaughter method showed a high potential to improve bleeding efficiency and meat drip loss than those non halal and decapitation methods. Further
research is needed to investigate the impact of halal slaughter method on meat quality parameters during post
mortem aging period.
This study was conducted following the animal ethics guidelines of the Research Policy of Universiti Putra Malaysia. It was financially supported by Universiti Putra Malaysia through project no: 9420400 titled “Scientific and Shari’ah analysis on the prohibition of unlawful foods in Islamic Law: Towards and integration between science and shari’ah”.