Evaluation of technological properties
Drip loss was measured according to Honikel (1998). After 24hrs storage of meat samples at 4oC, drip loss was calculated as the difference between initial and final weights and expressed as a percentage.
Cook-out-loss was evaluated using the method described by Piasentier et al (2003). Six hours after slaughter, meat samples in ziploc bags were immersed in a thermostatic water bath at 75oC for 15mins. Cook-out-loss was obtained as the difference between the initial and the final weights and expressed as a percentage.
Freezing loss was evaluated using the method described by Piasentier et al (2003). Meat samples were frozen at -20oC for 14days, then thawed to room temperature (21oC) and reweighed. Freezing loss was calculated as the difference in weight loss before and after freezing and expressed as a percentage.
Evaluation of chemical properties
Meat samples were minced and dried in a ventilated oven at 60oC until a constant weight was attained. The samples were analyzed for moisture, crude protein, crude lipid and ash contents as described (AOAC 2000).
Statistical analysis
ANOVA was done using the General Linear Model approach (SPSS version 19.0). Means were separated for significant differences (p<0.05) using Duncan’s multiple range test (Steel and Torrie 1980).
Results
Effect of production system on some physical properties of beef
Influence of production system on pH
Figure 1 shows the pH variations with time in the beef of animals from three production systems.
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Figure 1: pH evolution of beef from different production systems |
The highest pH value (one hour after slaughter) was recorded in carcasses from nomadism (pH1 = 6.94) and 48 hours after slaughter, the lowest value was recorded in ranched beef (pH48 = 5.30). It was observed that carcass pH was relatively very high during the first hour and dropped rapidly up to 24 hours after slaughter in all the three production systems. There were no significant differences (p>0.05) in pH values between carcasses from the different production systems from the time of slaughter up till 24 hours post slaughter although pH drop was greatest in ranched carcasses. At 48 hours post slaughter, the pH value of ranched beef was significantly lower (p<0.05) than that from nomadism and transhumance respectively. The pH values in carcasses from nomadism remained consistently higher than those from the other production systems throughout the storage period.
Influence of production system on temperature
Figure 2 reveals that 1hour after slaughter, the temperature in the beef from all three systems was quite high but dropped sharply up to 24 hours post slaughter and slowed down thereafter. The drop in temperature was more rapid in ranched carcass than in the other carcasses.
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Figure 2: Temperature evolution in beef from different production systems |
One hour after slaughter, the lowest temperature (28.9oC) was recorded in carcasses from transhumance and this was significantly lower (p<0.05) than the temperature recorded in samples from ranching and nomadism respectively (Table 1).
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Table 1: Mean temperature variations of beef from different production systems |
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Time after |
Production system |
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Nomadism |
Ranching |
Transhumance |
SEM |
Prob . |
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1 |
31.3a |
32.5a |
28.9b |
0.53 |
0.01 |
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12 |
24.5a |
20.1b |
23.2a |
0.51 |
0.00 |
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24 |
14.5a |
14.3a |
13.3a |
0.48 |
0.61 |
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48 |
10.0a |
10.9a |
10.8a |
0.34 |
0.80 |
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a, b Means in the same row with a common letter are not significantly different |
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At the 12th hour post slaughter, the temperature of carcasses from ranching was significantly lower than that from either nomadism or transhumance. At 24 hours post slaughter, the lowest temperature was recorded in beef from transhumance while at 48 hours temperature was lowest in beef from nomadism. However, no significant differences (p>0.05) between production systems were recorded beyond 12 hours of storage.
Influence of production system on some technological properties of beef
Table 2 summarizes the effect of production system on drip loss, cook-out-loss and freezing loss of Gudali beef from different production systems.
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Table 2: Technological properties of Gudali beef from different production systems |
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Technological property (%) |
Production system |
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Nomadism (n = 10) |
Ranching (n = 10) |
Transhumance (n = 10) |
SEM |
Prob. |
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Drip loss |
0.99a |
0.77a |
0.98a |
0.39 |
0.62 |
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Cook-out-loss |
25.2b |
19.7a |
24.7b |
3.15 |
0.03 |
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Freezing loss |
11.1a |
9.4a |
10.4a |
3.60 |
0.87 |
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a, b Means in the same row with a common letter are not significantly different |
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Drip loss was highest in beef from nomadism (0.99%) although there were no significant differences (p>0.05) between values from the three production systems. Cook-out-loss was least in beef from ranching (19.7%) and this was significantly lower than that in beef from transhumance and nomadism respectively. There were no significant differences in freezing loss (p>0.05) between the three production systems although it was highest in beef from nomadism and lowest in beef from ranching.
Influence of production system on some chemical properties of beef
The effect of production system on moisture, crude ash, crude protein and crude lipid contents are presented in Table 3.
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Table 3: Chemical properties of Gudali beef from different production systems |
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Chemical property (%) |
Production system |
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Nomadism (n = 10) |
Ranching (n = 10) |
Transhumance (n = 10) |
SEM |
Prob. |
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Moisture |
71.7b |
75.2a |
73.4ab |
6.15 |
0.99 |
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Crude ash |
1.62a |
1.55a |
1.56a |
0.75 |
0.81 |
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Crude protein |
21.4a |
24.4b |
22.9ab |
0.84 |
0.04 |
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Crude lipid |
0.39a |
0.97b |
0.79ab |
0.30 |
0.02 |
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a, b Means in the same row with a common letter are not significantly different |
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The lowest moisture content was recorded in beef from nomadism (71.7%) and it was statistically lower than from ranched beef (p<0.05).
The crude ash contents of beef from the three production systems were not significantly different from each other (p>0.05).
The highest crude protein content was recorded in beef from ranching (24.4%) and was significantly higher (p<0.05) than in beef from nomadism (22.9%).
Similarly, the highest crude lipid content was recorded in beef from ranching (0.97%) and was significantly higher (p<0.05) than in beef from nomadism (0.39%). Furthermore, the moisture, ash, protein and lipid contents in beef from ranching were not significantly different from those obtained in beef from transhumance (p>0.05).
Discussion
Effects of production system on some physical properties of beef
pH
The highest pH values were obtained 1hour after slaughter (pH1).The values ranged from 6.88-6.94 in all three production systems and these values are very close to the pH of a living muscle (7.0-7.2) as reported by Munchenje et al (2009b).
Within 24 hours post slaughter, the pH24 values dropped significantly to below 6.0 in carcasses from all three production systems. This is expected because under anaerobic conditions, glycogen is converted into lactic acid which accumulates in the animal carcass; the muscle gradually acidifies, causing a decline in muscle pH (Warriss 2000).
The pH24 values obtained fall within the normal range accepted for commercial beef (Tarrant 1989).Our results are similar to the results reported by Munchenje et al (2009b). The pH values obtained 48 hours after slaughter ranged from 5.30 to 5.52 for all the three production systems and these results were in accordance with the results of Corrazzin and Piasentier (2011).
The mean pH value from ranching was significantly lower than that from nomadism and transhumance respectively during 48 hours of storage. This implies that the animals under ranching had enough glycogen reserves (as a result of better nutrition) which continued to be converted into acid during prolonged storage (Warriss 2000).
Temperature
As expected, beef temperature dropped over time in all three production systems as the muscle starts preparing to get into a state of rigor. Our results were similar to those obtained by Bendall (1972). No definite trend was observed between the production systems. From the results obtained, there seems to be no relationship between temperature and pH in carcasses during storage. This suggests that carcass temperature may not have a direct influence on acid production post mortem.
Effect of production system on some technological properties of beef
Our results revealed that drip loss was low across all three production systems. Drip loss might have been as a result of protein denaturation (consequently increased bleeding) caused a rapid fall in pH post mortem (Huff-Lonergan and Lonergan 2005). Since drip loss directly affects juiciness and nutrient content of beef, the low values obtained in this study imply that Cameroonian beef is of good technological quality (Warriss 2000). Production system had little effect on drip loss since there were no statistical differences among beef samples from the different production systems. This corroborates with our observation of no significant differences in pH values among beef from the different production systems at 24 hours post slaughter.
The cook-out-loss was quite high (about 35%) in all the beef samples irrespective of production system. This may be because our samples were tested 6 hours post slaughter when the pH was still high (above 6). A high pH also contributes to protein denaturation and consequently increased exudation (Huff-Lonergan and Lonergan 2005). Our results are similar to those obtained by Jama et al (2008). However, cook-out losses of beef samples from nomadism and transhumance production systems were slightly higher than those reported by Jeremiah and Gibson (2003) but lower than those reported by Razminowicz et al (2006).
There were no differences in freezing loss between samples from the three production systems. These results are in line with those of Enfält et al (1997) who found no differences in freezing loss between samples frozen at -20 °C. Rapid freezing reduces pH changes post mortem thus exudation is subsequently minimized.
Effect of production system on some chemical properties of beef
The moisture content of beef varied significantly among the production systems. Lowest value was recorded in beef from nomadism. Low accessibility to drinking water by animals in this production system could account for the relatively low moisture content of its beef. These results are similar to those found by Clinquart et al (1994).
Production system had little effect on the ash content of beef. Similar results have been reported by others (Enfält et al 1997, Rowe et al 1999, French et al 2000). The values obtained were superior to those obtained by Prado et al (2009a) who reported that bulls had crude ash percentages varying between 1.03 and 1.18.
In this study, crude protein content obtained varied significantly between the systems. The results for transhumance and nomadism are similar to those of Arbele et al (2001) who found out that lean portions of red meat contain 19 to 23 percent protein; while crude protein content of beef from ranching was slightly higher than this interval. This is in agreement with Huff- Lonergan and Lonergan (2005) who found that the protein content of meat falls within 20-25%. Difference in management (nutrition) practices in the production systems greatly influences animal feeding and consequently protein build-up.
Production system significantly affected the crude lipid content of the resulting beef. Again, differences in management practices (especially trekking distance covered daily) would be responsible for the differences. The lowest crude lipid content was registered in nomadism, since animals continuously trek over very long distances consequently exhausting their lipid reserves. Since animals under ranching are more confined and do not undergo long distance trekking, their lipid reserves are not used up before slaughter.
Conclusions
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The pH values of the beef obtained 24 and 48 hours post slaughter for all the systems depicted that pH ranged from 5.3 – 5.8, which is the normal pH range recommended for beef of high quality. Significant differences were recorded at pH48 with nomadism recording the highest value. This implies that production system affects the pHu of beef.
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Production system influences technological properties of beef. Beef from ranching exhibited the best qualities: lowest drip, cook-out and freezing losses. This implies that, beef produced under the ranching system can be of high industrial value since it retains its juices and nutrients better than beef from the other production systems.
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Production system influences chemical properties of beef. Again, beef from ranching had the highest protein and lipid contents. This implies that beef produced under ranching is of better nutritive quality than that produced from either transhumance or nomadism.