pH is a logarithm used to measure the alkality and acidity of food. Meat of high quality has ultimate pH at the range of 5.4–5.6, Meat quality is significantly affected by preslaughter factors. The pH raw meat ranges from 6.10-6.71 while for processed ranges from 6.64-6.90. Meat with a pH above 6.2 tends to have tightly packed water-retaining fibres that impede oxygen transfer. The pH of processed meat was higher compared to the raw meat with chicken polony and ham having 6.90 and 6.81 respectively. If the pH of the meat drop to less than 5.2 it start to be rancid therefore not suitable for further processing or consumption. In conclusion the processing of meat has an effect on the pH of the meat all the processed meat products has the higher pH values compared to the raw. The aim of this study is to determine the difference between the pH of raw meat and processed meat
The pH of muscle tissue is extremely important to meat science since the pH at specific times during the conversion of muscle to meat, as well as the ultimate pH of meat, affects many quality factors. The quality factors affected by pH include: colour, grading characteristics and shrink of carcasses and wholesale cuts: texture, cooking loss and tender- ness of steaks and roasts; and processing and binding characteristics of comminuted and restructured meats( Duston, 1983). Fresh meat must have a pH value in the range of 5.5 to 6.2.1 During temporary storage, especially when it is not properly preserved, the fresh meat will turn rancid and have a pH value below 5.3(horiba 2002).
Meat quality is significantly affected by preslaughter factors. Atmospheric conditions in the pre- slaughter period, and especially those causing an additional stress for animals can be important. Seasonal changes in temperature can affect the level of glycogen in muscles after slaughter and the ultimate pH, and consequently the quality of meat. An increase in glycolysis results from excessive excitement, starving and stress caused by ambient temperature, which in turn leads to high post- mortem pH values and consequently meat colour is influenced (Kreikemeier et al., 1998; Abril et al., 2001; Honkavaara et al., 2003).
Meat of high quality has ultimate pH at the range of 5.4–5.6. At pH > 5.8 a decrease in meat delicacy as well as a possibility of maintaining good quality during cooling is observed. High pH is improper for sorting, confectioning and vacuum packaging of meat. Moreover, meat of a high ultimate pH can be characterized by gummy structure, increased water-holding capacity and decreased specific taste (Pipek et al., 2003; Villarroel et al., 2003). According to many studies the ultimate pH and meat colour are the most important indices of meat quality. They should be used in a standard evaluation of meat and especially in choosing meat for ageing process. The same quality parameters are taken into account in the evaluation of carcasses and meat intended for export (Page et al., 2001; Gońi et al., 2007). The aim of this study is to determine the difference of pH in raw meat and processed meat.
Materials and methods
The pH level of the meat samples was determined using a calibrated pH meter (Crison instruments, E- 042030, South African). The pH meter was calibrated by dipping the electrode into the buffers using acidic (4.01), neutral (7.00) and basic (9.21) buffers at 25°C. The raw meat products: beef, pork and mutton were reduced in size into smaller pieces. 10 g of each meat product was weighed using a weighing balance; 50 ml of distilled water was poured altogether with the meat piece into a stomacher bag and then homogenized for 2 minutes. The meat pH was measured in triplicates using a pH meter
Results and discussion
The pH raw meat ranges from 6.10-6.71, the raw meat has the average pH of 6.45 whereas the processed meat has the average pH value of 6.74. this shows that the processing steps have an effect on the pH value of the meat, hence it does not cause any deterioration of the meat, the meat starts to be rancid when the pH value drop lower than 5.2. The normal pH of meat before slaughter is between 6.9-7.1 but after slaughter the pH value decreases to 5.4-5.8, however during storage this pH value increases again slightly, this increase in pH is due to factors such as storage and processing steps together with the preservation measures taken to preserve the meat. Recent reviews on the relationship of post mortem pH decline and muscle tenderness have been conducted by Dutson (1983) and Marsh (1983a). Most authors agree that a high ultimate muscle pH (6.0 or greater) is associated with more tender muscle (Fredeen et al., 1974; Dransfield, 1981, Dutson et al., 1981. Meat with a pH above 6.2 tends to have tightly packed water-retaining fibres that impede oxygen transfer and promote longer survival of oxygen-scavenging enzymes, favouring deoxyMb rather than oxyMb. The purple-red myoglobin combines with the closed structure of the muscle to absorb rather than reflect light, making the meat appear dark. The pH of processed meat was higher compared to the raw meat with chicken polony and ham having 6.90 and 6.81 respectively, Schmidt and Trout (1984) demonstrated that when cooked to the same internal temperature, high-pH beef, pork and turkey muscle (pH > 6.0) was redder than low-pH muscle (pH > 5.5) and appeared undercooked, from the this results by Schmidt and trout together with the results it can be can be concluded that the processing aspect have an effect on the pH value of the meat.
Processing of meat product have an effect on the pH of meat. The slightly increase of pH on raw meat is due to the temperature of storage. pH can affect the colour stability and the texture of the meat.
- Andrés-Bello, A., Barreto-Palacios, V.I.V.I.A.N., García-Segovia, P., Mir-Bel, J. and Martínez-Monzó, J., 2013. Effect of pH on color and texture of food products. Food Engineering Reviews, 5(3), pp.158-170.
- Dutson, T.R., 1983, June. The measurement of pH in muscle and its importance to meat quality. In Reciprocal meat conference (Vol. 36, pp. 92-97).
- Gońi M.V., Beriain M.J., Indurain G., Insausti K. (2007): Predicting longissimus dorsi texture characteristics in beef based on early post-mortem colour measurements. Meat Science, 76, 38–45.
- Page J.K., Wulf D.M., Schwotzer T.R. (2001): A survey of beef muscle color and pH. Journal of Animal Science, 79, 678–687
- Pipek P., Haberl A., Jeleniková J. (2003): Influence of slaughterhouse handling on the quality of beef carcasses. Czech Journal of Animal Science, 39, 371– 378.
- Schmidt GR, Trout GR (1984) pH and color. Meat Ind 30(8):30–32 Varnam A, Sutherland JM (1995) Meat and meat products: technology, chemistry and microbiology. Chapman and Hall, London, p 430