Magnesium (Mg) is the second most abundant intracellular ion, and helps to maintain osmotic pressure, acid–base balance, membrane potential, substrate transport, and enzymatic cofactors. It is also possible that Mg antagonizes calcium within the muscle cell (necessary for muscle contraction) and, hence, has a relaxant effect on skeletal muscles. A number of studies have reported that feeding above the nutritional requirement of Mg to pigs in the last few days prior to slaughter improves pork colour and water-holding capacity, and it may affect lipid oxidation of stored pork. To date, no studies have been devoted to the effect of dietary Mg supplementation on pork in modified atmosphere packaging (MAP); therefore, the aim of this study was to compare the effect of dietary supplementation with different sources of Mg on pork quality during 13 days of storage at 4 ± 1 °C under modified atmosphere.
The experiment was conducted with 40 gilts (Pietrain × (Landrace × Large White)) which were fed one of four diets five days prior to slaughter: 1) control (basal) diet with no supplementation of Mg; 2) basal diet supplemented with 5 g/pig/day of Mg oxide (50% Mg); 3) basal diet supplemented with 12.5 g/pig/day of Mg sulphate (20% Mg); and 4) basal diet supplemented with 11.7 g/pig/day of Mg chelate (21.4% Mg) (consisting of 2.5 g elemental Mg for all diets supplemented). Supplementation with different Mg sources during the last five days prior to slaughter did not improve pH, colour, or Warner-Bratzler shear force values of pork (P > 0.05). On the other hand, results of this study suggest that supplementation of pig diets with Mg chelate may be effective in improving water?holding capacity of MAP pork during storage and reducing cooking losses (P ≤ 0.05). Furthermore, supplementation with Mg oxide and Mg chelate may have an antioxidant effect. Pork from pig supplemented with Mg oxide had the lowest TBARS values. Visual assessment of pork from pigs supplemented with Mg chelate resulted in generally higher colour, and lower exudative scores, culminating in greater overall acceptance scores throughout display. In contrast, the worst visual colour and overall acceptance evaluation were noted in chops from Mg sulphate supplemented pigs, whereas the worst visual exudative scores were noted for chops from Mg oxide supplemented pigs.
Based on the results from this experiment, dietary Mg chelate supplementation at a dose of 11.7 g/pig/day for five days prior to slaughter could be effective in improving water holding capacity and sensory visual assessment on pork during 13 days of storage in a high?oxygen (80% O2/20% CO2) packaging.
V Alonso, L Provincial, M Gil, E Guillén, P Roncalés and JA Beltrán, 2012. The impact of short-term feeding of magnesium supplements on the quality of pork packaged in modified atmosphere. Meat Science, 90: 52-59.