Dried milk mineral as an antioxidant in processed meats
Dr. Daren Cornforth, Utah State University
The effect of 0.5 –2.0 % MM was tested as an antioxidant in raw and cooked ground pork stored at -20 C for 4 months, compared to 0.01 % (fat basis) butylated hydroxytoluene (BHT) and 0.5% sodium tripolyphosphate (STP). TBA numbers were low (<0.45) and not significantly different (p>0.05) between raw meat treatments. TBA number was significantly lower (p<0.01) for all treatments with MM or STP after 4 months frozen storage, compared to controls or treatments with BHT. The mean TBA numbers for all MM and STP treatments were < 1.0 at 4 months storage, compared to 2.3 and 2.1 for control and BHT treatments, respectively.
Sensory testing was also done to determine at what level of TBA number do consumers reject the sample as too rancid. Preference test was chosen as an appropriate test. The patties were cooked and stored at 2 degrees C for 1, 2 and 3 days to get TBA numbers of 1.48, 3.37 and 3.94 respectively. Freshly cooked patties (TBA number = 0.409) and patties treated with 0.5% STP (TBA number=0.199) were used for comparisons. Panelists preferred (p<0.001) patties with TBA number 0.4 or less over patties with TBA numbers ³ 1.4.
In another study TBA numbers were measured on cooked pork patties as affected by 30, 60, 90 or 120 min of warm storage (71°C). TBA number increased from 0.32 at 0 min to 1.17 at 120 min. TBA numbers after 120 and 90 min were significantly higher than after 0 to 60 minutes. Thus patties could be kept warm for up to 60 minutes after cooking without significantly increasing TBA number.
In a comparison of milk mineral (MM) with other antioxidants at current use levels, milk mineral (1.5%), sodium tripolyphosphate (0.5%), and sodium nitrite (156 ppm) were significantly more effective than Rosemary oil extract (0.2% of meat weight) or BHT at 0:01% of fat weight. Milk mineral, sodium tripolyphosphate, and sodium nitrite are classified as type 2 antioxidants that bind iron, preventing it from catalyzing the propagation step of lipid oxidation. Rosemary and BHT are electron donors that inhibit the initiation step of lipid oxidation. In cooked ground pork after 13 days storage at 2C, samples with Rosemary oil or BHT were very rancid, with TBA values greater than 3.5. Samples with tripolyphosphate, milk mineral, or sodium nitrite had mean TBA values of 0.6, 1.7, and 1.1, respectively. Thus, milk mineral and other type 2 antioxidants were much more effective than the type 1 antioxidants, at current use levels in cooked ground pork during refrigerated storage.
Cornforth, D. P. and West E. M. 2002. Evaluation of the antioxidant effects of dried milk mineral in cooked beef, pork, and turkey. J. Food Sci. 67:615-618.
Preetha Jayasingh, in preparation.
Jayasingh, P. and Cornforth, D. P. Antioxidant effect of dried milk mineral in fresh and cooked ground pork. 2001. Reciprocal Meat Conf. Proc. 54:198.
Jayasingh, P., Carpenter, C.E. and Cornforth, D.P. 2003. Comparison of Type 1 and Type 2 antioxidant effectiveness in cooked ground pork during refrigerated storage. Abstract 76F – 26. Inst. Food Technol. National meeting, Chicago, Il, July 13-16.