Effects of conjugated linoleic acid on color and lipid oxidation of beef patties during cold storage S.J. Hur, B.W. Ye, J.L. Lee, Y.L. Ha, G.B. Park, S.T. Joo* Division of Applied Life Science, Graduate School, Gyeongsang National University, Chinju, Kyeongnam 660-701, South Korea Received 13 September 2002; received in revised form 22 April 2003; accepted 22 April 2003 Abstract The effects of conjugated linoleic acid (CLA) on color and lipid oxidation of beef patties were investigated. Ground beef was divided into three batches. The control patties were prepared with 90% lean meat and 10% tallow. The second treatment consisted of 90% lean meat with 9.5% tallow+0.5% CLA sources. The third treatment consisted of 90% lean meat with 8% tallow+2% CLA sources. The patties were wrap-packaged and then stored at 4  for 14 days. The CLA concentration significantly increased (P < 0.05) by substituting CLA sources for fat. Storage of the patties did not alter the CLA concentration in beef patties. The treatment substituted with CLA sources had significantly lower TBARS (2-thiobarbituric acid-reactive substances) values (P < 0.05) than the control. For oxymyoglobin contents and a* value, substituted CLA sources treatments had significantly higher values than the control. However, L* value significantly increased by substituting CLA sources for fat. # 2003 Elsevier Ltd. All rights reserved. Keywords: Conjugated linoleic acid (CLA); TBARS; Oxymyoglobin; Meat color; Beef patties 1. Introduction Lipid oxidation may initiate the oxidation of myo- globin to metmyoglobin, and thus, change meat color from red to unattractive brown. The color of meat is due to a balance between oxymyoglobin oxidation and metmyoglobin reduction (Faustman & Cassens, 1990). Greene (1969) first reported a correlation between lipid oxidation and metmyoglobin formation. The rate of meat discoloration is closely related to the rate of myo- globin oxidation induced by lipid oxidation (Yin & Faustman, 1993). Schaefer, Liu, Faustman, and Yin (1995) proposed that products of lipid oxidation are more water-soluble than their parent compounds and can enter cytoplasm where they interact with myoglobin to hasten its oxidation. A lot of antioxidants have been used for over 50 years to avoid, or at least delay, the autooxidation process of lipids (Cuvelier, Berset, & Richard, 1994). The improvement of the stability of myoglobin in the pre- sence of vitamin E has demonstrated a possible link between lipid oxidation and myoglobin oxidation. CLA has been recognized as having anticarcinogenic and antioxidative properties in several animals models (Ha, Storkson, & Pariza 1990). Also, CLA has been shown to have beneficial effects on human health (Ip, Scimeca, & Thompson, 1995). Du, Ahn, Nam, and Sell (2000) reported that color stability in fresh chicken meat was improved by dietary CLA. Also, Joo, Lee, Ha, and Park (2002) reported that dietary 5% CLA caused sig- nificantly lower L* and b* values than in control pork. They assumed that dietary CLA improved the oxidative stability of intramuscular fat in pork. CLA may improve the color stability of meat by slowing down the oxidative changes in lipids. CLA presence in meat is quite stable and does not participate in oxidation processes because there was no structural change in CLA during meat storage while the content of other polyunsaturated fatty acids decreased during storage due to oxidation. However, there is little information on the effects of CLA supplementation on color stability in beef. The purpose of this study was to determine the effects of substituted CLA sources for fat on lipid oxidation, color stability and fatty acid composition in beef patties. 0309-1740/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0309-1740(03)00104-9 Meat Science 66 (2004) 771–775 www.elsevier.com/locate/meatsci * Corresponding author. Tel.: +82-55-751-5511. E-mail address: stjoo@gsnu.ac.rk (S.T. Joo).