Effects of high pressure/thermal treatment on lipid oxidation in beef and chicken muscle H.J. Ma a , D.A. Ledward b , A.I. Zamri b , R.A. Frazier b, * , G.H. Zhou c a School of Food, Henan Institute of Science and Technology, 453003 Xinxiang, Henan, PR China b Department of Food Biosciences, University of Reading, P.O. Box 226, Whiteknights, Reading RG6 6AP, UK c College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China Received 17 May 2006; received in revised form 29 November 2006; accepted 2 March 2007 Abstract Lipid oxidation was studied in beef and chicken muscle after high pressure treatment (0.1–800 MPa) at different temperatures (20– 70 °C) for 20 min, prior to storage at 4 °C for 7 days. Pressure treatment of beef samples at room temperature led to increases in TBARS values after 7 days storage at 4 °C; however, the increases were more marked after treatment at pressures P400 MPa (at least fivefold) than after treatment at lower pressures (less than threefold). Similar results were found in those samples treated at 40 °C, but at 60 °C and 70 °C pressure had little additional effect on the oxidative stability of the muscle. Pressure treatments of 600 MPa and 800 MPa, at all temperatures, induced increased rates of lipid oxidation in chicken muscle, but, in general, chicken muscle was more stable than beef to pressure, and the catalytic effect of pressure was still seen at the higher temperatures of 50 °C, 60 °C and 70 °C. The addition of 1% Na 2 EDTA decreased TBARS values of the beef muscle during storage and inhibited the increased rates of lipid oxidation induced by pressure. The inhibition by vitamin E (0.05% w/w) and BHT (0.02% w/w), either alone or in combination, were less marked than seen with Na 2 EDTA, suggesting that transition metal ions released from insoluble complexes are of major importance in catalysing lipid oxi- dation in pressure-treated muscle foods. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: High pressure; Thermal treatment; Beef muscle; Chicken muscle; Lipid oxidation; Antioxidants 1. Introduction High pressure processed foods are a commercial reality in many parts of the world (Grant, Patterson, & Ledward, 2000) and interest in the technology is growing. Though the preservative effects of pressure processing on meat are well established (Ledward & Mackey, 2002), at sufficiently high pressure it makes the meat more susceptible to lipid oxida- tion (Angsupanich & Ledward, 1998; Cheah & Ledward, 1995, 1996; Kato & Hayashi, 1999; Ledward, 1998). It is also well established that heat also markedly decreases the oxidative stability of muscle foods (Beltran, Pla, Yuste, & Mor-Mur, 2003; Keller & Kinsella, 1973; Morrissey, Sheehy, Galvin, Kerry, & Buckley, 1998; Tichivangana & Morrissey, 1985). Heat and pressure related damage to the cell membrane is thought to be at least partially responsible for these changes (Kato & Hay- ashi, 1999; Orlien, Hansen, & Skibsted, 2000), and several workers also believe that the release or activation of tran- sition metal ions are involved (Apte & Morrissey, 1987; Shahidi & Hon, 1991), or that the haem pigments them- selves are the key factors (Johns, Birkinshaw, & Ledward, 1989). Pressure treatment of beef liver at 600 MPa caused a significant increase in the total amount of soluble iron (Defaye & Ledward, 1999), although soluble iron in beef decreased as the haemoproteins denatured and became insoluble. In addition, metal chelators such as citrate and ethylenediaminetetraacetic acid are very effective inhibitors of pressure-induced lipid oxidation in pork (Cheah & Led- 0308-8146/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2007.03.006 * Corresponding author. Tel.: +44 118 3788709; fax: +44 118 9310080. E-mail address: r.a.frazier@reading.ac.uk (R.A. Frazier). www.elsevier.com/locate/foodchem Food Chemistry 104 (2007) 1575–1579 Food Chemistry