Meat Science 74 (2006) 578–585 www.elsevier.com/locate/meatsci 0309-1740/$ - see front matter  2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2006.05.008 Contribution of postmortem changes of integrin, desmin and -calpain to variation in water holding capacity of pork W.G. Zhang, Steven M. Lonergan, Matt A. Gardner 1 , Elisabeth HuV-Lonergan ¤ Animal Science Department, Iowa State University, 2278 Kildee Hall, Ames, IA 50011, United States Received 28 February 2006; received in revised form 5 May 2006; accepted 8 May 2006 Abstract The purpose of this study was to examine the relationship between integrin, desmin, -calpain and water holding capacity in fresh pork. High levels of intact integrin at one day postmortem were negatively correlated with day 1 (P < 0.05) and days 1–5 (cumulative) drip loss (P < 0.05). High levels of intact integrin at Wve days postmortem were negatively correlated with days 1–7 (cumulative) purge loss (P < 0.05). Intensity of intact desmin at one day postmortem was positively correlated with days 1–7 purge loss (P < 0.01). There were pos- itive correlations between intensity of intact desmin at day 7 and day 1 (P < 0.01), days 1–5 drip loss (P < 0.01) and days 1–7 purge loss (P < 0.05). Autolysis of -calpain was associated with the degradation of desmin and drip or purge loss postmortem. Our results indicate that low levels of degradation of integrin and high levels of desmin degradation were associated with low drip loss values in fresh pork.  2006 Elsevier Ltd. All rights reserved. Keywords: -Calpain; Desmin; Drip loss; Integrin; Purge loss; Water holding capacity 1. Introduction The ability of meat to retain moisture during postmor- tem storage is referred to as its water holding capacity (WHC). Low WHC is associated with high drip or purge loss and subsequently reduces proWtability in meat pro- duction. Numerous and complex factors contribute to the considerable variability in WHC of meat. Genotype (Hamilton, Ellis, Miller, McKeith, & Parrett, 2000), diVer- ent stunning methods (Stoier, Aaslyng, Olsen, & Henckel, 2001), aging (Kristensen & Purslow, 2001), chilling rate (Maribo, Olsen, Barton-Gade, Moller, & Karlsson, 1998) and even protein oxidation (Rowe, Maddock, Lonergan, & HuV-Lonergan, 2004) may all aVect the WHC of meat. Recently, several authors have shown that degradation of cytoskeletal and other structural proteins plays an impor- tant role in drip loss (HuV-Lonergan & Lonergan, 2005; Kristensen & Purslow, 2001; Melody et al., 2004; Schafer, Rosenvold, Purslow, Andersen, & Henckel, 2002) and may work in concert with biophysical forces to inXuence WHC (for a review, see HuV-Lonergan & Lonergan, 2005; OVer & Trinick, 1983). Integrin, the heterodimeric cell adhesion molecule that links the extracellular matrix to the cytoskeleton, is impor- tant in controlling many steps in cell membrane-cytoskele- ton attachments and in signaling pathways (Hynes, 1992). In integrin, 18 - and eight -subunits have been identiWed (Plow, Haas, Zhang, Loftus, & Smith, 2000; van der Flier & Sonnenberg, 2001). -Chain integrin is responsible for the attachment of cell membrane to the cell cytoskeleton (van der Flier & Sonnenberg, 2001). The degradation of  1 integrin has been suggested to increase the drip channel for- mation between the cell and cell membrane. The resulting drip channel contributes to drip loss postmortem in pork (Lawson, 2004). One of the protease systems that is commonly thought to play a role in the degradation of several muscle cell * Corresponding author. Tel.: +1 515 294 9125; fax: +1 515 294 9143. E-mail address: elonerga@iastate.edu (E. HuV-Lonergan). 1 Present address: Cargill Meat Solutions, Wichita, KS 67219, United States.