Prediction of water-holding capacity and composition of porcine meat by comparative spectroscopy Jesper Brùndum a,b , Lars Munck a , Poul Henckel c , Anders Karlsson c , Eva Tornberg d , Sùren B. Engelsen a, * a Food Technology, Royal Veterinary and Agricultural University, Rolighedsvej 30, 1958 Frederiksberg, Denmark b SFK Technology, Transformervej 9, 2730 Herlev, Denmark c Department of Animal Product Quality, Danish Institute of Agricultural Sciences, Research Centre Foulum, PO Box 50, 8830 Tjele, Denmark d Department of Food Engineering, Lund University, PO Box 124, SE-22100 Lund, Sweden Received 10 July 1999; accepted 7 September 1999 Abstract Four spectroscopic instruments, a ®bre optical probe (FOP), a visual (VIS) and near infrared (NIR) re¯ectance spectro- photometer, a re¯ectance spectro¯uorometer and a low-®eld 1 H nuclear magnetic resonance (LF-NMR) instrument were used to perform measurements on two muscles (longissimus dorsi and semitendinosous) from 39 pigs, 18 of which were carriers of the Halothane gene. Water-holding capacity (drip loss and ®lter paper wetness) and chemical composition (intramuscular fat and water) of the muscle samples were determined for spectroscopic calibration. Prediction models were established by partial least squares regression to evaluate the potential of using the spectroscopic techniques in an on-line slaughterhouse system. VIS data gave good prediction models, indicating that current industrial colour systems can be advanced into more speci®c meat evaluation systems by including the entire visible spectral range. The FOP and ¯uorescence measurements were less successful, and suered from sampling problems since they measure only a small area. The best regression models were obtained from LF-NMR data for all reference quality measures and yielded a correlation coecient of 0.75 with drip loss. LF-NMR proved able to distinguish between the two muscles and the results for their longitudinal relaxation times, T 21 , were proportional to their average myo®brillar cross- sectional areas reported in the literature. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Chemometrics; Fluorescence; VIS; NIR; NMR; Porcine meat; WHC 1. Introduction Instrumental techniques for rapid screening of meat properties (e.g. water-holding capacity and chemical composition) which can be used to improve control and classi®cation of the product in mechanised processes are of great interest for both the industry and the consumers. The use of rapid spectroscopic techniques for (on-line) quality inspection of meat has been successfully demon- strated in a few applications. Jensen, Reenberg and Munck (1989) used ultraviolet ¯uorescence for detection of the tissue components of meat. Swatland (1995a), Swatland, Brooks and Miller (1998), Swatland and Find- lay (1997), Swatland, Gullett, Hore and Buttenham (1995b) and Swatland, Nielsen and Andersen (1995c) have proposed the use of ultraviolet ¯uorescence for measurement of connective tissue in relation to tender- ness in beef. The technique was validated by measure- ments on muscle of sensory properties, dynamic electromechanical toughness, and resistance to penetra- tion of a needle. Swatland (1995a) used visual re¯ec- tance to determine water-holding capacity, pH and light re¯ectance of porcine meat. Borggaard, Andersen and Barton-Gade (1989) and Andersen, Borggard and Niel- sen (1995) studied the relationships between a single near infrared wavelength (950 nm) and the water-hold- ing capacity (WHC) and intramuscular fat (IMF) in porcine meat. The NIR study on WHC by Borggaard et al. has recently been extended by taking measurements with ®bre optic probes at many NIR wavelengths by Forrest, Sheiss, Morgan and Gerrard (1997). There are many reports of the use of low-®eld nuclear magnetic resonance (LF-NMR) to measure water and 0309-1740/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0309-1740(99)00141-2 Meat Science 55 (2000) 177±185 www.elsevier.com/locate/meatsci * Corresponding author. Tel.: +45-35-28-3205; fax.: +45-3528-3245. E-mail address: se@kvl.dk (S.B. Engelsen).