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Several aspects of the water-holding capacity of fresh meat are discussed. After some compositional and structural characteristics of muscle are outlined, special attention is paid to post mortem muscle physiology and related mechanisms of fluid loss from meat. Finally, determinants of water-holding capacity (physiological factors, rearing conditions and processing factors) are described. From this review it can be concluded that the water-holding capacity and the subsequent drip loss are complex attributes of meat which are influenced by factors in the whole meat production chain. However, the effects of many factors, such as rearing conditions, administration of growth promoters, feed, and ageing of meat, are still not clear. To be able to optimize and control the water-holding capacity of meat, it is important to have information about the effects of each processing factor and the basic mechanisms involved. Once these mechanisms are known, the influence of biological and technological factors will be more predictable and more easy to control. Veterinarians can play an important role in this.

This study was designed to establish the effects of transport vibrations on the water-holding capacity of fresh non-stimulated veal and pork and electrically- and non-stimulated beef. Furthermore, drip production was followed during storage by various methods which were compared for their suitability in industrial practice and scientific research. During storage, the amount of drip increased, whilst the rate of drip formation decreased. Filter paper wetness measured at 1 day post mortem was positively correlated with drip lost over a period of 2 weeks of refrigerated storage in poly-ethylene bags (method 1) and poly-propylene containers (method 2). This suggests that the filter paper wetness test may be useful to predict drip loss of stored meat. Simulated transport did not result in higher drip losses, although a significant increase in filter paper wetness from the fresh cut surface of veal and pork was found, suggesting that transport affects the initial rate of drip production, but not the total amount of drip. In beef, transport simulation resulted in an increase in filter paper wetness from the surface of electrically-stimulated meat, stored for 1 or 2 weeks, indicating that fluid loss was elevated due to transport vibrations. However, this effect seemed to be related to the intrinsic water-holding capacity of the sample: meat with a low intrinsic water-holding capacity seemed to be more sensitive to transport vibrations than meat with a high intrinsic water-holding capacity.

In this study the effect of the rate of post mortem pH fall on the water-holding capacity of meat from moderately chilled veal carcasses was investigated. Also the relationship between muscle protein denaturation and drip loss of veal was examined. Three groups of 10 Friesian Holstein male veal calves each were selected on the basis of their pH in M. longissimus thoracis et lumborum (LTL) at 3 hr post mortem (pH(3)): (1) fast pH-fall, pH(3)6.2; (2) intermediate pH-fall, 6.5pH(3)6.6; (3) slow pH-fall, pH(3)6.7. After 48 hr of chilling the LTL was excised from the carcass and sampled for determination of drip loss, filter paper wetness, sarcomere length, protein solubility and transmission value. Differences in pH(3) were not associated with differences in drip loss, filter paper wetness or differences in protein denaturation. It is suggested that at the relatively high veal carcass chilling rate the effect of rate of pH-fall on protein denaturation and thus on drip loss is negligible. Drip loss of veal was highly correlated with both solubility of sarcoplasmic (r = -0.67; p0.001) and total muscle protein (r = -0.54; p0.01) and with transmission values (r = 0.66; p0.001). These results indicate that protein denaturation measurements may be a good predictor for drip loss of veal.

The effect of dietary vitamin E supplementation (2150 IU/head/day) on drip loss and related quality traits of bovine M. longissimus lumborum M. psoas major and M. semitendinosus was examined. The effect of vitamin E supplementation on drip loss seemed to depend on muscle studied. Drip loss of longissimus muscles was not significantly influenced, whereas supplemented semitendinosus muscles lost significantly less (p < 0.05) and supplemented psoas major muscles significantly more (p < 0.05) drip than did control counterparts. In both supplemented and control samples, sarcolemma failure occurred. No ultimate pH differences were detected between control and supplemented samples regardless of the muscle considered. In supplemented semitendinosus muscles, the decrease in drip loss was accompanied by an increase of sarcoplasmic protein solubility and sarcomere length. It is discussed that both these variables may be related to the stability of mitochondria and sarcoplasmic reticulum, as affected by dietary supplementation of vitamin E. However, this view deserves further investigation and more evidence is needed to establish the mechanism by which vitamin E influences drip loss.

The effect of low-voltage electrical stimulation on the water-holding capacity and protein denaturation of bovine longissimus thoracis and semimembranosus was studied in eight electrically stimulated (85 V, 14 Hz, 15 s; immediately after slaughter) and eight nonstimulated Friesian Holstein bull carcasses. At 24 h postmortem longissimus thoracis and semimembranosus were sampled for drip loss, thaw loss, filter paper wetness, myofibrillar water-holding capacity, protein content of drip, protein solubility, myofibrillar ATPase-activities, and bound phosphorylase. Electrical stimulation resulted in higher (P < .05) drip losses and filter paper wetness and lower (P < .05) myofibrillar water-holding capacity of semimembranous samples. The increased drip loss coincided with decreased (P < .05) sarcoplasmic protein solubility, decreased (P < .05) myofibrillar ATPase-activity, and decreased (P < .05) protein concentration of drip. In the longissimus thoracis, electrical stimulation resulted in a lower (P < .05) myofibrillar water-holding capacity. However, this was not reflected in higher drip losses. In this muscle, only a decreased (P < .05) sarcoplasmic protein solubility and increased (P < .05) amount of bound phosphorylase was observed. The results indicated that the negative effect of electrical stimulation on drip loss is possibly the result of myosin denaturation, which is determined by postmortem pH and temperature fall and thus varies by muscle studied. Sarcoplasmic protein denaturation seemed not to be involved in determining water-holding capacity.