Prediction of texture and colour of dry-cured ham by visible and near infrared spectroscopy using a fiber optic probe.

The potential of visible and near infrared spectroscopy to predict texture and colour of dry-cured ham samples was investigated. Sensory evaluation was performed on 117 boned and cross-sectioned dry-cured ham samples. Slices of approximate thickness 4cm were cut, vacuum-packaged and kept under frozen storage until spectral analysis. Then, Biceps femoris muscle from the thawed slices was taken and scanned (400-2200nm) using a fiber optic probe. The exploratory analysis using principal component analysis shows that there are two ham groups according to the appearance or not of defects. Then, a K nearest neighbours was used to classify dry-cured hams into defective or no defective classes. The overall accuracy of the classification as a function of pastiness was 88.5%; meanwhile, according to colour was 79.7%. Partial least squares regression was used to formulate prediction equations for pastiness and colour. The correlation coefficients of calibration and cross-validation were 0.97 and 0.86 for optimal equation predicting pastiness, and 0.82 and 0.69 for optimal equation predicting colour. The standard error of cross-validation for predicting pastiness and colour is between 1 and 2 times the standard deviation of the reference method (the error involved in the sensory evaluation by the experts). The magnitude of this error demonstrates the good precision of the methods for predicting pastiness and colour. Furthermore, the samples were classified into defective or no defective classes, with a correct classification of 94.2% according to pasty texture evaluation and 75.7% as regard to colour evaluation.

Relationship between pH before salting and dry-cured ham quality.

The effect of pH before salting on pork quality was studied in two sets of experiments: 904 hams, set A; and 104 hams, set B; the latter was used to verify the results from A. After pH measurements, the hams were subjected to the traditional process for producing Spanish dry-cured ham and then evaluated by an expert panel to correlate the sensory characteristics to the pH measurement before salting. The parameters evaluated were pastiness, softness, anomalous cut colour, crusting and white spots. Moisture, non-protein nitrogen, salt, protein, nitrate and nitrite were determined in samples from both experiments. The results obtained in experiment A showed that pastiness is closely related to the pH before salting (p<0.001), but not softness. From the receiver operating characteristics curve, a cut-off point of pH of 5.55 was selected to classify the raw material in two groups: normal-pH and low-pH hams. The pH before salting can also be correlated with the appearance of anomalous cut colour and crusting in hams. White spots were absent in both pH groups. Regarding compositional parameters, there were significant differences in moisture (p<0.001), salt (p<0.001), protein (p<0.001), non-protein nitrogen (p<0.001) and nitrate (p<0.05) contents between low-pH and normal-pH hams. The results from experiment B, confirmed the relationship between pH before salting and the appearance of defective texture and colour in the final product. Also results from experiment B confirmed the compositional parameters found in experiment A. Thus, the pH before salting is a good predictor for meat quality allowing the classification of the raw material in the first stage of manufacture. After classification, some modifications to the processing can improve the final characteristics of dry-cured hams.

New methods for acceleration of meat sample preparation prior to determination of the metal content by atomic absorption spectrometry.

Focused microwave-assisted digestion and ultrasound leaching have been applied for the extraction of Pb, Cd, Cr, Cu, Fe, Zn, Ca, and Mg from raw meat. Semimembranous muscle (SM) of raw pig ham was used for optimizing both the digestion and extraction steps by multivariate approaches. The detection and quantification limits were 0.5 and 0.9 microg kg(-1) for Pb, 0.06 and 0.1 microg kg(-1) for Cd, 0.2 and 1.2 microg kg(-1) for Cr, 0.4 and 3 microg kg(-1) for Cu, 0.04 and 0.1 mg kg(-1) for Fe, 0.012 and 0.017 mg kg(-1) for Zn, 0.3 and 0.4 mg kg(-1) for Ca, and 0.01 and 0.03 mg kg(-1) for Mg. The precision, expressed as relative standard deviation (RSD), ranged between 2.5 and 9.6% for focused microwave-assisted digestion and between 3.5 and 10.6% for ultrasound leaching. The methods were then compared with a reference method and applied to a certified reference material (bovine muscle 184, from the BCR). The t-test, applied to the results obtained from focused microwave-assisted digestion, revealed that they are in agreement (p>0.01) with the certified and estimated values in the case of Pb, Cd, Cr, Cu, Fe, Ca, Mg, and Zn but not in that of Fe. In the case of ultrasound leaching, only the extraction of Pb, Cu, and Ca was quantitative. The method based on microwave digestion provides more accurate and precise results than ultrasound leaching. These new procedures have many advantages with regards to conventional methods, namely, reduction of the extraction time, simplification of the process, avoidance of chemical emissions to the atmosphere, and no losses of metals by volatilization.

A survey of operative airway management practices for midface fractures.

We surveyed 218 Level I trauma centers to determine operative airway management preferences for patients with midface fractures requiring maxillomandibular fixation. A two-page survey was distributed to anesthesiologists, plastic surgeons, otolaryngologists, and oral surgeons participating in the management of major craniofacial trauma at each center. Specific fracture patterns were described, and the preferences for endotracheal intubation for operative management were surveyed among the respondents. We analyzed 105 responses from surgeons and 51 responses from anesthesiologists. Although there were differences in the preferences expressed by surgeons compared with anesthesiologists, more than 50% of the respondents in each practice category chose some form of nasotracheal intubation for fracture patterns involving the midface. Tracheostomy was a first choice for patients with panfacial fractures or those with loss of consciousness and midface fractures. This report serves as a basis for surgeons and anesthesiologists to review their practices and discuss planning of operative airway management for the patients with these fracture patterns. On the basis of this survey, midface fractures need not prohibit any consideration of nasotracheal intubation.

A study of the effects of epinephrine infiltration on delayed bleeding in a rat flap model.

Infiltrating the operative site prior to incision with an epinephrine solution will provide vasoconstriction and a dryer operative field. However, some surgeons fear that as the vasoconstrictive effects of the epinephrine subside, smaller vessels will rebleed and a hematoma may result. In this study, 51 rats were operated with two flaps. The ventral pedicled flap, based on the inferior superficial epigastric arteries, and the McFarlane dorsal skin flap were utilized. The perimeter of all flaps was infiltrated with one of the following test infusions: (1) no infiltrate (control group), (2) 1% lidocaine hydrochloric acid (HCl), (3) 2% lidocaine HCl, (4) 1% lidocaine HCl and epinephrine 1:100,000, and (5) 0.5% lidocaine HCl and epinephrine 1:200,000. Flaps were replaced in their beds. Animals were sacrificed 24 hours postoperatively. Flaps were raised at 26 hours and the coagulum weighed. No statistically significant difference was found between the weights of the coagulum of the infiltrated flaps versus the noninfiltrated flaps. Statistical power calculations on the main study flap yielded values greater than 80%. This suggests that the difference in delayed bleeding between noninfiltrated flaps and flaps infiltrated with various combinations of lidocaine and epinephrine was insignificant.

A biomechanical evaluation of cervical spinal stabilization methods in a bovine model. Static and cyclical loading.

A bovine model was developed for biomechanical evaluation of surgical procedures stabilizing traumatic cervical injuries disrupting the anterior and posterior spinal column. Cervical spinal segments and C4-5 functional spinal units were tested statically, and C4-5 functional spinal units were tested cyclically in evaluation of 1) the intact cervical spine, 2) Rogers' wiring method, 3) Bohlman's triple-wire technique, 4) sublaminar wiring, 5) anterior cervical plate instrumentation, and 6) posterior hook plate stabilization. Anterior cervical plate instrumentation proved inadequate, and was the least rigid, with axial and flexural loading (P less than 0.05). There was no significant difference between each of the three posterior wiring methods, and all generally restored stability to equal that of the uninjured intact cervical spine. Posterior hook plating with an interspinous bone graft serving as an extension block was the most effective method in reducing flexural stress across the injured C4-5 segment (P less than 0.05). Cyclical in vitro testing was the most sensitive method in highlighting mechanical differences between instrumentation systems, particularly with "on-line" continuous measurement of anterior and posterior strains. Anterior cervical plate stabilization does not appear to confer enough stability in cervical facet injuries to obviate the need for posterior cervical stabilization procedures. The recently developed posterior hook plate technique offers biomechanical advantages that should be weighed against the greater technical precision needed for insertion and the increased potential for neurologic and vascular complications.

A study of intrusion characteristics of low viscosity cement Simplex-P and Palacos cements in a bovine cancellous bone model.

Aseptic loosening is the most common long-term complication of cemented total hip arthroplasties (THA). The functional longevity of these implants depends on the bone-cement interface. The influence of cement injection pressure, type of cement, ambient temperature, chilling of the monomer, and centrifugation of cement-on-cement intrusion depth was investigated in specimens of bovine cancellous bone. In order to validate the bovine model for comparative purposes relative to use in man, a linear relationship between human and bovine cancellous bone was first demonstrated for various porosities and cement intrusion depth. Three cements (Low Viscosity Cement [LVC], Simplex-P, and Palacos) were intruded at three different pressures (20, 40, and 60 PSI) at the same ambient temperature and relative humidity into commercially prepared plugs of bovine cancellous bone. Cement intrusion depth was proportional to injection pressure for all three cements, but was significantly different for each cement at a given pressure. At 20, 40, and 60 PSI, Palacos had a cement intrusion depth of 1.4, 2.4, and 2.8 mm respectively, while the figures for Simplex-P were 2.2, 4.2, and 5.0 mm, and for LVC were 8.0, 12.0, and 14.6 mm. Ambient temperature had an inverse relationship with cement intrusion depth for all three cements given the same experimental conditions. Chilling the monomer increased the intrusion of Simplex-P to 5.8, 8.2, and 12.7 mm at 20, 40, and 60 PSI injection pressure respectively. Simplex-P intrusion depth was not modified by cement centrifugation at any of the three injection pressures tested.(ABSTRACT TRUNCATED AT 250 WORDS)