Use of gelatin gels as a reference material for performance evaluation of meat shear force measurements

Abstract: Establishing standards for meat tenderness based on Warner–Bratzler shear force (WBSF) is complicated by the lack of methods for certifying WBSF testing among texture systems or laboratories. The objective of this study was to determine the suitability of using gelatin gels as reference materials for performance testing of texture measurement systems. Three replications of 5 gels (15%, 20%, 25%, 30%, and 35% gelatin) were prepared, vacuum packaged, and stored at 4 °C until use. Three randomly selected strips from each gel were subjected to WBSF testing on 4 instruments (A, B, C, or D) on days 1 and 8. Additional strips from each gel were subjected to WBSF testing on instruments A and C on day 29. Regression line estimates for each set of gels were analyzed. Gel WBSF values ranged from 10 to 177 N. The WBSF by gel concentration response was highly linear (P < 0.0001) for all replications, instruments, and days of analysis. R²‐values across all sets of gels ranged from 0.9562 to 0.9998. On days 1 and 8, instruments A and D exhibited higher slope (P < 0.0001) and lower intercept (P < 0.0001) estimates than instruments B and C. Regression line parameters (slope, intercept, and R²‐values) were not influenced (P > 0.05) by length of gel storage (1, 8, and 29 d). Data from this study suggest that gelatin gels can be used for evaluating WBSF values from various instruments and for validating the performance of meat shear force testing. Practical Application: Validating the performance of meat shear force testing is vital to establishing meat tenderness standards. The gelatin gel standards developed in this study exhibited a highly linear, repeatable relationship with shear force and were found to be stable for at least a month. These gel standards would provide a tool for the meat industry to harmonize shear force measurements across laboratories and various texture measuring instruments.     

Functional anatomy of the cartilage of the distal phalanx and digital cushion in the equine foot and a hemodynamic flow hypothesis of energy dissipation

OBJECTIVES: To examine macro- and microscopic characteristics of cartilage of the distal phalanx (ungual cartilage [UC]) and digital cushion in the equine foot and to relate them to the foot's function of energy dissipation. ANIMALS: 85 horses and 5 foals of various breeds and ages. PROCEDURE: Feet, obtained at necropsy, were perfused with India ink (n = 30), latex (5), or polymer plastic (10). Select feet were examined histologically for tissue architecture and to identify elastic fibers. Immunochemistry to identify substance P peptides in nerves (feet from foals) and gold chloride impregnation of axons (n = 10) were performed. Feet were sectioned transversely (n = 27) or coronally (62 feet in a matched-paired study). Ungual cartilage was measured at the navicular bone. Digital cushions were examined for relative tissue composition between forefeet and hind feet. RESULTS: Ungual cartilage formed an axial projection that extended towards the midline to overlie the bars, and dorsally along the semilunar line of the distal phalanx. Ungual cartilage of forefeet was significantly larger than that of hind feet. The digital cushion was composed of fat and elastic tissues in feet with thin UC, or fibrous and fibrocartilaginous tissue and elastic tissue in feet with thicker UC. Sensory nerves and an extensive network of venovenous anastomoses were found in the UC. CONCLUSIONS AND CLINICAL RELEVANCE: Ungual cartilage and the digital cushion provide the basis for a hemodynamic flow hypothesis of energy dissipation. Maximum energy dissipation depends on proper hoof preparation and shoeing.     

Automated design of robust discriminant analysis classifier for foot pressure lesions using kinematic data

In the recent years, the use of motion tracking systems for acquisition of functional biomechanical gait data, has received increasing interest due to the richness and accuracy of the measured kinematic information. However, costs frequently restrict the number of subjects employed, and this makes the dimensionality of the collected data far higher than the available samples. This paper applies discriminant analysis algorithms to the classification of patients with different types of foot lesions, in order to establish an association between foot motion and lesion formation. With primary attention to small sample size situations, we compare different types of Bayesian classifiers and evaluate their performance with various dimensionality reduction techniques for feature extraction, as well as search methods for selection of raw kinematic variables. Finally, we propose a novel integrated method which fine-tunes the classifier parameters and selects the most relevant kinematic variables simultaneously. Performance comparisons are using robust resampling techniques such as Bootstrap 632+ and k-fold cross-validation. Results from experimentations with lesion subjects suffering from pathological plantar hyperkeratosis, show that the proposed method can lead to approximately 96% correct classification rates with less than 10% of the original features.     

Temperature-programmed desorption studies of methanol and formic acid decomposition on copper oxide surfaces

We have obtained temperature-programmed desorption data for methanol and formic acid adsorption on bulk powders of CuO and Cu₂O. Methanol adsorption on CuO at 300 K results in CO₂, H₂ and H₂O desorption at 550 K indicating formate decomposition; this decomposition temperature is very close to that obtained from the decomposition of formate produced by formic acid adsorption. No significant desorption was observed from vacuum-annealed Cu₂O following exposure to methanol due to the formation of a copper metal film at the surface. However, formic acid was adsorbed on this surface decomposing at significantly lower temperature, 485 K, than on CuO. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effect of utility time-varying pricing and load control strategies on residential summer peak electricity use: A review

Peak demand for electricity in North America is expected to grow, challenging electrical utilities to supply this demand in a cost-effective, reliable manner. Therefore, there is growing interest in strategies to reduce peak demand by eliminating electricity use, or shifting it to non-peak times. This strategy is commonly called “demand response”. In households, common strategies are time-varying pricing, which charge more for energy use on peak, or direct load control, which allows utilities to curtail certain loads during high demand periods. We reviewed recent North American studies of these strategies. The data suggest that the most effective strategy is a critical peak price (CPP) program with enabling technology to automatically curtail loads on event days. There is little evidence that this causes substantial hardship for occupants, particularly if they have input into which loads are controlled and how, and have an override option. In such cases, a peak load reduction of at least 30% is a reasonable expectation. It might be possible to attain such load reductions without enabling technology by focusing on household types more likely to respond, and providing them with excellent support. A simple time-of-use (TOU) program can only expect to realise on-peak reductions of 5%.     

Effects of electrical stimulation on early postmortem muscle pH and temperature declines in pigs from different genetic lines and halothane genotypes

The objective of this study was to determine if electrical stimulation (ES) early postmortem is an effective method to generate PSE-like meat. One hundred and thirty-eight gilts (85-125 kg) from heavy muscled (HM), normal muscled (NM), and light muscled (LM) porcine genetic lines were subjected to one of two treatments: ES (26 pulses of 500 V, 60 Hz) at 3 min postmortem or non-stimulated (NS). Pigs from HM line were further characterized as halothane (HAL) carriers (Nn) or non-carriers (NN). ES carcasses had lower (P<0.0001) pH values and higher (P<0.0001) temperature than NS carcasses during the first 56 min postmortem. ES carcasses had lower (P<0.0001) a*-values, and color and firmness scores, as well as higher (P<0.0001) drip loss and L*-values. No significant interactions were found between treatment and genetic line or HAL gene status with regard to pH, temperature, or quality characteristics. Temperature and pH declines within the first hour postmortem were not affected by genetic line, but slight (P<0.01) quality differences were observed. Nn and NN did not differ in pH or temperature within the first hour postmortem, but Nn carcasses had lower (P<0.01) color and firmness scores, and higher (P<0.05) drip loss. These results show that ES early postmortem is an effective method for simulating PSE development in pigs of different muscling and HAL gene status, and suggest that pH and temperature decline alone cannot explain all aspects of pork quality.