2008 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project is to develop prediction models using process kinetics fundamentals that describe the quality changes in meat products treated using hydrostatic pressure processing (HPP) and hydrodynamic pressure processing (HDP) systems. A computational modeling system will be useful to meat industry for predicting quality changes during high pressure processing of meats. 1b.Approach (from AD-416) A. Hydrostatic Pressure Processing Meat cuts, primarily beef loins obtained from meat packers and the animal science department at Virginia Tech, will be used for this project. Samples will be processed with high pressure processing at different pressure ranging from 70 MPa to 400 Mpa. High pressure processing system from Avure Technologies will be used to process the samples at various processing times, ranging from 10 seconds to 5 minutes. For each pressure-time combination, five different time intervals will be selected to obtain processed samples at various time intervals under the same pressure. This information is needed to generate the needed parameters in the quality kinetics models. B. Hydrodynamic Pressure Processing Samples will be processed with hydro-dyne unit or plastic explosive container (PEC) available at the USDA Beltsville facility. Samples will be treated with different charge levels and the pressure wave propagation will be monitored to study both the impact and after effects from the blast. The data obtained from both hydrostatic and hydrodynamic processing will be compared based on the energy input to the samples (pressure-time integrand). Quality Evaluation High pressure processed meat samples will be analyzed for color, tenderness (Warner-Bratzler shear force- WBS), texture profile (TPA), water holding capacity and flavor changes. Ultra-structural changes will be measured using scanning electron microscopy (SEM). Ultrasound and digital imaging will also be used to evaluate changes in texture and color, as a result of high pressure processing. The investigators will evaluate changes in color in the CIE L*a*b* color space using a CCD camera, and compare it to the values from the colorimeter. Textural changes can also be evaluated by both digital and ultrasonic imaging. Wavelet- and Fourier transform-based analysis will be performed for images obtained from ultrasound scans and the digital camera. These analysis techniques give abundant information on image texture. These textural values shall be correlated to readings from TPA, WBS scores, and SEM. In addition, ultrasound parameters such as velocity and time of flight shall also be used for developing correlation models. Computational Modeling For computational modeling on structural changes a finite element model will be developed using computational fluid dynamics modeling systems (FEMLAB). Prediction model(s) will be incorporated into computational modeling system to describe the changes in the meat products during high pressure processing. Finally, quality attributes results from selected process conditions will be compared with the model predictions. 3.Progress Report Hydrodynamic pressure has been considered as a new novel food processing technique to impart favorable textural changes in meat. Currently, very little work has been reported on the effect of HDP treatments on the quality of various meat products by means of mathematical modeling. We used three-dimensional finite-element-based, constitutive relationship model incorporating shockwave attenuation and elastic behavior to understand textural and structural changes on beef samples subjected to HDP treatment. The five independent elastic constants; Young’s Moduli in the longitudinal and transverse planes (Ep and Ez), Poisson’s ratios (Vp and Vzp), and shear modulus (Gzp) were used to characterize its response. The loin was modeled in a rough elliptical shape, with a major axis of 15 cm, a minor axis of 8 cm, and a thickness of 2.5 cm. The exerted pressure wave was assumed to be 800 MPa, only on one face of the sample and for simplicity purposes, no reflected wave was incorporated in the model. The Tamann equation of states (EOS) was used to describe the behavior of the pressure wave in an underwater media, through which propagating velocity of shockwave was determined, and other constitutive relationships were calculated. All modeling work was performed on FEMLAB 2.3. Results of our study indicated that only two constants were established out of the five constants for transverse-isotropic material. The constant values established were Ezp=6.5 kPa and Vzp=0.82. The value of shear-modulus calculated using the Tamann EOS yielded a value of 8400 MPa, exceeding the value of the incident pressure intensity. The research is in progress to ascertain all five independent transverse-isotropic constants and explore different EOS equations, namely Gruneisen EOS, to properly estimate bulk sound velocity and obtain realistic value for shear modulus. Optimization and sensitivity analysis will be performed upon estimation of all constants and these constants will be correlated to WBS shear and TPA textural features to establish a relationship between elastic behavior under HDP treatment to industrial standards. Monitoring activities included conference calls and site visits with the Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University at Blacksburg, VA.