Hydrodynamic Pressure Processing Research Articles

Applied and Emerging Methods for Meat Tenderization: A Comparative Perspective.

The tenderization process, which can be influenced by both pre- and post-slaughter interventions, begins immediately after an animal's death and is followed with the disruption of the muscle structure by endogenous proteolytic systems. The post-slaughter technological interventions like electrical stimulation, suspension methods, blade tenderization, tumbling, use of exogenous enzymes, and traditional aging are some of the methods currently employed by the meat industry for improving tenderness. Over the time, technological advancement resulted in development of several novel methods, for maximizing the tenderness, which are being projected as quick, economical, nonthermal, green, and energy-efficient technologies. Comparison of these advanced technological methods with the current applied industrial methods is necessary to understand the feasibility and benefits of the novel technology. This review discusses the benefits and advantages of different emerging tenderization techniques such as hydrodynamic-pressure processing, high-pressure processing, pulsed electric field, ultrasound, SmartStretch™ , Pi-Vac Elasto-Pack® system, and some of the current applied methods used in the meat industry.

Effect of electrohydraulic shockwave treatment on tenderness, muscle cathepsin and peptidase activities and microstructure of beef loin steaks from Holstein young bulls

Hydrodynamic pressure processing (HDP) or shockwave treatment improved tenderness (18% reduction in Warner–Bratzler shear force (WBSF) of beef loin steaks. Endogenous muscle proteolyic activities (cathepsins and peptidases) and protein fragmentation of sarcoplasmic and myofibrillar proteins detected by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) were not influenced by HDP. However, microstructure changes were clearly detected using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Specifically a disruption of the structure at the muscle fiber bundles and an increased endomysium space were observed. The present paper supports the evidence of physical disruption of the muscle fibers as a cause behind the tenderness improvement. The paper discusses the possible mechanisms responsible for the meat tenderisation induced by HDP treatment.

Chevon quality enhancement: Trends in pre- and post-slaughter techniques

Goat meat (chevon) consumption has increased in the US primarily due to the growing immigrant population. Chevon preference among mainstream consumers, however, has suffered from the misperception that it is inferior in quality to beef, lamb, or pork. Researchers have studied several pre- and post-slaughter techniques to enhance chevon quality. This paper will briefly review techniques that show promise to further improve quality characteristics of chevon. Among preslaughter factors, minimizing animal stress is an important step to quality chevon production, as stress can result in inferior meat quality characteristics. Diet can have a marked effect on nutritional properties of chevon, particularly fatty acid profile. Feeding goats a concentrate diet results in a higher level of oleic acid, but lower linolenic acid in the longissimus muscle, compared to feeding a hay diet. Dietary brown seaweed extract supplementation in goats results in increased color stability of chevon cuts because of higher antioxidant levels. Administration of a low dose of bovine somatotropin in goats does not influence meat quality characteristics or pre-rigor μ-calpain, m-calpain, and calpastatin activities. Several post-slaughter techniques have been studied and proven to be beneficial. It is well-established that aging chevon retail cuts significantly improves tenderness, and the caselife of chevon cuts is comparable to that of beef, lamb, and pork cuts. Postmortem electrical stimulation has been reported to significantly accelerate muscle glycolysis and improve tenderness of chevon. Subjecting deboned chevon cuts to hydrodynamic pressure processing or calcium chloride injections has been shown to significantly improve quality characteristics, particularly tenderness. With emerging markets for chevon in the US, there is a critical need for further research on pre- and post-slaughter techniques in goats to further improve product quality.

Microstructure alterations in beef intramuscular connective tissue caused by hydrodynamic pressure processing

Scanning electron microscopy (SEM) was utilized to evaluate microstructural changes in intramuscular connective tissue of beef semimembranosus muscle subjected to hydrodynamic pressure processing (HDP). Samples were HDP treated in a plastic container (HDP-PC) or a steel commercial unit (HDP-CU). Control and HDP samples were obtained immediately post-treatment and after 14days of aging for SEM and Warner–Bratzler shear force (WBSF) analysis. Immediately post-treatment, HDP treated samples exhibited lower (P<0.01) WBSF than did controls. After aging, HDP-PC samples had lower (P<0.01) WBSF than that of aged controls. SEM analysis indicated that HDP-PC treatment disrupted the integrity of the collagen fibril network of the endomysium in both the non-aged and aged samples. Aging effects on the intramuscular connective tissue were observed in the HDP-PC and control samples. Both WBSF and connective tissue changes were greater in the HDP-PC than in the HDP-CU treated samples. Data suggest that shockwave alterations to connective tissue contribute to the meat tenderization of HDP.

Alterations in the Sarcoplasmic Protein Fraction of Beef Muscle with Postmortem Aging and Hydrodynamic Pressure Processing

Capillary electrophoresis (CE) and reversed-phase high performance liquid chromatography (RP-HPLC) analyses were utilized to detect differences in the sarcoplasmic protein fractions of beef strip loins subjected to aging and hydrodynamic pressure processing (HDP) treatments. At 48 h postmortem, strip loins (n = 12) were halved and subjected to control or HDP treatments. Following treatment, each half was divided into 3 portions which were aged for 0, 5, and 8 d. After each aging period, steaks were removed for Warner-Bratzler shear force (WBSF) analysis and for the extraction of sarcoplasmic proteins which were analyzed by CE and RP-HPLC. Aging by HDP interactions were not detected using either separation technique. With CE analysis, no HDP effects were observed; however, the relative peak area of 8 protein peaks ranging in size from 17 to >200 kDa were influenced by postmortem aging. Separation of proteins by RP-HPLC demonstrated that HDP influenced the relative size of 2 protein peaks while postmortem aging effects were observed in 6 peaks. Alterations in the sarcoplasmic protein fractions detected by both CE and RP-HPLC were correlated to WBSF measurements. Overall, data demonstrate that HDP has minimal effects on sarcoplasmic proteins and that aging related changes in the water soluble protein fractions of muscle may be useful as indirect indicators of beef tenderness. Using 2 different postmortem tenderization techniques, aging and hydrodynamic pressure processing, this study demonstrates that postmortem changes in the soluble protein fraction of beef may be useful as potential indicators of meat tenderness.

Effects of hydrodynamic pressure processing on the marination and meat quality of turkey breasts

The effects of hydrodynamic pressure processing (HDP) on marination and meat quality characteristics of turkey breasts were investigated. Breast muscles from 45 turkey hens were removed from the carcasses within 30 min postmortem. From each bird, the breast from one side was treated with HDP and the other side served as a nontreated control. Breasts were then marinated in either 15 or 30% brine (water, salt, and phosphate) based on muscle weight with vacuum tumbling for 30 min or nonmarinated. The control and HDP-treated breasts from each bird received the same marination treatment. Brine uptake, processing yield, and cooking loss were measured as processing characteristics and texture, color, and expressible moisture were measured to document changes in meat quality. Hydrodynamic pressure processing increased (P < 0.001) brine uptake after 10 and 30 min of marination and increased (P < 0.001) processing yield compared with controls. The HDP-induced improvements in these processing characteristics were augmented at 30% brine levels compared with 15% brine. Cooking loss was lower (P < 0.001) in marinated breasts compared with nonmarinated samples. Hydrodynamic pressure processing decreased (P < 0.0001) Warner-Bratzler shear force and significantly influenced texture profile parameters, resulting in reduced hardness but increased cohesiveness and springiness compared with controls at both marination levels. Hydrodynamic pressure processing did not influence color (L*, a*, and b*) or expressible moisture values compared with controls at either marination level. Marinated samples (15 and 30% brine levels) had lower (P < 0.001) Warner-Bratzler shear force values and lower (P < 0.05) hardness, cohesiveness, and chewiness values compared with nonmarinated samples. Data from this study suggest that HDP enhances brine absorption, increases processing yield, and improves texture characteristics in marinated turkey breasts.

Effect of Hydrodynamic Pressure Processing on the Processing and Quality Characteristics of Moisture‐Enhanced Pork Loins

The objective of this study was to determine the influence of hydrodynamic pressure processing (HDP) and aging on the processing characteristics and final meat quality of moisture-enhanced pork loins. Boneless pork loins (n = 24) were split into 3 portions and assigned treatments: control (non-HDP treated, brine-injected), HDP treated before brine-injection, or HDP treated after brine-injection. Pork loins were injected with a salt/phosphate/water solution to 110% of original weight on day 0, intermittently tumbled 3 h, and then held overnight. Meat quality and protein characteristics were measured on days 1 and 8. HDP-treated loins had greater (P < 0.05) brine retention after overnight equilibration and a higher (P < 0.05) processing yield than controls. Warner-Bratzler shear force and expressible moisture decreased (P < 0.0001) with aging from days 1 to 8, but were not significantly affected by either HDP treatment. When the drip loss data from HDP treatments were pooled, HDP samples had lower drip loss values than controls. L* and b* measurements exhibited significant HDP by aging interaction effects, but a* was not influenced by either HDP or aging. Myofibrillar protein solubility and gel electrophoresis measurements of protein degradation were influenced by aging treatments. Data from this study suggest that HDP may have beneficial effects on the processing and final product quality of moisture-enhanced pork loins. This study demonstrates that hydrodynamic pressure processing (HDP) is an effective postharvest technology for improving the processing and meat quality characteristics of moisture-enhanced pork loin products, benefiting both meat processors and consumers.

EFFECT OF POSTMORTEM AGING AND HYDRODYNAMIC PRESSURE PROCESSING ON PORK LOIN QUALITY

ABSTRACT The objective of this study was to determine the influence of hydrodynamic pressure processing (HDP) and aging on the overall quality and protein characteristics of pork loins. Boneless pork loins (n = 12) were split into anterior and posterior halves and were assigned to control and HDP treatments. Following treatment on day 0, each half was divided into two portions (0 and 7 days aging). Samples were removed for the determination of Warner–Bratzler shear force (WBSF), centrifugal moisture loss (CML), gravitational drip loss (DL), color, protein solubility and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) analysis of whole muscle protein extracts. WBSF decreased with HDP (P &lt; 0.05) and aging treatments (P &lt; 0.0001). CML decreased (P &lt; 0.0001) with aging. Controls exhibited slightly less DL after 1 day than HDP samples, but the increase in DL between 1 and 7 days was similar for control and HDP samples. Treatment effects on L*, a* and b* measurements were minimal. Myofibrillar and total protein solubility were higher (P &lt; 0.01) in HDP samples compared with controls at day 0 but not at day 7. Sarcoplasmic protein solubility decreased (P &lt; 0.05) with aging. SDS‐PAGE analysis of muscle proteins demonstrated a strong aging effect and only minor HDP differences. With aging, bands corresponding to 30–33 and 135 kDa increased (P &lt; 0.0001), while bands corresponding to 38 and 95 kDa decreased (P &lt; 0.05) in intensity (relative to the actin band). The 60 kDa band intensity increased (P &lt; 0.05) with both aging and HDP treatments. Thus, data from this study suggest that HDP enhances aging tenderization in pork loins through the physical disruption of the muscle ultrastructure while having little detrimental effect on other parameters of pork quality.PRACTICAL APPLICATIONSThis study demonstrates that hydrodynamic pressure processing is an effective postharvest technology for enhancing aging tenderization in pork loins through the physical disruption of the muscle ultrastructure with minimal impacts on other pork quality parameters such as water‐holding capacity and color.

CONTROL OF LISTERIA MONOCYTOGENES ON FRANKFURTERS WITH ANTIMICROBIALS AND HYDRODYNAMIC PRESSURE PROCESSING*

ABSTRACT The antilisterial activity of sodium diacetate and pediocin (ALTA 2341) on frankfurters was evaluated in combination with hydrodynamic pressure processing (HDP). Minimum inhibitory concentration (MIC) of these strains as determined in tryptic soy broth was 0.4% and &gt;600 AU/mL, for sodium diacetate and ALTA 2341, respectively. Frankfurters were surface inoculated with a five‐strain mixture of Listeria monocytogenes after dipping in (1) control (sterile water); (2) 5% sodium diacetate; (3) 3% ALTA 2341(P1); (4) 6% ALTA 2341 (P2); (5) P1 + sodium diacetate; and (6) P2 + sodium diacetate for 5 min. The frankfurters were vacuum‐packaged and treated with hydrodynamic pressure or without HDP. Frankfurters were analyzed at 0, 7, 14 and 28 d for pH, L. monocytogenes (MOX) and aerobic (TSAYE) cell populations during storage at 4C. Antimicrobials and HDP treatment did not change (P &lt; 0.05) the frankfurter pH. HDP treatment significantly reduced (1 log10 cfu/g) L. monocytogenes populations in frankfurters. Dipping treatments containing sodium diacetate or ALTA 2341 did not significantly reduce L. monocytogenes in frankfurters. There was a no synergistic effect between ALTA 2341 and HDP for inhibition of L. monocytogenes. The reduction pattern in aerobic cell populations during storage of antimicrobials and HDP‐treated frankfurters was similar to that of L. monocytogenes reduction. These results indicate that the ALTA 2341 preparation was not efficient enough to kill L. monocytogenes. Other antimicrobials should be evaluated in conjunction with HDP treatment for synergistic inhibition of L. monocytogenes during storage at 4C.PRACTICAL APPLICATIONSSince the early 1980s, when Listeria monocytogenes was first recognized as an emerging food‐borne pathogen, numbers of outbreaks of human listeriosis have been reported. Many of these outbreaks are associated with processed meats. Because of the high mortality rate associated with listeriosis, a zero tolerance approach for L. monocytogenes in ready‐to‐eat meats and poultry products has been selected by many countries, including the U.S.A. We reported significant L. monocytogenes reduction in frankfurters using hydrodynamic pressure (HDP) treatment. HDP processing using a nonexplosive energy source can be used to reduce L. monocytogenes in frankfurters. While pediocin and organic acids used in our study reduce L. monocytogenes during storage, their practical use is not significant as the reduction is marginal. Other antimicrobials should be evaluated in conjunction with high‐pressure processing for required reduction of L. monocytogenes during storage at 4C.

EFFECT OF HYDRODYNAMIC PRESSURE PROCESSING AND AGING ON SARCOPLASMIC PROTEINS OF BEEF STRIP LOINS*

ABSTRACT This study evaluated the effects of hydrodynamic pressure processing (HDP) and aging on the sarcoplasmic proteins of beef strip loins. Loins (n = 12) were halved at 48 h postmortem and assigned to HDP or control treatments. Following treatment, each half was divided into three portions for aging (0, 5 or 8 d). Samples were removed for Warner‐Bratzler shear force (WBSF) determination and sarcoplasmic protein isolation. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) analysis demonstrated that aging significantly influenced the composition of the sarcoplasmic protein fraction and that HDP influenced protein bands corresponding to 143, 65, 44, 36 and 19 kDa. Changes in sarcoplasmic protein composition were significantly correlated to WBSF (r = −0.58 to 0.45). Sarcoplasmic protein solubility decreased with both HDP (P &lt; 0.05) and aging (P &lt; 0.0001). Changes in solubility were significantly correlated to SDS‐PAGE band intensities (r = −0.53 to 0.60). Data suggest that HDP and aging cause changes to sarcoplasmic proteins that may be indicators of proteolysis and tenderization.PRACTICAL APLICATIONSResults from this study demonstrate that postmortem aging and hydrodynamic pressure processing of beef influences the sarcoplasmic protein profile of the muscle. The relationships between these changes and Warner‐Bratzler shear force measurements suggest that sarcoplasmic protein changes may be potentially useful as tenderness indicators.

TENDERNESS IMPROVEMENT IN FRESH OR FROZEN/THAWED BEEF STEAKS TREATED WITH HYDRODYNAMIC PRESSURE PROCESSING*

ABSTRACT Tenderness improvement in fresh (F) or frozen/thawed (FT) beef steaks treated with hydrodynamic pressure processing (HDP) technology was examined. In Experiment 1, the effect of HDP and meat state at 48 h postmortem (fresh, never frozen compared to frozen at 48 h postmortem followed by thawing at 6 d postmortem) on meat tenderness at both day 1 and day 6 after HDP was evaluated. The effect of HDP was sustained throughout day 6 of aging.FT samples were 1 kg lower at day 1 compared to F samples and 0.8 kg lower at day 6. In Experiment 2, 40 boneless, rib‐eye sections (5 d postmortem) were used. One control steak was cooked fresh, while a second was frozen for 60 d. HDP was performed on the 40 F rib‐eye sections. Twenty of the HDP‐treated rib eyes were frozen after HDP treatment. The remaining 20 F HDP‐treated samples were cooked 24 h after treatment for tenderness determination. Sixty days after HDP treatment, the frozen control and HDP‐treated samples were thawed and cooked. Control (never frozen) steaks prior to HDP treatment had shear values of 6.5 kg. A 29% reduction in shear force was observed for HDP‐treated (F) samples. Freezing accounted for a 14% reduction in shear force. HDP treatment followed by freezing resulted in a 30% reduction in shear force compared to the frozen control samples.PRACTICAL APPLICATIONSPostmortem storage at refrigerated temperatures has been clearly demonstrated to improve meat tenderness. Freezing and then thawing meat has been shown to either improve tenderness, increase toughness or have no effect at all on meat tenderness. The use of hydrodynamic pressure processing (HDP) in conjunction with freezing meat either before or after HDP treatment was evaluated. Use of HDP, whether on fresh or frozen/thawed meat, successfully tenderized meat. Whether one freezes the meat before performing HDP or after HDP treatment, both successfully improve meat tenderness and the improvements are maintained even after frozen storage. Although freezing alone did show signs of improving meat tenderness, the magnitude of improvement was much less than the tenderness improvements found when using HDP technology.

EFFECT OF HYDRODYNAMIC PRESSURE PROCESSING AND AGING ON THE TENDERNESS AND MYOFIBRILLAR PROTEINS OF BEEF STRIP LOINS*

ABSTRACT This study evaluated the effects of hydrodynamic pressure (HDP) processing and aging on the tenderness and myofibrillar proteins of beef strip loins. Loins (n = 12) were halved at 48 h postmortem and assigned to HDP or control treatments. Following treatment, each half was divided into three portions for aging (0, 5 or 8 days). Samples were removed for Warner–Bratzler shear force (WBSF) determination and myofibrillar protein isolation. HDP decreased (P &lt; 0.0001) WBSF values 23% at 0, 5 and 8 days of aging. Myofibrillar fragmentation and myofibrillar protein solubility increased (P &lt; 0.01) with HDP and aging. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and Western blotting analysis of myofibrillar proteins showed that HDP and aging decreased the intensity of the troponin T (TnT) band and enhanced the accumulation of the 30 kD TnT degradation product. These data suggest that HDP is more effective than aging tenderization, and that HDP tenderization is caused by both protein degradation and physical disruption of the myofibril apparatus.PRACTICAL APPLICATIONSHydrodynamic pressure (HDP) processing was shown to instantaneously tenderize tough cuts of beef to tenderness levels attained following 8 days of postmortem aging. For the meat industry, these results demonstrate the potential benefits of alternative tenderization techniques, such as high‐energy shock waves. Observed changes in protein characteristics due to HDP and aging allow researchers to understand better potential mechanisms of meat tenderization.

EFFECTS OF HYDRODYNAMIC PRESSURE PROCESSING AND BLADE TENDERIZATION ON INTRAMUSCULAR COLLAGEN AND TENDERNESS‐RELATED PROTEIN CHARACTERISTICS OF TOP ROUNDS FROM BRAHMAN CATTLE*

ABSTRACT This study evaluated the effects of blade tenderization (BT), hydrodynamic pressure processing (HDP) and BT followed by HDP (BT + HDP) on collagen solubility and tenderness‐related protein characteristics in top rounds from Brahman cattle. Top rounds (n = 12) were divided in half and randomly assigned to HDP, BT or BT + HDP with each treatment sample having a paired control. HDP and BT + HDP increased (P &lt; 0.0001) collagen solubility, but the correlation between percent soluble collagen and tenderness was low (r = –0.41). All three treatments increased (P &lt; 0.01) fragmentation of myofibrils 35% compared with controls. HDP and BT + HDP treatments increased (P &lt; 0.05) the content of a 100 to 110‐kDa protein observed in myofibrillar protein fractions by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Minimal treatment differences were observed in sarcoplasmic proteins using SDS‐PAGE. Results suggest BT physically disrupts the muscle structure to improve tenderness while HDP tenderization potentially results from both physical disruption of the muscle structure and some form of direct alterations to muscle proteins.

COMBINING ANTIMICROBIALS AND HYDRODYNAMIC PRESSURE PROCESSING FOR CONTROL OF LISTERIA MONOCYTOGENES IN FRANKFURTERS*

ABSTRACT The safety of ready‐to‐eat meat products such as frankfurters can be enhanced by antimicrobials and postpackaging treatment to control the growth of Listeria monocytogenes. We evaluated the effectiveness of dipping frankfurters in sodium lactate (SL), sodium diacetate (SD) and nisin (N) solutions, followed by hydrodynamic pressure processing (HDP), to control L. monocytogenes during storage at 4C for 28 days. Frankfurters were surface inoculated with a five‐strain mixture of L. monocytogenes after dipping in (1) control (sterile water), (2) 10% SL, (3) 5% SD, (4) SL + SD, (5) N (5000 IU/mL), (6) N + SL, (7) N + SD and (8) N + SL + SD for 5 min. The frankfurters were vacuum packed and were either treated with or without hydrodynamic pressure. The frankfurters were periodically analyzed for populations of L. monocytogenes on modified Oxford agar, aerobic cell populations on tryptic soy agar with 0.6% yeast extract and pH on days 0, 7, 14 and 28. HDP treatment significantly reduced L. monocytogenes populations in frankfurters. Dipping treatments containing N showed greater L. monocytogenes reduction than that with SL and/or SD treatment; however, the difference was not significant. The combination of N and HDP treatment resulted in more than 2 log cfu/g reduction in L. monocytogenes populations after 28‐days storage. A synergistic effect between N and HDP was observed for inhibition of L. monocytogenes. The reduction in aerobic cell populations during storage of antimicrobials and HDP‐treated frankfurters was similar to that of L. monocytogenes. These results indicate that using N as a dipping treatment followed by HDP treatment is more effective for inhibition of the pathogen during storage at 4C.PRACTICAL APPLICATIONSHydrodynamic pressure processing, an innovative post‐harvest technology for meat tenderization, uses a high‐energy explosive to generate a supersonic shock wave in a liquid medium. HDP treatment, primarily studied for tenderness improvement in muscle food products, has been effective in reducing bacterial populations in meats. Nisin has greater antilisterial activity than sodium lactate or sodium diacetate. Dipping frankfurters in nisin followed by the hydrodynamic pressure treatment could be used to reduce 2 log L. monocytogenes populations in frankfurters during storage at 4C.

Effect of hydrodynamic pressure processing on the survival of Escherichia coli O157:H7 in ground beef

Hydrodynamic pressure processing (HDP), a novel non-thermal technology that uses a small amount of explosive (100 g) to generate a supersonic–hydrodynamic shock wave in a water filled steel container (54 L) was evaluated for inactivation of Escherichia coli O157:H7 (EHEC) in ground beef. The ground beef was inoculated with a six strain cocktail of E. coli O157:H7 at three different concentrations (10 3, l0 4 and l0 6 CFU/g). The following strains of E. coli O157:H7 were used in the cocktail: 3027-93, 3055-93, C7927, 43888, C9490, and green fluorescent protein-expressing E. coli O157:H7 B6-914 (GFP EC). Inoculated ground beef was wrapped in polyethylene wrap, vacuum packaged into multilayer barrier bags, heat shrunk and treated with HDP. The initial concentrations of EHEC were 1.29 × 10 3, 2.88 × 10 4, and 2.19 × l0 6 CFU/g. After HDP treatment, the EHEC populations were reduced ( P < 0.05) to 9.12 × 10 2, 2.40 × 10 4, and 1.91 × l0 6 CFU/g, respectively. A similar trend was observed for GFP EC which was also enumerated from the cocktail. The GFP EC initial populations of 4.26 × l0 2 and 3.72 × l0 3 CFU/g were reduced to 3.47 × 10 2, and 3.09 × l0 3 CFU/g, respectively. Although the reduction in EHEC populations due to HDP treatment was statistically significant, the practicability of the reduction was marginal. Therefore, other hurdle parameters should be included along with the HDP treatment for more practical inactivation of EHEC in ground beef. Hydrodynamic pressure processing has been applied for many unique applications including braking of ice sheets. The authors have originally developed the method of utilizing shock waves caused by explosives for tenderization of meat and are now attempting to extend the process towards microbial inactivation. The data suggest that the treatment applied only slightly reduced the population of E. coli 0157:H7 tested and suggest to modify the process including the use of extended shock waves as well as the combination with antimicrobial agents.

USE OF HYDRODYNAMIC PRESSURE PROCESSING AND BLADE TENDERIZATION TO TENDERIZE TOP ROUNDS FROM BRAHMAN CATTLE†

ABSTRACT Tenderization effects of hydrodynamic pressure processing (HDP), blade tenderization (BT) and a combination of BT followed by HDP (BT + HDP) were evaluated with 12 top rounds from Brahman cattle selected for toughness. Warner–Bratzler shear testing was performed on the day of treatment (D0) and after storage (D7). On D0, BT and HDP increased tenderness by 18% and BT + HDP yielded a 14% improvement over control steaks. Tenderness increased (P &lt; 0.05) for HDP and BT + HDP treatment between D0 and D7, whereas tenderness did not change for BT treatment. Control samples increased (P &lt; 0.05) in tenderness because of aging alone (20% improvement). Overall tenderness improvements for BT + HDP and HDP (D7) versus control (D0) were 37 and 29%, respectively. BT provided instant tenderization but without additional improvement during aging. HDP and BT + HDP resulted in instantaneous tenderization that also increased over time and provided the greatest amount of overall improvement in tenderness.

Reduction of Spoilage Microorganisms in Fresh Beef Using Hydrodynamic Pressure Processing

Hydrodynamic pressure processing (HDP) was investigated as a technology to reduce spoilage microorganisms found in fresh beef. In two separate studies (studies 1 and 2), retail ground beef and beef roasts were purchased (day 0). The roasts were divided into stew pieces (30 to 40 g). All meat samples, including control samples, were stored at 5°C for 20 h in a plastic film. After storage, designated samples were treated with HDP. In study 3, ground beef was treated with HDP (day 0) and stored aerobically (5°C) for 14 days with control samples. Each meat type was vacuum-packaged for HDP (100 g binary explosive, steel shock wave container). The pHs and the aerobic plate counts (log10 CFU/g) were measured on day 0 (studies 1 and 2) and on days 0, 7, and 14 (study 3) for control samples and for HDP-treated samples. There was no pH difference between control and HDP-treated meat types (studies 1 and 2); HDP reduced bacteria in both meat types in study 1 (2 log) and study 2 (1.5 log) on day 0. In study 3, there was a significant difference (P < 0.05) in pH between control meat (8.2) and HDP-treated meat (5.6) after storage. There was an immediate reduction (1.5 log) of microorganisms following HDP (day 0) and a 4.5-log difference between control samples (9 log) and HDP-treated samples (4.5) after 14 days of storage. With HDP, it is possible to reduce spoilage microorganisms found in or on different meat types (ground beef versus stew pieces), which could extend the shelf life of meat products.