Use Of High Pressure Processing Research Articles

Use of high-pressure processing and low-temperature storage to extend the performance shelf-life of two types of String cheese

The manufacturing method of String cheese is similar to Mozzarella, but the hot curd is extruded through narrow tubes or pipes, which align the protein fibers that provides the characteristic ability for consumers to pull strings from this cheese. Firmness is another important performance attribute for consumers who just bite into the String cheese without peeling off strings. There have only been a few studies on String cheese, but it is known that stringiness and firmness decrease during prolonged storage, which is a particular challenge for exporting String cheese. We explored 2 treatments to try to retain the stringiness and firmness of String cheese for longer storage periods. The techniques used were high pressure processing (HPP; 600 MPa for 3 min) and reduced storage temperature (0°C). In other cheese varieties, these techniques have helped extend the performance shelf-life. We tested these techniques using the 2 main types of commercial String cheese: direct acid (DASC) and cultured String cheese (CSC), that were obtained from 2 different manufacturing facilities. The DASC had higher fat (∼2.2%) and higher pH values (∼0.2 units) compared with the CSC. The CSC had higher protein content (∼3.4%), higher insoluble calcium content (∼8 mg insoluble Ca/g protein) and higher hardness values (∼4 N) compared with the DASC. Due to the compositional differences, the 2 varieties were statistically analyzed separately for all other attributes. In both cheese types, HPP caused an immediate reduction in stringiness, some solubilization of insoluble calcium, and a slight increase in the cheese pH values. HPP also caused a slight increase in the TPA hardness of the CSC samples until 14 d (possibly due to a slight increase in cheese pH). The use of the 0°C storage temperature reduced proteolysis and helped retain firmness during storage. Low temperature storage could help extend the performance shelf-life of String cheese by a couple of months, but HPP was not suitable as the process caused an immediate reduction in stringiness due to the disruption of the matrix induced by the HPP treatment.

Impact of High Pressure Processing on the Safety and Quality of Food Products: A Review.

High pressure processing (HPP) has become a practical food processing technique that meets the preferences of consumers seeking lightly processed, convenient, and fresh-tasting food options. This paper reviewed the latest research on the impact HPP on the safety and quality of food products. The use of HPP has been showing favorable growth in the food industry primarily due to its potential to not only enhance the nutritional content and sensory attributes of food products but also to substantially extend their shelf-life and bolster safety standards. HPP is the most used among non-thermal food processing technologies. While its direct application to milk for consumption falls short of delivering consistent quality, it proves effective as a pretreatment step and in products using milk as a primary ingredient. In the context of meat production, HPP reduces microbial loads and extends shelf-life, yet concerns persist regarding its impact on product quality. The absence of in-depth studies regarding the attributes of carrots that support pathogen regeneration emphasizes the need for comprehensive research in this area, which could have far-reaching implications for similar fruit and vegetable products. This review underscores the need for a balanced assessment of HPP's effects on food safety and quality, offering insights that can guide the food industry in adopting this technology while ensuring consumer satisfaction and safety.

Use of high pressure processing in combination with acidic electrolyzed water depuration for the shelf-life extension of blood clam (Tegillarca granosa)

Use of high pressure processing in combination with acidic electrolyzed water depuration for the shelf-life extension of blood clam (Tegillarca granosa)

Pilot Scale Assessment of High-Pressure Processing (HPP) to Enhance Microbiological Quality and Shelf Life of Fresh Ready-to-Eat (RTE) Blue Crab Meat.

Blue crab (Callinectes sapidus) is a highly valuable wild fishery species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico. The annual commercial production of live blue crabs is approximately 50,000 metric tons with a dockside value of USD 200 million. Presently the US blue crab processing industry sells crab meat in three basic forms: fresh crab meat, pasteurized crab meat, and frozen crab meat. By far "Fresh" is the most desirable form of crab meat. However, fresh crab meat has a limited shelf life. This study evaluated the effects of high-pressure processing (HPP) on enhancing the microbiological quality and shelf life of blue crab meat. Live blue crabs were pressure-cooked in a retort (≥115 °C for 4-6 min). The crab meat was handpicked, packed in plastic containers with seals, subjected to HPP treatment, and stored at 4 °C. Container integrity and water leakage issues were examined by observation in addition to weight comparison before and after HPP treatment; the shelf life of crab meat with and without HPP treatments was examined via microbiological tests and sensory evaluations. Results show that polypropylene containers sealed with 10K OTR (oxygen transmission rate) film could withstand high pressure without water leakage issues; HPP treatment at 600 MPa for 3 min could extend the shelf life of fresh, cooked, and handpicked crab meat from 6 days to 18 days based on the strictest APC (aerobic plate account) limit (APC ≤ 100,000 CFU/g). The sensory quality of the HPP-treated crab meat was well accepted throughout the 3-week storage period. The results support the use of HPP as an effective non-thermal processing technology to enhance the microbiological quality and extend the shelf life of fresh RTE blue crab meat.

High-Pressure Processing Helps Meet the Escherichia coli O157:H7 and Shiga Toxin–Producing E. coli (STEC) Performance Standards for Beef Summer Sausage

The United States Department of Agriculture–Food Safety Inspection Service (USDA-FSIS) performance standards require that manufacturers of fermented beef sausages validate their processes to achieve a 5-log reduction of Escherichia coli O157:H7 and Shiga toxin–producing E. coli (STEC). Most processors rely on rapid fermentation to a low pH and a mild heat treatment to achieve the lethality performance standard. However, this process alters the sensorial characteristics of traditional fermented sausages. An alternative method to achieve lethality using high-pressure processing (HPP) during the manufacture of summer sausage with higher pH (5.0) and minimal heat treatment was evaluated. Sausages inoculated with circa 9.1 log CFU/g of E. coli O157:H7 and 8.9 log CFU/g of STEC were fermented to target pH values of 4.6 or 5.0. Subsequently, fermented sausages were heated to endpoint temperatures of 54.4°C, 48.9°C, or 43.3°C to the total process treatments of (1) Process A: pH 4.6 and 54.4°C, simulated cold air chilling, (2) Process B: pH 5.0 and 54.4°C, simulated cold air chilling, (3) Process C: pH 5.0 and 54.4°C, ice bath chilling, (4) Process D: pH 5.0 and 48.9°C, ice bath chilling, and (5) Process E: pH 5.0 and 43.3°C, ice bath chilling. After processing, the product was subjected to HPP (586 MPa; 4°C±2°C) for hold times of 1, 150, or 300 s and a nontreated (no HPP) control. All treatments subjected to HPP for 150 and 300 s reduced (P≤0.05) E. coli (O157:H7 and STEC) populations by>5.0 log CFU/g and >7.5 logCFU/g, respectively. The use of HPP allows for the production of more mild beef summer sausage (pH 5.0 and a mild thermal treatment of 43.3°C) while still achieving USDA-FSIS performance standards for lethality.

Effect of high pressure processing and water activity on pressure resistant spoilage lactic acid bacteria (Latilactobacillus sakei) in a ready-to-eat meat emulsion model

The main use of High Pressure Processing (HPP) in food processing is microorganism inactivation, and studies demonstrated that the characteristics of matrix and microorganisms can interfere on it. As the behavior of lactic acid bacteria exposed to different water activity (aw) levels in a meat product is still unclear, this study aimed to determine the effect of pressure, time, and aw to inactivate Latilactobacillus sakei, a pressure resistant lactic acid bacteria (LAB) in a meat emulsion model through a response surface methodology. The meat emulsion model was designed with adjusted aw (from 0.940 to 0.960) and was inoculated with a pressure resistant LAB and processed varying pressure (400-600 MPa) and time (180–480 s), following the Central Composite Rotational Design (CCRD). The inactivation of the microorganism ranged from 0.99 to 4.12 UFC/g depending on the applied condition. At studied conditions, according to the best fitting and most significant polynomial equation (R2 of 89.73 %), in a meat emulsion model, aw had no influenced on HPP inactivation on LAB (p > 0.05) and only pressure and holding time had significative impact on it. The results of experimental validation of the mathematical model were satisfactory, confirming the suitability of the model. The information obtained in the present study stands out the matrix, microorganism and process effects at HPP efficiency. The answers obtained support food processors in product development, process optimization and food waste reduction.

Use of High-Pressure Processing to Improve the Redness of Dark-Cutting Beef

The objective was to evaluate the effects of high-pressure processing (HPP) levels on retail color of dark-cutting beef. Eight USDA Choice (mean pH=5.5; normal-pH beef) and 12 dark-cutting (mean pH=6.3) strip loins were obtained from a commercial packing plant within 2 d of harvest. Dark-cutting loins were cut into equal sections, vacuum packaged,and randomly assigned to 0 (no HPP), 300, 450, and 600 MPa of pressure for 90 s using chilled water. Following 48 h of dark storage at 2°C, dark-cutting loin sections were cut into 1.9-cm-thick steaks, placed in Styrofoam trays overwrapped in polyvinyl chloride (PVC) film, and placed in a simulated retail display for 8 d. The surface color readings were measured every 24 h using a HunterLab MiniScan XE Plus spectrophotometer, whereas a trained color panel (n=6) evaluated dis-coloration, paleness, and lean color on steaks. Lipid oxidation was evaluated on day 0, 4, and 8 of retail display, and structural changes were determined using light microscopy on day 0 of display. There was a significant HPP level×day of retail display interaction for all instrumental color measurements. Throughout the retail display, L* values of 450 and 600 MPa applied steaks were greater (P<0.05) than 300 MPa and controls. There was a significant pressure level×day of retail display interaction when panelists evaluated lean color and discoloration. Steaks treated at 300 MPa exhibited brighter red color and lower (P=0.0023) thiobarbituric acid reactive substance values than other pressure levels and normal-pH control steaks. Light microscopy analysis indicated that HPP increased space between muscle structures. In conclusion, low (300 MPa) and moderate (450 MPa) pressure levels can improve redness of dark-cutting steaks.

High pressure processing at the early stages of ripening enhances the safety and quality of dry fermented sausages elaborated with or without starter culture

To study the quality of chorizo de León dry fermented sausages (DFS), high pressure processing (HPP) applied at the early stages of ripening and the use of a functional starter culture were evaluated as additional safety measures. Furthermore, the ability to control the populations of artificially inoculated Listeria monocytogenes and Salmonella Typhimurium was investigated and the evolution of microbial communities was assessed by amplicon 16S rRNA metataxonomics. The use of HPP and the starter culture, independently or combined, induced a reduction of Listeria monocytogenes of 1.5, 4.3 and > 4.8 log CFU/g respectively, as compared to control. Salmonella Typhimurium counts were under the detection limit (<1 log) in all treated end-product samples. Both additional measures reduced the activity of undesirable microbiota, such as Serratia and Brochothrix, during the production of DFS. Moreover, the starter culture highly influencedthe taxonomic profile of samples.No adverse sensory effects were observed, and panelists showed preference for HPP treated DFS. In conclusion, this new approach of applying HPP at the early stages of ripening of DFS in combination with the use of a defined starter culture improved the safety and quality of the meat product.

Application of High Pressure Processing on Ultrasonically Treated Extract from Wild Bitter Gourd

Wild bitter gourd extracts, such as saponins, polysaccharides, and peptides, could be used to adjust blood sugar. The objective of this research was to explore the use of high pressure processing (HPP) for sterilization and acceleration of enzyme hydrolysis in the ultrasonic preparation of peptide extracts from wild bitter gourd. The results showed that the wild bitter gourd powder could be extracted via ultrasonic processing with water at 70 °C for only 20 min with a solid to liquid ratio of 1:20 to obtain the total protein content of 1.514 mg/g. The two sterilization methods for wild bitter gourd extract treated with papaya enzyme—for 2 h in the traditional autoclave at 121 °C for 15 min, or under HPP 300 MPa for 5 min—showed no significant effect on protein content, and both sterilization methods were effective. However, the extract sterilized with HPP had a significantly higher ability to scavenge DPPH free radicals. In addition, HPP (300 MPa for 5 min), combined with papaya enzyme to hydrolyze the wild bitter gourd extract, simultaneously pasteurized the extract and acquired the peptides from the wild bitter gourd extract Therefore, the ultrasonic extraction of wild bitter gourd, combined with HPP and enzyme hydrolysis, could greatly shorten the operation time (to only 5 min) for extracting the active peptides.

High-pressure processing of fish and shellfish products: Safety, quality, and research prospects.

Seafood products have been one of the main drivers behind the popularity of high-pressure processing (HPP) in the food industry owing to a high demand for fresh ready-to-eat seafood products and food safety. This review provides an overview of the advanced knowledge available on the use of HPP for production of wholesome and highly nutritive clean label fish and shellfish products. Out of 653 explored items, 65 articles published during 2016-2021 were used. Analysis of the literature showed that most of the earlier work evaluated the HPP effect on physicochemical and sensorial properties, and limited information is available on nutritional aspects. HPP has several applications in the seafood industry. Application of HPP (400-600 MPa) eliminates common seafood pathogens, such as Vibrio and Listeria spp., and slows the growth of spoilage microorganisms. Use of cold water as a pressure medium induces minimal changes in sensory and nutritional properties and helps in the development of clean label seafood products. This technology (200-350 MPa) is also useful to shuck oysters, lobsters, crabs, mussels, clams, and scallops to increase recovery of the edible meat. High-pressure helps to preserve organoleptic and functional properties for an extended time during refrigerated storage. Overall, HPP helps seafood manufacturers to maintain a balance between safety, quality, processing efficiency, and regulatory compliance. Further research is required to understand the mechanisms of pressure-induced modifications and clean label strategies to minimize these modifications.

High-Pressure Processing for Sustainable Food Supply

Sustainable food supply has gained considerable consumer concern due to the high percentage of spoilage microorganisms. Food industries need to expand advanced technologies that can maintain the nutritive content of foods, enhance the bio-availability of bioactive compounds, provide environmental and economic sustainability, and fulfill consumers’ requirements of sensory characteristics. Heat treatment negatively affects food samples’ nutritional and sensory properties as bioactives are sensitive to high-temperature processing. The need arises for non-thermal processes to reduce food losses, and sustainable developments in preservation, nutritional security, and food safety are crucial parameters for the upcoming era. Non-thermal processes have been successfully approved because they increase food quality, reduce water utilization, decrease emissions, improve energy efficiency, assure clean labeling, and utilize by-products from waste food. These processes include pulsed electric field (PEF), sonication, high-pressure processing (HPP), cold plasma, and pulsed light. This review describes the use of HPP in various processes for sustainable food processing. The influence of this technique on microbial, physicochemical, and nutritional properties of foods for sustainable food supply is discussed. This approach also emphasizes the limitations of this emerging technique. HPP has been successfully analyzed to meet the global requirements. A limited global food source must have a balanced approach to the raw content, water, energy, and nutrient content. HPP showed positive results in reducing microbial spoilage and, at the same time, retains the nutritional value. HPP technology meets the essential requirements for sustainable and clean labeled food production. It requires limited resources to produce nutritionally suitable foods for consumers’ health.

Xylooligosaccharides and their chemical stability under high-pressure processing combined with heat treatment

Xylooligosaccharides (XOS) are emerging prebiotic ingredients used for enriching food products due to their health-promoting properties. This study investigated XOS chemical stability after high-pressure processing (HPP) combined with heat treatment. First, orange juice was enriched with XOS (xylobiose, xylotriose, xylotetraose, xylopentaose, and xylohexaose), and then HPP-treated at 100, 300, and 600 MPa applying non-thermal (30 °C) and thermal (100 °C) conditions. Ascorbic acid (vitamin C) degradation was monitored to evaluate the extend of the severity of the treatments due to its low stability under high-energy process conditions. Also, quality attributes associated with fruit juices such as physicochemical properties (pH, soluble solid content, and ζ-potential), organic acid content (malic and citric acids), total phenolic content, antioxidant activity, and sugar content (glucose, fructose, and sucrose) were determined. The use of HPP combined with heat treatment degraded ascorbic acid up to 37% and promoted sucrose hydrolysis into glucose and fructose. However, our findings demonstrated that the XOS were chemically stable to HPP in the range of 100–600 MPa even applying thermal treatment. Therefore, XOS are promising ingredients for the formulation of functional plant-based beverages since their integrity was preserved under high mechanical and thermal stress conditions of 600 MPa and 100 °C.

High pressure processing pretreatment of Chinese mitten crab (Eriocheir sinensis) for quality attributes assessment

The present study evaluated high pressure processing (HPP) pretreatment effects on the quality attributes of Chinese mitten crab (Eriocheir sinensis). Process parameters were optimized (300 MPa for 5 min) and the effects of HPP pretreatment on the total edible part of Eriocheir sinensis were investigated. The results showed that steamed loss has no significant difference and water holding capacity of inner meat was increased by approximately 51.33% with HPP pretreatment. HPP pretreatment can also decrease hardness value of crab carapace and preserve texture properties of crab leg meat. Compared with raw inner meat, results of DSC analysis of inner meat with HPP pretreatment has revealed that the denaturation temperature and the enthalpy of protein were decreased remarkably. The results of water distribution indicated that HPP pretreatment reduced the loss of entrapped water in inner meat. Finally, compare with the conventional steamed crabs, it has been detected that the aroma of the edible viscera of crabs has a significant difference with HPP pretreatment. Above findings indicated that HPP pretreatment retains quality attributes of Eriocheir sinensis well, in the meantime improves the processing efficiency since steaming time can be reduced by applying HPP pretreatment. Industrial relevanceHPP is a novel non-thermal technique widely used in the field of food production. Compared with conventional thermal processing, it is important for assessing the impact of HPP pretreatment on the quality attributes of crab in order to obtain high-quality products. According to recent studies, HPP pretreatment has been confirmed to be able to improve the quality of hot processed crabs. By applying 300 MPa for 5 min on Eriocheir sinensis, the total edible part was improved, and the water holding capacity of crab inner flesh was increased. Moreover, HPP pretreatment can also decrease hardness value of crab carapace and preserve sensorial properties of crab leg meat. These results indicated HPP pretreatment retains high quality characteristics of Eriocheir sinensis and reduces steaming time by which means the processing efficiency can be improved. This work provided further support for the use of HPP in Eriocheir sinensis.

Processing of chestnut rose juice using three-stage ultra-filtration combined with high pressure processing

This work evaluated the effect of three-stage ultra-filtration (100 kDa, 5 kDa, and 5 kDa) and high pressure processing (HPP) on the quality of chestnut rose juice since a single processing technology could not make full use of the functional ingredients of juice. The 100 kDa membrane performed preliminary filtration, and the 5 kDa membrane performed SOD retention in the processing. The juice with high superoxide dismutase (SOD) activity was obtained after three-stage ultra-filtration and HPP. The SOD exhibiting higher antioxidant capacity was effectively recovered by 5 kDa membranes and its activity was 27748.44 U/mL. The technology could retain sugars [glucose (92.31%), arabinose (86.73%), and galactose (85.91%)], tartaric acid (82.35%) and total flavonoids (84.19%) of the juice. But the significant reduction of myricetin (73.24%), catechin (70.11%), quercetin (72.77%), and kaempferol (71.54%) in juice was observed. The total aerobic bacteria of high SOD juice remain stable after 60 days of storage at 4 °C. In general, the combined use of HPP and ultra-filtration has proven to be a potential technology for producing high SOD chest rose juice.

Effects of combined application of high‐pressure processing and active coatings on phenolic compounds and microbiological and physicochemical quality of apple cubes

In recent years the use of high-pressure processing (HPP) of fruit products has steadily increased due to its antimicrobial effectiveness and the retention of nutritional and quality attributes compared to conventional thermal technologies. Edible coatings are already being used to enhance the quality of minimally processed fruits. Thus, apple cubes (AC) and alginate-vanillin-coated apple cubes (AVAC) were subjected to HPP (400 MPa/5min/35 °C). The microbiological and physicochemical parameters were evaluated and the bioactive compounds were monitored before and after HPP of apple cubes. Also, an in vitro gastrointestinal digestion (GID) was conducted. HPP left L. monocytogenes counts below the detection limit (2log UFC g-1 ), regardless of the presence of coating. For E. coli, HPP + active coating showed a synergism affording the greatest reduction (>5log) for AVAC-HPP. Firmness was maintained in AVAC-HPP samples, while AC-HPP samples suffered reductions of 35%. Colour attributes were also better retained in AVAC-HPP samples. In general, HPP led to a decrease in phenolic compounds. Regarding the effects of GID, vanillin-based active coating exerted a protective effect on some phenolics. Thus, p-coumaroylquinic acid concentration was maintained for AVAC and AVAC-HPP during GID. Epigallocatechin, the compound with the highest concentration in apple cubes, increased for AVAC (106%) and AVAC-HPP (57%). Also, phloridzin concentration increased for AVAC-HPP (17%). At the end of GID, procyanidin B1 and epigallocatechin were the main phenolic compounds for all samples, AVAC showing the highest concentration. This work demonstrates that the combined application of HPP and active coatings on apple cubes could be used to obtain a safe and good-quality product. © 2021 Society of Chemical Industry.

Extending shelf life of desalted cod by high pressure processing

Salted fish need to be rehydrated before eaten, but rehydrated fish have a relatively short shelf life. To increase the shelf life the products can e.g. be frozen, packed in modified atmosphere or processed by high pressure (HPP). Here, rehydrated cod was packed with different packaging regimes; in vacuum, with CO2 emitter or in modified atmosphere [MAP], either alone or in combination with HPP. A shelf life study was performed, and headspace gas composition, drip loss, pH, colour, texture and microbial counts were assessed in the packaged and processed portions. The results showed that a shelf life of minimum 49 days can be obtained by treating the rehydrated cod by HPP or by combining HPP with modified atmosphere or in combination with a CO2 emitter. The results of this study have shown that different packaging and processing methods can increase the shelf life of desalted cod. Industrial relevanceThe growing trend and availability of “ready to cook” products are forcing the food industry to increase production of convenience products. Today desalted saltfish or clipfish need to be consumed immediately, stored chilled for a few days, stored frozen or being packed and/or processed to extend its shelf life. The use of high pressure processing represents a promising strategy to enhance the shelf-life of fish products. This study shows that HPP alone or combined with CO2 can extend the shelf life of rehydrated cod. Hence, these results can open up for new products.

Use of high-pressure processing (HPP) as an alternative method to standard raw milk processing

Use of high-pressure processing (HPP) as an alternative method to standard raw milk processing

The use of High-Pressure Processing (HPP) to improve the safety and quality of raw coconut (Cocos nucifera L) water

This research investigated the use of high-pressure processing (HPP) for inactivating vegetative pathogens and spoilage microbiota in fresh unfiltered coconut water (Cocos nucifera L) from nuts obtained from Florida and frozen CW from Brazil with pH >5.0 and storage at 4 °C. Additionally, CW was evaluated to determine if it supported the growth and toxin production of Clostridium botulinum with or without the use of HPP when stored at refrigeration temperatures. Samples of fresh unfiltered CW were inoculated to 5.5 to 6.5 logs/mL with multiple strain cocktails of E. coli O157:H7, Salmonella spp. and Listeria monocytogenes and HPP at 593 MPa for 3 min at 4 °C. HPP and inoculated non-HPP controls were stored at 4 °C for 54 and 75 days for Florida CW and Brazil CW, respectively. Results of analyses showed HPP samples with <1 CFU/mL and no detection (negative/25 mL) with enrichment procedures for the 3 inoculated pathogens for all analyses. The non-HPP control samples did not show growth of the pathogens but a gradual decrease in levels to ca. 3-Logs/mL by day 54 in the fresh Florida CW and similarly in frozen Brazil CW by Day 75. Microbial spoilage of uninoculated samples was evaluated for normal spoilage microbiota through 120 days storage at 4 °C. Microbial counts remained at ca. 2-logs with no detectable signs of spoilage for HPP samples through 120 d. The non-HPP control samples spoiled within 2 weeks of storage at 4 °C with gas production, cloudiness, and off-odors. To evaluate if CW supports the growth and toxin production of C. botulinum, samples of unfiltered and filtered (0.2 μm) CW were inoculated with either proteolytic or non-proteolytic C. botulinum spores at 2 log CFU/mL that were processed at 593 MPa for 3 min and stored at 4 °C and 10 °C for 45 days. Inoculated positive and non-inoculated negative controls were prepared and stored as the HPP treated and non-HPP samples. No growth of C. botulinum or toxin production was detected in either the unfiltered or filtered CW regardless if products were HPP treated or not. All inoculated samples with C. botulinum spores were enriched at Day-45 in PYGS media to determine the viability of the inoculated spores at the end of shelf-life and screened for C. botulinum toxins. In all samples, C. botulinum toxin Types A, B and E were detected indicating spores were viable throughout the storage. Type F toxin was not detected possibly due to inherent conditions in the samples that may affected toxin screening.

Inactivation of Shiga Toxin-Producing Escherichia coli in Refrigerated and Frozen Meatballs Using High Pressure Processing.

High pressure processing (HPP) was evaluated to inactivate Shiga toxin-producing Escherichia coli (STEC) in raw meatballs. Ground meat (>90% lean) was inoculated (ca. 7.0 log CFU/g) with a rifampicin-resistant cocktail of eight STEC strains (O26:H11, O45:H2, O103:H2, O104:H4, O111:H-, O121:H19, O145:NM, and O157:H7). Inoculated ground beef, ground veal, or a mixture of ground beef, pork, and veal were separately mixed with liquid whole eggs and seasonings, shaped by hand into meatballs (40 g each), and stored at −20 or at 4 °C for at least 18 h. Samples were then exposed to 400 or 600 MPa for 0 to 18 min. There were no differences (p > 0.05) in pathogen reduction related to the species of meat used or for meatballs that were refrigerated (0.9 to 2.9 log CFU/g) compared to otherwise similar meatballs that were stored frozen (1.0 to 3.0 log CFU/g) prior to HPP treatment. However, less time was needed to achieve a ≥ 2.0 log CFU/g reduction at 600 MPa (1 to 3 min) compared to 400 MPa (at least 9 min). This work provides new and practically useful information on the use of HPP to inactivate STEC in raw meatballs.

Texture of Fermented Summer Sausage With Differing pH, Endpoint Temperature, and High Pressure Processing Times

The objective was to evaluate the quality and texture of all-beef summer sausages produced with varying degrees of fermentation, endpoint cooking temperatures, and high pressure processing (HPP) hold times. Across 3 replications, sausages were fermented and (Process A) cooked to pH 4.6 and thermally processed to 54.4°C with smokehouse chilling, (Process B) cooked to pH 5.0 and thermally processed to 54.4°C with smokehouse chilling, (Process C) cooked to pH 5.0 and thermally processed to 54.4°C with rapid ice bath chilling, (Process D) cooked to pH 5.0 and thermally processed to 48.9°C with rapid ice bath chilling, and (Process E) cooked to pH 5.0 and thermally processed to 43.3°C with rapid ice bath chilling. After chilling, the sausages were sliced, layered, vacuum packaged, and subjected to HPP at 586 MPa for 0, 1, 150, or 300 s. Post HPP, the sausages were evaluated for objective color (n = 9), lipid oxidation (n = 9), water activity (n = 9), texture profile analysis (TPA; n = 15), sensory analysis (n = 9), and proximate analysis (n = 9). Neither process (combination of pH and endpoint temperature) nor HPP affected lipid oxidation (P = 0.45 and P = 0.69, respectively). Process A resulted in a lighter color (P &amp;lt; 0.01) compared to the other process treatments. Additionally, Process A was less red (P &amp;lt; 0.01) than all other process treatments, and Processes D and E were the reddest (P &amp;lt; 0.01). TPA and trained sensory analysis indicated that, as endpoint temperature increased, so did sample hardness (P &amp;lt; 0.05). Springiness, cohesiveness, and gumminess decreased (P &amp;lt; 0.05) as the endpoint temperature decreased. Although springiness and gumminess increased (P &amp;lt; 0.05) with longer HPP hold times, the panelists were unable to detect differences among samples with longer hold times. The use of HPP at 586 MPa for up to 300 s may be incorporated into manufacturing processes for semidry beef summer sausages with limited impacts on color and texture.