Effects of high pressure on meat: A review

High-Pressure Treatment in Combination with Reduced Sodium for Improving the Physicochemical Properties and Sensory Qualities of Pork Gels

High-pressure treatment was utilized in this study to produce high-quality, reduced-sodium pork gels with desirable texture and sensory properties, addressing the challenge of maintaining quality in low-sodium meat products to meet health-conscious consumer demands. High-pressure treatment applied within the range of 150-200 MPa significantly reduced cooking loss while maintaining moisture content and provided an ideal network structure for reduced-sodium pork gels. High-pressure treatment at up to 100-200 MPa, in combination with added sodium chloride and sodium polyphosphate, was evaluated for its effects on gel texture, with results indicating that high-pressure treatment significantly improved breaking stress (increased by 10.01% under 150 MPa and 14.66% under 200 MPa), modulus of elasticity (increased by 14.77% under 150 MPa and 24.17% under 200 MPa), and hardness (increased by 11.12% under 150 MPa and 11.45% under 200 MPa). Rheological characteristic measurements revealed that gel strength was highest at 150 MPa (G' = 443,000 Pa; G″ = 66,300 Pa and tanδ = 0.15), which showed higher G' and G″ values and similar tanδ compared to the 0.1 MPa, 2% NaCl + 0.5% SPP condition (G' = 334,000 Pa; G″ = 49,200 Pa; tanδ = 0.148). Protein analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a reduction in the α-actinin band with increased pressure, which suggested protein interactions were enhanced. Differential scanning calorimetry analysis indicated that protein denaturation occurred more readily at higher pressures (0.071 J/g at 0.1 MPa, 0.057 J/g at 150 MPa, and 0.039 J/g at 200 MPa). These findings underscore the value of treatment under high pressure at 150 MPa developing reduced-sodium meat products with desirable texture and flavor characteristics.

Research Progress and Teaching Exploration of Physical Processing Technology for Reduced-Salt Gel Meat Products

Salt assumes a significant role in the production of meat gels. Excessive intake of salt adversely affects human health, and consumers' demand for reduced-salt meat products is escalating. This review primarily introduces the characteristics of the physical processing technology of reduced-salt gel meat products, such as the technology of ultrasonic, high-pressure processing, beating, plasma, and magnetic field, and its role in reduced-salt gel meat processing, and explores means to improve the teaching effect of the physical processing technology of reduced-salt gel meat products in the major of Food Science and Engineering. It was found that physical processing techniques, such as ultrasound, high-pressure processing, and beating, could enhance the solubility and processing performance of myofibrillar protein by improving the meat structure and protein conformation, increasing the interaction between proteins, water, and fat molecules, and enhancing the texture, water-holding capacity, and sensory quality of reduced-salt gel meat products. In the promotion and teaching of physical processing technology, it is necessary to strengthen interdisciplinary integration and scientific research activities according to the customs, laws and regulations of different countries and regions, combined with the development frontier of the technology, and develop reduced-salt gel meat products that meet local needs according to local conditions.

Dry-Cured Sausages "Salchichón" Manufactured with a Valorized Ingredient from Red Grape Pomace (Var. Tempranillo)

The inclusion of an ingredient made from red grape pomace (RGP) var. Tempranillo was evaluated for the preservation of a traditional dry-cured sausages (salchichón). The pomace was valorized through thermal blanching (103 °C for 1 min) and hydrostatic high-pressure treatment (600 MPa/5 min) before the addition to salchichón. Four formulations of salchichón were evaluated, including a negative control (NC-without red grape pomace or synthetic additives), positive control (PC-with ascorbic acid and nitrites), low level (LL-0.5%), and high level (HL-1%) of RGP. Physicochemical, microbiological, and sensorial effects were analyzed. RGP reduced the final pH of salchichón and favored the growth of lactic acid bacteria at similar levels as PC. The addition of ascorbic acid and nitrites resulted in a final product with a redder and less yellow color than the other formulations. This cured color was not reached with the addition of RGP. However, its inclusion slightly reduced lipid and protein oxidation in salchichón. PC showed high levels of sulfur and terpene levels in a volatile profile, although at a sensory level, only differences in spicy taste were not noticed by panelists. The incorporation of the ingredient could enable the substitution of nitrites with valorized red grape pomace in sausages, although the desirable color achieved with nitrifying salts was not fully attained.

The Influence of High Hydrostatic Pressure on Selected Quality Features of Cold-Storage Pork Semimembranosus Muscle

The primary objective of this investigation was to assess the influence of high hydrostatic pressure (HHP) and the duration of cold storage on the physicochemical, technological, and sensory attributes as well as the nutritional composition and shelf life of meat. The experimental framework involved utilizing samples derived from the semimembranosus muscle of pork. Each muscle obtained from the same carcass was segmented into six distinct parts, with three designated as control specimens (K) and the remaining subjected to vacuum packaging and subsequent exposure to high hydrostatic pressure (200 MPa at 20 °C for 30 min). Comprehensive laboratory analyses of the meat were conducted at 1, 7, and 10 days post slaughter. The meat was cold-stored at +3 ± 0.5 °C. The findings of the study elucidated that the application of high hydrostatic pressure exhibited a favorable impact on the extension of the raw meat's shelf life. The tests showed a significant (p < 0.05) decrease in the total number of microorganisms compared to the control sample after 7 (K: 4.09 × 105, HHP: 2.88 × 105 CFU/g) and 10 (K: 7.40 × 105, HHP: 2.42 × 105 CFU/g) days of cold storage. It was also found that using HHP increased the pH value after 1 (K: 5.54, HHP: 5.77) and 7 (K: 5.60, HHP: 5.87) days of storage.

Diversified Techniques for Restructuring Meat Protein-Derived Products and Analogues

Accompanied by the rapid growth of the global population and increasing public awareness of protein-rich foods, the market demand for protein-derived products is booming. Utilizing available technologies to make full use of meat by-products, such as scraps, trimmings, etc., to produce restructured meat products and explore emerging proteins to produce meat analogues can be conducive to alleviating the pressure on supply ends of the market. The present review summarizes diversified techniques (such as high-pressure processing, ultrasonic treatment, edible polysaccharides modification, enzymatic restructuring, etc.) that have been involved in restructuring meat protein-derived products as well as preparing meat analogues identified so far and classifying them into three main categories (physical, chemical and enzymatic). The target systems, processing conditions, effects, advantages, etc., of the included techniques, are comprehensively and systemically summarized and discussed, and their existing problems or developing trends are also briefly prospected. It can be concluded that a better quality of restructured products can be obtained by the combination of different restructuring technologies. This review provides a valuable reference both for the research and industrial production of restructured meat protein-derived products and analogues.

Shade of Innovative Food Processing Techniques: Potential Inducing Factors of Lipid Oxidation

With increasing environmental awareness and consumer demand for high-quality food products, industries are strongly required for technical innovations. The use of various emerging techniques in food processing indeed brings many economic and environmental benefits compared to conventional processes. However, lipid oxidation induced by some "innovative" processes is often "an inconvenient truth", which is scarcely mentioned in most studies but should not be ignored for the further improvement and optimization of existing processes. Lipid oxidation poses a risk to consumer health, as a result of the possible ingestion of secondary oxidation products. From this point of view, this review summarizes the advance of lipid oxidation mechanism studies and mainly discloses the shade of innovative food processing concerning lipid degradation. Sections involving a revisit of classic three-stage chain reaction, the advances of polar paradox and cut-off theories, and potential lipid oxidation factors from emerging techniques are described, which might help in developing more robust guidelines to ensure a good practice of these innovative food processing techniques in future.

High-pressure processing of beef increased the in vitro protein digestibility in an infant digestion model

Beef is an ideal protein source for use as a complementary food in infants. Considering the limited protein-digesting capacity of infants, it is required to enhance protein digestibility while minimizing the deterioration of beef quality. Thus, this study aimed to determine the effects of high-pressure processing (HPP) on the physicochemical properties and in vitro digestibility of beef proteins in an infant digestion model. HPP at 200 and 300 MPa decreased the tryptophan fluorescence intensity of the myosin and actin fractions relative to that at 0.1 MPa (P < 0.05). Compared to treatment at 0.1 and 100 MPa, HPP at 300 MPa decreased α-helix and β-turn contents in the myosin and actin fractions (P < 0.05), whilst increasing the β-sheet content (P < 0.05). Beef actomyosin content decreased (P < 0.05) during HPP at 200 and 300 MPa (c.f., 0.1 and 100 MPa). After in vitro digestion of beef, HPP at 200 and 300 MPa increased the α-amino group content and the abundance of proteins below 3 kDa in the digesta (P < 0.05). However, due to the considerable lipid oxidation at 300 MPa, HPP at 200 MPa is ideal for improving the protein digestibility of beef when incorporated into complementary foods for infants.

Inactivation Kinetics of Foodborne Pathogens in Carrot Juice by High-Pressure Processing

In this study, Salmonella Typhimurium, Escherichia coli, and Listeria monocytogenes were separately inoculated in sterilized carrot juice and subjected to various types of high-pressure processing (HPP) at 200-600 MPa for 0.1-15 min to observe the effects of HPP on the inactivation kinetics of foodborne pathogens in carrot juice. The first-order model fits the destruction kinetics of high pressure on foodborne pathogens during the pressure hold period. An increase in pressure from 200 to 600 MPa decreased the decimal reduction time (D values) of S. Typhimurium, E. coli, and L. monocytogenes. Under pressure ≥ 400 MPa, the D values of E. coli were significantly higher than those of S. Typhimurium and L. monocytogenes, indicating that E. coli had greater resistance to high pressures than the others. The Zp values (the pressure range that causes the D values to change by 90%) of E. coli, S. Typhimurium, and L. monocytogenes were 195, 175, and 170 MPa, respectively. These results indicated that L. monocytogenes and E. coli were the most and least sensitive, respectively, to pressure changes. Additionally, the three bacteria were separately inoculated into thermal-sterilized carrot juice and subjected to 200-600 MPa HPP for 3 min. The treated carrot juices were stored at 4 °C for 27 d. Following S. Typhimurium and E. coli inoculation, the bacterial counts of the control and 200 MPa treatments remained the same during the storage duration. However, they decreased for the 300 and 400 MPa treatment groups with increasing storage duration. During the storage period, no bacterial growth was observed in the 500 and 600 MPa treatments. However, the bacterial number for the control and pressure treatment groups increased with prolonged storage duration following inoculation with L. monocytogenes. Therefore, following HPP, residual L. monocytogenes continued growing stably at low temperatures. Overall, HPP could inhibit and delay the growth of S. Typhimurium and E. coli in carrot juice during cold storage, but it was ineffective at inhibiting the growth of L. monocytogenes. There was a risk of foodborne illness despite the low-temperature storage of juice. The innovation of this preliminary study is to find the impact of high pressure on the inactivate kinetics of three food pathogens in carrot juice and its practical application in simulated contaminated juice.

Characterization of Growth Performance, Pork Quality, and Body Composition in Mangalica Pigs

European heritage breeds, such as the Blonde (B), Red (R), and Swallow-bellied (SB) Mangalica pig, display an extreme propensity to fatten and are reputed to produce superior quality pork. This suggests that Mangalica pork should command a higher price, and the Mangalica is a candidate breed to target niche markets within the United States. Our objectives were to test this hypothesis by (1) directly comparing growth performance and carcass merit of purebred Yorkshire (Y), B, R, and SB Mangalica pigs to identify the best breed for adoption, and (2) comparing indices of pork quality in purebred R, Y, and crossbred (R × Y) pigs to determine if crossbreeding represented a viable alternative to the adoption of purebred Mangalica. Daily feed intake, average daily gain (ADG), and feed efficiency were highest in Y and lowest in SB pigs with B and R ranked intermediately (p < 0.001). Backfat thickness was greatest in B and lowest in Y with R and SB ranked intermediately (p < 0.001). Marbling score was greatest in R pigs and lowest in Y pigs with B and SB ranked intermediately (p < 0.01). In contrast, loin eye area (LEA) was greatest in Y pigs compared to B, R, and SB (p < 0.001). Indices of meat quality were then compared in R, R × Y, and Y pigs. Backfat thickness and marbling scores were greater in R than R × Y and Y pigs (p < 0.001) while LEA was greater in Y than R × Y and R pigs (p < 0.001). Loin and ham ultimate pH, color, and firmness scores were significantly greater in R than R × Y or Y pigs (p < 0.05). Meanwhile, cook loss was significantly less in R than Y pigs (p < 0.007) while Warner-Bratzler Shear Force (WBS) was not different in chops between groups (p < 0.11). These data indicate that though Mangalica exhibit poorer growth performance, Mangalica pork exhibits superior pork quality attributes, suggesting that higher price points for Mangalica pork in niche markets are justified.

Determination of Optimal Harvest Weight for Mangalica Pigs Using a Serial Harvest Approach to Measure Growth Performance and Carcass Characteristics

Mangalica pigs are a popular niche breed given their reputation for superior pork quality. However, growth and carcass parameters for this breed are poorly documented. To better characterize optimal harvest weights for the Mangalica, a growth trial was conducted whereby pigs (n = 56) were randomly distributed across stratified harvest weights (50, 57, 68, 82, 93, 102, 127 kg) in a completely randomized design. Pigs were fed standard finisher rations with individual daily feed intakes and weekly body weights recorded for all animals. At 24 h postmortem, carcasses were split and ribbed with marbling and loin eye area (LEA) measured at the 10th rib. Primal cuts were fabricated and individually weighed. Fat back was separated from the loin and weighed. As expected, live weight significantly increased across the weight class (p < 0.0001). ADG was similar across classes up to 82 kg live weight, before steadily declining with increasing weight class (p < 0.0025). Likewise, feed efficiency did not differ between classes until weights heavier than 82 kg (p < 0.03). LEA significantly increased by class up to 82 kg and then plateaued as harvest weight increased further (p < 0.003). Marbling score significantly increased with increasing weight class up to 102 kg, where they then plateaued (p < 0.04). Fat back dramatically increased across all weight classes (p < 0.0001) despite negligible increases in LEA or marbling after 102 kg. Primal cut weights for the ham (p < 0.0001), loin (p < 0.0001), Boston butt (p < 0.0001), shoulder (p < 0.0001), and belly (p < 0.0001) all significantly increased with increasing live weight though significant fat deposition contributed to this gain. These data suggest an optimal harvest weight occurs between 82 to 102 kg, while offering little objective justification for harvesting Mangalica pigs at heavier live weights.

High-pressure pasteurization of low-acid chilled ready-to-eat food

The working population growth have created greater consumer demand for ready-to-eat (RTE) foods. Pasteurization is one of the most common preservation methods for commercial production of low-acid RTE cold-chain products. Proper selection of a pasteurization method plays an important role not only in ensuring microbial safety but also in maintaining food quality during storage. Better retention of flavor, color, appearance, and nutritional value of RTE products is one of the reasons for the food industry to adopt novel technologies such as high-pressure processing (HPP) as a substitute or complementary technology for thermal pasteurization. HPP has been used industrially for the pasteurization of high-acid RTE products. Yet, this method is not commonly used for pasteurization of low-acid RTE food products, due primarily to the need of additional heating to thermally inactivate spores, coupled with relatively long treatment times resulting in high processing costs. Practical Application: Food companies would like to adopt novel technologies such as HPP instead of using conventional thermal processes, yet there is a lack of information on spoilage and the shelf-life of pasteurized low-acid RTE foods (by different novel pasteurization methods including HPP) in cold storage. This article provides an overview of the microbial concerns and related regulatory guidelines for the pasteurization of low-acid RTE foods and summarizes the effects of HPP in terms of microbiology (both pathogens and spoilage microorganisms), quality, and shelf-life on low-acid RTE foods. This review also includes the most recent research articles regarding a comparison between HPP pasteurization and thermal pasteurization treatments and the limitations of HPP for low-acid chilled RTE foods.

Digestion Profiles of Protein in Edible Pork By-Products

Edible pork by-products are widely consumed in many areas, whereas their digestion characteristics have rarely been evaluated. This work compared the digestibility of protein in boiled pork liver, heart, tripe and skin with tenderloin as a control. Cooked skin showed the highest digestibility in the simulated gastric digestion, whereas its gastric digests were less digested in the simulated intestinal stage. In contrast, cooked tripe showed the lowest gastric digestibility but relatively higher intestinal digestibility. All the edible by-products showed lower digestibility than tenderloin, especially for pork liver, in which large undigested fractions (>300 μm) could be observed. Corresponding to these results, larger amount of bigger peptides was found in the digests of pork liver and skin. In addition, peptides in tripe (average bioactive probability = 0.385) and liver digests (average bioactive probability = 0.386) showed higher average bioactive probability than other samples. Tripe digests contained the highest level of free Asp, Gln, Cys, Val, Phe, Pro, Ser, Thr, Ile and Asn, whereas heart digests contained the highest level of free Leu, Met and Arg. These results could help to reveal the nutrition value of pork by-products.

Modifying textural and functional characteristics of fish (Nemipterus japonicus) mince using high pressure technology

Effect of high pressure in inducing textural and functional modification has been investigated in pink perch (Nemipterus japonicus) mince. Fish mince undergone pressurization at 200, 400 and 600 MPa for a holding period of 10 min and was compared against cooked mince (90 °C; 40 min). The treated mince at 400 and 600 MPa lost its natural viscosity and behaved like cooked mince through denaturation and formation of protein aggregates. Textural characterisation showed the retention of tenderness in 200 MPa treated samples, but become harder on application of higher pressures. Unlike heat gels, pressure induced gels were more smooth, white and elastic in nature. A decreased in reactive SH groups was observed in 400 and 600 MPa treated samples due to the formation of disulfide bonds. Hydrophobic concentration was higher in cooked and 600 MPa treatments whereas Ca2+-ATPase activity decreased after pressurization. On application of different pressures microbial reduction of 2-3 log cycles was achieved in the mince samples. Hence pressure treatments at lower ranges cannot alter the texture and functionality of protein and the mince can undergo processing as required. Besides extending shelf life, the treatments above 400 MPa can make irreversible effect on texture quality and protein functionality which is similar to that of cooking.

Monitoring the variations in physicochemical characteristics of squab meat during the braising cooking process

Braised squabs are traditional Chinese foods. However, the processing is highly experience dependent and lacks a theoretical basis. Hence, a comparative study of the physicochemical properties in different processing stages of braised squabs was necessary. We observed the physicochemical changes in the processing stages of braised squabs (raw meat, braised meat, and fried meat). The color parameters, moisture content, and drip loss rate gradually decreased during the processing. On the contrary, crude protein content and pH value were upregulated in the processing stages of braised squabs. Furthermore, the diameter of muscle fiber significantly increased in the braised meat and further decreased in the fried meat compared with the raw muscle fiber. Similarly, hardness, springiness, and chewiness were also increased in the braised step and decreased in the fried step. Additionally, the contents of essential amino acids remain unchanged. Hence, our results provided a certain reference value on the production of braised squabs.

The Effects of High-Pressure Processing on pH, Thiobarbituric Acid Value, Color and Texture Properties of Frozen and Unfrozen Beef Mince

In this study, beef mince (approximately 4% fat longissmus costarum muscle of approximately 2-year-old Holstein cattle) was used as a material. High-pressure processing (HPP) was applied to frozen and unfrozen, vacuum-packed minced meat samples. The pH and thiobarbituric acid (TBA) values of the samples were examined during 45 days of storage. Color values (L*, a* and b*) and texture properties were examined during 30 days of storage. After freezing and HPP (350 MPa, 10 min, 10 °C), the pH value of minced meat increased (p > 0.05) and its TBA value decreased (p < 0.05). The increase in pH may be due to increased ionization during HPP. Some meat peptides, which are considered antioxidant compounds, increased the oxidative stability of meat, so a decrease in TBA may have been observed after freezing and HPP. While the color change in unpressurized samples was a maximum of 3.28 units during storage, in the pressurized sample, it exceeded the limit of 10 units on the first day of storage and exceeded the limit of 10 units on the third day of storage in the frozen and pressurized sample. Freezing and HPP caused the color of beef mince to be retained longer. The hardness, gumminess, chewability, adherence, elasticity, flexibility values of the pressurized and pressurized after freezing samples were higher than those of the unpressurized samples during storage. On the other hand, the opposite was the case for the adhesiveness values. In industrial applications, meat must be pressurized after being vacuum packed. If HPP is applied to frozen beef mince, some of its properties such as TBA, color, and texture can be preserved for a longer period of time without extreme change.

Sampling Adipose and Muscle Tissue following Post-Harvest Scalding Does Not Affect RNA Integrity or Real-Time PCR Results in Market Weight Yorkshire Pigs

Improving production efficiency while enhancing pork quality is pivotal for strengthening sustainable pork production. Being able to study both gene expression and indices of pork quality from the same anatomical location of an individual animal would better enable research conducted to study relationships between animal growth and carcass merit. To facilitate gene expression studies, adipose and muscle tissue samples are often collected immediately following exsanguination to maximize RNA integrity, which is a primary determinant of the sensitivity of RNA-based assays, such as real-time PCR. However, collecting soft tissue samples requires cutting through the hide or skin. This leaves the underlying tissue exposed during scalding, poses possible food safety issues, and potentially confounds pork quality measures. To overcome these limitations, the effect of tissue sample timing post-harvest on RNA integrity, real-time PCR results, and pork quality measurements was investigated by sampling subcutaneous adipose tissue and longissimus thoracis et lumborum muscle immediately following either exsanguination, scalding, or chilling. Sampling time did not affect RNA quality, as determined by the RNA integrity number of RNA samples purified from either adipose (RIN; p > 0.54) or muscle tissue (p > 0.43). Likewise, the sampling time did not influence the results of real-time PCR analysis of gene expression when comparing RNA samples prepared from adipose or muscle tissue immediately following either exsanguination or scalding (p > 0.92). However, sampling tissue prior to scalding resulted in a greater visual color score (p < 0.001) and lesser L* (p < 0.001) and b* (p < 0.001) values without impacting the 24 h pH (p < 0.41). These results suggested that if both RNA-based assays and meat quality endpoints are to be performed at the same anatomical location on an animal, tissue sampling to facilitate RNA-based assays should occur at a time point immediately following scalding. These findings demonstrated that sampling of adipose and muscle tissue can be delayed until after scalding/dehairing without decreasing the RNA integrity or altering the results of real-time PCR assays, while doing so was associated with little impact on measures of pork quality.

Effect of Partial Substitution of Sodium Chloride (NaCl) with Potassium Chloride (KCl) Coupled with High-Pressure Processing (HPP) on Physicochemical Properties and Volatile Compounds of Beef Sausage under Cold Storage at 4 °C

This study aimed to evaluate the effects of partial substitution of sodium chloride (NaCl) with potassium chloride (KCl) in combination with high-pressure processing (HPP) on the physicochemical properties and volatile compounds of beef sausage during cold storage at 4 °C. Significant differences were found in the volatile compounds of beef sausages with 0%, 25%, and 50% NaCl contents partially substituted with KCl subjected to 28 days of storage and were well-visualized by heat map analysis. A total of 75 volatile compounds were identified and quantified in the beef sausages at the end of 28 days of storage, including 12 aldehydes, 4 phenols, 2 ketones, 18 alcohols, 8 acids, 3 esters, 14 terpenes, and 14 alkanes. Thirteen compounds had low odor activity values (OAV) (OAV < 1); however, high OAV (OAV > 1) were obtained after partial substitution of NaCl by KCl at 25% and 50% with HPP treatment compared to the non-HPP treated samples. In addition, 50% NaCl substitution with KCl in conjunction with HPP treatments increased thiobarbituric acid reactive substances (TBARS) by (0.46 ± 0.03 mg/MDA) compared with no HPP treatments. Replacement of 25% and 50% NaCl with KCl decreased TBARS by an average of 10.8% and 11.10%, respectively, compared to 100% NaCl coupled with HPP beef sausages. In summary, HPP and partial substitution of NaCl with KCl at 25% and 50% can be used to compensate for the reduction of NaCl in beef sausage by keeping the physical and flavor fraction at required levels.

Volatile compounds in high-pressure-treated dry-cured ham: A review

The use of high pressure processing (HPP) for the treatment of dry-cured ham and other meat products has considerably increased worldwide. Its well-documented lethal effect on pathogenic and spoilage bacteria ensures the microbial safety of dry-cured ham and extends its shelf life. However, the effects of HPP on the volatile compounds, odor and aroma of dry-cured ham are less known. In the present review, the effects of HPP on the enzymes and microorganisms responsible for the generation of volatile compounds in dry-cured ham and the changes in the levels of the main groups of volatile compounds resulting from different HPP treatments are discussed. Particular attention is devoted to the fate of odor-active compounds after HPP treatments and throughout further commercial storage. The use of efficient sensory techniques yielding odor and aroma outputs closer to those perceived by consumers is encouraged. Needs for future research on the volatile compounds, odor and aroma of HPP-treated dry-cured ham are highlighted.

Endogenous Proteolytic Systems and Meat Tenderness: Influence of Post-Mortem Storage and Processing

Meat proteolytic systems play a crucial role in meat tenderisation. Understanding the effects of processing technologies and post-mortem storage conditions on these systems is important due to their crucial role in determining the quality characteristics of meat and meat products. It has recently been proposed that tenderisation occurs due to the synergistic action of numerous endogenous proteolytic systems. There is strong evidence suggesting the importance of μ-calpain during the initial post-mortem aging phase, while m-calpain may have a role during long-term aging. The caspase proteolytic system is also a candidate for cell degradation in the initial stages of conversion of muscle to meat. The role of cathepsins, which are found in the lysosomes, in post-mortem aging is controversial. Lysosomes need to be ruptured, through aging, or other forms of processing to release cathepsins into the cytosol for participation in proteolysis. A combination of optimum storage conditions along with suitable processing may accelerate protease activity within meat, which can potentially lead to improved meat tenderness. Processing technologies such as high pressure, ultrasound, and shockwave processing have been reported to disrupt muscle structure, which can facilitate proteolysis and potentially enhance the aging process. This paper reviews the recent literature on the impacts of processing technologies along with post-mortem storage conditions on the activities of endogenous proteases in meat. The information provided in the review may be helpful in selecting optimum post-mortem meat storage and processing conditions to achieve improved muscle tenderness within shorter aging and cooking times.

High Hydrostatic Pressure Treatment Ensures the Microbiological Safety of Human Milk Including Bacillus cereus and Preservation of Bioactive Proteins Including Lipase and Immuno-Proteins: A Narrative Review

Breast milk is the nutritional reference for the child and especially for the preterm infant. Breast milk is better than donated breast milk (DHM), but if breast milk is not available, DHM is distributed by the Human Milk Bank (HMB). Raw Human Milk is better than HMB milk, but it may contain dangerous germs, so it is usually milk pasteurized by a Holder treatment (62.5 °C 30 min). However, Holder does not destroy all germs, and in particular, in 7% to 14%, the spores of Bacillus cereus are found, and it also destroys the microbiota, lipase BSSL and immune proteins. Another technique, High-Temperature Short Time (HTST 72 °C, 5–15 s), has been tried, which is imperfect, does not destroy Bacillus cereus, but degrades the lipase and partially the immune proteins. Therefore, techniques that do not treat by temperature have been proposed. For more than 25 years, high hydrostatic pressure has been tried with pressures from 100 to 800 MPa. Pressures above 400 MPa can alter the immune proteins without destroying the Bacillus cereus. We propose a High Hydrostatic Pressure (HHP) with four pressure cycles ranging from 50–150 MPa to promote Bacillus cereus germination and a 350 MPa Pressure that destroys 10⁶ Bacillus cereus and retains 80–100% of lipase, lysozyme, lactoferrin and 64% of IgAs. Other HHP techniques are being tested. We propose a literature review of these techniques.

In Vitro Protein Disappearance of Raw Chicken as Dog Foods Decreased by Thermal Processing, but Was Unaffected by Non-Thermal Processing

Simple Summary

Chicken meat is widely used as a dog food due to its high nutritional values and palatability. Pasteurization is important to ensure the safety of chicken meat: thermal processing and non-thermal processing including high-pressure processing, ultraviolet-light emitting diode radiation, electron-beam irradiation, and gamma-ray irradiation. The influence of these pasteurization methods on nutrient digestibility is of interest. In the present work, the effects of thermal and non-thermal processing methods on protein digestibility of chicken meat were measured using in vitro assays. Protein digestibility of chicken meat was decreased by high-temperature processing at 70, 90, and 121 °C. However, non-thermal processing methods including high-pressure processing, ultraviolet-light emitting diode radiation, electron-beam irradiation, and gamma-ray irradiation did not affect protein digestibility of chicken meat. The present study indicates that nutritional values of chicken meat were maintained when non-thermal processing methods are used whereas they were decreased by thermal processing methods.

Abstract

The objectives of the present study were to determine the influence of thermal and non-thermal processing procedures on in vitro ileal disappearance (IVID) of dry matter (DM) and crude protein (CP) in chicken meat as dog foods using 2-step in vitro assays. In thermal processing experiments, IVID of DM and CP in chicken meat thermally processed at 70, 90, and 121 °C, respectively, with increasing processing time was determined. For non-thermal processing experiments, IVID of DM and CP in chicken meat processed by high-pressure, ultraviolet-light emitting diode (UV-LED), electron-beam, and gamma-ray was determined. Thermal processing of chicken meat at 70, 90, and 121 °C resulted in decreased IVID of CP (p < 0.05) as heating time increased. In non-thermal processing experiment, IVID of CP in chicken meat was not affected by high-pressure processing or UV-LED radiation. In vitro ileal disappearance of CP in electron-beam- or gamma-ray-irradiated chicken meat was not affected by the irradiation intensity. Taken together, ileal protein digestibility of chicken meat for dogs is decreased by thermal processing, but is minimally affected by non-thermal processing methods.

Effect of high-pressure treatment and storage temperature on top-quality (Montanera) Iberian dry-cured pork sausages (chorizo)

The stability after hydrostatic high pressure (HHP) (600 MPa/8 min/10 °C) and 180 days of storage at 4 and 20 °C was evaluated on Iberian dry-cured pork sausages (chorizo) packaged sliced or as half-pieces from pigs raised outdoors. Microbiological, physical-chemical, oxidative, and sensory changes were analyzed. The evolution of mesophilic aerobic and molds and yeasts counts was different in the half and sliced packaged pork sausages after processing and during storage. Sliced and half-packaged pork sausages had instrumental color stability after HHP and during storage. TBA-RS values were quite stable in both products. Protein oxidation values of pork sausage in half-products were increased by at 20 °C. In sliced pork sausage, both HPP and 20 °C storage favored the development of protein oxidation at the end of storage. In the sensory analysis, the sliced product developed more rancidity than the half-pieces during the storage. Therefore, the storage temperature has great importance for the preservation of dry-cured pork sausages, the increases of protein oxidation, and rancidity could reduce the shelf-life at these conditions. The presentation of the product is also relevant when HHP is applied, and this would also compromise the stability of the product when it is stored at room temperature. PRACTICAL APPLICATION: Chorizo is a traditional dry-fermented pork sausage that is generally considered to be microbiologically safe. However, the initial contamination of the raw materials, and some processes, such as the slicing or packaging, can compromise the safety of these products. Additionally, packaged dry-cured sausages require long shelf-life, and although they are normally stored at refrigeration temperature; sometimes, they are preserved at room temperature. The application of hydrostatic high pressure could increase the safety of dry-cured meat products even when they are stored at room temperature. Initial characteristics of each type of pork sausage could determine their technological behavior during processing or during storage under different conditions.

Effects of high-pressure treatment on the structure and function of myofibrils

The effects of high pressure (40-70 MPa) on the structure and function of myofibrils were investigated by high pressure microscopy. When this pressure was applied to myofibrils immersed in relaxing solution, the sarcomere length remained almost unchanged, and the A band became shorter and wider. The higher the applied pressure, the faster the change. However, shortening and widening of the A band were not observed when pressure was applied to myofibrils immersed in a solution obtained by omitting ATP from the relaxing solution. However, even under these conditions, structural loss, such as loss of the Z-line structure, occurred. In order to evaluate the consequences of this pressure-treated myofibril, the oscillatory movement of sarcomere (sarcomeric oscillation) was evoked and observed. It was possible to induce sarcomeric oscillation even in pressure-treated myofibrils whose structure was destroyed. The pressurization reduced the total power of the sarcomeric oscillation, but did not change the average frequency. The average frequency did not change even when a pressure of about 40 MPa was applied during sarcomeric oscillation. The average frequency returned to the original when the pressure was returned to the original value after applying stronger pressure to prevent the sarcomere oscillation from being observed. This result suggests that the decrease in the number of myosin molecules forming the crossbridge does not affect the average frequency of sarcomeric oscillation. This fact will help build a mechanical hypothesis for sarcomeric oscillation. The pressurization treatment is a unique method for controlling the structure of myofibrils as described above.

The use of high hydrostatic pressure in the technology of whole muscle meat products

The work examined the effect of high hydrostatic pressure on the chemical composition and microbiological indicators of poultry meat. Data on the mass fraction of moisture, fat, protein and ash before and after processing the product with high hydrostatic pressure are presented. Pressure treatment modes are justified, at which it is possible to obtain finished products. The formulation of a whole-muscle product from poultry meat has been developed, as well as a technological scheme for preparing a new product using innovative technology.

Changes in food quality and microbial composition of Russian sturgeon (Acipenser gueldenstaedti) fillets treated with low temperature vacuum heating method during storage at 4 °C

Russian sturgeon is a high-quality cultured fish and traditional heating methods may lead to deterioration of its food quality. This study aimed to evaluate the food quality and microbial composition of sturgeon fillets by low temperature vacuum heating (LTVH) and storage at 4 °C. The treatments varied in temperature (50, 60, and 70 °C) and duration (15 and 30 min); samples treated by traditional heating (100 °C, 15 min) methods were included as controls. We found that LTVH could reduce the values of lightness (L*), yellowness (b*), and pH and increase the values of redness (a*), chewiness, and hardness, to promote food quality. The biogenic amine content declined with the increase in heating temperature and time, the histamine of most concern was low at the end of storage, the values of LTVH70-30 and TC was 33.12 ± 1.25 and 30.39 ± 0.86 mg/kg. The total viable count (TVC) and biogenic amines showed the same trend, and the finial TVC values of LTVH60-30, LTVH70-15, LTVH70-30 and TC were 6.72 ± 0.17, 6.33 ± 0.18, 6.18 ± 0.08 and 5.93 ± 0.16 log CFU/g, which did not exceed the limit value (7 log CFU/g), indicating that the biosafety risk was reduced. According to the high-throughput sequencing results, the microbial composition of LTVH samples showed a lesser abundance pseudomonads than that found in the control. Thus, LTVH technology could be used as an alternative to traditional heating treatment.

High-pressure processing of meat: Molecular impacts and industrial applications

High-pressure processing (HPP) has been the most adopted nonthermal processing technology in the food industry with a current ever-growing implementation, and meat products represent about a quarter of the HPP foods. The intensive research conducted in the last decades has described the molecular impacts of HPP on microorganisms and endogenous meat components such as structural proteins, enzyme activities, myoglobin and meat color chemistry, and lipids, resulting in the characterization of the mechanisms responsible for most of the texture, color, and oxidative changes observed when meat is submitted to HPP. These molecular mechanisms with major effect on the safety and quality of muscle foods are comprehensively reviewed. The understanding of the high pressure-induced molecular impacts has permitted a directed use of the HPP technology, and nowadays, HPP is applied as a cold pasteurization method to inactive vegetative spoilage and pathogenic microorganisms in ready-to-eat cold cuts and to extend shelf life, allowing the reduction of food waste and the gain of market boundaries in a globalized economy. Yet, other applications of HPP have been explored in detail, namely, its use for meat tenderization and for structure formation in the manufacturing of processed meats, though these two practices have scarcely been taken up by industry. This review condenses the most pertinent-related knowledge that can unlock the utilization of these two mainstream transformation processes of meat and facilitate the development of healthier clean label processed meats and a rapid method for achieving sous vide tenderness. Finally, scientific and technological challenges still to be overcome are discussed in order to leverage the development of innovative applications using HPP technology for the future meat industry.

Quality changes in high pressure processed tan mutton during storage

The current study investigated the effects of high pressure (HP) treatment at 200 MPa and 500 MPa on quality characteristics of post-rigor tan mutton stored for 7 days at 4 °C, and textural changes were monitored during storage by means of the stress relaxation test. Application of 500 MPa high pressure significantly increased the elasticity and stiffness of meat after 7 days of storage (P < 0.05), accompanied by a lighter and less red appearance and markedly enhanced centrifugal loss during storage campared to untreated (P < 0.05). High pressure treatment at 200 MPa also substantially increased the lightness of samples throughout storage (P < 0.05), and showed a significant increase in stiffness at the end of storage (P < 0.05). Immunoblotting and electrophoresis (SDS-PAGE) analysis of key structural proteins revealed that myosin heavy chain denaturation began at 200 MPa, while actin denaturation occurred at 500 MPa. Troponin-T was continuously degraded in different treatments as storage progressed, and 200 MPa treatment and untreated represented similar degradation patterns, while 500 MPa treatment displayed more intense intact troponin-T at 38 kDa degradation. Results suggest that HP induced changes in cytoskeleton proteins, thereby affecting texture, water holding properties and lightness.

Advanced Tenderization of Brine Injected Pork Loin as Affected by Ionic Strength and High Pressure

This study investigated the effects of brine injection and high hydrostatic pressure (HHP) on the quality characteristics of pork loin. Brine with ionic strength conditions (0.7% vs 1.5% NaCl, w/v) were injected into pork loins, and the meat was pressurized up to 500 MPa for 3 min. As a quality indicator, moisture content, color, cooking loss and texture profile analysis (TPA) of pork loins were estimated. Based on the results, brine with low ionic strength (0.7% NaCl) resulted in low injection efficiency and high cooking loss, although, it improved tenderness of pork loin at moderate pressure level (~200 MPa). While high ionic strength condition (1.5% NaCl injection) lowered the hardness of pork loins at relatively high HHP level (400-500 MPa), it also caused high cooking loss. To commercialize the brine injected pork loins, it was necessary to regulate brine compositions, which was not evaluated in this study. Nevertheless, the present study demonstrated that brine injection followed by moderate pressure (200 MPa) could improve the tenderness of pork loins without causing other major quality losses.

Effect of high-pressure processing and chemical composition on lipid oxidation, aminopeptidase activity and free amino acids of Serrano dry-cured ham

Lipid oxidation and proteolysis are essential processes in Serrano dry-cured ham quality. The influence of high pressure processing (HPP) at 600 MPa for 6 min on lipid oxidation, aminopeptidase (AP) activities and free amino acids (FAA) in ripened Serrano hams of different chemical composition after 5 months at 4 °C were studied. HPP increased lipid peroxidation indexes. Composition influenced both indexes, with higher levels in hams of medium or high intramuscular fat (IMF) content and in hams of low or medium salt content or salt-in-lean ratio. HPP lowered AP activities by more than 50%. Composition also affected AP activities, with lower levels in hams of low a_w, high IMF content, low salt content or low salt-in-lean ratio. At the end of refrigerated storage, HPP only affected Arg and Tyr levels. Many of the individual FAA reached higher levels in hams of low a_w, medium or high IMF content, low or medium salt content, or low or medium salt-in-lean ratio.

Effect of low-temperature vacuum heating on physicochemical properties of sturgeon (Acipenser gueldenstaedti) fillets

BACKGROUND

Sturgeon is popular for its nutritious value and its taste. However, sturgeon fillets are traditionally heated in 100 °C boiling water, resulting in unfavorable taste and with a negative effect on the quality. This study considered the effect of combinations of vacuum and low-temperature treatments (LTVH groups) on sturgeon fillets compared with the traditional heat treatment (TC groups).

RESULTS

The results show that the LTVH groups had lower cooking-loss rates. All LTVH fillets were changed to a white color, and appeared 'done', as did the TC fillets. The LTVH and TC methods gave rise to significant differences in texture: the springiness of the LTVH groups decreased with heating time, and decreased rapidly in the TC groups (P < 0.05); hardness and chewiness increased with time and temperature in the LTVH groups, but decreased in the TC groups. More compact and denser gaps were observed in LTVH70 groups and TC groups. Less protein and lipid oxidation was evident in LTVH groups, including more myofibril protein solubility; there was less protein aggregation, fewer thiobarbituric acid reactive substance, and Schiff base.

CONCLUSION

Vacuum and low-temperature treated sturgeon fillets can be served as a good alternative. This treatment caused slight tissue damage and less proteolysis and lipid oxidation, which is beneficial for the quality of aquatic products.

High-pressure processing of usually discarded dry aged beef trimmings for subsequent processing

In this study, we investigated if the usually discarded trimmings from dry aged beef can be incorporated into raw fermented sausages as a substitute for fresh beef without altering any major characteristics. Dry aged trimmings were subjected to high-pressure processing (600 MPa, 3 min hold) to reduce the bacterial load, achieving a 3-log reduction. HPP-treated dry aged beef trimmings were then incorporated into raw fermented sausages (60% pork and 40% beef). Beef was substituted with trimmings in different concentrations (7.5, 12.5, 25, 50, 100%). Due to the substitution, the water content of the sausages was reduced depending on the amount of beef substituted. Consequently, the sausages with substituted beef, for example, 50 and 100%, achieved the same water content after 5.4 and 3.7 days, respectively, than control sausage at day 9. However, the substitution (100%) affected the fat content, which contributes to significant differences (p < .05) in firmness during ripening.