Effect of High Pressure and Salt on Pork Meat Quality and Microstructure

Effects of sodium chloride substitutes on physicochemical properties of salted beef

In this study, beef was marinated with different low-sodium salt substitutes and heated and aged by employing superheated steam roasting and traditional roasting to investigate the effects of the various substitutes on the physicochemical properties, texture profile, sensory properties, volatile compounds, microstructural characteristics, and safety of cured and aged beef. Twenty kilograms of beef were arbitrarily divided into five treatments and pickled with different low-sodium salt substitutes. The results revealed no significant differences in saltiness, physicochemical characteristics, texture profile, or volatile compounds between the T2 and T3 and T1 (100% NaCl, T1; 75% KCl + 25% NaCl, T2; 50% KCl + 50% NaCl, T3) samples. Furthermore, the T4 and T5 (50% NaCl + 25% KCl + 20% MgCl2 + 5% CaCl2, T4; 100% yeast extract, T5) samples had lower saltiness than the T1 sample. The plasmolysis percentage and osmotic pressure of the T2 and T3 samples were lower than those of the T1 sample. Therefore, reducing sodium by substituting NaCl with 50% KCl or 75% KCl maintained an acceptable sensory and safety profile for beef consumption.

Analyzing the effects of nonthermal pretreatments on the quality of microwave vacuum dehydrated beef using terahertz time-domain spectroscopy and near-infrared hyperspectral imaging

Both nonthermal pretreatment and nondestructive analysis are effective technologies in improving drying processes. This study evaluated the effects of different pretreatment methods on the quality of beef dehydrated by microwave vacuum drying (MVD) and compared the MVD process performance comprising real-time moisture content (MC), MC loss, colour content, and shrinkage rate using different optical sensing methods including terahertz time-domain spectroscopy (THz-TDS) and near-infrared hyperspectral imaging (NIR-HSI). Results indicated that osmotic pretreatment improved the drying rate of MVD beef with lower changes in colour and shrinkage rate. Both THz-TDS-based and NIR-HSI-based on-site direct scanning and in-situ in-direct sensing showed accurate prediction results, with best R²_p of 0.9646 and 0.9463 for MC and R²_p of 0.9817 and 0.9563 for MC loss prediction, respectively. NIR-HSI visualisation of MC results showed that ultrasound pretreatment curbed but osmotic pretreatment promoted nonuniform distribution during MVD. This research should guide improving the industrial MVD drying process.

Principles, Application, and Gaps of High-Intensity Ultrasound and High-Pressure Processing to Improve Meat Texture

In this study, we evaluate the most recently applied emerging non-thermal technologies (NTT) to improve meat tenderization, high-intensity ultrasound (HIUS), and high-pressure processing (HPP), aiming to understand if individual effects are beneficial and how extrinsic and intrinsic factors influence meat toughness. We performed a systematic literature search and meta-analysis in four databases (Web of Science, Scopus, Embase, and PubMed). Among the recovered articles (n = 192), 59 studies were included. We found better sonication time in the range of 2-20 min. Muscle composition significantly influences HIUS effects, being type IIb fiber muscles more difficult to tenderize (p < 0.05). HPP effects are beneficial to tenderization at 200-250 MPa and 15-20 min, being lower and higher conditions considered inconclusive, tending to tenderization. Despite these results, undesirable physicochemical, microstructural, and sensory alterations are still unknown or represent barriers against applying NTT at the industrial level. Optimization studies and more robust analyses are suggested to enable its future implementation. Moreover, combining NTT with plant enzymes demonstrates an interesting alternative to improve the tenderization effect caused by NTT. Therefore, HIUS and HPP are promising technologies for tenderization and should be optimized considering time, intensity, pressure, muscle composition, undesirable changes, and combination with other methods.

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.

Effects of protein posttranslational modifications on meat quality: A review

Meat quality plays an important role in the purchase decision of consumers, affecting producers and retailers. The formation mechanisms determining meat quality are intricate, as several endogenous and exogenous factors contribute during antemortem and postmortem periods. Abundant research has been performed on meat quality; however, unexpected variation in meat quality remains an issue in the meat industry. Protein posttranslational modifications (PTMs) regulate structures and functions of proteins in living tissues, and recent reports confirmed their importance in meat quality. The objective of this review was to provide a summary of the research on the effects of PTMs on meat quality. The effects of four common PTMs, namely, protein phosphorylation, acetylation, S-nitrosylation, and ubiquitination, on meat quality were discussed, with emphasis on the effects of protein phosphorylation on meat tenderness, color, and water holding capacity. The mechanisms and factors that may affect the function of protein phosphorylation are also discussed. The current research confirms that meat quality traits are regulated by multiple PTMs. Cross talk between different PTMs and interactions of PTMs with postmortem biochemical processes need to be explored to improve our understanding on factors affecting meat quality.

Physicochemical and sensory properties of carabeef treated with Bacillus subtilis (Ehrenberg) Cohn protease as meat tenderizer

This study investigated the use of Bacillus subtilis protease powder (CTC E-ssentials™ MT-70N) as a carabeef tenderizer. The effect of the bacterial protease on the characteristics of carabeef was determined, and its effectiveness was compared to a commercial meat tenderizer containing papain. Only B. subtilis protease showed significant enzyme activity (80-190 U/g), while the commercial meat tenderizer had no activity (0 U/g). Results from the shear force device revealed that 0.35% B. subtilis protease was the optimal concentration required to induce significant tenderization in carabeef (282 g/cm²) and reduce carabeef toughness by 80%. Proximate analysis showed that carabeef treated with B. subtilis protease had significantly higher crude protein (37%) than the negative control (34%) and carabeef-treated commercial meat tenderizer (31%). Sensory evaluation revealed that carabeef treated with 0.35% B. subtilis protease is more tender than untreated carabeef and those treated with the commercial meat tenderizer. Moreover, the carabeef was not over-tenderized and is palatably acceptable. Hence, B. subtilis protease can be used as a meat tenderizer in place of available commercial tenderizers containing plant-derived proteases.

Monitoring oxidation during the storage of pressure-treated cooked ham and impact on technological attributes

High-pressure processing is a post-processing preservation method commonly used on meat products. However, it can affect the structural properties and the physico-chemical properties of the meat. The aim of this study was to compare the physical properties, lipid and protein oxidation of control and treated (500 MPa, 20 °C, 5 min) cooked ham during subsequent storage (21 days at 4 °C). High pressure processing induced increase of hardness and syneresis after 7 days of storage. The redness (a*) was slightly affected by the high pressure treatment but not the lightness (L*) and the yellowness (b*). However, the fluctuation of color was not clearly visible. Evaluation of primary (conjugated dienes) and secondary (malondialdehyde MDA and thiobarbituric reactive substances TBA-RS) lipid oxidation products showed that pressure increases oxidation of lipids. Whereas, high pressure processing had no immediate effect on MDA and TBA-RS content, higher amount compared to control were observed during the refrigerated storage. This lipid oxidation could be due to the release of prooxidant iron from hemoproteins after the high pressure treatment. Finally, the determination of free and accessible thiols showed that the high pressure treatment leads to a protein oxidation.

Physicochemical, Microstructural, and Microbiological Properties of Skipjack Tuna (Katsuwonus pelamis) After High-Pressure Processing

Properties of skipjack tuna loins subjected to high-pressure processing (HPP) at 150 to 600 MPa for 1 to 5 min were compared with those of loin that underwent steam cooking for 10 min. Protein denaturation in HPP-treated loins increased with increasing pressure level, but these loins retained between 1.1% and 2.4% more water than steam-cooked loin. Water holding capacity decreased from 57% to 44% when the loins were treated at 600 MPa. ΔE value of HPP loins was between 5.8 and 26.3 when treated at 150 to 600 MPa, whereas it was 34.1 for steam-cooked sample. Hardness of HPP loins increased from 648 to 1,019, 1,918, 5,249, and 4,092 g and springiness changed from 85.2% to 79.7%, 78.2%, 91.7%, and 90.7%, respectively, when treated at 150, 300, 450, and 600 MPa. Protein fibers of HPP loins had a more irregular shape than those of steam-treated loin. Histamine levels of HPP-treated loins were in the range of 3.08 to 3.35 μg/g, identical to that of steam-treated loin. Thiobarbituric acid assay demonstrated that the level of lipid oxidation increment in HPP-treated loins was twice as high as that in steam-cooked one. Undesirable volatile compound contents in tuna loins decreased with increasing degree of protein denaturation. Steam cooking and HPP at 150, 300, 450, and 600 MPa decreased the total aerobic counts by 4.75, 0.12, 1.20, 4.69, and 6.08 log CFU/g, respectively. These results suggest that HPP at 450 MPa and above has the potential to be used as an alternative to the tuna precooking process.

PRACTICAL APPLICATION

Information presented here can serve as a guideline for the selection of appropriate conditions for HPP of tuna loins. Our results show that HPP has a potential to replace the highly energy-intensive steam precooking step, which is traditionally required in a canned tuna production process.

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.

High pressure processing of meat: effects on ultrastructure and protein digestibility

The effects of high pressure processing (HPP, at 175 and 600 MPa) on the ultrastructure and in vitro protein digestion of bovine longissimus dorsi muscle meat were studied. HPP caused a significant change in the visual appearance and texture of the meat subjected to HPP at 600 MPa so that it appeared similar to cooked meat, unlike the meat subjected to HPP at 175 MPa that showed no significant visible change in the colour and texture compared to the raw meat. The muscles were subjected to digestion under simulated gastric conditions for 1 h and then under simulated small-intestinal conditions for a further 2 h. The digests were analysed using gel electrophoresis (SDS-PAGE) and ninhydrin assay for amino N. The effect of the acid conditions of the stomach alone was also investigated. Reduced SDS-PAGE results showed that pepsin-digested (60 min) HPP meats showed fewer proteins or peptides of high molecular weight than the pepsin-digested untreated meat, suggesting more breakdown of the parent proteins in HPP-treated meats. This effect was more pronounced in the muscles treated at 600 MPa. These results are in accordance with microscopy results, which showed greater changes in the myofibrillar structure after simulated gastric digestion of the sample processed at 600 MPa than at 175 MPa. Transmission electron microscopy also showed the presence of protein aggregates in the former sample, resulting probably from protein denaturation of sarcoplasmic proteins, in the subcellular space and between myofibrils; along with cell contraction (similar to that caused by heating) in the former.

Microstructure, microbial profile and quality characteristics of high-pressure-treated chicken nuggets

High-pressure processing (300 MPa for 5 min) as a non-thermal post-processing intervention was employed to improve the shelf life and qualities of cooked refrigerated chicken nuggets. Pomegranate peel extract (1%) was also used as a source of natural antioxidant and antimicrobial in chicken nuggets. Microstructure, microbial profile, instrumental colour, texture profile and lipid oxidation were evaluated. High-pressure treatment and pomegranate peel extract did not influence significantly the colour and textural properties of cooked chicken nuggets. Thiobarbituric acid reactive substance values significantly (p < 0.05) increased in pressure-treated nuggets. Microstructural studies revealed shrinkage in the structure and loosening of the dense network of meat emulsion due to high-pressure treatment. Pressure treatment resulted in a reduction of 2-3.0 log10 cfu/g in total plate count and Enterobacteriaceae count. Molecular characterization studies revealed that Enterobacter amnigenus and Enterobacter sp. in control and Bacillus licheniformis, Enterococcus gallinarum and Acinetobacter baumannii in high-pressure-treated chicken nuggets were the major spoilage bacteria.