Effect of high pressure processing and cooking treatment on the quality of Atlantic salmon

Essentiality of dietary cholesterol and its interactions with phospholipid in juvenile slipper lobster (Thenus australiensis)

This study was conducted to verify the essentiality of dietary cholesterol for early juvenile slipper lobster, Thenus australiensis (initial weight 4.50 ± 0.72 g, mean ± SD, CV = 0.16), and to explore the potential for interactions between dietary cholesterol and phospholipid. An 8-week experiment was conducted using six experimental feeds containing three supplemental cholesterol concentrations (0, 0.2 and 0.4% dry matter) at two supplemental phospholipid concentrations (0% and 1.0% dry matter). Dietary cholesterol concentrations of ≥ 0.2% resulted in up to threefold greater weight gain compared to 0% dietary cholesterol, but without any significant main or interactive dietary phospholipid effect. An interaction was observed for lobster survival with lowest survival (46%) recorded for combined 0% cholesterol and 0% phospholipid compared to every other treatment (71-100%). However, all surviving lobsters at 0% dietary cholesterol, regardless of dietary phospholipid level, were in poor nutritional condition. Apparent feed intake (AFI) was significantly higher at dietary cholesterol ≥ 0.2% but was lower for each corresponding dietary cholesterol level at 1% dietary phospholipid. This implied that the feed conversion ratio was improved with supplemental phospholipid. In conclusion, this study confirms the essential nature of dietary cholesterol and that dietary phospholipid can provide additional benefits.

Application of a stoichiometric bioenergetic approach and whole-body protein synthesis to the nutritional assessment of juvenile Thenus australiensis

The present study successfully combined a stoichiometric bioenergetic approach with an endpoint stochastic model to simultaneously determine specific dynamic action, metabolic substrate use and whole-body protein synthesis in juvenile slipper lobster Thenus australiensis. Juvenile lobsters were fasted for 48 h to investigate routine metabolism before receiving a single meal of formulated feed containing 1% 15N-labeled Spirulina. Postprandial oxygen consumption rate, dissolved inorganic carbon, and total nitrogen excretion returned to the pre-feeding level within 24 h. The rate of whole-body protein synthesis was 0.76 ± 0.15 mg CP g-1 day-1, with a significant reduction from 24 to 48 h post-feeding. The postprandial increase in whole-body protein synthesis accounted for 13-19% of total oxygen uptake. Protein was the primary energy substrate for 48 h fasted (45% oxygen consumption) and post-feeding lobster (44%), suggesting that dietary protein was not efficiently used for growth. The secondary energy substrate differed between carbohydrates in 48 h fasted and lipids in post-feeding lobsters. The present study recommends integrating protein synthesis into protein requirement experiments of marine ectotherms to acquire a more comprehensive picture of protein and energy metabolism and nutritional physiology crucial for formulating cost-effective aquafeeds.

Quality of bee pollen submitted to drying, pasteurization, and high-pressure processing - A comparative approach

Bee Pollen is a valuable and useful natural food product that can be used for different purposes, among which medical ones. This matrix is deemed a superfood because of its chemical composition, which is rich in nutrients and possesses significant bioactivities, including antioxidant and microbiological properties. Nevertheless, the storage conditions and processing methods must be optimized to maintain their properties and maximise their application. This work investigates the best bee pollen conservation process and its impact on individual constituents. Monofloral bee pollen was analysed for 30 and 60 days after three different storage processes (drying, pasteurization, and high-pressure pasteurization). The results showed a decrease mainly in fatty acid and amino acid content for the dried samples. The best results were obtained with high-pressure pasteurization, maintaining the proteins, amino acids and lipids characteristics of pollen and the lowest microbial contamination.

Physicochemical and structural changes of myofibrillar proteins in muscle foods during thawing: Occurrence, consequences, evidence, and implications

Myofibrillar protein (MP) endows muscle foods with texture and important functional properties, such as water-holding capacity (WHC) and emulsifying and gel-forming abilities. However, thawing deteriorates the physicochemical and structural properties of MPs, significantly affecting the WHC, texture, flavor, and nutritional value of muscle foods. Thawing-induced physicochemical and structural changes in MPs need further investigation and consideration in the scientific development of muscle foods. In this study, we reviewed the literature for the thawing effects on the physicochemical and structural characters of MPs to identify potential associations between MPs and the quality of muscle-based foods. Physicochemical and structural changes of MPs in muscle foods occur because of physical changes during thawing and microenvironmental changes, including heat transfer and phase transformation, moisture activation and migration, microbial activation, and alterations in pH and ionic strength. These changes are not only essential inducements for changes in spatial conformation, surface hydrophobicity, solubility, Ca2+ -ATPase activity, intermolecular interaction, gel properties, and emulsifying properties of MPs but also factors causing MP oxidation, characterized by thiols, carbonyl compounds, free amino groups, dityrosine content, cross-linking, and MP aggregates. Additionally, the WHC, texture, flavor, and nutritional value of muscle foods are closely related to MPs. This review encourages additional work to explore the potential of tempering techniques, as well as the synergistic effects of traditional and innovative thawing technologies, in reducing the oxidation and denaturation of MPs and maintaining the quality of muscle foods.

Using OPLS-DA to Fingerprint Key Free Amino and Fatty Acids in Understanding the Influence of High Pressure Processing in New Zealand Clams

This study investigated the effect of high pressure processing (HPP) on the fatty acids and amino acids content in New Zealand Diamond Shell (Spisula aequilatera), Storm Shell (Mactra murchisoni), and Tua Tua (Paphies donacina) clams. The clam samples were subjected to HPP with varying levels of pressure (100, 200, 300, 400, 500, and 600 MPa) and holding times (5 and 600 s) at 20 °C. Partial Least Squares Discriminant Analysis (PLS-DA) and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) were deployed to fingerprint the discriminating amino and fatty acids post-HPP processing while considering their inherent biological variation. Aspartic acid (ASP), isoleucine (ILE), leucine (LEU), lysine (LYS), methionine (MET), serine (SER), threonine (THR), and valine (VAL) were identified as discriminating amino acids, while C18:0, C22:1n9, C24:0, and C25:5n3 were identified as discriminating fatty acids. These amino and fatty acids were then subjected to mixed model ANOVA. Mixed model ANOVA was employed to investigate the influence of HPP pressure and holding times on amino acids and fatty acids in New Zealand clams. A significant effect of pressure levels was reported for all three clam species for both amino and fatty acids composition. Additionally, holding time was a significant factor that mainly influenced amino acid content. butnot fatty acids, suggesting that hydrostatic pressure hardly causes hydrolysis of triglycerides. This study demonstrates the applicability of OPLS-DA in identifying the key discriminating chemical components prior to traditional ANOVA analysis. Results from this research indicate that lower pressure and shorter holding time (100 MPa and 5 s) resulted in the least changes in amino and fatty acids content of clams.

A novel hybrid system for automatic detection of fish quality from eye and gill color characteristics using transfer learning technique

Fish remains popular among the body's most essential nutrients, as it contains protein and polyunsaturated fatty acids. It is extremely important to choose the fish consumption according to the season and the freshness of the fish to be purchased. It is very difficult to distinguish between non-fresh fish and fresh fish mixed in the fish stalls. In addition to traditional methods used to determine meat freshness, significant success has been achieved in studies on fresh fish detection with artificial intelligence techniques. In this study, two different types of fish (anchovy and horse mackerel) used to determine fish freshness with convolutional neural networks, one of the artificial intelligence techniques. The images of fresh fish were taken, images of non-fresh fish were taken and two new datasets (Dataset1: Anchovy, Dataset2: Horse mackerel) were created. A novel hybrid model structure has been proposed to determine fish freshness using fish eye and gill regions on these two datasets. In the proposed model, Yolo-v5 and Inception-ResNet-v2 and Xception model structures are used through transfer learning. Whether the fish is fresh in both of the Yolo-v5 + Inception-ResNet-v2 (Dataset1: 97.67%, Dataset2: 96.0%) and Yolo-v5 + Xception (Dataset1: 88.00%, Dataset2: 94.67%) hybrid models created using these model structures has been successfully detected. Thanks to the model we have proposed, it will make an important contribution to the studies that will be conducted in the freshness studies of fish using different storage days and the estimation of fish size.

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.

Effects of High Hydrostatic Pressure and Storage Temperature on Fatty Acids and Non-Volatile Taste Active Compounds in Red Claw Crayfish (Cherax quadricarinatus)

The effects of high hydrostatic pressure (treated with 200, 400 and 600 MPa) and storage temperatures (4 °C and −20 °C) on the fatty acids and flavor compounds of red claw crayfish were studied. HHP decreased the PUFA, GMP, IMP and AMP, citric and lactic acids, and PO43− contents, but the FAA, Ca2+ and Cl− contents increased in HHP-treated crayfish compared to untreated crayfish at 0 d. Storage at −20 °C could restrain the fatty acids and flavor contents compared to those stored at 4 °C. The GMP, AMP, citric acid and PO43− contents decreased, and Ca2+ and Cl− contents increased after storage at 4 °C for 15 d (p < 0.05). HHP at 200 and 400 MPa increased EUC on 0 d. No significant changes in EUC were observed after storage at −20 °C for 15 d, significant decreases were noted at 4 °C than the crayfish stored for 0 d (p < 0.05), except for the untreated group. Generally, HHP at 200 or 400 MPa, and storage at −20 °C is beneficial according to the shelling rates and EUC of crayfish.

Analysis of Alternative Shelf Life-Extending Protocols and Their Effect on the Preservation of Seafood Products

Seafood is essential to a healthy and varied diet due to its highly nutritious characteristics. However, seafood products are highly perishable, which results in financial losses and quality concerns for consumers and the industry. Due to changes in consumer concerns, demand for healthy products has increased. New trends focusing on reducing synthetic preservatives require innovation and the application of additional or alternative strategies to extend the shelf life of this type of product. Currently, refrigeration and freezing storage are the most common methods for fish preservation. However, refrigeration alone cannot provide long shelf-life periods for fish, and freezing worsens sensorial characteristics and consumer interest. Therefore, the need to preserve seafood for long periods without exposing it to freezing temperatures exists. This review focuses on the application of other approaches to seafood products, such as biodegradable films and coating technology; superchilling; irradiation; high-pressure processing; hyperbaric storage; and biopreservation with lactic acid bacteria, bacteriocins, or bacteriophages. The efficiency of these techniques is discussed based on their impact on microbiological quality, sensorial degradation, and overall preservation of the product’s nutritional properties. Although these techniques are already known, their use in the industrial processing of seafood is not widespread. Thus, the novelty of this review is the aggregation of recent studies on shelf life extension approaches, which provide useful information for the selection of the most appropriate technology and procedures and industrial innovation. Despite the fact that all techniques inhibit or delay bacterial proliferation and product decay, an undesirable sensory impact may occur depending on the treatment conditions. Although no technique appears to replace refrigeration, the implementation of additional treatments in the seafood processing operation could reduce the need for freezing, extending the shelf life of fresh unfrozen products.

Impact of High-Pressure Treatment on Amino Acid Profile, Fatty Acid Compositions, and Texture of Yellowfin Seabream (Acanthopagrus arabicus) Filets

This work describes the optimization of the pressure–time combination for the inactivation of Listeria monocytogenes in fish medium using a wide range of pressure (225–525 MPa) and holding time (5–30 min). Thereafter, the yellowfin seabream (Acanthopagrus arabicus) filets (100 g each) were subjected to high-pressure (HP) treatment at the optimum pressure/time combination, and the impact of HP on the amino acid profile, fatty acid profiles, color, and texture was assessed. Glycine, glutamic acid, and alanine were recorded as the major amino acids, which did not change significantly after pressurization. Conversely, alanine—the leading free amino acid—dropped significantly after treatment. The fatty acid analysis indicated that oleic acid and palmitic acid accounted for 29.88 and 25.59% of the total fatty acids, respectively. Pressurization did not influence the fatty acid profiles, nutritional quality indices, and hardness of yellowfin seabream fish. The color pigments of filets, measured as a* and b*, changed significantly after the treatment. Overall, this work indicates that HP treatment can be utilized to maintain the nutritional quality of seabream filets; however, further research is needed to maintain the visual color of the fish.

Protein sources influence both apparent digestibility and gastrointestinal evacuation rate in juvenile slipper lobster (Thenus australiensis)

Apparent digestibility and gastrointestinal evacuation rate were measured to assess the potential of five commercially available protein sources for their inclusion in feeds for juvenile slipper lobster, Thenus australiensis. Protein sources tested were fishmeal, krill meal, lupin meal, soybean meal and squid by-product meal. Apparent digestibility of crude protein ranged from 79.6% to 95.3%, with fishmeal protein significantly less digestible than lupin meal, squid by-product meal and soybean meal. Gastrointestinal evacuation rate was estimated from marker replacement, where yttrium oxide replaced ytterbium oxide. Faeces were collected every 3 h for 48 h, and a kinetic model was used to calculate the rate and time for the second marker to replace the first marker. Gastrointestinal evacuation (≥ 95%) was completed between 4 and 6 h with no significant differences among protein sources. Faeces consisted of both markers in equal parts 2.7 to 5.0 h after the feed switch, with lupin meal reaching the midpoint significantly faster than squid by-product meal and reference feed. The present study is the first in crustaceans to examine the relationship between apparent digestibility and gastrointestinal evacuation, showing more digestible protein sources had slower evacuation rates. The combined approach provides deeper insight into crustaceans' digestive physiology and helps understand their ability to digest specific ingredients. Further research is recommended to understand protein requirements in a broader context to verify highly digestible protein sources meet all nutritional requirements.

Effect of High Hydrostatic Pressure Treatment on Urease Activity and Inhibition of Fishy Smell in Mackerel (Scomber japonicus) during Storage

In this study, the physicochemical changes related to fishy smell were determined by storing high hydrostatic pressure (HHP)-treated mackerel (Scomber japonicus) meat in a refrigerator for 20 days. The inhibition of crude urease activity from Vibrio parahaemolyticus using HHP treatment was also investigated. The mackerel meat storage experiment demonstrated that production of trimethylamine (TMA) and volatile basic nitrogen (VBN), the main components of fishy smell, was significantly reduced on the 20th day of storage after the HHP treatment compared to the untreated mackerels. The results demonstrated that the increased ammonia nitrogen rates in the 2000, 3000, and 4000 bar, HHP-treated groups decreased by 23.8%, 23.8%, and 31.0%, respectively, compared to the untreated groups. The enzyme activity of crude urease was significantly reduced in the HHP-treated group compared to that in the untreated group. Measurement of the volatile organic compounds (VOCs) in mackerel meat during storage indicated that the content of ethanol, 2-butanone, 3-methylbutanal, and trans-2-pentenal, which are known to cause off-flavor due to spoilage, were significantly reduced by HHP treatment. Collectively, our results suggested that HHP treatment would be useful for inhibiting the activity of urease, thereby reducing the fishy smells from fish and shellfish.

Water holding properties of Atlantic salmon

With global seafood production increasing to feed the rising population, there is a need to produce fish and fishery products of high quality and freshness. Water holding properties, including drip loss (DL) and water holding capacity (WHC), are important parameters in determining fish quality as they affect functional properties of muscles such as juiciness and texture. This review focuses on the water holding properties of Atlantic salmon and evaluates the methods used to measure them. The pre- and postmortem factors and how processing and preservation methods influence water holding properties and their correlations to other quality parameters are reviewed. In addition, the possibility of using modelling is explained. Several methods are available to measure WHC. The most prevalent method is the centrifugation method, but other non-invasive and cost-effective approaches are increasingly preferred. The advantages and disadvantages of these methods and future trends are evaluated. Due to the diversity of methods, results from previous research are relative and cannot be directly compared unless the same method is used with the same conditions.

Effect of High-Pressure Processing on Physico-Chemical, Microbiological and Sensory Traits in Fresh Fish Fillets (Salmo salar and Pleuronectes platessa)

High-pressure (HP) treatment could lead to several advantages when applied to fish and seafood since it would affect the extension of the shelf life of this highly perishable food. In this regard, this study aimed to evaluate the effect of high-pressure treatment (500 MPa for 2 min at a temperature of 4 °C) on changes in quality on two different kinds of fresh fish fillets (Salmo salar and Pleuronectes platessa). Specifically, physico-chemical (VOCs, untargeted metabolomics spectra, pH and color), microbiological (Enterobacteriaceae, Pseudomonas spp., mesophilic and psychrotrophic bacteria) and sensory traits were evaluated at different days of refrigerated storage. From the results obtained, it is possible to state that the high pressure significantly (p ≤ 0.05) reduced microbial growth for each investigated microorganism. Regarding the colorimetric coordinates, no remarkable effects on a* and b* indices were found, while a significant effect (p = 0.01) was observed on the colorimetric index L*, making the HP-treated samples lighter than their respective controls. The sensory analysis showed that for the odor attribute, the HP treatment seems to have had a stabilizing action during shelf-life. Moreover, the treated samples obtained a better score than the respective controls (p ≤ 0.05). With regards to texture and appearance attributes, the treatment seems to have had a significant (p ≤ 0.05) effect, making the treated samples more compact and opaque than controls, therefore resulting in the loss of the characteristics of raw fish for the treated samples. Moreover, from a chemical point of view, HP treatment prevents the development of volatile sulfides and delays the formation of histamine (p ≤ 0.05). Very interestingly, the metabolomic approach revealed novel dipeptide markers for the HP procedure.

Effects of high-pressure treatment on the muscle structure of salmon (Salmo salar)

High pressure (HP) is a non-thermal treatment that is generally used to reduce the microbiological contamination of food products, such as Atlantic salmon (Salmo salar). However, HP is known to alter the stability of proteins and can therefore affect the quality of salmon flesh. In this study, the effects of HP treatment for 5 min at 200, 400 and 600 MPa on the structure of Atlantic salmon were investigated. Transversal histological sections revealed a decrease in the fibre size from 200 MPa associated with an expansion of the extracellular spaces. Connective tissue was found to be modified from 400 MPa, resulting in an increase in its surface area. Fourier transform infrared (FT-IR) microspectroscopy revealed a reduction in the α-helix content and an increase in the aggregated β-sheet structure content with increasing pressure, reflecting a change in the secondary structure of proteins from 200 MPa.

High-Pressure Processing for the Production of Added-Value Claw Meat from Edible Crab (Cancer pagurus)

High-pressure processing (HPP) in a large-scale industrial unit was explored as a means for producing added-value claw meat products from edible crab (Cancer pagurus). Quality attributes were comparatively evaluated on the meat extracted from pressurized (300 MPa/2 min, 300 MPa/4 min, 500 MPa/2 min) or cooked (92 °C/15 min) chelipeds (i.e., the limb bearing the claw), before and after a thermal in-pack pasteurization (F₉₀¹⁰ = 10). Satisfactory meat detachment from the shell was achieved due to HPP-induced cold protein denaturation. Compared to cooked or cooked-pasteurized counterparts, pressurized claws showed significantly higher yield (p < 0.05), which was possibly related to higher intra-myofibrillar water as evidenced by relaxometry data, together with lower volatile nitrogen levels. The polyunsaturated fatty acids content was unaffected, whereas the inactivation of total viable psychrotrophic and mesophilic bacteria increased with treatment pressure and time (1.1-1.9 log₁₀ CFU g^-1). Notably, pressurization at 300 MPa for 4 min resulted in meat with no discolorations and, after pasteurization, with high color similarity (ΔE* = 1.2-1.9) to conventionally thermally processed samples. Following further investigations into eating quality and microbiological stability, these HPP conditions could be exploited for producing uncooked ready-to-heat or pasteurized ready-to-eat claw meat products from edible crab.

Preliminary Evaluation of a Novel Microwave-Assisted Induction Heating (MAIH) System on White Shrimp Cooking

The microwave-assisted induction heating (MAIH) system provides comprehensive heating by combining microwave heating (with 1300 W of power and 2450 MHz of frequency) in the top part and induction heating (with 1800 W of power) in the bottom part. In this study, fresh white shrimps were placed in a sealed crystallized polyethylene terephthalate (CPET) container and heated in the MAIH system at two temperatures (130 and 90 °C) from 60 to 120 s. Afterwards, the shrimp samples were rapidly cooled, and the changes in the shrimp quality, including the appearance, cook loss, aerobic plate count (APC), color values, and texture, during the heating process were analyzed. The results demonstrate that longer heating times decrease the APC levels, but increase the cook loss, color values (lightness, redness, and whiteness), and texture (hardness, cohesiveness and chewiness) of the white shrimp samples. In particular, the white shrimp is fully cooked and gains a completely red appearance, along with no APC detected after heating in the MAIH system at 130 °C for at least 80 s or at 90 °C for at least 100 s. In summary, to achieve a good appearance, no APC detected, and low cook loss, the following heating conditions are recommended for cooking white shrimp in the MAIH system: heating at 130 °C for 80 s or at 90 °C for 100 s. This novel MAIH technology allows food to be heated and sterilized after being packed, thereby eliminating the post-pollution issue. To the best of the authors’ knowledge, this is the first study to evaluate the use of MAIH in the application of food processing.

Non-Thermal Methods for Ensuring the Microbiological Quality and Safety of Seafood

A literature search and systematic review were conducted to present and discuss the most recent research studies for the past twenty years on the application of non-thermal methods for ensuring the microbiological safety and quality of fish and seafood. This review presents the principles and reveals the potential benefits of high hydrostatic pressure processing (HHP), ultrasounds (US), non-thermal atmospheric plasma (NTAP), pulsed electric fields (PEF), and electrolyzed water (EW) as alternative methods to conventional heat treatments. Some of these methods have already been adopted by the seafood industry, while others show promising results in inactivating microbial contaminants or spoilage bacteria from solid or liquid seafood products without affecting the biochemical or sensory quality. The main applications and mechanisms of action for each emerging technology are being discussed. Each of these technologies has a specific mode of microbial inactivation and a specific range of use. Thus, their knowledge is important to design a practical application plan focusing on producing safer, qualitative seafood products with added value following today’s consumers’ needs.

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.

Effect of High Hydrostatic Pressure Processing on the Chemical Characteristics of Different Lamb Cuts

The non-thermal high-pressure processing (HPP) technique has been used to increase the shelf life of food without compromising their nutritional and sensory qualities. This study aims to explore the potential application of HPP on New Zealand lamb meat. In this study, the effect of HPP, at different pressure treatments (200-600 MPa) on eight different lamb meat cuts in terms of lipid oxidation, fatty acid and free amino acid content were investigated. In general treatments between 400 and 600 MPa resulted in higher oxidation values in eye of loin, flat, heel, and tenderloin cuts. Saturated and monounsaturated fatty acid content were significantly lower with HPP treatment of almost all cuts (except rump and heel cuts) at all pressures. Polyunsaturated fatty acid content was significantly lower in HPP-treated inside, knuckle, and tenderloin cuts at 600 MPa compared to control. Nine essential free amino acids (valine, leucine, isoleucine, methionine, phenylalanine, lysine, histidine, tyrosine and tryptophan), and eight non-essential free amino acids (alanine, glycine, threonine, serine, proline, aspartic acid, glutamic acids and ornithine) were identified in the lamb cuts. HPP increased the total free amino acid composition significantly compared to control at all pressures for almost all cuts except the inside and eye of loin cuts. This study suggests that higher pressure treatments (i.e., 400 and 600 MPa) resulted in higher TBARS oxidation levels. Additionally, significant decreases in saturated and monounsaturated fatty acids and increase free amino acid content were observed in the majority of HPP-treated samples compared to control.

Physiological status and nutritional condition of cultured juvenile Thenus australiensis over the moult cycle

The moult cycle is arguably the most critical aspect of crustacean biology and is associated with dramatic changes in behaviour, physiology and condition. Here we describe the first detailed investigation of the combined changes in morphology, physiological status and nutritional condition over the moult cycle of juvenile T. australiensis. Haemolymph refractive index (measured as Brix) was evaluated as a non-destructive method for predicting physiological status and nutritional condition. Post-moult, inter-moult and pre-moult stages were identifiable by microscopic examination of the pleopod distal tips, though differentiation of the pre-moult substages was not possible using this technique. Monitoring of ecdysial suture lines on the exoskeleton gill chambers was found to be highly useful for visually determining progression through the pre-moult stage and predicting the timing of ecdysis. A classical pattern of inter-moult growth was observed where size and wet weight remained relatively uniform over the moult cycle while highly significant changes in whole-body composition were simultaneously observed over time. Growth was most evident by changes in dry weight and dry matter content which more than doubled by the onset of pre-moult. Changes in dry matter content were generally mirrored by Brix and whole-body crude protein, total lipid and gross energy content. Brix strongly correlated with dry matter content and significant correlations were also found for all other primary measures of nutritional condition. Typical moult-related changes were also found for circulating ecdysteroids. This study clearly demonstrates pronounced cyclical changes in physiology and condition of juvenile T. australiensis over a typical moult cycle. The significant correlations between haemolymph and whole-body composition validates Brix as a practical and non-destructive method to objectively assess physiological status, nutritional condition and quality in T. australiensis and further demonstrates its potential for individual crustacean assessment in experimental research and practical commercial applications.

Effect of high pressure processing on the microstructure, myofibrillar protein oxidation, and volatile compounds of sauce lamb tripe

In this study, sauce lamb tripe was used as the research object. High pressure processing (HPP) was carried out at 100, 250, and 400 MPa, with holding times of 5, 10, 15, 20, and 25 min at 25 °C, respectively. The effects of HPP on the microstructure and volatile compound content of sauce lamb tripe and the properties of myofibrillar protein were studied. The degree of protein oxidation was most significant at 400 MPa for 25 min. The secondary structure of myofibrillar protein became unstable and the microstructure of the sauce lamb tripe became loose at 400 MPa. The retention of hydrocarbons, aldehydes, alcohols, and ketones was maximum at 250 MPa for 15 min, and the flavor-contributing compound (3-Hydroxy-2-butanone) was also retained by 11.9% on ketones at 250 MPa for 15 min. The results showed that myofibrillar protein was appropriately oxidized; the sauce lamb tripe had better microstructure and several representative volatile compounds after HPP. Therefore, better processing conditions for sauce lamb tripe were 250 MPa for 15 min.

Combined Treatments of High Hydrostatic Pressure and CO2 in Coho Salmon (Oncorhynchus kisutch): Effects on Enzyme Inactivation, Physicochemical Properties, and Microbial Shelf Life

This study focused on applying different high hydrostatic pressure + carbon dioxide (HHP + CO2) processing conditions on refrigerated (4 °C, 25 days) farmed coho salmon (Oncorhynchus kisutch) to inactivate endogenous enzymes (protease, lipase, collagenase), physicochemical properties (texture, color, lipid oxidation), and microbial shelf life. Salmon fillets were subjected to combined HHP (150 MPa/5 min) and CO2 (50%, 70%, 100%). Protease and lipase inactivation was achieved with combined HHP + CO2 treatments in which lipase activity remained low as opposed to protease activity during storage. Collagenase activity decreased approximately 90% during storage when applying HHP + CO2. Combined treatments limited the increase in spoilage indicators, such as total volatile amines and trimethylamine. The 150 MPa + 100% CO2 treatment was the most effective at maintaining hardness after 10 days of storage. Combined treatments limited HHP-induced color change and reduced the extent of changes caused by storage compared with the untreated sample. Microbial shelf life was extended by the CO2 content and not by the HHP treatments; this result was related to an increased lag phase and decreased growth rate. It can be concluded that combining HHP and CO2 could be an effective method of inactivating endogenous enzymes and extend salmon shelf life.

Effect of High-Pressure Processing (HPP) on the Fatty Acid Profile of Different Sized Ragworms (Hediste diversicolor) Cultured in an Integrated Multi-Trophic Aquaculture (IMTA) System

Ragworms (Hediste diversicolor) cultured under integrated multi-trophic aquaculture (IMTA) conditions display an improved fatty acids (FA) profile than conspecifics from the wild, thus being more suitable for maturation diets of marine fish and shrimp. Nonetheless, their use may represent a potential pathway for pathogens. The objective of the present study was to determine if high-pressure processing (HPP), as an approach to safeguard microbiological safety, could promote significant shifts on the FA profiles of different sized ragworms. An analysis of similarities (ANOSIM) revealed the existence of significant differences in the FA profile and lipid quality indexes (atherogenicity (AI), thrombogenicity (TI) and polyene (PI)) of control and HPP treated ragworms of all tested sizes (small, medium and large). Saturated (SFA) and monounsaturated FA (MUFA) increased after HPP, while polyunsaturated FA (PUFA; FA with 2 or 3 double bonds) and highly unsaturated FA (HUFA; FA with ≥ 4 double bonds) decreased. The amount of docosahexaenoic acid (DHA) in polychaetes exposed to HPP decreased an average of 25%, when compared with the levels recorded in control groups. The values of PI significantly decreased after HPP, while those of AI and TI displayed a significant increase. Despite the shifts in the FA profile of ragworms exposed to HPP, these still display a superior profile to that of wild specimens, namely the presence of DHA. Therefore, HPP can be considered as a suitable approach to safeguard the biosecurity of cultured polychaetes, without compromising their nutritional value, and support the principles of circular economy through the use of IMTA.

Physicochemical Properties and Consumer Acceptance of High-Pressure Processed, Sous Vide-Cooked Lobster Tails

Sous vide (SV) and high-pressure processing (HPP) are promising techniques in the development of high-quality seafood products. The objectives of this study were to evaluate the impacts of HPP on the physicochemical quality and consumer acceptance of subsequently SV-cooked lobster tails. Raw shucked lobster tails were processed at 150 or 350 MPa for 5 or 10 min. Subsequently, half were SV cooked to a core temperature of 65 °C/10 min. Texture profile analysis, shear force, color, salt soluble protein content, water-holding capacity (WHC), moisture content, and weight loss were analyzed. Pressurization at 150 MPa/10 min decreased (P < 0.05) the hardness of raw lobsters compared to non-HPP-treated controls. However, 350 MPa for 5 or 10 min increased (P < 0.05) the shear force in raw and SV-cooked samples. HPP increased (P < 0.05) the L^* values but did not affect moisture content, WHC, or weight loss of raw or SV-cooked lobsters. Lobsters were subjected to consumer acceptability testing using a 9-point hedonic scale. Although panelists rated the flavor, texture, and overall liking of the 350 MPa/10 min samples higher than the control and 150 MPa/10 min samples, there were no significant differences among treatment means, indicating that physicochemical changes induced by HPP did not affect consumer acceptance. In addition, approximately 84% of panelists reported that the 350 MPa product met their expectations compared to approximately 75% for the control and 150 MPa treatments. These results suggest that HPP has the potential to be applied in combination with SV cooking to produce consumer-acceptable, value-added lobster products. PRACTICAL APPLICATION: Lobsters are an expensive menu item in restaurants. However, they are susceptible to being overcooked using conventional methods, producing a tough and rubbery texture. Sous vide cooking is reported to provide evenly cooked lobsters with a succulent and juicy texture. In this study, lobsters were sous vide cooked to reach a core temperature of 65 °C, and then maintained at that temperature for 10 min. The application of moderate processing pressures to vacuum-packaged raw lobsters prior to SV cooking altered some physicochemical attributes but has the potential to increase the availability of high-quality, minimally processed seafood with good consumer acceptability.

Effects of high hydrostatic pressure-assisted thawing on the physicohemical characteristics of silver pomfret (Pampus argenteus)

Effects of high hydrostatic pressure-assisted thawing (HPAT, 100, 150, and 200 MPa) on the physicochemical characteristics of silver pomfret were evaluated in comparison with conventional (water immersion thawing, WIT) thawed samples. HPAT significantly decreased the thawing time, as well as the cooking and total losses. The maximum water holding capacity was observed at 100 MPa. Color changed obviously at ≥150 MPa, resulting in a cooked appearance. Samples thawed with HPAT showed better texture quality and lower lipid oxidation. The levels of myofibrillar protein oxidation and surface hydrophobicity increased, while Ca2+-ATPase activities decreased as the pressure increased. The oxidation of myofibrillar protein was significantly decreased at 100 MPa; total sulfhydryl content was 30.85% higher than that of WIT. Overall, 100 MPa is the optimum treatment condition for silver pomfret thawing without negative effects on quality of the product. HPAT can be a potential alternative to produce high-quality thawed fish.

Selective laser broiling of Atlantic salmon

Selective laser broiling is a novel food processing technique that utilizes a 2-axis mirror galvanometer system to direct laser power to cook raw food. Unlike conventional cooking processes, laser cooking benefits from the high spatial and temporal precision of power delivery. In this investigation, we use a trochoidal scanning pattern to optimize the cooking of Atlantic salmon (Salmo salar), which is used as a model food system. We vary geometry of the trochoidal cooking pattern (circle diameter, circle density, and period) as well as the heat flux (2.71 MW/m² and 0.73 MW/m²) and power (2 W and 5 W) of the blue laser and measure the internal temperature and depth of heat penetration via color analysis. Heat generated by blue laser operating at 445 nm has a thermal penetration depth nearing 2 mm in salmon and provide sufficient protein denaturation for cooking thin food layers. We achieve food safe cooking temperatures (>62.8 °C) in the salmon fillets and desirable color and textural changes through the use of high speeds and repetitive exposure. Ultimately, the goal of this study is to explore laser cooking of meat with an eye to applications both in food printing as well as an augmentation of conventional oven cooking.

Changes to the tropomyosin structure alter the angiotensin-converting enzyme inhibitory activity and texture profiles of eel balls under high hydrostatic pressure

Changes in the structure of tropomyosin (TM) altered the texture profiles of eel balls and the inhibitory activity of the angiotensin-converting enzyme (ACE). The secondary and tertiary structure of TM was determined after high hydrostatic pressure (HHP) treatment. The correlation between the spatial structure of TM and the texture profiles of eel balls was developed and discussed. The β-sheet was converted to a β-turn and a random coil when treated at HHP (200-400 MPa), meanwhile the α-helix unfolded and was converted into a β-sheet, β-turn and a random coil with treatment at 500 and 600 MPa. The surface hydrophobicity (H0) was increased and the sulfhydryl (SH) content decreased with an increase in the pressure. The results indicated that the texture profiles of eel balls showed a negative relationship with the α-helix, β-sheet and SH content. The texture profiles of eel balls were greatly enhanced after treatment at 500 and 600 MPa, leading to the improved surface network of the eel ball products. The ACE inhibitory activity of TM after HHP treatment exhibited a positive relationship with the β-sheet content in the protein. The ACE inhibitory activity was preserved under 600 MPa.

Principles and recent applications of novel non-thermal processing technologies for the fish industry-a review

Thermal treatment is a traditional method for food processing, which can kill microorganisms but also lead to physicochemical and sensory quality damage, especially to temperature-sensitive foods. Nowadays consumers' increasing interest in microbial safety products with premium appearance, flavor, great nutritional value and extended shelf-life has promoted the development of emerging non-thermal food processing technologies as alternative or substitution to traditional thermal methods. Fish is an important and world-favored food but has a short shelf-life due to its extremely perishable characteristic, and the microbial spoilage and oxidative process happen rapidly just from the moment of capture, making it dependent heavily on post-harvest preservation. The applications of novel non-thermal food processing technologies, including high pressure processing (HPP), ultrasound (US), pulsed electric fields (PEF), pulsed light (PL), cold plasma (CP) and ozone can extend the shelf-life by microbial inactivation and also keep good sensory quality attributes of fish, which is of high interest for the fish industry. This review presents the principles, developments of emerging non-thermal food processing technologies, and also their applications in fish industry, with the main focus on microbial inactivation and sensory quality. The promising results showed great potential to keep microbial safety while maintaining organoleptic attributes of fish products. What's more, the strengths and weaknesses of these technologies are also discussed. The combination of different food processing technologies or with advanced packaging methods can improve antimicrobial efficacy while not significantly affect other quality properties under optimized treatment.

Effect of high-pressure processing pretreatment on the physical properties and colour assessment of frozen European hake (Merluccius merluccius) during long term storage

Fish freshness is lost by autolytic degradation produced by endogenous enzymes. Frozen storage is one of the most used methods to preserve fish properties. However, protein denaturation has shown to be a major problem for frozen European hake (Merluccius merluccius), leading to texture losses and off-odour development. The aim of this work was to study the changes produced by high-pressure processing (HPP) before freezing on quality of frozen European hake stored at -21 °C for 12 months. The effect of HPP (150-450 MPa) on mechanical properties and expresible water was evaluated in raw and cooked fish samples. The effect on colour (L*, a* and b*) was assessed only in raw fish. Results showed that HPP before freezing is beneficial to maintain expresible water in good levels up to 6 months. The luminosity significantly increased with pressure level. Textural profile of raw samples showed that HPP increased hardness, adhesiveness and springiness of frozen hake. Cooked samples were also affected by HPP, being the best results obtained at 300 MPa for 6 months of frozen storage. Overall, results showed that HPP improves the quality of frozen hake.