Lipid hydrolysis and oxidation development in frozen mackerel (Scomber scombrus): Effect of a high hydrostatic pressure pre-treatment

The Effect of Low Temperature Storage on the Lipid Quality of Fish, Either Alone or Combined with Alternative Preservation Technologies

Marine foods are highly perishable products due to their high content of polyunsaturated fatty acids, which can be readily oxidized to form peroxides and secondary oxidation products, thus conferring such foods undesirable organoleptic characteristics and generating harmful compounds that are detrimental to the health of consumers. The use of preservation methods that minimize lipid oxidation is required in the fishing and aquaculture industries. Low temperature storage (chilling or freezing) is one of the most commonly used preservation methods for fish and seafood, although it has been shown that the oxidation of the lipid fraction of such products is partially but not completely inhibited at low temperatures. The extent of lipid oxidation depends on the species and the storage temperature and time, among other factors. This paper reviews the effect of low temperature storage on the lipid quality of fish, either alone or in combination with other preservation techniques. The use of antioxidant additives, high hydrostatic pressure, irradiation, ozonation, ultrasounds, pulsed electric fields, and the design of novel packaging can help preserve chilled or frozen fish products, although further research is needed to develop more efficient fish preservation processes from an economic, nutritional, sensory, and sustainable standpoint.

Effect of Rigor Stage and Pressurisation on Lipid Damage, Total Volatile Amine Formation and Autolysis Development in Palm Ruff Stored on Ice

The effect of the rigor stage (pre or post) and previous high-pressure processing (HPP; 450 and 550 MPa for 3 min) was checked during the storage on ice of farmed palm ruff (Seriolella violacea). Fish processed in pre-rigor conditions led to higher and lower levels (p < 0.05) of moisture and lipid contents in chilled fish, respectively, when compared to their counterpart samples processed in the post-rigor stage. Pre-rigor fish showed a higher (p < 0.05) quality level than post-rigor samples according to the assessment of the K value (59.0-92.1 and 70.3-96.3 ranges, respectively), fluorescent compounds (0.29-1.11 and 0.37-1.90 ranges, respectively), free fatty acids (FFA) (15.1-188.0 and 33.8-232.5 g·kg^-1 lipids ranges, respectively), and total volatile amines (216.3-387.6 and 217.7-412.2 g·kg^-1 muscle ranges, respectively). Pressure-treated fish showed higher (p < 0.05) quality retention than non-treated samples according to the formation of fluorescent compounds (0.29-0.86 and 0.85-1.90 ranges, respectively), FFA (15.1-50.6 and 58.9-223.5 g·kg^-1 lipids ranges, respectively), and total volatile amines (216.3-250.3 and 351.1-412.2 g·kg^-1 muscle ranges, respectively) and the evolution of the K value (59.0-77.2 and 86.9-96.3 ranges, respectively). The use of pre-rigor fish and previous HPP is recommended for the commercialisation of the current species as a fresh product.

Effects of High-Voltage Atmospheric Cold Plasma Treatment on Microbiological and Quality Characters of Tilapia Fillets

Cold plasma (CP) has become an alternative to conventional thermal processing of food products. In this study, the effect of cold plasma treatment time on the inactivation and quality of tilapia fillets was investigated. The surfaces of tilapia fillets were inoculated with Salmonella enteritis (S. enteritis), Listeria monocytogenes (L. monocytogenes), and a mixture of both before being treated with cold plasma at 70 kV for 0, 60, 120, 180, 240, and 300 s. With the extension of treatment time, the number of colonies on the surface of the fillets decreased gradually; after 300 s of cold plasma treatment, S. enteritis and L. monocytogenes populations were reduced by 2.34 log CFU/g and 1.69 log CFU/g, respectively, and the a* value and immobile water content decreased significantly (p < 0.05), while the free water content increased significantly (p < 0.05). TBARS value increased significantly (p < 0.05) to 1.83 mg MDA/kg for 300 s treatment. The carbonyl value and sulfhydryl value of sarcoplasmic protein significantly (p < 0.05) increased and decreased, respectively, as treatment time extension, while no significant changes were found in myofibrillar protein. No significant differences were observed in pH, b* value, elasticity, chewiness, thiol value, and TVB-N value. The results showed that cold plasma had an inactivation effect on tilapia fillets and could preserve their original safety indicators. It was concluded that CP treatment could be used as an effective non-thermal method to maintain the quality of tilapia fillets and extend their shelf-life.

Effect of High-Pressure Processing on Fresh Sea Urchin Gonads in Terms of Shelf Life, Chemical Composition, and Microbiological Properties

Paracentrotus lividus is a widespread sea urchin species appreciated worldwide for the taste of its fresh gonads. High-pressure processing (HPP) can provide a thermal equivalent to pasteurization, maintaining the organoleptic properties of the raw gonads. This study evaluated HPP technology’s effect at 350 MPa and 500 MPa on microbial inactivation and biochemical characteristics of P. lividus gonads. HPP at 350 MPa resulted in a higher decrease in protein and free amino acids associated with a loss of olfactory, color, and gustatory traits and a visual alteration of the texture. On the other hand, gonad samples stored for 40 days after treatments at 500 MPa showed a good organoleptic profile similar to fresh gonads. Furthermore, only 500 MPa effectively reduced mesophilic bacteria contamination among the two HPP treatments carried out. Total lipids increased during storage; however, the SAFA/PUFA rate was homogeneous during HPP trials ranging from 2.61–3.91 g/100 g. Total protein decreased more than 40% after HPP at 350 MPa, whereas, after 500 MPa, it remained stable for 20 days. The amount of free amino acid constantly decreased during storage after HPP at 350 MPa and remained constant at 500 MPa. HPP can effectively remove the bacterial flora and inactivate enzymes, maintaining the properties of the fresh sea urchin gonads.

Optimisation of Healthy-Lipid Content and Oxidative Stability during Oil Extraction from Squid (Illex argentinus) Viscera by Green Processing

Green extraction was applied to Argentinean shortfin squid (Illex argentinus) viscera, consisting of a wet pressing method including a drying step, mechanic pressing, centrifugation of the resulting slurry, and oil collection. To maximise the oil yield and ω3 fatty acid content and to minimise the oil damage degree, a response surface methodology (RSM) design was developed focused on the drying temperature (45-85 °C) and time (30-90 min). In general, an increase of the drying time and temperature provided an increase in the lipid yield recovery from the viscera. The strongest drying conditions showed a higher recovery than 50% when compared with the traditional chemical method. The docosahexaenoic and eicosapentaenoic acid contents in the extracted oil revealed scarce dependence on drying conditions, showing valuable ranges (149.2-166.5 and 88.7-102.4 g·kg^-1 oil, respectively). Furthermore, the values of free fatty acids, peroxides, conjugated dienes, and ω3/ω6 ratio did not show extensive differences by comparing oils obtained from the different drying conditions. Contrary, a polyene index (PI) decrease was detected with increasing drying time and temperature. The RSM analysis indicated that optimised drying time (41.3 min) and temperature (85 °C) conditions would lead to 74.73 g·kg^-1 (oil yield), 1.87 (PI), and 6.72 (peroxide value) scores, with a 0.67 desirability value.

High-pressure pretreatment in albacore (Thunnus alalunga) for reducing freeze-driven weight losses with minimal quality changes

BACKGROUND

This research evaluates the application of high-pressure processing (HPP) before freezing to reduce weight loss related to thawing and cooking of frozen albacore steaks (Thunnus alalunga) with a minimal impact on fish quality (color, texture, soluble protein, lipid oxidation). Albacore steaks were HPP pretreated (200, 250, and 300 MPa for 0, 2, 4 and 6 min), frozen (-20 °C, 5 m s^-1 ), thawed (4 °C; 24 h), and then analyzed.

RESULTS

At lower pressures (200 MPa) there was a clear effect of pressurization time on most of the fish quality parameters tested (thawing loss, L* value, b* value, ΔE, adhesiveness, springiness, salt-soluble protein content), whereas at higher pressures (300 MPa) similar changes took place independently of the pressurization time. High-pressure processing had no impact on lipid oxidation . A pressure of 200 MPa applied for 6 min decreased thawing, cooking, and total weight losses (53.7%, 55.4%, and 51.0% lower than the frozen control, respectively) although it led to noticeable changes in color. A pressure of 200 MPa applied for 2 min decreased thawing, cooking, and total weight losses by 23.2%, 44.0% and 33.7% with respect to the frozen control, respectively, with only minor changes in color.

CONCLUSION

High-pressure processing pretreatment could be a promising tool for reducing weight loss in frozen fish when HPP conditions are properly selected. A pressure of 200 MPa applied for 2 min could be a good compromise treatment, cutting thawing and cooking losses in albacore, and reducing HPP-mediated color alterations and the related possible consumer rejection. © 2020 Society of Chemical Industry.

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.

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.

Effect of incorporation of natural chemicals in water ice-glazing on freshness and shelf-life of Pacific saury (Cololabis saira) during -18 °C frozen storage

BACKGROUND

Microbial spoilage and lipid oxidation are two major factors causing freshness deterioration of Pacific saury (Cololabis saira) during frozen storage. To provide a remedy, the effects of several natural chemicals incorporated alone or in combination in traditional water ice-glazing on the freshness and shelf-life of Pacific saury during frozen storage at -18 °C were investigated. Pacific sauries were subjected to individual quick freezing followed immediately by dipping into cold tap water (control) or solutions containing nisin, chitosan, phytic acid (single-factor experiment) or their combinations ((L₉ (3⁴ ) orthogonal experiment) for 10 s at 1 °C and then packaged in polypropylene bags before frozen storage at -18 °C. The storage duration tested was up to 12 months.

RESULTS

All ice-glazing treatments with individual chemicals could significantly (P < 0.05) inhibit the accumulation of thiobarbituric acid-reactive substances (TBARS), total volatile basic nitrogen (TVB-N) and histamine as well as the increase in bacterial total viable count (TVC) compared with controls, while the combination treatments gave even better effects. The L₉ (3⁴ ) orthogonal experiment showed that the optimal combination was A₂ B₁ C₂ (i.e. 0.5 g L^-1 nisin, 5 g L^-1 chitosan and 0.2 g L^-1 phytic acid). The TBARS, TVB-N, histamine and TVC values in A₂ B₁ C₂ -treated samples remained far below the maximum acceptable limit for good-freshness fish after 12 months of frozen storage at -18 °C.

CONCLUSION

The incorporation of natural chemicals tested herein in ice-glazing could inhibit microbial spoilage and lipid oxidation and therefore maintain the freshness of Pacific saury during frozen storage. Under the optimal conditions, the shelf-life of Pacific saury could be extended up to 12 months at -18 °C. The study indicated that the combination treatment with natural chemicals could be commercially utilized to maintain the freshness and prolong the shelf-life of Pacific saury. © 2017 Society of Chemical Industry.

Effect of frozen-storage period on quality of American sirloin and mackerel (Scomber japonicus)

This study aimed to study the effect of frozen-storage period on the quality of sirloin and mackerel (Scomber japonicus). The samples were evaluated after being kept in frozen storage at -17.9 °C for different periods of time (1, 8, 15, 22, and 29 days). The frozen storage resulted in increase in ice crystal formation on the surface of both sirloin and mackerel. Frozen-storage period had an effect on the increase in the drip loss of both sirloin and mackerel with a positive correlation (p < 0.05) as well as on the decrease in the hardness of sirloin with a negative correlation (p < 0.05). During the frozen-storage period, the 2-thiobarbituric acid reactive substance level was increased in mackerel while the level in sirloin was maintained; both levels were within safe limits. Consequently, a 29-day freezing period is postulated to have little effect on the quality of sirloin and mackerel.