Smoking of Fish and Seafood: History, Methods and Effects on Physical, Nutritional and Microbiological Properties

Applications of Near-Infrared Spectroscopy for Nondestructive Quality Analysis of Fish and Fishery Products

Fish has become one of the most popular aquatic products for its beneficial effects. The quality of fish and fishery products may be influenced by their geographical origin, transportation, processing, and storage conditions. The availability of rapid and reliable techniques is important for nondestructive determination of their quality. Recently, near-infrared spectroscopy (NIRS) has been widely employed in the nondestructive evaluation of fish and fishery products. However, a comprehensive review on NIRS for this topic remains to be published. Based on this demand, the applications of NIRS in the nondestructive evaluation of fish and fishery products have been discussed in this review. This review firstly introduces the fundamentals of NIRS. Then the application of NIRS for the assessment of species, geographical origin, adulteration, freshness, nutrient components, and texture is summarized. In addition, the application of near-infrared hyperspectral imaging technology in fish and fishery products is also discussed. Finally, the challenges and prospects are outlined. The current review may provide a reference for research on NIRS in this field. In the future, NIRS could be used for online assessment of quality attributes in the fish industry through the development of new instruments and chemometrics.

Identification and quantification of flavor compounds in smoked tuna fish based on GC-Orbitrap volatolomics approach

Cold smoking enhances the appeal of fish products, offering consumers a smooth texture and a delicate smoky flavor. This study aims to explore variations in the volatile profile from different exposure times during cold smoking processing (light, moderate, and full-cure) in tune samples. An innovative untargeted analytical approach, headspace solid-phase microextraction combined with gas chromatography and a hybrid quadrupole-orbitrap mass analyzer, was employed to identify 86 volatiles associated with the cold smoking process. Most of these compounds, including phenols, furan derivates, aldehydes, cyclic ketones, and different aromatic species, were found to contribute to the smoke odor. The development of a QuEChERS-based extraction and clean-up method facilitated the quantification of 25 relevant smoky markers across all smoking degrees, revealing significant concentration differences after 15 h of smoking. This research sheds light on the dynamics of cold smoking impact and its on the flavor profile and safety quality of processed fish products.

Chitosan edible coating: a potential control of toxic biogenic amines and enhancing the quality and shelf life of chilled tuna filets

Edible films and coatings offer great potential to support sustainable food production by lowering packaging waste, extending product shelf life, and actively preserving food quality. Using edible coatings containing plant extracts with antioxidant and antibacterial characteristics could help to enhance the quality and shelf life of fish products. In this study, the combination effect of chitosan with beetroot, curcumin, and garlic extracts on biogenic amines (BAs) reduction, biochemical quality [pH, thiobarbituric acid index (TBA), trimethylamine (TMA), and total volatile base (TVB)], shelf life and sensory characteristics of tuna filets was investigated over 14 days of refrigerated storage compared to control (uncoated) samples. The results showed that the coated samples experienced a lower increase in BAs levels than the control samples. Among the treated samples, chitosan incorporated with curcumin (CH-C) showed the highest reduction in BAs formation (1.45 – 19.33, 0.81 – 4.45, and 1.04 – 8.14 mg/kg), followed by chitosan with garlic (CH-G) (1.54 – 21.74, 0.83 – 5.77, and 1.08 – 8.84 mg/kg), chitosan with beetroot extract (CH-B) (1.56 – 31.70, 0.84 – 6.79, and 1.07 – 10.82 mg/kg), and chitosan without extract addition (CH) (1.62 – 33.83, 0.71 – 7.82 and 1.12 – 12.66 mg/kg) compared to control samples (1.62 – 59.45, 0.80 – 11.96, and 1.14 – 20.34 mg/kg) for histamine, cadaverine, and putrescine, respectively. In addition, the rate of increase in pH, TBA, TMA, and TVB of all coated treatments was lower than in the control samples. Sensory evaluation results revealed that chitosan-treated samples incorporated with beetroot, garlic, and curcumin extracts showed good quality and acceptability characteristics. Overall, chitosan edible coatings incorporated with beetroot, garlic, and curcumin extracts reduced the formation of biogenic amine, delayed biochemical deterioration, and extended the shelf life of tuna filets. Among the treated samples, CH-C demonstrated a remarkable superiority in all the studied parameters. Therefore, this study provides a promising strategy for the incorporation of active compounds in edible coatings to improve the quality and safety of foods during storage.

A Risk-Benefit Analysis of First Nation's Traditional Smoked Fish Processing

First Nations (FN) communities have traditionally used smoke to preserve fish for food security purposes. In this study, an assessment of chemical and microbiological food safety, together with nutritional quality, was conducted on fish preserved using traditional smoke processing. High-molecular-weight polycyclic aromatic hydrocarbons (PAH) residues accounted for only 0.6% of the total PAH in traditionally fully smoked salmon, and Benzo(a)pyrene (B(a)P) was not detected in the FN smoked or commercial smoked fish, respectively. The antimicrobial activity of the solvent extracts derived from smoked fish towards Listeria innocua was very low but detectable. The practice of using full and half-smoked processing for fish reduced all of the fatty acid concentrations and also minimized the further loss of essential omega-3 fatty acids to a greater extent than non-smoked fish during storage (p < 0.05). This finding corresponded to lower (p < 0.05) lipid oxidation in smoked fish. We conclude that the benefits of reducing lipid oxidation and retaining essential fatty acids during storage, together with a potentially significant reduction in Listeria contamination, are notable benefits of traditional smoke processing. Although B(a)P was not detected in FN smoked fish, attention should be given to controlling the temperature and smoking period applied during this processing to minimize potential long-term risks associated with PAH exposure.

Effect of dry salt versus brine injection plus dry salt on the physicochemical characteristics of smoked salmon after filleting

Smoked fish fillets are pre-salted as a food conservation and quality preservation measure. Here we investigated biochemical and sensory aspects of smoked salmon fillets. Left-side salmon fillets were dry-salted while the right-side fillets underwent a mixed salting method consisting of an injection of saturated brine followed by surface application of dry salt. After 6 h of salting, all the fillets were smoked. At each step of the process, quality was evaluated using instrumental measurements (pH, color, texture, water content, salt content, a_w), and lipid distribution was visualized by MRI. Mixed-salted fillets had a higher salt content than dry-salted fillets and variability in salt distribution was dependent on the salting process. However, these variations had no effect on pH, color or texture, which showed similar values regardless of salting method. Fatty areas had a lower salt content due to slower diffusion of aqueous salt solutions through them. Mixed salting speeds up the salting of the muscle without significantly affecting the quality traits of the salmon fillet.

Effects of Spray-Drying and Freeze-Drying on Bioactive and Volatile Compounds of Smoke Powder Food Flavouring

Transforming liquid smoke to powder form can provide convenience for use and storage. Liquid smoke was prepared by fast pyrolysis technology using a fluidised bed and converted to smoke powder by spray-drying or freeze-drying processes. Both drying processes effectively retained the bioactive compounds in the powder encapsulates with retention efficiencies up to 80%. The bioactive capacities were approximately two times higher than liquid smoke. Spray-drying did not induce thermal damage to the bioactive compounds, and the dominant compounds were retained in the powders. Gas chromatography–mass spectrometry and principal component analysis indicated that the chemical composition was not significantly changed after both drying methods, but small molecular carbonyls, furans and phenols were partially lost. The spray-dried particles had a spherical shape, while freeze-dried particles had irregular shapes because of different powder preparation methods. The particle size of spray-dried powders was in the range of 6.3 to 6.9 µm, while the value for freeze-dried powders was decreased from 580.4 to 134.7 µm by increasing the maltodextrin concentration. The freeze-dried powders performed better in terms of flowability and cohesiveness because of their relatively high density and large particle size. This study revealed that both encapsulation methods could efficiently prepare smoke powder. Spray-drying process would be suitable for large-scale production, while freeze-drying could be used to optimize the encapsulation efficiency of bioactive compounds.

Mild processing of seafood-A review

Recent years have shown a tremendous increase in consumer demands for healthy, natural, high-quality convenience foods, especially within the fish and seafood sector. Traditional processing technologies such as drying or extensive heating can cause deterioration of nutrients and sensory quality uncompilable with these demands. This has led to development of many novel processing technologies, which include several mild technologies. The present review highlights the potential of mild thermal, and nonthermal physical, and chemical technologies, either used alone or in combination, to obtain safe seafood products with good shelf life and preference among consumers. Moreover, applications and limitations are discussed to provide a clear view of the potential for future development and applications. Some of the reviewed technologies, or combinations thereof, have shown great potential for non-seafood products, yet data are missing for fish and seafood in general. The present paper visualizes these knowledge gaps and the potential for new technology developments in the seafood sector. Among identified gaps, the combination of mild heating (e.g., sous vide or microwave) with more novel technologies such as pulsed electric field, pulsed light, soluble gas stabilization, cold plasma, or Ohmic heat must be highlighted. However, before industrial applications are available, more research is needed.

Effect of Cold Smoking and Natural Antioxidants on Quality Traits, Safety and Shelf Life of Farmed Meagre (Argyrosomus regius) Fillets, as a Strategy to Diversify Aquaculture Products

Aquaculture has been playing a leading role over the years to satisfy the global growing demand for seafood. Moreover, innovative techniques are necessary to increase the competitiveness, sustainability and profitability of the seafood production chain, exploiting new species from the aquaculture, such as meagre (Argyrosomus regius), to develop value-added products and diversify their production. In the present work, the effectiveness of cold smoking combined with antioxidants (SA) compared to cold smoking alone (S) on meagre fillets, the quality and shelf life were investigated. Sensory, biochemical, physical–chemical and microbiological analyses were performed on the smoked fillets during vacuum-packaged storage for 35 days at 4 ± 0.5 °C. The results showed positive effects of the SA treatment on the biochemical parameters of meagre fillets. The total volatile basic nitrogen (TVB-N) in smoked meagre fillets was significantly lower in the SA treatment at the end of storage compared to the S treatment. Moreover, SA had a positive effect on lipid peroxidation. Lower values of malondialdehyde (mg MDA/kg) were observed in the SA treatment during preservation compared to the S treatment. This work will contribute to the growth of the fish production chain, producing a value-added fish product by exploiting meagre, whose production has been increasing over decades.

Effect of Processing on Fish Protein Antigenicity and Allergenicity

Fish allergy is a life-long food allergy whose prevalence is affected by many demographic factors. Currently, there is no cure for fish allergy, which can only be managed by strict avoidance of fish in the diet. According to the WHO/IUIS Allergen Nomenclature Sub-Committee, 12 fish proteins are recognized as allergens. Different processing (thermal and non-thermal) techniques are applied to fish and fishery products to reduce microorganisms, extend shelf life, and alter organoleptic/nutritional properties. In this concise review, the development of a consistent terminology for studying food protein immunogenicity, antigenicity, and allergenicity is proposed. It also summarizes that food processing may lead to a decrease, no change, or even increase in fish antigenicity and allergenicity due to the change of protein solubility, protein denaturation, and the modification of linear or conformational epitopes. Recent studies investigated the effect of processing on fish antigenicity/allergenicity and were mainly conducted on commonly consumed fish species and major fish allergens using in vitro methods. Future research areas such as novel fish species/allergens and ex vivo/in vivo evaluation methods would convey a comprehensive view of the relationship between processing and fish allergy.

Combination of Freezing, Low Sodium Brine, and Cold Smoking on the Quality and Shelf-Life of Sea Bass (Dicentrarchus labrax L.) Fillets as a Strategy to Innovate the Market of Aquaculture Products

Simple Summary

The growing fish consumption driven by the increased production, the concomitant reduction in wastage, and the huge amount of fish food traded globally, makes it important to address the sustainability, profitability, security, and safety issues related to the seafood production sector. Toward this direction, innovative methods extending shelf-life, maintaining seafood quality, safety and nutritional characteristics and that open new market opportunities, satisfy consumer preferences, and improve product traceability are required. Answering this call, this study aimed to develop a new value added product exploiting a species largely cultured in Italy (i.e., European sea bass). In particular, sea bass fillets were cold smoked using both fresh and frozen fillets to understand the effectiveness of this kind of processing on developing a new fish product and whether the quality of the raw material that could be affected by freezing and thawing could change the quality of the final product. It was seen that the quality of the raw material was affected by the time of frozen storage and that these starting conditions consequently impaired the quality of the smoked fillets. However, cold smoking was proven to be an effective process to develop a valuable product contributing to the growth of the aquaculture sector.

Abstract

Aquaculture is playing a leading role in both meeting the growing demand for seafood and increasing the sustainability of the fish production sector. Thus, innovative technologies that improve its sustainability, competitiveness, and safety are necessary for growth in the sector. This study aimed to develop cold smoked sea bass fillets from aquaculture. The aptitude of frozen and fresh fillets for cold smoking was investigated by processing both fresh and thawed fillets kept previously at −20 °C for 15, 30, 60, and 90 days. Moreover, to develop a low-salt product, fillets were immersed in low-sodium or standard brine. Sensory, biochemical, and physical-chemical analyses were performed on both the raw fillets and the smoked fillets during vacuum packaged storage for 35 days at 1 ± 0.5 °C. Young modulus values, representative of texture and sensory evaluation, showed that the quality of fresh fillets was better compared to the thawed ones, thus affecting the quality of the final product as the correlation between parameters showed (principal component analysis). Cold smoking was effective in both maintaining the total volatile basic nitrogen (TVB-N) below the threshold for spoilage and preventing lipid peroxidation. Moreover, partial sodium replacement by potassium did not alter the sensory attributes of smoked fillets, which maintained high scores up to 21 days.

Improvement of Sensorial, Physicochemical, Microbiological, Nutritional and Fatty Acid Attributes and Shelf Life Extension of Hot Smoked Half-Dried Pacific Saury (Cololabis saira)

Half-dried Pacific saury of Cololabis saira (HDPS) is a fatty fish of high nutritional value with remarkable consumer interest in the Asia Pacific region, however, it undergoes various deteriorative changes associated with browning, bacterial contamination, oxidation, and decreased sensory attributes while marketed in various processed forms. To withstand these complications, research aimed to investigate the hot smoking technology to improve physicochemical, microbiological, and sensory attributes of HDPS with prolonged shelf life in storage conditions. The HDPS fillets were processed with hot smoking (70 °C) using various sawdust materials of Apple, Chestnut, Oak, Cherry, and Walnut, wherein the smoke time was set at different time points of 0, 20, 25, and 30 min. The results indicated that 25 min of smoking time with the selective Oak sawdust showed better sensorial characteristics, physicochemical properties, and microbiological qualities. Moreover, HDPS possessed higher nutritional value and valuable functional fatty acids, particularly docosahexaenoic acid and eicosapentaenoic acid, having a storage ability of up to 30 days at 10 °C. The processed HDPS offered a reduced level of Trimethylamine-N-oxide and Benzo[a]pyrene contents, indicating the acceptable and safe for human consumption. Therefore, HDPS with hot smoking could likely be a promising technique for preserving the premium quality of the product by providing desired characteristics of health and nutrition to end-point consumers.

Primary Investigation into the Occurrence of Hydroxymethylfurfural (HMF) in a Range of Smoked Products

5-Hydroxymethylfurfural (HMF) is produced in foods through many different pathways. Recently, studies have revealed its potential mutagenic and carcinogenic properties. Determination of HMF was originally used as an indicator of both the extent of thermal processing a food had undergone and food quality. It has been identified in a variety of food products such as bread, breakfast cereals, fruit juices, milk, and honey. In addition to the thermal processes that lead to the formation of HMF during thermal treatment, food smoking also creates conditions that result in the formation of HMF. This can take place within the food due to the elevated temperatures associated with hot smoking or by the proximity of the products of the pyrolysis of the wood matrix that is used for smoking (cold smoking). This may lead to further contamination of the product by HMF over and above that associated with the rest of the preparation process. Until now, there have been no studies examining the relation between the smoking procedure and HMF contamination in smoked food. This study is a primary investigation measuring HMF levels in three categories of smoked food products, cheese, processed meat, and fish, using HPLC-UV. The amount of HMF found in all three product categories supports our hypothesis that HMF levels are due to both internal pathways during processing and external contamination from the smoke generation matrix (wood) employed. The results ranged from 1 ppb (metsovone traditional Greek smoked cheese) to 4 ppm (hot-smoked ready-to-eat mackerel). Subsequently for smoked cheese products, a correlation was found between HMF and phenolic compounds generated by the smoking procedures and identified by SPME-GCMS. It was observed that cheese samples that had higher concentrations of HMF were also found to have higher concentrations of syringol and cresols. It is important therefore to understand the smoking procedure’s effect on HMF formation. This will aid in the development of mitigation strategies to reduce HMF formation while retaining the flavour of the smoked products.

Effects of gamma radiation combined with cinnamon oil on qualities of smoked salmon slices inoculated with Shewanella putrefaciens

Smoked salmon slices inoculated with Shewanella putrefaciens were untreated (CK) or treated with 2 kGy gamma radiation (G), 1% (v/v) cinnamon oil (C), or the combination of them (G+C), and then packaged and stored at 4°C for 10 days. Microbiological and physiochemical analyses were then carried out. All treatments showed a better effect on inhibiting the increase in total viable counts, total volatile basic nitrogen, and thiobarbituric acid-reactive substances than CK, especially the treatment of G+C. In addition, the combination treatment also showed a best effect on retarding the reduction in polyunsaturated fatty acids of salmon samples in all treatments. These results indicated that treatments of gamma radiation and cinnamon oil on salmon samples, especially the combination treatment, can be used to maintain the quality of smoked salmon slices.

Effects of dry brining, liquid smoking and high-pressure treatment on the physical properties of aquacultured King salmon (Oncorhynchus tshawytscha) during refrigerated storage

BACKGROUND

Aquacultured King salmon (Oncorhynchus tshawytscha) pieces were dry brined with a salt/brown sugar mix, dipped in liquid smoke for 3 min, vacuum packed, high hydrostatic pressure (HHP) treated at 600 or 200 MPa for 5 min and stored at 4 °C for up to 40 days.

RESULTS

The surface redness (average a*) of the samples increased after dry brining, then decreased after liquid smoke treatment. HHP did not change the outside color of liquid-smoked samples. However, the inside color changed depending on pressure. HHP-treated control samples without dry brining and liquid smoking changed to a pale pink color. HHP at 600 MPa resulted in a significant increase in hardness. Compared with fresh samples, dry-brined samples had reduced water activity, while samples dipped in liquid smoke had lower pH values.

CONCLUSION

Dry brining and liquid smoking protect the outside color of salmon against changes caused by HHP. The increase in hardness may counteract the softening of the smoked salmon tissue over time.