Quality enhancement in refrigerated red drum (Sciaenops ocellatus) fillets using chitosan coatings containing natural preservatives

Active Biodegradable Films Based on Sweet Lime Peel Residue and Its Effect on Quality of Fish Fillets

Residual sweet lime peels after the extraction of essential oil by solvent free microwave extraction were used for developing biodegradable film. Glycerol as a plasticizer, soya lecithin as an emulsifier and sweet lime essential oil (0, 1, 2 and 3%) as an active agent was employed. Developed films were analyzed for their mechanical, barrier and antimicrobial properties. The films (with 3% essential oil) which reported highest antimicrobial property against E. coli (24.24 ± 2.69 mm) were wrapped on fish fillet and stored at the refrigerated condition for 12 days. The quality of fish fillets was evaluated every 4 days and compared with polyethylene wrapped and control fish fillets. The active film wrapped sample showed less surface microbial count (3.28 ± 0.16 log cfu/cm²) compared to polyethylene wrapped sample. The hardness values were increased during storage and cohesiveness and springiness of all wrapped samples decreased from day 0 to day 12.

Fresh Fish Degradation and Advances in Preservation Using Physical Emerging Technologies

Fresh fish is a highly perishable food characterized by a short shelf-life, and for this reason, it must be properly handled and stored to slow down its deterioration and to ensure microbial safety and marketable shelf-life. Modern consumers seek fresh-like, minimally processed foods due to the raising concerns regarding the use of preservatives in foods, as is the case of fresh fish. Given this, emergent preservation techniques are being evaluated as a complement or even replacement of conventional preservation methodologies, to assure food safety and extend shelf-life without compromising food safety. This paper reviews the main mechanisms responsible for fish spoilage and the use of conventional physical methodologies to preserve fresh fish, encompassing the main effects of each methodology on microbiological and chemical quality aspects of this highly perishable food. In this sense, conventional storage procedures (refrigeration and freezing) are counterpointed with more recent cold-based storage methodologies, namely chilling and superchilling. In addition, the use of novel food packaging methodologies (edible films and coatings) is also presented and discussed, along with a new storage methodology, hyperbaric storage, that states storage pressure control to hurdle microbial development and slow down organoleptic decay at subzero, refrigeration, and room temperatures.

The application of polyphenols in food preservation

Polyphenols are a kind of complex secondary metabolites in nature, widely exist in the flowers, bark, roots, stems, leaves, and fruits of plants. Numerous studies have shown that plant-derived polyphenols have a variety of bioactivities due to their unique chemical structure, such as antioxidant, antimicrobial, and prevention of chronic diseases, cardiovascular disease, cancer, osteoporosis, and neurodegeneration. With the gradual rise of natural product development, plant polyphenols have gradually become one of the research hotspots in the field of food science due to their wide distribution in the plants, and the diversity of physiological functions. Owing to the extraordinary antioxidant and antibacterial activity of polyphenols, plant-derived polyphenols offer an alternative to chemical additives used in the food industry, such as oil, seafood, meat, beverages, and food package materials. Based on this, this chapter provides an overview of the potential antioxidant and antibacterial mechanisms of plant polyphenols and their application in food preservation, it would be providing a reference for the future development of polyphenols in the food industry.

Effects of Whey Protein Isolate-Based Film Incorporated with Tarragon Essential Oil on the Quality and Shelf-Life of Refrigerated Brook Trout

The efficiency of some films prepared from heat-denatured whey protein isolate solutions on the quality and shelf-life of brook trout samples during storage at 4 °C was studied in this research (WPIf-a film based on whey protein isolate and WPIf+2.5%TEO-a film based on whey protein isolate incorporated with 2.5% tarragon essential oil). The control and covered fish samples were periodically assessed (at 3 days) over 15 days of storage for the physicochemical (pH; EC, electrical conductivity; TVB-N, total volatile basic nitrogen; TBARS, thiobarbituric acid reactive substances; color), microbiological (TVC, total viable count; PTC, psychrotrophic count; LAB, lactic acid bacteria; H₂S-producing bacteria), and sensory properties (color discoloration; odor; overall acceptability). The WPIf+2.5%TEO has proven enhanced quality preservation effects compared to WPIf by showing lower values for physicochemical parameters, lower microbial loads, and higher sensory scores in the fish sample. All these effects have led to an extension of the sample’s shelf-life. In conclusion, the tarragon essential oil has conferred antioxidant and antimicrobial properties to the film. Thus, the WPIf+2.5%TEO could be a promising material for the packaging of fresh brook trout during refrigerated storage.

Shelf Life Extension of Veal Meat by Edible Coating Incorporated with Zataria multiflora Essential Oil

The present research aimed to investigate the preservative effects of a sodium caseinate (SC) coating enriched with Zataria multiflora Boiss. essential oil (ZMEO) at 0.5, 1, or 1.5% on the product life of meat during storage at 4°C. Over a 15-day period, the meat samples were refrigerated and analyzed every five days. The treated samples had markedly less psychrotrophic bacteria, lactic acid bacteria, Enterobacteriaceae, and total viable counts relative to the control throughout storage. In terms of the sensory, chemical (PV, TBARS, and pH), and microbial characterization, undesirable results were attained in the control sample after 10 days of refrigerated storage, whereas samples coated with SC/ZMEO, especially at higher essential oil concentrations (1 and 1.5%), proved to be significantly more stable (P<0.05). However, high concentration of ZMEO (1.5%) gave an unpleasant effect on sensory attributes of meat samples. Notably, the SC/1% ZMEO coating led to good overall acceptability of the veal specimens even after 15 days of refrigeration. Hence, this coating is recommended as a replacement for synthetic preservatives and flavorings for meat products given that it preserved the quality of refrigerated veal samples for over two weeks.

Edible Coating and Pulsed Light to Increase the Shelf Life of Food Products

The application of edible coatings (EC) in combination with pulsed light (PL) treatments represents an emerging approach for extending the shelf life of highly perishable but high value-added products, such as fresh-cut fruits and vegetables. The surface of these products would benefit from the protective effects of ECs and the PL decontamination capability. This review describes in detail the fundamentals of both EC and PL, focusing on the food engineering principles in the formulation and application of EC and the delivery of efficient PL treatments and the technological aspects related to the food characterization following these treatments and discussing the implementation of the two technologies, individually or in combination. The advantages of the combination of EC and PL are extensively discussed emphasizing the potential benefits that may be derived from their combination when preserving perishable foods. The downsides of combining EC and PL are also presented, with specific reference to the potential EC degradation when exposed to PL treatments and the screening effect of PL transmittance through the coating layer. Finally, the potential applications of the combined treatments to food products are highlighted, comparatively presenting the treatment conditions and the product shelf-life improvement.

Effects of chitosan grafted phenolic acid coating on microbiological, physicochemical and protein changes of sea bass (Lateolabrax japonicus) during refrigerated storage

This project aimed to evaluate the effects of gallic acid (GA) and protocatechuic acid (PA) grafted onto chitosan (CS) on the improved quality of sea bass (Lateolabrax japonicus) during refrigerated storage. The incorporation of GA and PA onto CS (CS-g-GA and CS-g-PA) were achieved by the carbodiimide-mediated grafting procedure. Samples were treated with different solutions (deionized water [CK], 1% CS [m/v], 1% CS-g-GA [m/v], and 1% CS-g-PA [m/v]) for 10 min, which were then stored at 4 °C. Microbiological quality, including total viable counts (TVC), psychrophilic bacterial counts (PBC), Pseudomonas bacterial counts, and H₂ S-producing bacterial counts were measured. Physicochemical parameters, including pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA) value, water holding capacity (WHC), and K value, were measured. The changes in protein characteristics, including sulfhydryl groups (SH), Ca²⁺ -ATPase activity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and tertiary structure of protein were analyzed periodically, along with texture profile analysis (TPA). The results demonstrated that the CS copolymers treatment exhibited better preservation effects. The CS-g-GA and CS-g-PA treatments could significantly inhibit the growth of microorganisms and retard the increase of pH, TVB-N, TBA, WHC, and K-value during refrigerated storage compared with the CK and CS groups. Additionally, the CS-g-GA and CS-g-PA treatments could delay the protein oxidation by keeping a higher SH level and Ca²⁺ -ATPase activity. The CS copolymers treatment could also extend the shelf life for another 6 days compared with that of CK. As a result, CS copolymers can be employed in a promising method for the preservation of sea bass. PRACTICAL APPLICATION: The incorporation of gallic acid and protocatechuic acid onto chitosan (CS-g-GA and CS-g-PA) showed superior antioxidant and antimicrobial activities when applied on sea bass. The CS-g-GA and CS-g-PA coatings could maintain the quality and freshness of refrigerated sea bass. Additionally, this research could provide a theoretical basis for the application of graft copolymers on the preservation of aquatic products.

Effect of the Combination of Vanillin and Chitosan Coating on the Microbial Diversity and Shelf-Life of Refrigerated Turbot (Scophthalmus maximus) Filets

The effect of the combination of vanillin and chitosan (VC) coating on the microbiota composition and shelf-life of turbot (Scophthalmus maximus) filets during a 15-day storage period at 4 ± 1°day was investigated in this study. The control and coated fish samples were analyzed periodically for sensory and chemical attributes [total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), and pH] and the presence of dominant spoilage microbiota. The results suggested that the sensory and the chemical quality of turbot filets effectively improved after treatment with vanillin (final concentration 2 mg/ml) combined with 1% chitosan, and the shelf-life was prolonged for 6 to 7 days compared with the control group. Furthermore, high-throughput sequencing showed that Proteobacteria (52.2%) and Firmicutes (29.8%) were the dominant bacteria at the phylum level in fresh turbot filets, while Pseudomonadaceae (40.2%) and Lactobacillaceae (39.4%) were the dominant bacteria at the family level in deteriorated turbot filets. However, after VC treatment, the relative abundance of Pseudomonadaceae and Lactobacillaceae decreased significantly due to the growth inhibition of potential bacteria, specifically spoilage bacteria, along with the rich bacterial diversity at the end of storage. Therefore, our data indicated that VC treatment might be effective in decreasing bacteria-induced quality deterioration and in extending the shelf-life of refrigerated turbot filets.

Effects of different thawing methods on physicochemical properties and structure of largemouth bass (Micropterus salmoides)

To evaluate the physicochemical properties and structure of thawed fillets, following six treatments were used: conventional thawing, microwave thawing, microwave or ultrasound combined with vacuum thawing, magnetic nanoparticles combined with microwave or far-infrared thawing. The thawing loss, cooking loss, pH, color, texture change, water-holding capacity, and water migration of fish fillets were determined. The total volatile base nitrogen and thiobarbituric acid were used to determine the degree of protein degradation and lipid oxidation. Microscope observations and scanning electron microscope (SEM) were used to observe fiber microstructure. Results indicated that both microwave combined with vacuum thawing and far-infrared combined with magnetic nanoparticles thawing had desirable physicochemical properties as compared to other thawing methods. The lower total volatile base nitrogen and thiobarbituric acid values had less effect on protein degradation and lipid oxidation of thawing process. Besides, both microwaves combined with vacuum thawing and far-infrared combined with magnetic nanoparticles thawing samples had no significant difference in immobilized and bond water compared with fresh sample. SEM and microscopic observation showed that the myofibril bundles were arranged regularly and smoothly in microwave combined with vacuum thawing and far-infrared combined with magnetic nanoparticles thawing samples compared with other thawed methods. Thus, the microwave combined with vacuum thawing and far-infrared combined with magnetic nanoparticles thawing as potential thawing methods could be used to maintain the quality of thawed fish fillets. PRACTICAL APPLICATION: Largemouth bass (Micropterus salmoides) is a good source of animal protein. The fish needs to be frozen for circulation because of geographical and seasonal factors, so thawing methods can directly affect the quality of thawed fish. The results showed that the microwave combined with vacuum and the magnetic nanoparticles combined with far-infrared thawing could better maintain the quality of thawed fish.

Preparation, physicochemical and preservation properties of Ti/ZnO/in situ SiOx chitosan composite coatings

BACKGROUND

Among nanomaterials, Ti and ZnO nanoparticles are often chosen as preservation materials because of their antibacterial properties. Chitosan, as a natural biopolymer, has potential because of its abundance, compatibility and antibacterial properties. To improve the physicochemical and preservation properties of in situ SiOx chitosan (CS) composite coating, Ti/ZnO/SiOx CS composite coatings were prepared with Ti-doped ZnO (Ti/ZnO) nanorods and nanoballs. The composite coating structures were characterized by Fourier transform infrared, X-ray diffraction and scanning electron microscopy, and their physicochemical and preservation properties were determined simultaneously.

RESULTS

The results show that the Ti/ZnO nanoparticles are beneficial to homogeneous dispersion of in situ synthesized nano SiOx in the CS coating, and that Ti/ZnO nanoballs have better dispersion than Ti/ZnO nanorods. Moreover, strong hydrogen bonds are formed among Ti/ZnO nanoparticles and in situ synthesized nano SiOx and CS molecules, and the primary structure of CS is disorganized. Thereby, the gas permeabilities and mechanical properties of the CS coatings are improved due to modification of Ti/ZnO nanoparticles, and the Ti/ZnO nanoballs/SiOx CS composite coating is optimal. The preservation properties of the CS coatings on Sciaenops ocellatus are significantly improved, and those of Ti/ZnO/in situ SiOx CS composite coatings are superior.

CONCLUSION

The preservation properties of the CS composite coatings on S. ocellatus are significant, and the Ti/ZnO nanoballs/SiOx CS composite coating is even better. Therefore, the co-modification method of in situ nanoparticles and antibacterial nanoparticles may be a promising method to improve the preservation properties of CS coatings. © 2019 Society of Chemical Industry.

Chitosan-starch film containing pomegranate peel extract and Thymus kotschyanus essential oil can prolong the shelf life of beef

The aim of the current study was to investigate the effects of pomegranate peel extract (PPE) and chitosan-starch (CH-S) composite film incorporated with Thymus kotschyanus essential oil (TEO) on the shelf-life of beef during storage period of 21 days at 4 °C. The physico-mechanical parameters, the color and Fourier Transform Infrared spectra values of the films were determined. Changes in odor, color, pH, thiobarbituric value for lipid oxidation levels and Pseudomonas spp. total viable counts, lactic acid and Listeria monocytogenes were determined during the storage time. All treated films showed lower elongation, strength and transparency values compared with chitosan - starch (CH-S) group. Results showed that CH-S-PPE 1%-TEO 2% treatment had the highest inhibition effect against L. monocytogenes. The bacterial counts and lipid oxidation were successfully inhibited using PPE and TEO. CH-S-PPE 1% group containing up to 2% TEO had the best acceptable sensory characteristic. Beef samples wrapped with CH-S film containing PPE and TEO also had longer shelf life.

Effects of chitosan-based coatings on storage quality of Chinese shrimp

We investigated the effects of chitosan-based coatings on the preservation quality of refrigerated Chinese shrimp for 12 days. Samples of Chinese shrimp were subjected to three different coating treatments, namely chitosan (CH), chitosan and ε-polylysine (CH + ε-PL), chitosan combined with ε-polylysine and carrageenan (CH + ε-PL + CA), and compared with a control. The bacteriological characteristics [total viable count (TVC)], chemical indexes including pH, thiobarbituric acid (TBA) value, K-value, and total volatile basic nitrogen (TVB-N), texture (hardness, chewiness, and elasticity), and sensory changes were assessed. The increases in TVC, pH, TBA, K-value, and TVB-N were observed to be delayed by preservation treatments, and the textural and sensory characteristics indicated that the treated shrimp were preserved more effectively than the control. Treatment with chitosan combined with ε-polylysine and carrageenan was the most effective preservation method than treatment with chitosan alone or chitosan and ε-polylysine; the shelf life was also prolonged. Therefore, treatment with chitosan combined with ε-polylysine and carrageenan is proposed as a potential method for shelf life extension of Chinese shrimp for refrigerated storage.

Recent progress in biomedical applications of chitosan and its nanocomposites in aquaculture: A review

Chitosan nanoparticles (CSNPs) are the nanostructures of chitosan biopolymer which is derived from chitin polysaccharide, the main component of crustacean shells. Chitosan is a biocompatible, nontoxic and biodegradable polymer soluble in acidic solutions and easily excreted from kidneys. It is widely used in medical and pharmaceutical applications including artificial matrices for tissue engineering, drug transport, targeted drug delivery and protein or gene delivery. The antimicrobial activities of chitosan and CSNPS against different bacterial, fungal and viral pathogens made them valuable for several biological applications including food preservation purposes. In addition, they have immunomodulatory effects on fish and crustaceans providing direct positive impact on aquaculture and fish farming industry. Sustained release of some bioactive ingredients such as hormones, vitamins, nutrients and antioxidants has improved the biological activities of fish. Furthermore, CSNPs have recently been employed to diagnose fish diseases. In this review, we present the medical and biological applications of chitosan and CSNPs on aquatics to provide an update on recent advances and the potential for further advanced applications for aquaculture in the future.

A novel pH-sensing indicator based on bacterial cellulose nanofibers and black carrot anthocyanins for monitoring fish freshness

A novel intelligent pH-sensing indicator based on bacterial nanocellulose (BC) and black carrot anthocyanins (CA) was developed and characterized to monitor the freshness/spoilage of rainbow trout and common carp fillet during the storage at 4 °C. The indicator displayed wide color differences from red to gray over the 2-11 pH range, which was clearly discerned by the naked eye. The fabricated pH-sensing indicator showed distinguishable color changes during fresh (deep carmine color), best to eat (charm pink color), and spoiled (jelly bean blue and khaki colors) stages of both fish fillets. Moreover, a strong and positive correlation was obtained between the total color differences values of the indicator and bacterial count (R = 0.952 and 0.991) and total volatile basic nitrogen (R = 0.815 and 0.92) in rainbow trout and common carp samples. The results of this work demonstrated a significant correspondence of fish shelf life and color changes of a nanocellulose-based pH-sensing indicator.

Intelligent pH-sensitive indicator based on starch-cellulose and alizarin dye to track freshness of rainbow trout fillet

A novel pH-sensitive indicator was prepared by incorporation of alizarin in a starch-cellulose paper to monitor the freshness of rainbow trout fillet. Water solubility of the fabricated indicator reduced by incorporation of alizarin, while the percentage of swelling didn't change. FTIR certified that alizarin was properly incorporated which was revealed by the formation of intermolecular hydrogen bonding in the cellulose-starch matrix. SEM and ultraviolet-visible spectrum results also demonstrated that alizarin had good compatibility with the components of the indicator. The alizarin-starch-cellulose indicator (ASC) had greater color efficiency from yellow to purple at pH 2-11 and greater color stability after two months of storage at 4 °C. It can be concluded that the color changes of ASC, from orange to reddish brown, were entirely corresponded with TVB-N contents of fish, which presents a satisfactory capability of developed indicator to identify the initiation of spoilage in the refrigerated fish fillet.

Dynamic Detection of Biogenic Amines as a Quality Indicator and Their Relationship with Free Amino Acids Profiles in Large Yellow Croaker (Pseudosciaena crocea)

The production of biogenic amines (BAs) set considerable obstacles in seafood preservation. However, the characteristic BAs and their roles in the spoilage profiles in large yellow croaker were still poorly understood. The BAs contents, free amino acids (FAAs) contents, aerobic bacterial count, sensory evaluation and several characteristic physicochemical indexes were monitored during storage at 4 °C. It's forcefully uncovered that the putrescine and cadaverine were the main BAs and the sum value of them could be used as a novel quality indicator instead of BAI. The reasonable limitation for unaccepted corruption was suggested be around 60 mg/kg. The regression model (r > 0.8, P < 0.05) at 4 °C indicated a significant correlation between the main BAs and total volatile basic nitrogen (TVB-N), protein hydrolysis index (P.I.%) as well as pH value, offering a new interpretation form for the physiochemical properties of BAs in aquatic products. Additionally, the evolution of FAAs show the predominant role of lysine, proline, histidine, glycine, and alanine during the whole storage and it can be concluded that BAs biosynthesis in large yellow croaker were moderately related with their precursor substance. This work provides a preliminary insight into the origin of BAs in large yellow croaker. PRACTICAL APPLICATION: It was proposed that the sum value of putrescine and cadaverine which were the main BAs can be used as a novel quality indicator instead of BAI in large yellow croaker. And the regression models of BAs and other physiochemical indexes provided a new perspective for comprehending the spoilage profiles involving BAs biosynthesis. The study may potentially contribute to improving the evaluation of seafood freshness and provide new target site for seafood preservation.

The Modification of In Situ SiOx Chitosan Coatings by ZnO/TiO2 NPs and Its Preservation Properties to Silver Carp Fish Balls

The composite chitosan coatings were prepared and characterized to evaluate their preservation properties for silver carp fish balls, and the microstructures and physicochemical properties of the coatings were improved by in situ nano silicon oxide (SiOx) and zinc oxide/titania (ZnO/TiO₂ ) nano-particles (NPs). In the chitosan coatings, when the chitosan combines with NPs by chemical bonds, the crystal lattice is slightly changed due to the modification of NPs. The chitosan coatings modified by NPs showed few cracks, among which sodium hexametaphosphate (SHMP) modified ZnO/TiO₂ /SiOx-chitosan (ZTS-CS) coating is proved to be the optimal one. The change of the freshness index and the texture of the fish balls are delayed by the coatings due to their gas permeability and antibacterial properties. The preservation properties of the chitosan coatings for Silver Carp fish balls are improved by in situ SiOx, and further improved by co-modification of ZnO/TiO₂ NPs. Furthermore, the surface modification of ZnO/TiO₂ NPs enhances the preservation properties of the chitosan coating. PRACTICAL APPLICATION: In our previous study, in situ SiOx was found to improve antibacterial and preservation properties of chitosan coating, leading to extending shelf time of Sciaenops ocellatus. In order to further improve properties of chitosan coatings, we added nontoxic edible nano materials to the in situ SiOx chitosan coatings. In situ SiOx modified by ZnO/TiO₂ NPs were synthesized, measured, and characterized in this study, and were applied for the preservation of silver carp fish balls. It could serve as a potential preservation material due to the increasing mechanical preservation properties. Through the results, the ZnO/TiO₂ /SiOx-chitosan (ZTS-CS) coatings have potential as application in the food industry to guarantee food quality and extend shelf life of products.

Edible Films and Coatings for Fresh Fish Packaging: Focus on Quality Changes and Shelf-life Extension

Fresh fish is extensively consumed and is one of the most-traded food commodities in the world. Conventional preservation technologies include vacuum and modified atmosphere packaging, but they are costly since requires capital investment. In the last decade, research has been directed towards the development of antimicrobial packaging systems, as an economical alternative to these. This paper outlines antimicrobial films and coatings applied so far on fresh fish, their efficacy against targeted microorganism/group and effects on chemical quality of the product. Findings show that edible films/coatings incorporated with different active agents applied to fresh fish are able to inhibit the microbial growth and decrease the rate of fish nutrients degradation, thus preventing the formation of chemical metabolites; a shelf-life extension of 6 to 13 days was obtained for fish fillets, depending on the species on which the active packaging materials were applied. The manufacturing use of these formulations could lead to a significant reduction in fish waste, consequently, a diminution of economic losses for fish traders and retailers. Therefore, their industrial production and commercialization could be an exploitable sector by the packaging industry.

Effects of sodium alginate coating containing Mentha spicata essential oil and cellulose nanoparticles on extending the shelf life of raw silver carp (Hypophthalmichthys molitrix) fillets

The aim of the present study was to evaluate the effects of sodium alginate (SA) coatings containing Mentha spicata essential oil (MSO; 0.5 and 1%) and cellulose nanoparticles (CN; 0.25 and 0.5%) on chemical (total volatile base nitrogen content and peroxide value), microbial (total viable count, psychrotrophic count, Pseudomonas spp., and Enterobacteriaceae), and sensory (odor, color, and overall acceptability) properties of raw silver carp fillets during 14 days of refrigerated storage. The MSO was mostly comprised of carvone (78.76%) and limonene (11.50%). SA + MSO 1% + CN 0.5% was most effective in extending the shelf life of silver carp fillets, followed by SA + MSO 1% + CN 0.25%, SA + MSO 1%, SA + MSO 0.5% + CN 0.5%, SA + MSO 0.5% + CN 0.25%, SA + MSO 0.5%, SA + CN 0.5%, SA +CN  0.25%, and SA. Incorporation of MSO 0.5% didn't have any adverse effect on odor, color, and overall acceptability of treated samples.

Comparison of sensory and instrumental methods for the analysis of texture of cooked individually quick frozen and fresh-frozen catfish fillets

Catfish fillet texture is important to consumers, especially if the texture is not what the consumer expects. Therefore, it is important to be able to assure that texture quality is consistent. Texture is a humanly perceived sensory trait and can be costly to processors when texture quality is substandard. Instrumental methods of monitoring texture are much less costly over time than maintaining a sensory quality panel. The purpose of this research was to develop methods for monitoring texture quality using reliable instrumental methods. A descriptive sensory texture panel evaluated fresh-frozen and individually quick frozen (IQF) catfish fillets and was compared to the instrumental analysis of the same cooked fish, using texture profile analysis (TPA). The TPA evaluation was more successful for identifying differences between IQF and fresh-frozen catfish, with the most significance (p < 0.02) seen for the attributes springiness, resilience, chewiness-1, hardness-1, and residual parameters of springiness, chewiness-1, chewiness-1b, and hardness-1b. For sensory evaluation, only moisture release and moisture retention were this significant. Overall, IQF fillets were more moist and cohesive, with fresh-frozen fillets greater in all other parameters. Predictive equations were developed for sensory texture attributes from various TPA attributes calculated from the compression-force curves generated from two compressions of a ball probe. In the fresh-frozen catfish, sensory attributes firmness, flaky, moisture retention, and residual cohesiveness of mass had correlation coefficients (R) of 0.50 or greater. For the IQF catfish, all sensory attributes had an R of less than 0.4. The firmness sensory attribute had TPA predictor variables in both fresh-frozen and IQF that consisted mainly of hardness, chewiness, or thickness-related attributes. Based on results, instrumental texture of catfish should be measured before further processing, such as IQF.

Effect of a Sodium Alginate Coating Infused with Tea Polyphenols on the Quality of Fresh Japanese Sea Bass (Lateolabrax japonicas) Fillets

Sodium alginate (SA) and tea polyphenols (TP) are natural preservatives commonly used in the food industry, including the production of fish products. The effect of SA coating infused with TP on the quality of fresh Japanese sea bass (Lateolabrax japonicas) fillets was evaluated over a 20-day period at 4 °C. SA (1.5%, w/v) or TP (0.5%, w/v) treatment alone, and the SA coating infused with TP (SA-TP) all reduced microbial counts, with the SA-TP providing the greatest effect. Fish fillet samples treated with SA-TP had significantly lower levels of total volatile basic nitrogen, lipid oxidation, and protein decomposition during the storage period, relative to the remaining treatments. The samples treated with SA-TP had the highest sensory quality rating as well. Collectively, sodium alginate coating infused with tea polyphenols may represent a promising treatment for preservation of Japanese sea bass fillets during cold storage.

PRACTICAL APPLICATION

The sodium alginate-tea polyphenols composite coating has strong potential to be used as a new biopreservative for maintaining fish fillet quality.

Antioxidant and Antimicrobial Activities of (-)-Epigallocatechin-3-gallate (EGCG) and its Potential to Preserve the Quality and Safety of Foods

Quality deterioration of fresh or processed foods is a major challenge for the food industry not only due to economic losses but also due to the risks associated with spoiled foods resulting, for example, from toxic compounds. On the other hand, there are increasing limitations on the application of synthetic preservatives such as antioxidants in foods because of their potential links to human health risks. With the new concept of functional ingredients and the development of the functional foods market, and the desire for a "clean" label, recent research has focused on finding safe additives with multifunctional effects to ensure food safety and quality. (-)-Epigallocatechin-3-gallate (EGCG), a biologically active compound in green tea, has received considerable attention in recent years and is considered a potential alternative to synthetic food additives. EGCG has been shown to prevent the growth of different Gram-positive and Gram-negative bacteria responsible for food spoilage while showing antioxidant activity in food systems. This review focuses on recent findings related to EGCG separation techniques, modification of its structure, mechanisms of antioxidant and antimicrobial activities, and applications in preserving the quality and safety of foods.