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This study focused on the quality loss inhibition of fish muscle during refrigerated storage. Two parallel experiments were carried out that were focused on the employment of pitaya (Stenocereus thurberi) extracts in biodegradable packing films. On the one hand, a pitaya–gelatin film was employed for hake (Merluccius merluccius) muscle storage. On the other hand, a pitaya–polylactic acid (PLA) film was used for Atlantic mackerel (Scomber scombrus) muscle storage. In both experiments, fish-packing systems were stored at 4 °C for 8 days. Quality loss was determined by lipid damage and microbial activity development. The presence of the pitaya extract led to an inhibitory effect (p < 0.05) on peroxide, fluorescent compound, and free fatty acid (FFA) values in the gelatin–hake system and to a lower (p < 0.05) formation of thiobarbituric acid reactive substances, fluorescent compounds, and FFAs in the PLA–mackerel system. Additionally, the inclusion of pitaya extracts in the packing films slowed down (p < 0.05) the growth of aerobes, anaerobes, psychrotrophs, and proteolytic bacteria in the case of the pitaya–gelatin films and of aerobes, anaerobes, and proteolytic bacteria in the case of pitaya–PLA films. The current preservative effects are explained on the basis of the preservative compound presence (betalains and phenolic compounds) in the pitaya extracts

This work addressed the preservative behaviour of different icing media containing extracts from the alga Bifurcaria bifurcata. A comparative study of the antimicrobial and antioxidant effects of aqueous and ethanolic extracts of this macroalga was carried out. Whole hake (Merluccius merluccius) pieces were stored in ice containing either kind of extract and analysed for quality changes throughout a 13-day storage period. A progressive loss of microbial and biochemical quality was detected in all batches as chilling time increased. A significant inhibitory effect (p < 0.05) on microbial activity could be observed as a result of including the aqueous (lowering of psychrotrophic and lipolytic counts and pH value) and ethanolic (lowering of psychrotrophic and lipolytic counts) extracts. Additionally, both kinds of extract led to a substantial inhibition (p < 0.05) in the lipid hydrolysis rate (formation of free fatty acids), greater in the case of the batch containing ethanolic extract. Concerning lipid oxidation, a similar inhibitory effect (p < 0.05) on the formation of secondary compounds (thiobarbituric acid substances) was noticed in fish specimens corresponding to both alga extracts; however, more (p < 0.05) peroxide formation was detected in fish corresponding to the ethanolic extract batch. A preservative effect can be concluded for both kinds of extract; this effect agrees with previous studies reporting the presence of hydrophilic and lipophilic bioactive compounds in B. bifurcata.

Lyophilized alga Fucus spiralis powder was incorporated into a gelatin-based film and employed as a packaging system for mackerel (Scomber scombrus) muscle portions throughout a 9-day refrigerated storage period at 4 °C. In global terms, a progressive loss of quality could be observed in fish muscle with increasing storage time. Comparisons between batches allowed us to conclude an inhibitory effect of F. spiralis-containing films on microbial activity (assessment of aerobes, psychrotrophs, and proteolytic bacteria) and on lipid hydrolysis (as determined by free fatty acid formation) in mackerel muscle. The presence of the lyophilized macroalga in the packaging film also led to a higher retention of primary (peroxides) and secondary (thiobarbituric acid reactive substances) lipid oxidation compounds, while the formation of fluorescent compounds (interaction compounds between lipid oxidation compounds and nucleophilic molecules present in the fish muscle) decreased. Both antimicrobial and antioxidant effects were more intense when the concentration of alga in the packaging film was increased. The preservative effect resulting from the presence of F. spiralis in gelatin-based films demonstrates the potential employment of such bioactive films to improve the retention of fish quality and enhance its commercial value

This study analyzed the antimicrobial effect of aqueous extracts of flour obtained from red alga (Gelidium sp.) both in vitro, against most common food pathogenic and spoilage bacteria, and in a food model system during the chilled storage of Atlantic mackerel (Scomber scombrus). Results of in vitro assays allowed the conclusion that the aqueous flour extracts have antimicrobial activity against Gram-negative bacteria such as Enterobacteriaceae (Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae) and proteobacteria (Vibrio alginolyticus), and against Gram-positive bacteria such as Bacillus cereus and B. subtilis. In the food model study, different concentrations of the flour extract were present in the icing medium, microbial and chemical analyses being carried out in fish muscle at different storage times. An inhibitory effect (p < 0.05) on microbial growth (aerobes, psychrotrophs, Enterobacteriaceae, and proteolytic and lipolytic bacteria) and on chemical quality indices (pH, total volatile amines, and trimethylamine) was concluded. This effect was more pronounced when the flour extract concentration in the ice increased and at advanced storage times. This study provides a first approach to the beneficial use of flour of the alga Gelidium as a new preserving strategy for chilled fish

Las algas marinas forman parte de la dieta humana en algunos países asiáticos desde la antigüedad. Recientemente, su uso está recibiendo un creciente interés en el mundo occidental debido a sus excelentes propiedades nutricionales, así como por su aporte en componentes con propiedades antimicrobianas, antioxidantes, antiinflamatorias y antitumorales [1,2]. Entre estas algas, Bifurcaría bifurcata destaca por su abundancia en las costas atlánticas de Portugal, Francia y España [3] así como por sus propiedades conservantes demostradas en diversos experimentos in vitro [4]. Este estudio se centra en la utilización de esta macroalga parda al objeto de mejorar la calidad de pescado comercializado en estados fresco y enlatado. Para ello, se utilizaron disoluciones acuosas de extractos de dicha alga para la elaboración del hielo utilizado como medio de conservación en refrigeración de gallo (Lepidorhombus whiffiagonis); los efectos de los extractos del alga sobre el desarrollo de la actividad microbiana y la alteración lipídica fueron analizados durante un periodo de conservación de 14 días. Por otra parte, los extractos de B. bifurcata fueron incluidos en el medio de cobertura empleado durante el enlatado de caballa atlántica (Scomber scombrus); después de tres meses de conservación del producto enlatado, se analizaron los efectos originados sobre la calidad del pescado. En lo que respecta al estudio de gallo refrigerado, se observó un marcado efecto inhibidor en el desarrollo de distintos grupos microbianos (aerobios, psicrótrofos, Enterobacterias, proteolíticos y lipolíticos), así como en la formación de ácidos grasos libres y compuestos fluorescentes. Por su parte, el experimento de enlatado de caballa reflejó un efecto inhibidor por parte del extracto de alga sobre la formación de compuestos fluorescentes y sobre el incremento de los parámetros L* y b* de color. Se concluye que ambas estrategias (inclusión en el hielo de refrigeración y en el medio de cobertura del enl

The use of packaging films containing natural preservative compounds attracts great attention for the quality improvement of seafood. Microalga spirulina (Spirulina platensis) represents a potential source of high added-value and preservative biocompounds. The goal of this study was to enhance the quality of refrigerated Atlantic mackerel (Scomber scombrus) by including a protein concentrate (PC) of spirulina in a gelatine-based film. Quality changes in fish muscle were monitored by microbial and chemical analyses throughout an 11-day refrigerated storage (4 °C). As a result of the presence of spirulina PC in the film, an antimicrobial effect (p < 0.05) was concluded as determined by comparative evolution of aerobes and psychrotrophs, while no effect (p > 0.05) was concluded for Enterobacteriaceae, proteolytics and lipolytics counts. Furthermore, a lower (p < 0.05) formation of trimethylamine and free fatty acids was detected. Lipid oxidation, measured by fluorescent compounds formation, also exhibited lower average values in fish corresponding to the batch containing spirulina concentrate. The preservative effects observed can be explained on the basis of the presence of antimicrobial and antioxidant compounds in the microalga concentrate. It is proposed that the current packaging system may constitute a novel and promising strategy to enhance the quality of commercial refrigerated fatty fish.

This study focusses on the employment of a gelatine-based biofilm during fish refrigeration. In it, a Fucus spiralis protein hydrolysate (PH) is included in the biofilm and used as packaging system in European hake (Merluccius merluccius) slices during the refrigerated storage (up to 6 days at 4 ºC). A progressive quality loss can be observed in hake slices by increasing the storage time. However, comparison with control fish shows a partial inhibitory effect on microbial activity development (counts assessment of aerobes, psychrotrophs, Enterobacteriaceae, proteolytics, lipolytics and anaerobes) and lipid oxidation (determination of thiobarbituric acid and fluorescence indices) and hydrolysis (free fatty acids formation) in hake samples packaged in the alga-gelatine condition. A preservative effect resulting from the PH presence in the gelatine-based biofilm is concluded, this showing a quality and safety enhancement and a potential commercial value increase. Further research focused on the optimisation of the current biofilm preparation ought to be addressed.

The current study represents an attempt to apply the alga Undaria pinnatifida for the quality enhancement of fish products. For it, ethanolic extracts of this alga were included in the icing system during the chilling storage of megrim (Lepidorhombus whiffiagonis). Lipid damage and microbial activity were analysed in megrim muscle after 0, 2, 6 and 9 days. An inhibitory effect (p < 0.05) on lipid hydrolysis (free fatty acids assessment) development could be observed as a result of the alga presence in the icing medium. In this study, a low formation of primary (i.e., peroxides) and secondary (thiobarbituric acid reactive substances) lipid oxidation compounds was inferred in both control and treated fish samples. However, determination of fluorescent compounds (tertiary lipid oxidation compounds) revealed lower average scores for treated megrim at advanced storage periods (6-9 days), so that a partial inhibition of lipid oxidation development could be concluded as a result of the presence of the alga extract in the icing medium. Compositional analyses revealed a polyphenol content of 11±1 mg gallic acid equivalent g-1 of lyophilised alga and an antioxidant capacity of 27 % (DPPH assay). Interestingly, aerobes, proteolytic and lipolytic bacteria growth was partly slowed down as compared to their control counterparts. Consequently, the proposed novel employment of U. pinnatifida can be considered a promising strategy to enhance seafood quality

The first goal of this work was to enhance the quality of chilled fish by applying a preliminary dipping treatment containing a bioactive extract from the alga Fucus spiralis. Megrim (Lepidorhombus whiffiagonis) specimens were dipped in aqueous solutions containing two different concentrations of the alga extract (0.50% and 0.10% alga/dipping solution, w/v; HAC and LAC batches, respectively). In addition, two control batches were considered (water dipping control and no dipping control). Microbial, chemical and sensory qualities were assessed in fish specimens after 0, 2, 6, 9 and 13 days of chilled storage. An antimicrobial effect at advanced stages of storage (9–13-day period) was observed as determined by the comparative evolution of aerobes, psychrotrophs and Enterobacteriaceae counts in megrim muscle. Likewise, a protective effect against specific lipolytic and proteolytic spoilage bacteria was also achieved at that storage period, as well as a decrease of free fatty acids formation. However, alga extract in the dipping medium had no effect (p > 0.05) on the increase of lipid oxidation in fish muscle throughout chilled storage. Interestingly, average scores revealed improved sensory quality in megrim corresponding to the HAC batch for the 9–13-day chilled period. Consequently, the proposed novel dipping treatment can be considered of interest for both on-board and in-land fish storage, due to the simple methodology employed and the resulting protective effects on fish quality.

The employment of an ethanolic extract of quinoa (Chenopodium quinoa Willd.) as a novel preservation medium and as a source of bioactive compounds is tested for chilled fish storage. For this purpose, specimens from an under-valued pelagic species (Atlantic chub mackerel, Scomber colias) are stored in ice including quinoa at two concentrations: 80% aq. (v/v) ethanol extracts (0.05 and 0.20 g lyophilized quinoa extract L 1 icing solution; Q-1 and Q-2 batches, respectively) and compared to a control icing condition (Q-0 batch). The evolution of fish quality is assessed during a 13-day chilled storage period. The presence of the most concentrated quinoa extract (i.e., Q-2 batch) in the icing medium implied lower (p<0.05) lipid oxidation (thiobarbituric acid and fluorescence values) and hydrolysis (free fatty acids formation and lipolytic bacteria counts), as well as to a decrease in pH and trimethylamine values. Such effects are more pronounced at advanced storage times. Furthermore, fish specimens from Q-0 and Q-1 batches do not exhibit acceptable quality at the end of storage time, while those from the Q-2 batch still exhibit acceptable quality at that moment; interestingly, quality limit aspects are skin, eyes, and external odor. Practical Applications: Under the conditions tested, a novel quinoa-based system is proposed as a suitable tool for the improvement of a chilled fatty fish species and consequent extension of its shelf-life. This preservative strategy matches with current interest in the search for effective antioxidants and antimicrobials from natural sources to replace synthetic preservatives in the food sector. Additionally, this preservative strategy has proven to increase the technological aptitude and, accordingly, the commercialization possibilities, of a currently under-valued fish species. The innovative treatment reported in this study opens the way to the employment of this strategy to current commercial seafoods (namely, lean and fatty fish). Fu

Seaweeds have attracted an increasing attention as a new source for bioactive compounds, these include preservative compounds. This study is a first attempt to employ alga Cystoseira compressa for the preservation of chilled fish. For it, a combined ethanol–aqueous extract of this alga was included in the icing system and employed as chilling medium for the storage of horse mackerel (Trachurus trachurus) for 11 days. On the basis of the microbial groups (aerobes, psychrotrophs, proteolytic, lipolytic and Enterobacteriaceae bacteria) assessed, an inhibitory effect (p < 0.05) on microbial activity in horse mackerel muscle was observed as a result of including the alga extract in the icing medium; such preservative effect was also proved by chemical determinations related to microbial activity (pH and trimethylamine values). Additionally, a significant decrease (p < 0.05) of lipid hydrolysis (free fatty acids formation) and oxidation (fluorescent compounds formation) in fish was also observed as a result of the presence of C. compressa extracts in the icing medium. The icing medium proposed in this work (i.e., the combination of ethanolic and aqueous extracts of C. compressa) may constitute a promising strategy to the application of natural algae extracts for fatty fish storage and enhance quality retention during commercialisation