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In this study, novel functional ZEO-complex gels were prepared using sodium alginate, inulin, grape seed extract (GSE), and Zanthoxylum bungeanum essential oil (ZEO) as the primary raw materials. The effect of the addition of inulin, GSE, and ZEO on water vapor permeability (WVP), tensile strength (TS), and elongation at break (EAB) of ZEO-complex polysaccharide gels was investigated. A comprehensive score (Y) for evaluating the characteristics of ZEO-complex polysaccharide gels was established by principal component analysis. MATLAB analysis and box-Behnken design describe each factor’s four-dimensional and three-dimensional interactions. It was found that Y could reach the maximum value when the ZEO addition was at a moderate level (C = 2%). The optimum preparation process of ZEO-complex polysaccharide gels was as follows: the addition of inulin was at 0.84%, the addition of GSE was at 0.04%, and the addition of ZEO was at 2.0785%; in this way, the Y of ZEO-complex polysaccharide gels reached the maximum (0.82276). Optical scanning and X-ray diffraction tests confirmed that the prepared ZEO-complex gels have a smooth and continuous microstructure, good water insulation, and mechanical properties. The storage test results show that ZEO-complex polysaccharide gels could play a significant role in the storage and fresh-keeping of grass carp, and the physicochemical properties of complex polysaccharide gels were improved by adding ZEO. In addition, according to the correlation of fish index changes during storage, adding ZEO in complex polysaccharide gels was closely correlated with the changes in fish TBARS and TVB-N oxidation decay indices. In conclusion, the ZEO-complex polysaccharide gels prepared in this study had excellent water insulation, mechanical properties, and outstanding fresh-keeping effects on grass carp.

The origin of fish smoking dates back to antiquity. It is thought that the process was started by hanging the fish product over a fire which was used to reduce the moisture content of the product. Further advancement was made traditionally by the erection of mud, bricks or corrugated iron angle bar. The gas smoking kiln has been developed using locally available materials in the study area towards improving the existing fish smoking kiln techniques. The objective of this work is to improve the quality of smoked fish in Kainji Lake Basin in Nigeria at minimum production cost. The preliminary test performance of the kiln has been conducted using Clarias gariepinus. The result obtained shows that the kiln is less labour intensive and can handle different sizes of fish faster with better appearance of the end product than the conventional smoking methods.

Ice is commonly used to preserve fish, but ice crushers are not always available in rural and remote areas of Bangladesh. A low-cost hand-operated ice crusher machine was developed in the Department of Farm Power and Machinery at Bangladesh Agricultural University. The machine yielded a throughput capacity of 21.6 kg min-1 with an average loss of 13.1%. The average time to crush a 10.6 kg ice block was 21.6 seconds. The total deformation, strain energy, maximum shear stress, and structural error were estimated as 0.0046 mm, 0.0031 MJ, 28 MPa, and 0.0025 MJ, respectively, for a single spike of the crusher. The average revolution per minute of the crushing cylinder was 493.6, with a maximum value of 634.7, and the maximum vibration frequency was 10.7 Hz. The maximum noise level during crushing operation was 92.9 dB, which was within the acceptable range. The machine's ergonomic assessment after operation yielded a satisfactory result. On average, the operators' blood pressure (systolic and diastolic), pulse rate, and respiration rate were 138.4 and 74.2 mm (Hg), 105.4 per minute, and 20 per minute, respectively. The results of the performance evaluation indicate that the device appears to be a suitable input for marginal fish farmers with inadequate access to electricity. [Fundam Appl Agric 2022; 7(1.000): 60-74]

Fresh fish is a perishable food in which chemical (namely oxidation) and microbiological degradation result in undesirable odor. Non-processed fish (i.e., raw fish) is increasingly commercialized in packaging systems which are convenient for its retailing and/or which can promote an extension of its shelf-life. Compared to fish sent to its retail unpackaged, fish packaging results in a modification of the gaseous composition of the atmosphere surrounding it. These modifications of atmosphere composition may affect both chemical and microbiological degradation pathways of fish constituents and thereby the volatile organic compounds produced. In addition to monitoring Total Volatile Basic Nitrogen (TVB-N), which is a common indicator to estimate non-processed fish freshness, analytical techniques such as gas chromatography coupled to mass spectrometry or techniques referred to as “electronic nose” allow either the identification of the entire set of these volatile compounds (the volatilome) and/or to selectively monitor some of them, respectively. Interestingly, monitoring these volatile organic compounds along fish storage might allow the identification of early-stage markers of fish alteration. In this context, to provide relevant information for the identification of volatile markers of non-processed packaged fish quality evolution during its storage, the following items have been successively reviewed: (1) inner atmosphere gaseous composition and evolution as a function of fish packaging systems; (2) fish constituents degradation pathways and analytical methods to monitor fish degradation with a focus on volatilome analysis; and (3) the effect of different factors affecting fish preservation (temperature, inner atmosphere composition, application of hurdle technology) on volatilome composition.

Two edible coatings (gelatin coating and ginger essential oil-gelatin coating) were prepared to maintain the flavor quality of fish fillets at two storage temperatures (4 °C and 25 °C). The effects of coating on fish fillets were evaluated by detecting the physical properties, microstructure, microbial properties, volatile flavor and taste flavor of fish. In the same coating method, fish fillets stored at 4 °C showed better effect than that at 25 °C on maintain water content, color and texture, however, fish fillets stored at 25 °C were closer to fresh fish in volatile flavor and taste flavor than that at 4 °C; whatever the storage temperature, coating could slow down the growth of fish microorganisms, maintain water content, color, texture, volatile flavor and taste flavor of fish fillets; GGC exhibited better effect on maintain flavor quality than GC.

The high susceptibility of harvested fresh fish to immediate deterioration has resulted in the fundamental need for fish preservation to maintain its nutritional quality, minimize changes in its physical appearance, taste and lengthen shelf life. The insecticide, pirimiphos methyl (actellic dust) has been utilized in the storage of dried products against insect infestation, thereby increasing their shelf life. This study investigated the effect of pirimiphos methyl on the proximate and mineral composition of Synodontis nigrita and Tilapia mariae in Jamieson River which were purchased from the fish landing site in Sapele Delta State, Nigeria. The fish samples were divided into three batches of fresh samples (batch I), oven – dried samples (batch II) and actellic dust treated samples (batch III). The proximate composition (moisture, protein, fat, ash, crude fibre, and carbohydrate) and mineral content (sodium, potassium, calcium, and magnesium) of the samples were determined using the AOAC standard methods. Results showed that actellic dust treatment greatly increased the protein (19.35 to 23.31%), fat (8.12% to 22.31%), and raw fibre content (0.69 to 8.03%) in S. nigrita and protein (7.09 to 25.46%), fat (5.13 to 11.70%), and raw fibre content (3.40 to 14.23%) in T. mariae. The mineral elements analyzed showed no well-defined order across the treatment levels with potassium being the most abundant mineral element in all fish samples. Actellic dust has been shown to improve the proximate composition and shelf life of both fish species studied, and its use as a fish preservative is therefore recommended.

Microbial spoilage of fish is attributed to quorum sensing (QS)-based activities. QS is a communication process between the cells in which microorganisms secrete and sense the specific chemicals (autoinductors, AIs) that regulate proteolysis, lipolysis, and biofilm formation. These activities change the organoleptic characteristics and reduce the safety of the products. Although the microbial community of fish is diverse and may consist of a range of bacterial strains, the deterioration of fish-based products is attributed to the growth and activity of Pseudomonas spp. This work summarizes recent advancements to assess the influence of QS mechanisms on seafood spoilage by Pseudomonas spp. The quorum sensing inhibition (QSI) in the context of fish preservation has also been discussed. Detailed recognition of this phenomenon is crucial in establishing effective strategies to prevent the premature deterioration of fish-based products.

Glucose oxidase (GOx) with high enzyme activity at low temperature (4°C) is potentially useful for food preservation, especially for aquatic products preservation. A cold-active GOx with approximately 83% similarity to known protein sequences, was isolated from Penicillium sp. MX3343 and expressed in Pichia pastoris X33. Through high cell density fermentation, the yield of recombinant enzyme (named GOxP5) reached 458.6 U/mL. GOxP5 showed optimal activity at 30°C and pH 5.5, and was stable at a broad pH range from pH 2–6. Moreover, GOxP5 could maintain 72% maximum activity at 4°C, suggesting its application for the preservation of aquatic products at low-temperatures. Importantly, GOxP5 showed a good antimicrobial effect against common fish pathogenic bacteria (Listeria monocytogenes and Vibrio parahaemolyticus). Moreover, sensory, microbiological (total bacterial count), and physicochemical (total volatile basic nitrogen and pH) systematic analyses proved GOxP5 to be an excellent freshness preserving agent in the context of the grass carp. These favorable enzymatic properties of GOxP5 make it potentially useful in food biopreservation, and the effect was better compared to the commonly used chemical preservatives.

This study aimed to increase the antibacterial activity of chitosan-polylactic acid (PLA) composite film by adding nisin and ethylenediaminetetraacetic acid (EDTA). We evaluated the mechanical, physicochemical, and antibacterial properties of various PLA composite films, as well as the enhancement effect of PLA composite films with EDTA + nisin on the preservation of grouper fillets. Films of PLA alone, PLA plus chitosan (C5), PLA plus nisin + EDTA (EN2), and PLA plus chitosan plus nisin + EDTA (C5EN1 and C5EN2) were prepared. The addition of EDTA + nisin to the chitosan-PLA matrix significantly improved the antibacterial activity of the PLA composite film, with C5EN1 and C5EN2 films showing the highest antibacterial activity among the five films. Compared with the fish samples covered by C5, the counts of several microbial categories (i.e., mesophilic bacteria, psychrotrophic bacteria, coliforms, Aeromonas, Pseudomonas, and Vibrio) and total volatile basic nitrogen content in fish were significantly reduced in the samples covered by C5EN1. In addition, the counts of samples covered by C5EN1 or C5 were significantly lower compared to the uncovered and PLA film-covered samples.

This research prepared chitosan–PLA plastic films by extrusion, analyzed the physical and mechanical properties and antibacterial activity of the fabricated plastic films, and used them to preserve grouper fillet. We added chitosan (220 kDa, 93% DD) in the weight ratio of 0.5–2% into the PLA to prepare the chitosan–PLA films. With the increasing chitosan dosage, both the water vapor transmission rate and moisture content of chitosan–PLA films increased. Among the three doses of chitosan (0.5%, 1%, and 2%) added to PLA, 0.5% chitosan–PLA film had the highest antibacterial activity. This plastic film had an inhibitory efficiency of over 95% against Escherichia coli, Pseudomonas fluorescens, and Staphylococcus aureus. The action of covering the fish fillet with 0.5% chitosan–PLA film significantly reduced several microbes’ counting (i.e., mesophiles, psychrophiles, coliforms, Pseudomonas, Aeromonas, and Vibrio) and total volatile basic nitrogen (TVBN) value in the grouper fillets stored at 4 °C. Thus, such action prolongs the fish fillets’ shelf life to up to at least nine days, and this 0.5% chitosan–PLA film shows promising potential for preserving refrigerated fish.

Microbial mats have been repeatedly suggested to promote early fossilization of macroorganisms. Yet, experimental simulations of this process remain scarce. Here, we report results of 5 year-long experiments performed onfish carcasses to document the influence of microbial mats on mineral precipitation during early fossilization. Carcasses were initially placed on top of microbial mats. After two weeks, fishes became coated by the mats forming a compact sarcophagus, which modified the microenvironment close to the corpses. Our results showed that these conditions favoured the precipitation of a poorly crystalline silicate phase rich in magnesium. This talc-like mineral phase has been detected in three different locations within the carcasses placed in microbial mats for more than 4 years: 1) within inner tissues, colonized by several bacillary cells; 2) at the surface of bones of the upper face of the corpse buried in the mat; and 3) at the surface of several bones such as the dorsal fin which appeared to be gradually replaced by the Mg-silicate phase. This mineral phase has been previously shown to promote bacteria fossilization. Here we provide first experimental evidence that such Mg-rich phase can also be involved in exceptional preservation of animals.