Fish silage: a review

Optimization of a hatchery residue fermentation process for potential recovery by black soldier fly larvae

The conventional management of hatchery residues (HR) poses environmental issues and health risks for handlers. This study evaluates the potential of fermentation to reduce pathogens and odors in HR, enabling them to be recovered into feed using black soldier fly. This saprophagous edible insect is valued for its ability to efficiently bioconvert organic residues into high-quality biomass. Due to the low carbohydrate content of HR, whey permeate was added at lactose inclusion levels of 0, 5, 15, 25, and 35% (dry basis) to optimize fermentation. Using a commercial ferment starter culture (0.3%, wet basis), HR were fermented under semi-anaerobic conditions for two weeks. Fermentation metrics, including pH, microbiological loads (total aerobic mesophilic, presumptive lactic acid bacteria, coliforms, Escherichia coli), volatile fatty acids, and volatile organic compounds, were monitored at days 0, 3, 7, and 14. Optimal stabilization was achieved with lactose inclusion of 15 to 35% after 7 days, which reduced pH (<5.3), increased lactic (87.82 mg/g) and acetic (20.28 mg/g) acid production, and decreased coliform and Escherichia coli counts below detection limit (1.7 log cfu/g). The production of compounds associated with unpleasant odors was also limited. The use of a ferment did not result in a greater reduction of coliform counts, the initial loads of lactic acid bacteria (> 7 log cfu/g) being sufficient to initiate spontaneous fermentation. However, ferment was found to be efficient in heated HR. These findings demonstrate the effectiveness of fermentation for stabilizing HR, highlighting its potential for integration into insect bioconversion systems.

LED induced non-thermal preservation of muscle foods: A systematic review

LED technology has emerged as a promising non-thermal preservation method for highly perishable muscle foods like meat and fish. Muscle foods are most susceptible to spoilage due to their high moisture content and nutrient density, which create an ideal environment for microbial growth, chemical oxidation, and enzymatic activity, which negatively alter their quality. LED treatment offers an effective solution by significantly reducing microbial loads and extending shelf life without adversely affecting sensory and nutritional properties. Specific wavelengths of LED light induce microbial inactivation through mechanisms like DNA damage, lipid oxidation, and protein alteration. Studies have shown that LED treatment can preserve the fresh-like quality of muscle foods by mitigating common spoilage processes. The advantages of LED technology include its non-thermal nature, ability to integrate with other preservation methods, and controllability in terms of intensity and wavelength. This enables for tailored applications based on food type and spoilage risks. As consumer demand grows for safe, chemical-free food options, LED technology addresses this need while enhancing food safety and quality. Further research is encouraged to optimize LED applications in various muscle food preservation contexts. With its exceptional ability to produce DNA damage in bacteria, inactivate enzymes, and malfunction biological activities, LED could serve as an inexpensive processing intervention to safeguard the quality of meat and seafood products. This review underscores the potential of LED technology as a promising alternative to traditional preservation methods for decontamination of muscle food.

Upgrading Marine Oils from Cod (Gadus morhua) On-Board the Deep-Sea Vessels-From Waste to Value

Significant amounts of marine raw material are lost on-board the deep-sea vessels due to fast quality degradation. Optimal on-board handling and processing strategies can upgrade these resources from waste to food ingredients rich in nutrients such as omega-3 fatty acids. The objective of this study was to investigate the effect of raw material freshness and sorting on the quality, composition and yield of oil produced thermally from cod (Gadus morhua) residuals on-board a commercial trawler. Oil was produced from whole viscera fractions with liver or out-sorted livers right after a catch and after chilled storage for up to 6 days. The results showed that significantly higher oil yields could be obtained if the raw materials were stored for 1 day or longer. However, an undesired emulsion was formed when viscera were stored for 4 days. All oils were rich in health beneficial omega-3 fatty acids, but viscera oils had generally lower quality with higher levels of free fatty acids and oxidation products. However, out-sorting of the liver was not necessary to meet guidelines for high-quality fish oil. Both viscera and liver could be stored for up to 2 days at 4 °C prior to oil production and still meet quality criteria for food applications. These results demonstrate a large potential in upgrading currently wasted marine raw materials into high-quality food ingredients.

Characterization and Evaluation of Proteolysis Products during the Fermentation of Acid Whey and Fish Waste and Potential Applications

Reduction of waste in the food industry is critical to sustainability. This work represents one strategy of valorizing waste streams from the dairy (acid whey) and fisheries industries (fish waste) using fermentation. The main approach was to characterize the peptides produced by this fermentation under three conditions: (1) fermentation without adding inoculum; (2) with the addition of a single lactic acid bacterial strain; and (3) the addition of a consortium of lactic acid bacteria. Previous results indicated that the rapid acidification of this fermentation was advantageous for its food safety and microbial activity. This work complements our previous results by defining the rate of peptide production due to protein digestion and using two-dimensional (2D) gel electrophoresis and proteomic analysis to give a more detailed identification of the peptides produced from different waste streams. These results provide important information on this process for eventual applications in industrial fermentation and, ultimately, the efficient valorization of these waste streams.

Effect of antioxidants on lipid oxidation in herring (Clupea harengus) co-product silage during its production, heat-treatment and storage

Provided high product quality, ensilaging can be used to valorize fish filleting co-products into a silage suitable for food applications. However, a documented challenge for products from hemoglobin-rich fish raw materials is the high susceptibility to lipid oxidation, calling for stabilization by antioxidants. In a comparison among different rosemary-containing antioxidants and isoascorbic acid, we here found that the commercial mixture Duralox MANC-213 (MANC) provided the best protection against peroxide value and 2-thiobarbituric acid reactive substances (TBARS) development during ensilaging of herring filleting co-products (0–7 days, 22 °C), and also during subsequent heat-treatment (30 min, 85 °C). Increasing MANC concentration from 0.25 and 0.75 to 1.25% lowered TBARS values from 43.53 and 25.12 to 18.04 µmole TBARS/Kg silage, respectively, after 7 days of ensilaging. During storage at 4 °C/22 °C in presence of MANC, 1.25% provided the highest protection with 87–90% and 66–73% lower TBARS, at 4 °C and 22 °C, respectively, at 6 months compared to the controls. At this time point, heat-treated silages had lower protein degree of hydrolysis and free amino acids values than the non-heat-treated one. Regardless of antioxidant addition, total volatile basic nitrogen (TVB-N) formation still increased during the storage, but, overall, TVB-N values in silages were below the acceptable limit of 30 mg TVB-N/100 g fish for human consumption. Together with lipid oxidation data, this suggest that herring silage produced in presence of antioxidants can be used both for high quality feed and food applications.

Biologia futura: medicinal plants-derived bioactive peptides in functional perspective-a review

Bioactive peptides (BPs) are 3-20 amino acid residues, with a molecular weight lower than 6 kDa; originated from the breakdown of proteins by endogenous and exogenous peptidases. While intact in protein these peptides do not exert any biological activity, but as they release from their parent protein, they exert various pharmacological activities such as antidiabetic, antihypertensive, anticancerous, anti-inflammatory, antimicrobial, antioxidant, and immunomodulatory. Such peptides exist in all living organism like plants, animals, marine organism and also present in food products derived from them. BPs obtained from dairy food products, cereals, vegetables have been gaining much more importance now-a-days, but little work has been done on bioactive peptides obtained from medicinal plants. Some of the medicinal plants such as Tinospora cordifolia Sterculia foetida, Benincasa hispida, Parkia speciosa, Linum usitatissimum, Salvia hispanica and Ziziphus jujube have been explored for bioactive peptides. Current review is aimed to provide a complete information of medicinal plants derived BPs along with the surge of new materials, new plants which will provide more solutions for handling some of the major human health problems of twenty-first century. This review will also be helpful to researchers in providing valuable information about the extraction, separation, characterization of BPs, their known peptide sequences and various pharmacological activities exerted by medicinal plants-derived bioactive peptides.

Comparative assessment of amino acids composition in two types of marine fish silage

Fish silage is a brown liquefied product achieved by the action of enzymes when finely grounded whole/parts of either single or mixed fish types are subjected to acidification. This study made a comparative assessment of biochemical and nutritive properties, especially the amino acid composition in supernatant phase of formic acid silages prepared from two fish types, Indian mackerel (Rastrelliger kanagurta) and false travely (Lactarius lactarius) representing fat fish (FF, fat content > 5%) and lean fish (LF, fat content < 5%), respectively during 35 days of fermentation (DoF). Significantly higher content of total amino acid (TAA) and free amino acids (FAA) were recorded in FFS (TAA, 41.2 ± 0.03 mg/g; FAA, 31.3 ± 0.003 mg/g) compared to LFS (TAA, 35.8 ± 0.07 mg/g; FAA, 18.26 ± 0.003 mg/g; FAA, 31.3 ± 0.003 mg/g) (p < 0.05). At the end of 35 DoF, the concentrations of amino acids such as asparagine, histidine, isoleucine, valine, cysteine, serine, lysine and arginine were significantly higher in FFS as compared to LFS. The relative amino acid composition of FFS and LFS varied in accordance with DoF and the relationship was found to be highly significant (ANOVA, p < 0.00001). High concentrations of l-amino acids such as leucine, glutamic acid and arginine were recorded in both FFS and LFS. In conclusion, the analysis suggested that a fermentation period of 25–30 days showed a significant effect on the composition of amino acids in both types of ensilage compared to other fermentation periods (p < 0.05). Considering the role of amino acids in enhancing the plant growth and proliferation, the findings of the present study are quite useful.

Seafood Waste Management Status in Bangladesh and Potential for Silage Production

Frozen shrimp and fish are the second most valuable export items from Bangladesh. Thus, in processing industries, a considerable amount of seafood waste is produced every year. Neglecting seafood waste leads to serious forms of wastage. The purpose of this survey-based study was to estimate the amount of seafood waste produced and understand the existing waste management practices in Bangladesh. Potential for seafood waste-based silage production and its utilization were also studied. Across the seafood industry, around 43,321 tons of seafood waste are produced every year. The highest amount of seafood waste is produced in Khulna, followed by Chittagong, Cox’s Bazar, Dhaka, and Sylhet. Local people consume a portion of fresh shrimp carapace and heads and gills of large fish. A portion of seafood waste is also used to feed aquaculture species. Moreover, parts of dried shrimp shells, appendages, and fish scales, air bladders, and fins are exported to some Asian countries. The prospect of fish silage production constitutes a promising new development for animal feed production in Bangladesh. The availability of waste materials from seafood processors and the demand from feed millers favor the conditions for silage production. However, in order for the seafood waste-based silage industry to flourish, the establishment of supply chains for seafood waste and end products (silage) is required. Studies on growth performance, muscle quality, and digestibility of animal feed with silage-based diets are required for farmed species.

Bacterial Diversity Analysis and Evaluation Proteins Hydrolysis During the Acid Whey and Fish Waste Fermentation

The disposal of acid whey (Aw), a by-product from fermented products, is a problem for the dairy industry. The fishery industry faces a similar dilemma, disposing of nearly 50% of fish processed for human consumption. Economically feasible and science-based alternatives are needed to overcome this problem. One possible solution is to add value to the remaining nutrients from these by-products. This study focuses on the breakdown of nutrients in controlled fermentations of Aw, fish waste (F), molasses (M), and a lactic acid bacteria (LAB) strain (Lr). The aim was to assess the dynamic variations in microbial diversity and the biochemical changes that occur during fermentation. Four treatments were compared (AwF, AwFM, AwFLr, and AwFMLr), and the fermentation lasted 14 days at 22.5 °C. Samples were taken every other day. Colorimetric tests for peptide concentrations, pH, and microbial ecology by 16S-v4 rRNA amplicon using Illumina MiSeq were conducted. The results of the microbial ecology showed elevated levels of alpha and beta diversity in the samples at day zero. By day 2 of fermentation, pH dropped, and the availability of a different set of nutrients was reflected in the microbial diversity. The fermentation started to stabilize and was driven by the Firmicutes phylum, which dominated the microbial community by day 14. Moreover, there was a significant increase (3.6 times) in peptides when comparing day 0 with day 14, making this treatment practical and feasible for protein hydrolysis. This study valorizes two nutrient-dense by-products and provides an alternative to the current handling of these materials.

Fish and fish waste-based fertilizers in organic farming - With status in Norway: A review

This paper reviews relevant knowledge about the production and uses of fertilizers from fish and fish waste (FW) that may be applicable for certified organic farming, with a focus on crop and horticultural plants. Fish industries generate a substantial amount of FW. Depending on the level of processing or type of fish, 30-70% of the original fish is FW. Circular economy and organic farming concepts were used to evaluate the potential of production of fertilizers from captured fish. Fertilizers produced from captured fish promote the recycling of nutrients from the sea and back to terrestrial environments. Nutritional composition of FW is assessed to determine the potential to supply plant nutrients such as nitrogen, or a combination of nitrogen and phosphorous, or to enrich a compost. Methods used in processing of FW to produce fish- emulsion, fish hydrolysate/fish silage, fish-compost and digestate from anaerobic digestion/co-digestion are presented. Using information about commercially available fish-based fertilizers listed by the Organic Materials Review Institute (OMRI), we present a scenario for establishing fish/FW-based fertilizers industry and research in Europe. With Norway's 9th position among top ten global capture producers and focus in Norway on developing organic farming, we brief how FW is currently utilized and regulated, and discuss its availability for possible production of FW-based organic fertilizers. The amount of FW available in Norway for production of fertilizers may facilitate the establishment of an industrial product that can replace the currently common use of dried poultry manure from conventional farming in organic farming.

Protein Recovery from Underutilised Marine Bioresources for Product Development with Nutraceutical and Pharmaceutical Bioactivities

The global demand for dietary proteins and protein-derived products are projected to dramatically increase which cannot be met using traditional protein sources. Seafood processing by-products (SPBs) and microalgae are promising resources that can fill the demand gap for proteins and protein derivatives. Globally, 32 million tonnes of SPBs are estimated to be produced annually which represents an inexpensive resource for protein recovery while technical advantages in microalgal biomass production would yield secure protein supplies with minimal competition for arable land and freshwater resources. Moreover, these biomaterials are a rich source of proteins with high nutritional quality while protein hydrolysates and biopeptides derived from these marine proteins possess several useful bioactivities for commercial applications in multiple industries. Efficient utilisation of these marine biomaterials for protein recovery would not only supplement global demand and save natural bioresources but would also successfully address the financial and environmental burdens of biowaste, paving the way for greener production and a circular economy. This comprehensive review analyses the potential of using SPBs and microalgae for protein recovery and production critically assessing the feasibility of current and emerging technologies used for the process development. Nutritional quality, functionalities, and bioactivities of the extracted proteins and derived products together with their potential applications for commercial product development are also systematically summarised and discussed.

Valorization of Proteins from Co- and By-Products from the Fish and Meat Industry

Large volumes of protein-rich residual raw materials, such as heads, bones, carcasses, blood, skin, viscera, hooves and feathers, are created as a result of processing of animals from fisheries, aquaculture, livestock and poultry sectors. These residuals contain proteins and other essential nutrients with potentially bioactive properties, eligible for recycling and upgrading for higher-value products, e.g. for human, pet food and feed purposes. Here, we aim to cover all the important aspects of achieving optimal utilization of proteins in such residual raw materials, identifying those eligible for human consumption as co-products and for feed applications as by-products. Strict legislation regulates the utilization of various animal-based co- and by-products, representing a major hurdle if not addressed properly. Thorough understanding and optimization of all parts of the production chain, including conservation and processing, are important prerequisites for successful upgrading and industrial implementation of such products. This review includes industrially applied technologies such as freezing/cooling, acid preservation, salting, rendering and protein hydrolysis. In this regard, it is important to achieve stable production and quality through all the steps in the manufacturing chain, preferably supported by at- or online quality control points in the actual processing step. If aiming for the human market, knowledge of consumer trends and awareness are important for production and successful introduction of new products and ingredients.

Fermentation of non-sterilized fish biomass with a mixed culture of film-forming yeasts and lactobacilli and its effect on innate and adaptive immunity in mice

Non-sterilized fish waste containing fish bones was fermented using combined starter cultures of film-forming yeast (Candida ethanolica) and lactic acid bacteria (LAB; Lactobacillus casei and Lactobacillus rhamnosus) in order to obtain a liquefied fermented broth without spoiling. During the entire fermentation, the number of LAB cells was maintained at a high level (6 × 10(8)-5 × 10(7) cells/ml). Although the number of general bacteria was 10(6)cell/ml after adding non-sterilized fish biomass, its growth was suppressed to be 1-3 × 10(4) cells/ml. The entire biomass had completely liquefied and the fermented broth contained all 20 α-amino acids composed of protein and also various kinds of minerals in abundance. The weight of mice group fed the fermented broth content feed (sample feed) for 31 days significantly increased compared with that fed no broth feed (control feed) (21.37 g vs 20.76 g (p < 0.05). No abnormal behavior and appearance were observed. All internal organs (the heart, the liver, the lung, the intestines, and the spleen) of both groups were confirmed to be normal by visual observation. In peripheral blood, the percentages of NK cells and CD8+ T cells of the mice in the sample feed group increased significantly relative to those in the control feed group (NK cells: 19% vs 11%, CD8+ T cells: 9% vs 5%, p < 0.05). In the spleen, the percentage of NK cells in the sample feed group also increased significantly compared to that in the control feed group (p < 0.05). The fermented fish biomass is expected to be effective for innate and adaptive immunity and thus fit for animal feed.

Nutritive value of diets containing fish silage for juvenile Litopenaeus vannamei (Bonne, 1931)

BACKGROUND

Fish wastes has been used for many years as an alternative in feeds for aquaculture. In the present study weight gain of juvenile white shrimp Litopenaeus vannamei fed diets including fish waste silage (WS), fish waste silage with soybean meal SBM (WS + S) or fish waste meal (WM) was compared. A conventional acidic silage process was applied to obtain from wastes (skin, heads, bones and viscera) of snapper (Lutjanus spp.), grunt (Haemulon plumieri), and grouper (Epinephelus spp.) an ingredient rich in protein.

RESULTS

After 3 days ensilage more than 90% protein was hydrolysed. Waste material processed at pH 3.8 lost about 24% tryptophan. Butylated hydroxytoluene (BHT) prevented lipid oxidation, as shown after 45 days with malonaldehyde production. Shrimp fed WS + S diet gained 0.7 g per week higher than those fed WS and WM diets with 0.3 g per week (P < 0.05).

CONCLUSION

WS processed with formic acid under conditions of low pH is beneficial for the white shrimp L. vannamei. It sustained reasonable weight gain combined with soybean meal in practical diets. On the other hand, BHT addition was beneficial in preventing oxidative action during silage preparation.

Upgrading of sea by-products: potential nutraceutical applications

Since many years, numerous kinds of processes based on enzymatic hydrolysis at various pH, involving added plant or bacterial enzymes after inactivation by heating of endogenous enzymes present in the raw material or, alternatively, based on the action of endogenous enzymes, have contributed to the degradation of marine by-product proteins in order to produce fractions exerting biological activities. Peptides obtained by enzymatic hydrolysis of fish proteins exhibit not only nutritional but also biological properties of dietary uses, or even therapeutic potential. In this review, we have focused on the different enzymatic processes able to generate bioactive peptides from marine by-products and exerting high potential in nutraceutical applications to fight against important public health issues like obesity, stress, hypertension, and migraine. Beyond the nutraceutical and pharmaceutical aspects, this way of valorization is also included in the necessary development of by-product fishing industries for economic and ecological reasons in the worldwide context of marine resources depletion.

Effect of ensiling and organic solvents treatment on proteolytic enzymes of layer chicken intestine

Effect of ensiling and organic solvents on the protein extractability and on the activities of the proteolytic enzymes of layer chicken intestine was evaluated. The protein content of water extract of layer chicken intestine was 2.45 mg/ml. Highest proteolytic activity (26.3 units) was observed at pH 10.6 and lowest at pH 6.8 (7.2 units). Higher acidic proteolytic activities were observed at pH 2.4, pH2.8 and at pH 5. Acid ensiling resulted in 65.6% reduction in acidic protease activity compared to 57.4% reduction by fermentation ensiling. Neutral and alkaline protease activities were also reduced up to a maximum of 41.8% and 46.5%, respectively. A ratio of 1:1.5 of cold acetone to intestine homogenate was found best for enhancing the neutral and alkaline protease activity. The study revealed that layer chicken intestine is a rich source of proteases especially of neutral and alkaline proteases, which could be harvested for commercial purposes and both acid and fermentation ensiling of layer chicken intestine resulted in reduction of protein extractability and enzyme activity. Treatment with acetone almost doubled the activities of neutral and alkaline proteases compared to initial values in water extract of fresh intestines.

Media preparation using tuna-processing wastes for improved lipase production by shrimp gut isolate Staphylococcus epidermidis CMST Pi 2

Extracellular lipase production by Staphylococcus epidermidis CMST Pi 2 isolated from the intestine of shrimp Penaeus indicus has been investigated in shake-flask experiment using different preparations of tuna-processing waste such as raw fish meat, defatted fish meat, alkali hydrolysate, and acid hydrolysate as nitrogen source. Among the tested tuna preparations, defatted fish meat supported the maximum lipase production, and 2.5% concentration of the same was found to be optimum for maximizing the lipase production. The effect of carbon sources on lipase production revealed that glucose aided the higher lipase production than any other tested carbon source and a concentration of 2% glucose registered as optimum to enhance the lipase production. The halotolerancy of S. epidermidis CMST Pi 2 for lipase production indicated that 4% of sodium chloride was optimum to yield maximum lipase. Among the surfactants tested, lipase production was high in Tween 20 added medium when compared to other surfactants, and its optimum concentration recorded was 0.8%. Partial characterization of crude enzyme revealed that pH 7 and 55 degrees C temperature were optimum for maximum lipase activity.

Effects of different dietary levels of fish protein hydrolysates on growth, digestive enzymes, gut microbiota, and resistance to Vibrio anguillarum in European sea bass (Dicentrarchus labrax) larvae

Two fish protein hydrolysates (FPH) were incorporated into four diets prepared for start-feeding sea bass larvae, at two different levels (10% and 19% of total ingredients): a commercial FPH, CPSP, in which the molecular mass of the main fraction of soluble peptides (51%) was between 500-2500 Da, and an experimental FPH obtained by acidic silage of sardine offal, SH, with a main portion of soluble peptides (54%) ranging from 200 to 500 Da. The diet with 10% of the commercial FPH gave the best results in terms of growth, survival and intestinal development, as evaluated by the early activity of digestive enzymes in the brush border membrane (alkaline phosphatase and aminopeptidase N). This was related to the low level of Vibrio spp. counted in the larvae of group C10. The high dose of FPH, especially in the experimental preparation rich in short peptides, seemed to favour the dominance of Vibrio sp. TYH3, which behaved opportunistically. The effect of the experimental FPH was ambiguous, since early larvae challenged with Vibrio anguillarum were more resistant to the pathogen, especially at high FPH dose (group S19). This might be due either to direct antagonism between V. anguillarum and Vibrio sp. TYH3, or to the stimulation of the immune response in the larvae. These results indicate that different molecular weight fractions and concentrations of feed-soluble peptides may affect the growth performance and immunological status of sea bass larvae. Consequently, a low dose of commercial FPH seems advisable, both for larval development and for the bacterial environment, although further research is required to determine and characterize peptide fractions that may have a beneficial effect on growth and immune response, and to determine their optimal inclusion levels in diets for sea bass larvae.

Fish and Shellfish Upgrading, Traceability

Recognition of the limited biological resources and the increasing environmental pollution has emphasised the need for better utilisation of by-products from the fisheries. Currently, the seafood industry is dependent on the processing of the few selected fish and shellfish species that are highly popular with consumers but, from economic and nutritional points of view, it is essential to utilise the entire catch. In this review, we will focus on recent developments and innovations in the field of underutilised marine species and marine by-product upgrading and, more precisely, on two aspects of the bioconversion of wastes from marine organisms, i.e. extraction of enzymes and preparation of protein hydrolysates. We will deal with the question of accurate determination of fish species at the various steps of processing. Methods of genetic identification applicable to fresh fish samples and to derived products will be described.