Biopreservation and the Safety of Fish and Fish Products, the Case of Lactic Acid Bacteria: A Basic Perspective

Abstract

Through fishing and aquaculture activities, humans have access to fish, which are a basic food source in the diet due to their nutritional value. Fish are widely distributed and commercialized worldwide in different products (e.g., whole fresh, filleted, sliced, frozen, dried, smoked, salted, and canned fish, among others). Because of their composition and nutritional value, fish are highly susceptible to spoilage and contamination, mainly by microorganisms, compromising their safety, shelf life, and availability; therefore, consuming fish can become a risk to public health. Foodborne diseases are considered important global public health problems because of their incidence, consequences, mortality, and negative economic impact on the population. Among the foods commonly associated with foodborne diseases are fish and fish products contaminated by various agents that are harmful to health throughout the food chain. Because of the constant growth of the population and the demand for greater quantities of food, the search for and development of technologies for the generation and availability of fresh, safe food with nutritional and sensorial qualities has increased. This is how biopreservation emerges, which, through the application of lactic acid bacteria and/or metabolites, is positioned as a sustainable, economic, and simple alternative for obtaining fish and fish products and making them available for human and/or animal consumption. Therefore, this work focuses on providing a basic and general perspective and information through the search, collection, and analysis of information in various databases, such as Google Scholar, SciELO, Redalyc, ScienceDirect, and/or institutional repositories, regarding fish production, nutritional properties, foodborne diseases, causal agents, and their associations with fish and fish products. Additionally, this study describes the biopreservation process through the use of lactic acid bacteria and/or metabolites to extend shelf life and promote the safety and nutritional and sensory qualities of fish and fish products intended for human and/or animal consumption.

1. Introduction

The safety of a food product is the guarantee that it will not harm the health of those who consume it [1,2]. Throughout the food chain (from the field to the consumer table), food can be contaminated by various physical, chemical, and biological hazards, compromising its safety and leading to repercussions on the health and quality of life of the population [1,2,3].

Safety constitutes one of the four basic groups of characteristics that, along with nutritional, organoleptic, and commercial characteristics, encompass the total quality of food [4,5]. Globally, one of the main problems for many countries is the supply, quality, and safety of foods that are sufficient to meet the needs of a constantly growing population [2,6]. The increasing population around the world puts pressure on food production, handling, and distribution systems. Therefore, the demand for a greater food quantity may cause challenges in food quality and safety and the associated risks to consumer health [2].

Fish are nutritious, are an important part of the human diet, and are considered one of the most produced and commercialized foods around the world. Likewise, fish and fish products are highly susceptible to contamination and spoilage, and their consumption causes disease outbreaks at the global level [7,8,9,10,11].

Product safety is imperative in the food industry as an evident and nonchangeable component in relation to other characteristics (appearance, flavor, and cost, among others) [4]. The food industry must guarantee quality in the foods generated and marketed through the application of various control systems that ensure the reduction to safe levels or the absence of various hazards, including microbiological hazards in the food environment [1,4,12].

Over time, various technologies have been developed to preserve and increase the availability of high-quality, nutritious, and safe foods [5,6,13,14]; however, microbiological risks may persist and can lead to diseases due to the consumption of foods contaminated with various microorganisms [5]. Therefore, producers continue to search for alternatives to preserve the microbiological quality of foods that ensure safety, minimize spoilage, and extend shelf life. One alternative ecological approach that contributes to food safety through the reduction in microbial agents associated with spoilage and diseases in consumers is biopreservation, which is defined as the extension of shelf life and food safety through the use of natural, controlled microbiota or their respective antimicrobial compounds [5,15].

The application of biopreservation methods in fish and fish products through the use of lactic acid bacteria or metabolites has been reported to benefit product safety, shelf-life extension, and availability for human consumption, and the usefulness of biopreservation for the generation of feed in animal production has also been noted.

Therefore, the objective of this work is to provide a basic and general perspective and information through the search, collection, and analysis of information in various databases, such as Google Scholar, SciELO, Redalyc, ScienceDirect, and/or institutional repositories, regarding fish production, nutritional properties, foodborne diseases, causal agents, and their associations with fish and fish products. This work also describes the biopreservation methods that use lactic acid bacteria and/or metabolites to extend shelf life and promote the safety and nutritional and sensory qualities of fish and fish products intended for human or animal consumption.

2. Food and Fish

Feeding is a fundamental activity in human life; through this process, the nutrients in food are absorbed, which is necessary to obtain the energy and structural components that cells require to perform their vital functions [16,17].

A healthy diet is one that combines foods in a balanced way to satisfy the nutritional needs for healthy growth and the development of physical and intellectual abilities, in addition to reducing the risk of chronic diseases related to diet [16,18]. Fish are among the foods that constitute a healthy diet [19,20] and are defined as any food intended for human or animal consumption that can be extracted from oceanic or continental waters [21].

Fish are a basic constituent of the human diet due to their highly nutritious contribution through proteins (16–21% high biological value and digestibility), polyunsaturated lipids (0.2–25%), omega-3 and omega-6 fatty acids, carbohydrates (<0.5%), and vitamins and minerals (1.2–1.5%), and they are also the most widely distributed and commercialized foods worldwide [7,21,22,23,24]. Notably, the nutritional value of fish depends on the species to which they belong, age, season of the year, environment, type of diet, migratory swimming, sexual changes related to spawning, capture conditions, cultivation, handling, processing, transportation, distribution, and storage [22,23].

Fish for human consumption come from capture fishing and continental or marine aquaculture activities, where in 2018, global fish production from both activities was estimated at 178.5 million tons in live weight, of which 156.4 million tons were for direct human consumption, with a per capita consumption of 20.5 kg [7]. Despite being a food with high nutritional qualities, the high rate of consumption as well as its approximately neutral pH, high water content, and nonprotein nitrogen content makes fish highly susceptible to spoilage and contamination due to autolysis (enzymes present in tissues and viscera), microbial activity, hydrolysis reactions, and lipid oxidation, limiting the consumption of fish and increasing the risk to human health [21,23,25,26].

3. Foodborne Diseases

Foodborne diseases are considered serious public health problems worldwide because of their morbidity, mortality, negative socioeconomic impact on productivity, food trade, and health service costs, and they require the implementation of laws and regulations regarding food safety [12,27,28,29].

Foodborne diseases are defined as syndromes derived from the ingestion of food and/or water with harmful agents in quantities such that they affect the health of the consumer. These diseases present a variety of gastrointestinal symptoms, such as nausea, vomiting, diarrhea, abdominal pain, and fever; in some cases, they present severe complications, such as sepsis, meningitis, abortions, Reiter syndrome, and Guillain–Barré syndrome, and may cause death. Additionally, foodborne illnesses have a greater impact on children, pregnant women, elderly individuals, people with immunological conditions, and those in places where poor hygienic/sanitary habits and overcrowded conditions are practiced [27,28].

It is estimated that 600 million people become sick worldwide annually from consuming contaminated foods, with diarrheal diseases being the most common [29]. More than 250 causal agents of foodborne illnesses have been reported, the majority being those of biological origin, such as bacteria, viruses, and parasites [28,30]. The incidence of these diseases has increased considerably during recent decades because of the increase in population, globalization of the food market, changes in eating habits, technological advances in production, increases in the use of additives, increases in the consumption of manufactured goods, the emergence of new forms of transmission and vulnerable population groups, and increases in resistance to antimicrobials [12,28].

Foodborne diseases can be classified into two types: (a) food infections caused by the ingestion of food contaminated with microorganisms that establish and multiply in the consumer, which have two variants: (1) invasive infections, where the microorganisms colonize tissues and organs of the affected person, such as Salmonella sp., Aeromonas sp., Campylobacter sp., Shigella sp., Vibrio parahaemolyticus, Yersinia sp., and enteroinvasive Escherichia coli, and (2) toxicoinfections, where microorganisms are capable of colonizing and multiplying in the intestinal tract of the host and excrete toxins, such as Vibrio cholerae, Bacillus cereus (a producer of enterotoxins), Clostridium botulinum, Clostridium perfringens, and enteropathogenic variants of E. coli; and (b) food poisoning, which is caused by ingesting food contaminated with enough toxins produced during microbial proliferation that is incorporated accidentally, incidentally, or intentionally in any phase of the food chain. Some of the producing microorganisms are Clostridium botulinum, Bacillus cereus (emetic toxin producers), and Staphylococcus aureus [28,31].

Notably, the intrinsic characteristics of the food matrix are determining factors in the susceptibility to and development of microbial contamination. Therefore, foods with high protein levels, such as meat, fish, eggs, milk, and milk derivatives, are considered high-risk foods and have frequently been associated with cases or outbreaks of disease worldwide [8,9,10,11,31,32].

Fish and fish products have been associated around the world with outbreaks of diseases derived from their consumption due to their contamination by various physical, chemical, and biological hazards (

Table 1. Various contaminants and hazards are responsible for waterborne diseases and the consumption of fish and fish products in humans [33,34,35,36,37,38,39,40].

Risk	Causal Agent	Example(s)
Biological	Bacteria	Mycobacterium spp., Streptococcus iniae, Photobacterium damselae, Vibrio sp., Salmonella spp., Shigella sp., Plesiomonas shigelloides, Edwardsiella tarda, and Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Clostridium sp., Legionella pneumophila, Bacillus cereus, Campylobacter jejuni, Aeromonas sp. Pseudomonas sp., and Yersinia sp.
	Parasites	Gnathostoma sp., Cryptosporidium spp., Giardia duodenalis, Toxoplasma gondii, Pseudoterranova sp., Anisakis sp., Phocanema spp., Angiostrongylus sp., Contracaecum sp., Diphyllobothrium sp., Phagicola sp., Clonorchis sp., Paragonimus sp., Heterophyes sp., and Cryptosporidium sp.
	Virus	Adenovirus, norovirus, astrovirus, hepatitis A, hepatitis E, rotavirus, and enterovirus
Chemical	Biotoxins	Ciguatoxin, scaritoxin, maitotoxin, tetrodotoxin, palytoxin, okadaic acid, gempilotoxin, and mycotoxins
	Heavy Metals	Copper, chromium, arsenic, mercury, lead, cadmium, nickel, zinc, and manganese
	Organic Compounds	Pesticides, microplastics, antibiotics, hormones, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenyl ethers, and dioxins
	Biogenic Amines	Spermidine, spermine, putrescine, cadaverine, and histamine
Physical	Objects from capture activities, handlers, infrastructure and processing, and warehouse equipment	Glass, metal, wood, bones, stones, jewelry elements, fishing line, plastic, and hooks

), with the latter being bacteria, viruses, and parasites, the most common causal agents in reported outbreaks [8,9,10,11,29,31,32].

4. Microbiology and Safety of Fish

The composition and proportion of the bacterial microbiota in freshly caught fish depend on (1) endogenous factors that are species- and population-specific, including host ancestry, genotype, and diet, whereas others are specific to each individual and include parasite load, immunological status, and life history; and (2) exogenous factors that include the composition of bacterial plankton, the environmental conditions of the capture area, including physicochemical parameters (temperature), and the degree of water contamination [22,34,41,42]. Microorganisms are found on the external surfaces of live and freshly caught fish tissues such as the skin, gills, and intestines [20]. Microbial levels in cold-water fish (<10–15 °C) are generally 10²–10⁴ CFU/cm² on the skin and gill surfaces, whereas in warm-water organisms, the levels range from 10³ to 10⁶ CFU/cm² [34]; within the intestines, microbial levels can be between 10³ and 10⁹ CFU/g [22], where the quantity, nature, and origin of the food consumed by fish has a qualitative and quantitative effect on the microbiota [34]. On the other hand, for warm-water fish, the bacteria are mainly mesophilic [34]; in temperate-water fish, they are mainly Gram-negative psychrophiles that can grow at temperatures between 0 °C and 25 °C, and the genera present are Pseudomonas sp., Moraxella sp., Acinetobacter sp., Shewanella sp., Flavobacterium sp., Vibrio sp., and Aeromonas sp. Gram-positive organisms such as Bacillus sp., Micrococcus sp., Clostridium sp., Lactobacillus sp., and Coryneform can be found in different proportions but are less common than Gram-negative bacteria [22,34,43]. Gram-negative bacteria in warm-water fish are generally similar to those in cold-water fish, whereas in freshwater fish, similar species are observed, except that Aeromonas sp. Replaces Vibrio sp. [34]. In contaminated water, high levels of members from the Enterobacteriaceae family, such as Escherichia coli and Salmonella spp., can be found [42,43].

Microbial activity is one of the main factors responsible for fish spoilage. The muscle of a healthy and/or recently caught fish is sterile because the immune system prevents the growth of bacteria in the muscle. Once death occurs, bacteria invade tissues through the gills, along blood vessels, and directly through the skin and membranes of the ventral cavity [22,23,42,43]. Psychrotrophs and mesophiles at growth temperatures of 20–35 °C cause the deterioration of fish stored above 15 °C for 1 to 2 days [34]. Some of the bacteria generally associated with the spoilage of refrigerated and unpreserved fish are Aeromonas sp., Vibrio sp., Moraxella sp., Acinetobacter sp., Pseudomonas spp., P. phosphoreum, and Shewanella putrefaciens [22,24,44]; the latter predominates at low temperatures and aerobic conditions, while P. phosphoreum participates in spoilage under anaerobic conditions, and aerobic Gram-negative bacteria predominate in decomposed fish at relatively high temperatures (10–37 °C), where Aeromonas sp. And Vibrio sp. [22,44] are most abundant. Microbial activity in the components of fish tissue (nonprotein nitrogen, amino acids, peptides, and proteins) results in the loss of juiciness, firm texture, discoloration, and the formation of unpleasant ammoniacal flavors and odors due to the production of various short-chain organic acids, amines, esters, alcohols, aldehydes, ketones, volatile sulfides, hypoxanthine, and trimethyl amine (TMA), whose levels are generally related to the degree of fish spoilage [22,25,43,44].

On the other hand, the presence of bacteria in fish is of interest to public health because many of these microorganisms are pathogenic in nature and are transmitted to humans through direct contact with or the consumption of fish, where they can cause disease. These microorganisms are usually divided into two groups: (1) native bacteria that are common and widely distributed in aquatic environments around the world, where water temperature has a selective effect; some of these are Clostridium botulinum, Plesiomonas shigelloides, Listeria monocytogenes, Vibrio sp., Aeromonas sp., and Pseudomonas sp., among others; and (2) nonnative bacteria or enterobacteria, such as Serratia sp., Proteus sp., Salmonella spp., Shigella sp., E. coli, Campylobacter jejuni, and Yersinia enterocolitica, among others, in addition to Clostridium perfringens and S. aureus, whose presence in fish is due to human or animal fecal contamination of aquatic environments as well as poor hygiene practices and conditions in postcapture handling [25,34,35,42,45].

The importance of the microbiological profile of fish and fish products lies in determining the presence of pathogenic microorganisms, spoilage, and shelf life; additionally, the microbiological profile is associated with and evaluated with the conditions and hygienic practices applied throughout the different phases of the food chain that prevent diseases derived from the consumption of these products [22,46].

5. Biopreservation

Fish processing and preservation methods have been developed to prevent or slow microbial growth. Among the most common methods are the use of ice, refrigeration, and freezing, which reduce microbial growth at low temperatures; however, these methods have disadvantages such as short storage times or, in the case of freezing, high implementation costs. Other preservation methods used individually or in combination include pulsed electric fields, pulsed light, electrolyzed water, ultrasound, modified atmospheres, high pressures, heat treatment (canning, cooking, and smoking), dehydration (drying, salting, and smoking), and pH reduction (pickling and fermentation) [25,46,47,48]. Because of the demand from consumers around the world for fresh, minimally processed foods without chemical additives that are safe, sensorially acceptable, and nutritious, preservation methods have been developed that involve the use of microorganisms [46,49,50,51].

Biopreservation or biocontrol is defined as the extension of the shelf life and safety of a food product using natural or controlled microbiota and/or antimicrobial compounds [5,15,51]. The main biological agents used in biopreservation are lactic acid bacteria (LAB) and/or metabolites, bacteriophages, and endolysins, which have been used to improve the quality, safety, and preservation of foods [50,51,52,53,54,55].

Microorganisms in biopreservation processes perform their functions by occupying the same niche that pathogens do, competing for space and nutrients, producing antimicrobial substances, and, in the case of those of a probiotic nature, acting at the level of the intestine, preventing pathogens from carrying out adhesion and invasion processes, and activating an immune response as a defensive barrier [50,56]. However, despite its shelf life and product safety benefits, biopreservation does not replace safe and quality management systems that involve good hygiene practices such as hazard analysis systems and critical control points (HACCPs), among others, throughout the food chain. Thus, good hygiene practices should always be considered essential for improving the safety and quality of foods such as fish because they represent an excellent medium for pathogenic and microbial growth and are associated with spoilage that reduces shelf life and causes numerous foodborne illness cases [1,50,56].

5.1. Lactic Acid Bacteria (LAB)

Lactic acid bacteria (LAB) are microorganisms that can be found in different natural environments. This group includes the following genera of bacteria: Aerococcus, Alloiococcus, Carnobacterium, Enterococcus, Dolosigranulun, Lactobacillus, Lactococcus, Leuconostoc, Oenococcus, Globicatella, Lactosphaera, Pediococcus, Streptococcus, Tetragenococcus, Vagococcus, Bifidobacterium, and Weisellabacterias [57,58]. Among their characteristics are that they are Gram-positive, nonspore-forming, nonmotile, oxidase- and catalase-negative; do not reduce nitrates; present a morphology in the form of cocci or microaerophilic or facultative anaerobic bacilli; have a DNA composition of 55 mol% G + C; ferment carbohydrates to obtain energy (which allows for their classification as homofermentative, whose only final product is lactic acid); and are heterofermentative, which means they produce succinate, ethanol, acetate, and CO₂ in addition to lactic acid (Table 2) [1,55,57,59,60,61]. LAB have been present in the human diet for a long time and can be found in different foods, such as dairy products, meats, and alcoholic beverages [61,62].

LAB are “generally recognized as safe” (GRAS) by the Food and Drug Administration (FDA) and the Qualified Presumption of Safety (QPS) by the European Food Safety Authority (EFSA) because they reproduce naturally in many food systems and have been used for a long time in the production of widely consumed fermented foods, which is why they present great potential for their use in biopreservation processes. Some LAB are even considered probiotics because they confer health benefits to consumers [15,55,61,63].

LAB and their different metabolites generated during growth (exopolysaccharides, lactic-, acetic-, formic-, propionic-, and butyric acid, ethanol, acetoin, hydrogen peroxide, diacetyl, phenyl lactate, hydroxy-phenyl lactate, cyclic dipeptides, biosurfactants, bacteriocins, and carbon dioxide, among others) play important roles in fermented foods by influencing nutritional and sensory properties (texture, aroma, and characteristic flavor) in addition to exerting a preservation effect on the products, improving their safety and shelf life by inhibiting the growth of spoiling microorganisms and pathogens without favoring the development of antimicrobial resistance [1,5,43,59,60,61,63,64,65]. Antimicrobial resistance is currently considered a serious public health problem worldwide due to the inappropriate and excessive use of antimicrobials in human and animal therapeutics, such as food additives and growth promoters in food production [66,67,68,69].

Table 2. Lactic acid bacteria, antimicrobial metabolites, and glucose fermentation metabolism [1,59,60,70,71].

Microorganism	Produced Bacteriocin	Fermentation Metabolism
Lactococcus lactis	Nisin	Homofermentative
Pediococcus acidilactici	Pediocin	Homofermentative
Lactobacillus sakei	Sakacin	Heterofermentative
Enterococcus faecium	Enterocin	Homofermentative
Leuconostoc mesenteroides	Mesenterocin	Heterofermentative
Lactobacillus casei	Caseicin	Heterofermentative
Lactobacillus helveticus	Helveticin	Heterofermentative

Table 2. Lactic acid bacteria, antimicrobial metabolites, and glucose fermentation metabolism [1,59,60,70,71].

Microorganism	Produced Bacteriocin	Fermentation Metabolism
Lactococcus lactis	Nisin	Homofermentative
Pediococcus acidilactici	Pediocin	Homofermentative
Lactobacillus sakei	Sakacin	Heterofermentative
Enterococcus faecium	Enterocin	Homofermentative
Leuconostoc mesenteroides	Mesenterocin	Heterofermentative
Lactobacillus casei	Caseicin	Heterofermentative
Lactobacillus helveticus	Helveticin	Heterofermentative

Bacteriocins

Bacteriocins are antimicrobial peptides synthesized by lactic acid bacteria at the level of ribosomes, modified or not in the transduction stage, that are secreted into the extracellular medium [15,56,60]. In general, they are synthesized when microorganisms are under stress conditions while proliferating, which also depends on the ecosystem, pH, redox potential, amount of nutrients (carbon/nitrogen), growth phase, temperature, and available oxygen [15,72].

Bacteriocins have antimicrobial effects through different mechanisms, such as inhibiting the synthesis of peptidoglycan; interfering with the metabolism of DNA, RNA, and proteins; enzymatic activity [73]; membrane modulation of sensitive cells; destabilization and permeabilization through the formation of ion channels, through which compounds such as amino acids, ATP or potassium exit the cell; and/or decreasing the cellular synthesis of molecules, thereby causing the death of bacterial cells [15,55,56,58,74].

Notably, bacteriocins and their activity can be affected by factors such as the presence of proteolytic enzymes and the composition of the food matrix (fat and saline contents), and it has been noted that bacteriocins are generally stable in response to heat and a wide pH range [73,75]. These antimicrobial peptides are also colorless, odorless, and tasteless, which expands their potential for use in different areas, such as the food, pharmaceutical, and agricultural industries [73].

Bacteriocins are classified on the basis of characteristics such as the producing microorganism, molecular weight, physical properties, chemical structure, mode of action, and genetic and biochemical characteristics [55,56,58,60,74].

The classification involves bacteriocins class I: lantibiotics. These are small peptides that are active at the membrane level; they have some unusual amino acids, such as lanthionine, β-methyl-lanthionine, and dehydroalanine, that are formed due to modifications after the translation process; and they have poor heat stability and polycyclic peptides (<5 kDa) with modified amino acids. Owing to their structure and mode of action, lantibiotics are subdivided into the following classes: class Ia: elongated, cationic, and amphipathic peptides, an example of which is nisin; and class Ib: globular and hydrophobic peptides that act as enzyme inhibitors, whose molecular mass is 2–3 kDa [72,76,77,78].

Class II linear bacteriocins are not post-translationally modified and are small (<10 kDa) and thermostable peptides with a helical amphiphilic structure. Five subclasses can be identified. Class Iia peptides have great potential for use in food preservation and medical applications and have the consensus sequence in the N-terminal region TGNGVXC (Tyr-Gly-Asn-Gly-Val-Xaa-Cys). The characteristic representatives of class Iia bacteriocins are pediocin PA-1 and sakacin P. [72,76,77].

Class Iib bacteriocins have a pore-forming complex consisting of two different peptides. Both peptides are necessary for better antimicrobial activity. This group includes lactococcal G and plantaricins EF and JK. Class Iic bacteriocins are small, thermostable, and unmodified cyclic peptides transported by leader peptides. In this subclass, the bacteriocins divergycin A and acidocin B have been reported [72,76,77]. Class Iid includes single peptide bacteriocins that are not post-translationally modified and do not present characteristic pediocin-like features. An example of this group is aureocin A53. Class Iie consists of bacteriocins composed of three or four peptides, unlike pediocin. An example is aureocin A70, which is active against Listeria monocytogenes [76].

Class III peptides have high molecular weights (>30 kDa), complex structures, and thermolability. The best-known bacteriocins of this class are helveticin J. V, acidophilicin A, and lactacins A and B. [72,76,77].

Class IV bacteriocins are complex cyclic peptides with protein and lipid or carbohydrate fractions that are necessary for their biological activity, such as lactocin S or lipoproteins (mesenterocin 52). Class V bacteriocins have a circular structure and are not post-translationally modified. Enterocin AS-48 and gasericin A belong to Class V [72,76,77].

Biopreservation processes through the use of LAB and/or bacteriocins can be applied to fish and other foods through different methods: (1) adding a viable pure culture of LAB that generate bacteriocins; (2) adding bacteriocin preparations (crude extracts), fermented liquor, or concentrates from the growth of bacteriocin-producing LAB; (3) incorporating pure or partially pure bacteriocins produced by LAB as additives; and (4) incorporating or immobilizing bacteriocin in or on packaging materials for the development of bioactive food packaging [1,58,72,79]. Likewise, the use of LAB or bacteriocins in foods can be performed individually or in combination with mild physicochemical treatments or at low concentrations of natural chemical preservatives, representing an alternative for safety and extending the shelf life of foods by inhibiting pathogens and saprophytes present without modifying the nutritional and sensory characteristics of the products [5,58]. Different studies about the use of LAB and/or metabolites in fish preservation have been reported globally. Some examples are presented in

Table 3. Studies carried out on the application of lactic acid bacteria (LAB) or metabolites for the preservation of fish and fish products.

Fish/Byproduct	Application Conditions	Analyzed Microorganisms	Biocontrol	Limitations	Source
Lubin fillets (Centropomus undecimalis)	Immersion in 2% sodium alginate coating containing L. reuteri at 24 and 48 h of fermentation and storage at 4 °C.	Aerobic, psychotropic, and enterobacterial microorganisms.	Reduction in the growth of aerobic, psychotropic, and enterobacteria compared to control fillets. Improves the color and texture of foods due to fermentation, maintaining a compact structure and reducing oxidation reactions.	NR	[80]
Lubin fillets	Use of nisin by immersion at 0.8% for 10 min and stored for 8 days at 4 °C.	Aerobic mesophiles. Psychrotroph aerobes. Enterobacteriaceae.	Negative control (day 6): 6.66 log CFU/mL. Nisin (day 8): 6 log CFU/mL. Negative control (day 6): 8.58 log CFU/mL. Nisin (day 8): 7.54 log CFU/mL. Negative control (day 6): 5.26 log CFU/mL. Nisin (day 8): 5.46 log CFU/mL. Longer useful life reducing its oxidation and microbial growth.	Little effect on Enterobacteriaceae	[72]
Gutted trout	Use of nisin by spraying at a final concentration of 100 μg/g; vacuum packaged and stored at 4 ± 0.5 °C/16 days.	Aerobic mesophiles. Aerobic psychotrophs.	Negative control (day 12): >6 log CFU/g Nisin (day 12): 4 log CFU/g Negative control (day 12): >6 log CFU/g Nisin (day 12): 4 log CFU/g Extension of shelf life by reducing its oxidation and microbial growth.	NR	[81]
Cold smoked salmon	Use of L. sakei CTC494 inoculated (1% v/w) to a final concentration of 4.6 log CFU/g. Vacuum packed and stored at 8 °C/21 days.	L. monocytogenes.	Growth inhibition of L. monocytogenes for 21 days.	NR	[82]
Cachama fillets (Piaractus brachypomus × Colossoma macropomum)	L. plantarum LPBM10 bacteriocin crude extract added to the surface of each fillet in 1 mL corresponding to 40 mg of extract, vacuum packed, and stored in refrigeration at 3 ± 0.5 °C/30 days.	Mesophiles. Psychotrophs. Total coliforms. Fecal coliforms.	In the study, counts of 5.2 log cycles were reached in fillets with bacteriocin extract and 6.4 log cycles for the control. The total coliforms obtained an initial count of 2.6 log cycles, which did not change during the study. The count of fecal coliforms, at the end of storage, decreased 1.5 log cycles in fillets treated with crude bacteriocin extract compared to the control. Useful life extension and they did not negatively influence the sensory characteristics of the product.	The activity of the biopreservative agent is a function of the food matrix and temperature used.	[83]
Scomber scombrus meat for burger.	Microcin MccJ25(G12Y) addition and mixing with meat in a proportion of 63 μg/g and stored at 4 °C/10 days.	E. cloacae generating histamine and poisoning.	The initial load of ~105 CFU/g of E. cloacae microcin-treated samples decreased by approximately 2 log10 CFU/g on the first day, followed by a final reduction of ~1 log10 CFU/g.	Additional studies aimed at the application and use of higher concentrations of MccJ25 (G12Y) to accentuate its antimicrobial activity and evaluate combinations with other bacteriocins that amplify the antimicrobial spectrum.	[84]
Sea bass (Dicentrarchus labrax) fillets.	Immersion of fillets for 10 min in Lactococcus lactis nisin solution at different concentrations (0.2, 0.4, and 0.8% w/v) and storage at 4  ±  2 °C/12 days.	Total mesophilic viable, total psychrophilic viable, and total Enterobacteriaceae.	The aerobic mesophile counts achieved for the control on day 7 were >6.66 log CFU/g, and on day 8, they were 7.05–7.09 log CFU/g for the nisin-treated fillets. Total psychrophiles reached their maximum level of 8.58 log CFU/g on day 8 for the control while the lowest counts were in the fillets with 0.8% nisin treatment. The counts were in the range of 7.54–7.63 log CFU/g on day 8. Total Enterobacteriaceae counts were below 5 log CFU/g with nisin treatment except the control group, concluding that the application of nisin extends the shelf life of the fillets up to 2 days at 4  ±  2 °C.	NR	[85]

NR—Not Reported.

.

On the other hand, Castillo-Jiménez et al. [46] evaluated the effects of the immersion of Lactobacillus plantarum and Lactobacillus acidophilus on Oreochromis niloticus fillets and their subsequent storage at 5 °C for 30 days. After 10 days of storage, the fillets with LAB presented counts of 5.94 log CFU/g of LAB and <2.7 log CFU/g of coliforms and psychrophiles, whereas the control fillets presented counts of 1.2 log CFU/g of LAB, where total coliforms and psychrophiles exceeded the limit allowed for human consumption, indicating that biopreservation with lactic acid bacteria had an inhibitory effect on the microbiota associated with the spoilage of fish due to the production of organic acids and/or bacteriocins; among these, L. plantarum had a shelf life of up to 20 days.

Talledo et al. [47] analyzed the effects on physicochemical properties (pH, water loss, and total volatile nitrogen bases) and the inhibition of microbiological spoilage of red tilapia fillets (Oreochromis sp.), which were preserved at 3 ± 0.5 °C for 30 days to use Streptococcus thermophilus and Lactobacillus acidophilus by immersion, and concluded that LAB are capable of inhibiting the growth of mesophiles and E. coli related to the proteolytic deterioration of fish muscle, preserving them for longer and maintaining the physicochemical and microbiological quality of the fillets within the established technical standards and maintaining the quality of the product’s sensory attributes for up to 30 days.

Salazar et al. [49] studied the effects of antimicrobial extracts obtained from individual and mixed cultures of LAB (Lactobacillus plantarum, Pediococcus acidilacti, and Leuconostoc mesenteroides) applied to tilapia fillets and subsequently vacuum packed and stored at 8 °C for 10 days. With the immersion application of these extracts on the fillets, the researchers indicated that the concentrations of aerobic mesophiles and total coliforms were reduced by 2.8 and 1.6 log cycles, respectively, compared with those of the control, generating an increase of up to three days in the storage time of the product. These researchers concluded that the extracts inhibit the growth of spoilage microbiota, favor shelf life and marketing, and constitute an alternative to replace chemical preservatives without affecting the organoleptic characteristics of the product.

Kaktcham et al. [86] evaluated the antimicrobial effects of partially purified nisin produced by Lactococcus lactis subsp. Lactis in comparison to those of a chemical preservative (sodium benzoate) when inoculated together with Vibrio sp. In fish pâté and subsequently stored at 10 °C for 20 days. The researchers noted the ability of bacteriocin to inhibit the growth of Vibrio sp. By reducing the microbial load in fish pâté by 0.4 log10 CFU/g after 10 days of storage, compared with 0.3 log10 CFU/g after 5 days when sodium benzoate is used; they concluded that bacteriocin can be successfully used as a preservative to improve the safety, hygienic quality, and shelf life of fish pâté without affecting sensory properties.

5.2. Silage

The industrial processing of fish generates a large amount of waste (approximately 60%, consisting of fins, scales, heads, viscera, skeleton, skin, and meat remains) as well as losses in handling, which represent approximately 29 million tons of waste worldwide, causing protein waste and contributing to environmental pollution [65,87]. In the use of waste that can constitute approximately 70% of the initial weight, the production of fish silage generates nutritionally, quality, and microbiologically stable foods intended for animal consumption [87,88,89].

Silage is a semiliquid pasty product made from whole fish or waste preservation methods [88,89]. Silage is made by incorporating organic acids, inorganic acids, or both, called chemical silage, or by lactic acid fermentation using a source of carbohydrates with bacteria, called biological silage [1,65].

Organic silage is an alternative protein source to fishmeal with high economic value for animal feed; it also presents antibacterial and antioxidant benefits and is a source of probiotics [65,90]. Fermentation can be carried out with inoculants of the different strains of lactic acid bacteria (Lactobacillus sp., Streptococcus sp., and Bifidobacterium ssp.) and various sources of carbohydrates, such as corn flour, oat flour, honey, and molasses [65,87,88,91,92,93]. Lactic acid fermentation stabilizes and maintains the nutritional quality of silage because of the antimicrobial activity of the organic acids, bacteriocins, hydrogen peroxide, or diacetyl generated, and a decrease in pH helps preservation by enhancing the aroma and flavor thus reducing the growth of fungi, pathogenic bacteria, and bacteria responsible for spoilage [65,87,92]. On the other hand, during this process, the fish proteases are activated, resulting in an increase in the digestibility of the product [65]. Biological silage has a final stability at an average pH of 4 to 4.5 and a titratable acidity of 3.2% [93] and remains similar to the raw material for approximately 30 days [91]. Silage production is considered an economical, safe, and versatile technology that is easy to implement, has a minimum energy requirement, and is applied at artisanal and industrial levels, in addition to the fact that the ensiling process can be an alternative means to generate economic income from discarded waste [1,65,94].

Table 4. Application of lactic acid bacteria (LAB) in the production of silage from fish and/or fish products.

Raw Material (Fish or Byproducts)	Microorganisms for Biopreservation	Application	Source
Head, spine, and tail of fish: 40%; fish viscera: 30%; fish skin 20%; crab remains 10%	Lactobacillus bulgaricus and Streptococcus thermophilus	Diets for fattening birds	[95]
Head, fins, spine, and salmonid viscera	Lactobacillus bulgaricus	Fish feeding	[96]
Waste from Bagre panamensis, Peprilus snyderi, Sphyraena ensis, Trachynotus ovatus, Argyrosomus regius, and Diplodus vulgaris	Lactobacillus sp. Or Lactobacillus B2 and pineapple peel	Ruminant feeding	[65]
Prawn head and residue from the filleting of Selene peruvian	Lactobacillus fermentus	Pig feeding	[97]
Fractions derived from the filleting of Oreochromis niloticus (head, skeleton, tail, viscera, and skin)	Lactobacillus ssp.	Diets for channel catfish	[98]
Cooked products and tuna organs	Lactobacillus plantarum	Diets for tilapia (Oreochromis niloticus)	[99]
Fish viscera (liver, stomach, intestine, swim bladder, kidney, spleen, and gonads)	Lactobacillus sp.	Diets for feeding juvenile Tambaqui (Colossoma macropomum)	[100]
Fresh sardine waste (heads, viscera, scales, fins, bones, and skin)	Lactobacillus plantarum and Aspergillus oryzae	Diets for feeding broiler chickens	[101]
Fresh prawn heads	Lactobacilus fermentum and Lactobacilus lactis	Biofertilizer in grass cultivation and as feed for pigs	[102]
Discard fish (Equulites klunzingeri and Carassius gibelio)	Streptococcus spp., L. brevis, L. plantarum, P. acidilactici, and E. gallinarum	Source of animal nutrition protein	[90]

shows the different raw materials used for biological silage and their main uses.

Among the disadvantages of fish silage may be that although it is generally produced and stored in a liquid form close to the place where it is used, the high water content in this product makes its transportation over long distances uneconomical, and production at the industrial scale is limited. On the other hand, because of the high level of unsaturated lipids, fish silage is susceptible to oxidation and the formation of toxic products, affecting the nutritional value and quality during storage. Additionally, oxidation changes the flavor, color, and texture of silage. Likewise, the oxidation process can be accelerated if the ensiled fish is in contact with light and air; therefore, removing fat during silage preparation or adding antioxidants can achieve a more uniform and stable product. However, synthetic antioxidants can be expensive and metabolize slowly in animal muscle, and their presence in products may be prohibited [103].

5.3. Fermentation in Food and Fish

Fish are highly perishable foods due to their endogenous microbial and enzymatic activities [104]. Fermentation is a traditional food preservation method and is generally used to improve the safety, shelf life, and organoleptic and nutritional attributes of foods intended for human consumption [105].

Fish and fermented products are produced and consumed in different parts of the world, especially in many countries in Europe, Africa, and Asia, where they are part of the food culture (

Table 5. Some of the different fermented fish-based foods intended for human consumption.

Fermented Product	Country	Fish	Reference
Surströmming	Sweden	Freshly caught Baltic herring (Clupea harengus var. Membras)	[108]
Ndagala	Burundi (Africa oriental)	Limnothrissa miodon or Stolothrissa tanganicae	[104,109,110]
Adjonfa o Gyagawere	Cote d’Ivoire	Catfish, stingray, tiger fish, octopus, tuna, and mackerel, among others	[104,110]
Feseekh	Egypt	Bouri fish (Mugil cephlus)	[110]
Terkeen/mindesh	Sudan	Tilapia o Alestes sp.	[102,111]
Pekasam	Malaysia	Freshwater fish and marine fish	[112]
Pla ra/pla daek	Thailand	Gourami, snakehead, catfish, or small fishes	[113]
Koami and Ounago	Japan	Shrimp (Mysis spp.) and small fish	[104,114]
Jeotkals	Korea	Squid, anchovies, pollock, and shrimp, among others	[104,112,115]
Bagoong and Patis	Philippines	Stolephorus sp., Sardinella fmbriata, and Decapterus sp., shrimp, slipmouth, freshwater porgy, oysters, clams, and other shellfish	[104,112,116]
Shidal	India and Bangladesh	Puntius sp. (generally Puntius sophore) and Stipinna phasa	[112]

) [104,105,106,107]. Most of the fish associated with fermentation processes are fatty and of low commercial value (hake, skate, mackerel, catfish, and anchovies, among others) [104].

The action of preserving fish by fermentation is considered obsolete because of the introduction of the cold chain and the development of a variety of preservation technologies, mainly in Western countries. However, because of the sensory characteristics such as flavor and texture, among other preservation characteristics that the fermentation of fish entails, the demand for fermented fish products has increased worldwide and is considered a means of transforming and diversifying the sensory demands of fish consumers [106].

Fermented fish are fresh fish subjected to desirable biochemical changes such as the acidification (the metabolism of sugar sources such as rice, flour, and fruits), gelation, and degradation of proteins and lipids derived from the action of microorganisms or endogenous enzymes [104,105,106]. These changes produce antimicrobial substances (lactic acid, bacteriocins, benzoic acid, diacetyl, and mevalolactone, among others), reducing the risk of contamination by pathogenic microorganisms (e.g., E. coli, Listeria monocytogenes, S. aureus, Clostridium botulinum, or altering agents); increasing shelf life; modifying the elasticity, cohesion, and hardness of the products; and releasing compounds related to aroma, flavor, and nutrients with greater digestibility and absorption [105,107]. Furthermore, fermentation changes the digestibility and nutritional and bioactive characteristics of fish matrices, giving rise to antioxidant, antihypertensive, anticancer, and anticoagulant components that can have beneficial effects on human health through consumption [106,117].

Fermented fish are classified according to different factors, such as (a) the appearance of the final product (fermented whole or in pieces, pastas, and sauces), (b) the processing method (spontaneous fermentation and the use of a starter culture), (c) the type of substrate (using fish and salt, as well as fish, salt, and carbohydrates), and (d) salt addition (zero, low, and high) [105]. Lactic acid bacteria (LAB) are usually the microbiota responsible for fermentation and the sensory characteristics of products. These microorganisms can come from the environment where they are made (raw materials and additives) with the initial LAB load estimated in most fermented products being 5 to 6 log CFU/g [104].

The LAB commonly found in fermented fish include Lactobacillus spp., Streptococcus sp., Vagococcus sp., Pediococcus sp., Tetragenococcus sp., Weissella sp., and Leuconostoc sp., some of which include Lactobacillus helveticus, Lactococcus lactis, Lactobacillus alimentarius, L. farciminis, L. kimchi, L. plantarum, Pediococcus pentosaceus, L. garviae, W. confusing, L. pentosus, P. acidilactici, L. brevis, L. confuses, and L. fermentum [104,106,112,117].

The production of fermented fish products varies by region, the availability of raw materials, and consumption habits [104,106]. Additionally, factors such as raw materials, fermentation temperature, fermentation time, humidity, and salt concentration affect the fermentation process and lead to changes in proteins, lipids, and flavors [106,118].

The basic methods for generating fermented fish include initial washing, scaling, evisceration and cutting, subsequent salting, and drying; some include smoking or marinating, and the product obtained is mixed with additives and placed in containers for fermentation [104,106,117].

Salt is a necessary component in fermented fish and interferes with the solubilization of proteins and the flavor of the product, increasing yield and influencing texture [104]. The salt content of fish products can be classified as high (20 to 30%) or low (6 to 8%) [104,105]. Low salt concentrations can generate a bacteriostatic effect, reducing water activity and giving rise to products with a pH between 4.8 and 5.1, whereas at high salt concentrations, a lower population of LAB is produced. When the salt concentration is greater than 7%, LAB do not exceed 7 log CFU/g, resulting in a final pH in the product between 4.8 and 6.6; however, this value favors contamination and health risk due to the presence of S. aureus and mycotoxigenic fungi [104].

The sensory attributes of fermented fish influence acceptability. The characteristic flavor of fermented products is associated with proteolysis and lipolysis activities, with microbial metabolism being important for these activities and for the generation of associated compounds such as aldehydes, acids, hydrocarbons, alcohols, ketones, esters, furans, and nitrogen-containing compounds [106]. On the other hand, when fermented fish are obtained, defects in color can be generated where the reaction between protein degradation products and lipid oxidation can lead to darkening. Moreover, defects in aroma and flavor may be due to the enzymatic degradation of nucleotides and nucleosides (giving rise to inosine, hypoxanthine, and ribose, among other compounds), the microbial reduction of trimethyl amine oxide to trimethylamine, dimethylamine and formaldehyde, and the oxidative rancidity of lipids. Likewise, products fermented from lean fish may have a pink appearance because of the growth of halophilic bacteria or a discolored appearance caused by the growth of osmophilic fungi [104].

In summary, the use of microorganisms and metabolites through biopreservation processes as well as in the preparation of fermented foods, whether intended for human or animal consumption, allows for the extension of the shelf life and availability of fish and natural products from the sustainable process, with the contributions of little or no chemical additives, high nutritional value, safety, easy preparation, and preservation because the use of any other preservation method (i.e., refrigeration) is not necessary [43] (Figure 1).

6. Conclusions

Fish are highly nutritious foods, are basic components of the human diet, and are produced and marketed worldwide. Furthermore, owing to their intrinsic properties, such as pH, water activity, and nutrients, fish are also very susceptible to contamination and spoilage throughout the food chain by various saprophytic and pathogenic microorganisms, making them a vehicle for diseases and a food product with a short shelf life and availability for consumption.

The demand for food by a constantly growing population has led to an increase in the production and availability of food at all levels of the supply chain, and the implementation of actions to guarantee food safety must be considered at all times to ensure human and animal health.

Over the years, various technologies focused on food preservation have been developed, such as the addition of chemical substances and the application of low or high temperatures such that the availability of nutritious and safe foods is favored. However, several of these technologies have economic, access, or environmental drawbacks in their use, in addition to considering that consumers have recently focused on the search for and availability of more natural or fresh foods (including fish) without the application of chemical additives.

Biopreservation, through the use of microorganisms, particularly lactic acid bacteria or their metabolites, is considered an alternative to the use of chemical substances, contributing to the bioactive properties, nutritional quality, safety, shelf-life extension, and availability of fish and fish products for human or animal consumption. Notably, the use of these microorganisms must always complement and not replace the implementation of hygiene practices and conditions in the production of these foods.

Biopreservation processes in various foods are ancient and continue to be useful, and scientific advancements have contributed to revealing and understanding some of the benefits of the use of lactic acid bacteria in foods. In addition to changes in eating habits and the search for a healthy lifestyle among the population, these changes have contributed to promoting the interest and consumption of foods subjected to these preservation conditions. On the other hand, the use of lactic acid bacteria in biopreservation processes applied to fish and fish products intended for human or animal consumption is still under investigation, and more information is still needed on their versatility and impact on stability, nutritional composition, and safety in different production processes and products, as well as their joint application with other preservation technologies.