Purification and characterisation of transglutaminase from four fish species: Effect of added transglutaminase on the viscoelastic behaviour of fish mince

Enzymes from Fishery and Aquaculture Waste: Research Trends in the Era of Artificial Intelligence and Circular Bio-Economy

In the era of the blue bio-economy, which promotes the sustainable utilization and exploitation of marine resources for economic growth and development, the fisheries and aquaculture industries still face huge sustainability issues. One of the major challenges of these industries is associated with the generation and management of wastes, which pose a serious threat to human health and the environment if not properly treated. In the best-case scenario, fishery and aquaculture waste is processed into low-value commodities such as fishmeal and fish oil. However, this renewable organic biomass contains a number of highly valuable bioproducts, including enzymes, bioactive peptides, as well as functional proteins and polysaccharides. Marine-derived enzymes are known to have unique physical, chemical and catalytic characteristics and are reported to be superior to those from plant and animal origins. Moreover, it has been established that enzymes from marine species possess cold-adapted properties, which makes them interesting from technological, economic and sustainability points of view. Therefore, this review centers around enzymes from fishery and aquaculture waste, with a special focus on proteases, lipases, carbohydrases, chitinases and transglutaminases. Additionally, the use of fishery and aquaculture waste as a substrate for the production of industrially relevant microbial enzymes is discussed. The application of emerging technologies (i.e., artificial intelligence and machine learning) in microbial enzyme production is also presented.

Trash to Treasure: An Up-to-Date Understanding of the Valorization of Seafood By-Products, Targeting the Major Bioactive Compounds

Fishery production is exponentially growing, and its by-products negatively impact industries' economic and environmental status. The large amount of bioactive micro- and macromolecules in fishery by-products, including lipids, proteins, peptides, amino acids, vitamins, carotenoids, enzymes, collagen, gelatin, chitin, chitosan, and fucoidan, need to be utilized through effective strategies and proper management. Due to the bioactive and healthy compounds in fishery discards, these components can be used as functional food ingredients. Fishery discards have inorganic or organic value to add to or implement in various sectors (such as the agriculture, medical, and pharmaceutical industries). However, the best use of these postharvest raw materials for human welfare remains unelucidated in the scientific community. This review article describes the most useful techniques and methods, such as obtaining proteins and peptides, fatty acids, enzymes, minerals, and carotenoids, as well as collagen, gelatin, and polysaccharides such as chitin-chitosan and fucoidan, to ensure the best use of fishery discards. Marine-derived bioactive compounds have biological activities, such as antioxidant, anticancer, antidiabetic, anti-inflammatory, and antimicrobial activities. These high-value compounds are used in various industrial sectors, such as the food and cosmetic industries, owing to their unique functional and characteristic structures. This study aimed to determine the gap between misused fishery discards and their effects on the environment and create awareness for the complete valorization of fishery discards, targeting a sustainable world.

Transglutaminases: part I-origins, sources, and biotechnological characteristics

The transglutaminases form a large family of intracellular and extracellular enzymes that catalyze cross-links between protein molecules. Transglutaminases crosslinking properties are widely applied to various industrial processes, to improve the firmness, viscosity, elasticity, and water-holding capacity of products in the food and pharmaceutical industries. However, the extremely high costs of obtaining transglutaminases from animal sources have prompted scientists to search for new sources of these enzymes. Therefore, research has been focused on producing transglutaminases by microorganisms, which may present wider scope of use, based on enzyme-specific characteristics. In this review, we present an overview of the literature addressing the origins, types, reactions, and general characterizations of this important enzyme family. A second review will deal with transglutaminases applications in the area of food industry, medicine, pharmaceuticals and biomaterials, as well as applications in the textile and leather industries.

Current insight and futuristic vistas of microbial transglutaminase in nutraceutical industry

Microbial transglutaminase (MTGase) has become a driving force in the food industry cross-linking the food proteins. MTGase-the nature's molecular glue is recognized to reorient food protein's functional properties without affecting its nutritive value. The scope and approach of this review is to have insight on the action mechanism of MTGase and impact of molecular linkage on functional proteins in various protein moieties in development of innovative features in food production for better consumer's choice and satisfaction. The study covers a wide range of published work across food industries involving innovative use of MTGase, an environment friendly production approach for commercial utilization to get better outcome in terms of culinary delight. The intrinsic biochemical properties and structural information by sequence analysis and clustering validates the mode of reaction mechanism of the biological glue enzyme. The review singles out how the MTGase emerged as a prime choice in ever evolving food industry.

Characterization of a cold-active transglutaminase from a crayfish, Pacifastacus leniusculus

Transglutaminase (TGase) from signal crayfish (Pacifastacus leniusculus) and its activity at low temperatures was studied. TGase is an abundant protein in the hematopoietic (HPT) cells and this tissue was used for TGase enzyme preparation. The optimal temperature and pH for the activity of crayfish TGase were determined. We found that TGase activity at 4 °C showed nearly the same activity as at a temperature of 22 °C. TGase activity from crayfish was compared with guinea pig liver TGase activity at 4 °C and the crayfish TGase displayed a higher activity while guinea pig liver TGase had a very low activity at this low temperature. By comparing kinetic parameters to guinea pig liver TGase, the results showed that a high activity of crayfish TGase was due to a decreasing K_m value for pentylamine as a substrate, while it did not affect the k_cat value (at 22 °C). The amino acid sequences of a krill and a crayfish TGase, which both are cold adapted, do not give any clue to why these two enzymes are cold-adapted. These results demonstrate that crayfish TGase is adapted to have significant activity at low temperatures and since crayfish are living in quite cold waters this is an interesting adaptation of this enzyme.

Effects of Micron Fish Bone with Different Particle Size on the Properties of Silver Carp(Hypophthalmichthys molitrix)Surimi Gels

Qualities of silver carp surimi (SCS) gels incorporated with micron fish bone of different particle size (22 to 0.12 μm) were evaluated. Textural values, whiteness, and water holding capacity of the SCS gels with setting significantly increased (P<0.05) as the micron fish bone particle size decreased. As the particle size decreased, more calcium ion was apparently released from the fish bone (P<0.05). Consequently the released calcium ion increased the activity of endogenous transglutaminase (TGase) and resulted in the formation of more myosin heavy chain (MHC) cross-links in the SCS gel with setting. Fish bone with particle size below 0.48 μm was steadily trapped in the three-dimensional SCS gel network without disrupting the matrices. Results indicated that size reduction of the incorporated micron fish bone improved qualities of the SCS gel with setting by the means of releasing more calcium ion and maintaining better gel matrices.

Enzymes from Seafood Processing Waste and Their Applications in Seafood Processing

Commercial fishery processing results in discards up to 50% of the raw material, consisting of scales, shells, frames, backbones, viscera, head, liver, skin, belly flaps, dark muscle, roe, etc. Besides, fishing operations targeted at popular fish and shellfish species also result in landing of sizeable quantity of by-catch, which are not of commercial value because of their poor consumer appeal. Sensitivity to rapid putrefaction of fishery waste has serious adverse impact on the environment, which needs remedial measures. Secondary processing of the wastes has potential to generate a number of valuable by-products such as proteins, enzymes, carotenoids, fat, and minerals, besides addressing environmental hazards. Fishery wastes constitute good sources of enzymes such as proteases, lipases, chitinase, alkaline phosphatase, transglutaminase, hyaluronidase, acetyl glycosaminidase, among others. These enzymes can have diverse applications in the seafood industry, which encompass isolation and modification of proteins and marine oils, production of bioactive peptides, acceleration of traditional fermentation, peeling and deveining of shellfish, scaling of finfish, removal of membranes from fish roe, extraction of flavors, shelf life extension, texture modification, removal of off-odors, and for quality control either directly or as components of biosensors. Enzymes from fish and shellfish from cold habitats are particularly useful since they can function comparatively at lower temperatures thereby saving energy and protecting the food products. Potentials of these applications are briefly discussed.

Separation of transglutaminase by thermo-responsive affinity precipitation using l-thyroxin as ligand

Transglutaminase (TGase) is widely used in the food industry. In this study, TGase was purified by affinity precipitation using l-thyroxin, coupled to a thermo-responsive polymer (PNBN), as an affinity ligand. The lower critical solution temperature and recovery of the affinity polymer were 31.0 °C and 99.6 %, respectively. The optimal adsorption condition was 0.02 mol/L phosphate buffer (pH 5.0). The recoveries 99.01 % (protein) and 98.85 % (activity) were obtained by 0.2 mol/L Gly-NaOH buffer (pH 10.0) as the elution agent. Circular dichroism spectroscopy and FortéBio Octet system were used to explore the interactions between l-thyroxin and TGase. The results show that l-thyroxin is suitable for affinity precipitation of TGase. The purity of the final product was verified using sodium dodecyl sulfate polyacrylamide gel electrophoresis.

Effect of transglutaminase on quality characteristics of a value-added product tilapia wastes

The aim of this work was to evaluate the physico-chemical, instrumental color and texture, and sensory qualities of restructured tilapia steaks elaborated with small sized (non-commercial) tilapia fillets and different levels of microbial transglutaminase (MTG). Four concentrations of MTG were used: CON (0 % MTG), T1 (0.1 % MTG), T2 (0.5 % MTG), and T3 (0.8 % MTG). In addition, bacterial content and pH shifts were also evaluated during 90 days of frozen storage. The different levels of MTG did not affect (P > 0.05) either the proximate composition of the restructured tilapia steaks or the bacterial growth during the frozen storage. MTG improved (P < 0.05) cooking yield and instrumental hardness and chewiness as well as sensory (salty taste, succulence and tenderness) attributes; strongly contributing to greater overall acceptance. Therefore, restructured tilapia steaks manufactured with MTG are potentially valued-added products with good consumer acceptance and better purchase-intention than steaks formulated with 0 % MTG.