Fish Scale Valorization by Hydrothermal Pretreatment Followed by Enzymatic Hydrolysis for Gelatin Hydrolysate Production

Protein and Polysaccharide Recovery from Shrimp Wastes by Natural Deep Eutectic Solvent Mediated Subcritical Water Hydrolysis for Biodegradable Film

Environmental pollution is a significant problem due to the improper disposal of plastics and shrimp shells outdoors. Therefore, the synthesis of biodegradable film from waste materials is highly important. The novelty of this research lies in the extraction of protein hydrolysates and chitosan from shrimp shells, as well as the fabrication of biodegradable film from these materials. In this study, the composite films were produced using the solution casting method. Moreover, the combined effect of ultrasound pretreatments (UPT) and natural deep eutectic solvents (NADES) was investigated as extraction media, to determine their potential impact on shrimp waste subcritical water hydrolysis (SWH). Shrimp shells were submitted to UPT in NADES solution, followed by SWH at different temperatures ranging from 150 to 230 °C under 3 MPa for 20 min. Then, the physiochemical properties and bioactivities of the hydrolysates were assessed to determine their suitability for use in biodegradable packaging films. Additionally, the physiochemical properties and bioactivities of the resulting hydrolysates were also analyzed. The highest amount of protein (391.96 ± 0.48 mg BSA/g) was obtained at 190 °C/UPT/NADES, and the average molecular size of the protein molecules was less than 1000 Da with different kinds of peptide. Overall, combined UPT and SWH treatments yielded higher antioxidant activity levels than individual treatments. Finally, the application of composite films was evaluated by wrapping fish samples and assessing their lipid oxidation. The use of higher concentrations of protein hydrolysates significantly delayed changes in the samples, thereby demonstrating the film's applicability.

Feasibility of Enzymatic Protein Extraction from a Dehydrated Fish Biomass Obtained from Unsorted Canned Yellowfin Tuna Side Streams: Part II

The enzymatic extraction of proteins from fish biomasses is being widely investigated. However, little or almost no research has paid attention to the exploitation of unsorted fishery biomasses. This work is part of a larger study, Part I of which has already been published, and focuses on an extensive characterization of two collagenous samples, namely gelatin (G) and hydrolyzed gelatin peptides (HGPs), extracted from a dehydrated fish biomass coming from unsorted canned yellowfin tuna side streams. The results indicate crude protein fractions of 90-93%, pH values between 3 and 5, white-yellow colors, collagen-like FTIR spectra, and 17% in terms of total amino acid content. Viscosity and the study of dynamic viscous-elastic behavior were analyzed. Thermo-gravimetric analysis was performed to assess the residual ashes. Both samples were investigated to determine their molecular weight distribution via size-exclusion chromatography, with a higher total average molecular weight for G compared to HGPs, with values of 17,265.5 Da and 2637.5 Da, respectively. G demonstrated technological properties similar to analogous marine gelatins. HGPs demonstrated antioxidant activity as per FRAP assay. All the results open up new perspectives for the potential use of these substances in biodegradable packaging, dietary supplements, and skin care cosmetics.

Enhancing activity of food protein-derived peptides: An overview of pretreatment, preparation, and modification methods

Food protein-derived peptides have garnered considerable attention due to their potential bioactivities and functional properties. However, the limited activity poses a challenge in effective utilization aspects. To overcome this hurdle, various methods have been explored to enhance the activity of these peptides. This comprehensive review offers an extensive overview of pretreatment, preparation methods, and modification strategies employed to augment the activity of food protein-derived peptides. Additionally, it encompasses a discussion on the current status and future prospects of bioactive peptide applications. The review also addresses the standardization of mass production processes and safety considerations for bioactive peptides while examining the future challenges and opportunities associated with these compounds. This comprehensive review serves as a valuable guide for researchers in the food industry, offering insights and recommendations to optimize the production process of bioactive peptides.

Upcycling fish scales through heating for steganography and Rhodamine B adsorption application

With increasing population and limited resources, a potential route for improving sustainability is increased reuse of waste materials. By re-looking at wastes, interesting properties and multifunctionalities can be discovered in materials previously explored. Despite years of research on bio-compatible fish scales, there is limited study on the fluorescence property of this abundant waste material. Controlled denaturation of collagen and introduction of defects can serve as a means to transform the fluorescence property of these fish scale wastes while providing more adsorption sites for pollutant removal, turning multifunctional fish scales into a natural steganographic material for transmitting text and images at both the macroscopic and microscopic levels and effectively removing Rhodamine B pollutants (91 % removal) within a short contact time (10 minutes). Our work offers a glimpse into the realm of engineering defects-induced fluorescence in natural material with potential as bio-compatible fluorescence probes while encouraging multidimensional applicability to be established in otherwise overlooked waste resources.

Succinylation of zein and gelatin hydrolysates improved their ice recrystallization inhibition activity

The goal of this research was to enhance the ice recrystallization inhibition (IRI) activity of zein and gelatin hydrolysates (ZH and GH, respectively) by succinylation modification. ZH was prepared by Alcalase treatment for 3 h and then modified by succinic anhydride (SA); whereas GH was made by Alcalase hydrolysis for 0.25 h and succinylated by n-octylsuccinic anhydride (OSA). After 0.5 h of annealing at -8 °C at 40 mg/mL, modified hydrolysates decreased the average Feret's diameter of ice crystal from 50.2 μm (polyethylene glycol, negative control) to 28.8 μm (SA modified ZH) and 29.5 μm (OSA modified GH) in comparison to the unmodified hydrolysates, which had the crystal size of 47.2 μm (ZH) and 45.4 μm (GH). Also, the two succinylated samples had altered surface hydrophobicity, which potentially contributed to their enhanced IRI activity. Our results indicate that succinylation of food-derived protein hydrolysates can improve their IRI activity.

Turning Food Protein Waste into Sustainable Technologies

For each kilogram of food protein wasted, between 15 and 750 kg of CO2 end up in the atmosphere. With this alarming carbon footprint, food protein waste not only contributes to climate change but also significantly impacts other environmental boundaries, such as nitrogen and phosphorus cycles, global freshwater use, change in land composition, chemical pollution, and biodiversity loss. This contrasts sharply with both the high nutritional value of proteins, as well as their unique chemical and physical versatility, which enable their use in new materials and innovative technologies. In this review, we discuss how food protein waste can be efficiently valorized not only by reintroduction into the food chain supply but also as a template for the development of sustainable technologies by allowing it to exit the food-value chain, thus alleviating some of the most urgent global challenges. We showcase three technologies of immediate significance and environmental impact: biodegradable plastics, water purification, and renewable energy. We discuss, by carefully reviewing the current state of the art, how proteins extracted from food waste can be valorized into key players to facilitate these technologies. We furthermore support analysis of the extant literature by original life cycle assessment (LCA) examples run ad hoc on both plant and animal waste proteins in the context of the technologies considered, and against realistic benchmarks, to quantitatively demonstrate their efficacy and potential. We finally conclude the review with an outlook on how such a comprehensive management of food protein waste is anticipated to transform its carbon footprint from positive to negative and, more generally, have a favorable impact on several other important planetary boundaries.

Valorisation of keratinous wastes: A sustainable approach towards a circular economy

The valorisation of keratinous wastes involves biorefining and recovering the bioresource materials from the keratinous wastes to produce value-added keratin-based bioproducts with a broad application, distribution, and marketability potential. Valorisation of keratinous wastes increases the value of the wastes and enables more sustainable waste management towards a circular bioeconomy. The abundance of keratinous wastes as feedstock from agro-industrial processing, wool processing, and grooming industry benefits biorefinery and extraction of keratins, which could be the optimal solution for developing an ecologically and economically sustainable keratin-based economy. The transition from the current traditional linear models that are deleterious to the environment, which end energy and resources recovery through disposal by incineration and landfilling, to a more sustainable and closed-loop recycling and recovery approach that minimises pollution, disposal challenges, loss of valuable bioresources and potential revenues are required. The paper provides an overview of keratinous wastes and the compositional keratin proteins with the descriptions of the various keratin extraction methods in biorefinery and functional material synthesis, including enzymatic and microbial hydrolysis, chemical hydrolysis (acid/alkaline hydrolysis, dissolution in ionic liquids, oxidative and sulphitolysis) and chemical-free hydrolysis (steam explosion and ultrasonic). The study describes various uses and applications of keratinases and keratin-based composites fabricated through various manufacturing processes such as lyophilisation, compression moulding, solvent casting, hydrogel fabrication, sponge formation, electrospinning, and 3D printing for value-added applications.

Effects of Spray Drying and Freeze Drying on Physicochemical Properties, Antioxidant and ACE Inhibitory Activities of Bighead Carp (Aristichthys nobilis) Skin Hydrolysates

The physicochemical, structural properties, antioxidant, and angiotensin I-converting enzyme (ACE) inhibitory activities of fish skin protein hydrolysate (SPH) that were freeze-dried (SPH-FD) and spray-dried (SPH-SD) were investigated. SPH-SD showed abundant volatile compounds, higher DPPH radical scavenging activity and ferrous iron chelating activity than SPH-FD, while the ABTS radical scavenging activity and ACE inhibitory activity were not influenced by the drying method. Amino acid compositions showed a higher proportion of proline and hydroxyproline residues in SPH-FD. The major molecular weights were both distributed below 1000 Da. SPH-SD had spherical structures, while SPH-FD had glass shard-like structures. The results indicated that the drying method could affect the physicochemical properties of hydrolysates, and SPH-SD showed potential prospects in developing functional fortified foods.

Evaluation of Scales of Tilapia Sp. and Sciaenops ocellatus as Low Cost and Green Adsorbent for fluoride Removal From Water

Water containing more than 1.5 mg/L of fluoride is considered toxic as it causes dental, kidney, and other health problems. With the purpose of helping alleviate these problems by exploring a treatment method for fluoride contamination, this study was to assess the suitability of scales of Tilapia Sp. and Sciaenops ocellatus as a cheaper source of adsorbent for the removal of fluoride from drinking water. The samples which were obtained from the Lapaz Market in Accra, Ghana, underwent treatment to eliminate any impurities. They were then ground into powder and treated with aluminum hydroxide [Al(OH)₃]. The treated samples were used for the removal of fluoride from spiked solutions prepared in the laboratory. Batch adsorption was performed by varying parameters such as adsorbent dose (1–8 g/L), initial concentration (2 mg/L to 10 mg/L), and contact time (30–300 min) at pH of 7. A one-way ANOVA was used to validate the significance of the defluoridation process with respect to the different experimental conditions. The optimum adsorbent dose, initial concentration, and contact time were found to be 4 g/L, 10 mg/L, and 300 min, respectively. The results revealed that the maximum percentage removal of fluoride was 76% by Tilapia Sp. and 70% by Sciaenops ocellatus at the optimum conditions. This is an indication that both Tilapia Sp. And Sciaenops ocellatus scales are suitable adsorbents for the removal of fluoride from water. The fluoride adsorption kinetics followed the pseudo-second-order model, and the adsorption isotherm fitted the Freundlich Isotherm model better than the Langmuir Isotherm model. The adsorption intensity and adsorption capacity for Tilapia Sp. were 3.484 L/mg and 0.065 mg/g, and that of Sciaenops ocellatus 3.195 L/mg and 0.045 mg/g respectively.

Valorization of fish byproducts: Sources to end-product applications of bioactive protein hydrolysate

Fish processing industries result in an ample number of protein-rich byproducts, which have been used to produce protein hydrolysate (PH) for human consumption. Chemical, microbial, and enzymatic hydrolysis processes have been implemented for the production of fish PH (FPH) from diverse types of fish processing byproducts. FPH has been reported to possess bioactive active peptides known to exhibit various biological activities such as antioxidant, antimicrobial, angiotensin-I converting enzyme inhibition, calcium-binding ability, dipeptidyl peptidase-IV inhibition, immunomodulation, and antiproliferative activity, which are discussed comprehensively in this review. Appropriate conditions for the hydrolysis process (e.g., type and concentration of enzymes, time, and temperature) play an important role in achieving the desired level of hydrolysis, thus affecting the functional and bioactive properties and stability of FPH. This review provides an in-depth and comprehensive discussion on the sources, process parameters, purification as well as functional and bioactive properties of FPHs. The most recent research findings on the impact of production parameters, bitterness of peptide, storage, and food processing conditions on functional properties and stability of FPH were also reported. More importantly, the recent studies on biological activities of FPH and in vivo health benefits were discussed with the possible mechanism of action. Furthermore, FPH-polyphenol conjugate, encapsulation, and digestive stability of FPH were discussed in terms of their potential to be utilized as a nutraceutical ingredient. Last but not the least, various industrial applications of FPH and the fate of FPH in terms of limitations, hurdles, future research directions, and challenges have been addressed.

Steam Explosion-Assisted Extraction of Protein from Fish Backbones and Effect of Enzymatic Hydrolysis on the Extracts

The development of an efficient pretreatment, prior to enzymatic hydrolysis, is a good strategy for the sustainable use of refractory fish byproducts. This study compared hydrothermal pretreatments at 159 °C for 2 min, followed by water extraction (steam explosion-assisted extraction, SE) and 121 °C for 70 min (hot-pressure extraction, HPE), for the recovery of proteins from fish backbones. The effect of enzymatic hydrolysis on the properties of the obtained fish bone protein (FBP) was also evaluated. The results demonstrated that FBP had high contents of protein (81.09-84.88 g/100 g) and hydroxyproline (70-82 residues/1000 residues). After hydrolysis with Flavourzyme, for 3 h, the FBP hydrolysates that were pretreated with SE (SFBP-H) exhibited a better degree of hydrolysis (DH) and nitrogen recovery (NR), and a higher level of umami taste free amino acids (151.50 mg/100 mL), compared with the HPE-treated samples. The obtained SFBP-H mainly distributed below 3000 Da and had strong scavenging effects on 1,1-diphenyl-2-picrylhydrazy (DPPH) (IC₅₀ = 4.24 mg/mL) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) (IC₅₀ = 1.93 mg/mL) radicals. Steam explosion-assisted extraction is a promising route for recovering proteins from native fish bone materials, and improving the flavor and antioxidant activity of the hydrolysates.

Antioxidant and Cryoprotective Effects of Bone Hydrolysates from Bighead Carp (Aristichthys nobilis) in Freeze-Thawed Fish Fillets

Bone hydrolysates from bighead carp (Aristichthys nobilis) were prepared using Protamex and Alcalase with degrees of hydrolysis (DH) of 5%, 10% and 15%. The antioxidant activity of bone hydrolysates was evaluated in vitro and then the hydrolysates with better antioxidant activity were used to immerse bighead carp fillets through a vacuum impregnation process at concentrations of 1% and 2%. Among the six hydrolysates, fish bone hydrolyzed with Protamex at DH 10% exhibited the highest ability to scavenge 1, 1-diphenyl-2-picrylhydrazyl (DPPH) (88.79%), 2, 2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) (57.76%) and hydroxyl radicals (62.72%), as well as to chelate ferrous ions (91.46%). The hydrolysates effectively postponed freezing- and thawing-induced protein/lipid oxidation. Compared with the fillets without treatment, the impregnated fillets had higher sulfhydryl contents, greater Ca²⁺-ATPase activity, lower carbonyls and lower thiobarbituric acid-reactive substances (TBARS). Bone hydrolysates also have a positive effect on the texture and water-holding ability of freeze-thawed fish fillets. Fish bone hydrolysates of Protamex could serve as potential antioxidants to preserve fish fillets.

Optimization of enzymatic hydrolysis of red tilapia scales (Oreochromis sp.) to obtain bioactive peptides

The objective of this study was to optimize the conditions of enzymatic hydrolysis (type of enzyme, pH, temperature (T), substrate (S) and enzyme concentration (E)) to increase content of soluble peptides (P), antioxidant activities and degree of hydrolysis DH (%), in hydrolysates. Also, the effect of scaling up from a 0.5 L to a 7.5 L reactor, was evaluated. Hydrolysis was carried out for 3 h in a 500 mL reactor, with Alcalase® 2.4 L and Flavourzyme® 500 L enzymes. A second experimental design was then developed with S and E as factors, where DH, P and antioxidant activity, were response variables. The Alcalase® 2.4 L was the most productive enzyme, with optimal S and E of 45 g/L and 4.4 g/L, respectively. Its hydrolysates showed antioxidant activities with IC50 of 0.76 g/L, 12 g/L and 8 g/L for ABTS, FRAP and ICA, respectively. The scale up didn't showed negative effect on the hydrolysis.

Applications and analysis of hydrolysates in animal cell culture

Animal cells are used in the manufacturing of complex biotherapeutic products since the 1980s. From its initial uses in biological research to its current importance in the biopharmaceutical industry, many types of culture media were developed: from serum-based media to serum-free to protein-free chemically defined media. The cultivation of animal cells economically has become the ultimate goal in the field of biomanufacturing. Serum serves as a source of amino acids, lipids, proteins and most importantly growth factors and hormones, which are essential for many cell types. However, the use of serum is unfavorable due to its high price tag, increased lot-to-lot variations and potential risk of microbial contamination. Efforts are progressively being made to replace serum with recombinant proteins such as growth factors, cytokines and hormones, as well as supplementation with lipids, vitamins, trace elements and hydrolysates. While hydrolysates are more complex, they provide a diverse source of nutrients to animal cells, with potential beneficial effects beyond the nutritional value. In this review, we discuss the use of hydrolysates in animal cell culture and briefly cover the composition of hydrolysates, mode of action and potential contaminants with some perspectives on its potential role in animal cell culture media formulations in the future.

Water retention capabilities of collagen, gelatin and peptide as studied by IR/QCM/RH system

In this study, water retention properties of triple helix collagen, gelatin (separated single chains) and peptide (broken peptide fragments) were studied by using IR micro-spectroscopy equipped with a relative humidity (RH) control system and quartz crystal microbalance (QCM). Adsorbed water ratios (wt%) are found to be in the order of collagen, gelatin and peptide (at about RH = 60%, 22 wt% for collagen, 14 wt% for gelatin and 9 wt% for peptide). Free water molecules with longer H bonds are the major adsorbed water species for collagen, gelatin and peptide. IR band shifts and changes in normalized band areas of functional groups are generally larger for collagen than gelatin and peptide, indicating larger interactions of water molecules with functional groups such as aliphatic CH₂, CH₃, amides, COO^- and C-O for collagen. Relations between normalized band areas show that water molecules are interacting with aliphatic CH species and C-O bonds of collagen. Since the fibril structures of collagen triple helices are reported to be cross-linked by sugars, water molecules can be attracted to polar C-O bonds of sugars linking collagen triple helices in fibrils and they are interacting with adjacent aliphatic CH side chains on the surface of fibrils.

Extraction, anti-tyrosinase, and antioxidant activities of the collagen hydrolysate derived from Rhopilema hispidum

The study was conducted to determine anti-tyrosinase and antioxidant activities of the extracted collagen hydrolysate (CH) derived from Malaysian jellyfish, Rhopilema hispidum. Collagen was extracted using 1:1 (w:v) 0.1 M NaOH solution at temperature 25 °C for 48 hr followed by treatment of 1:2 (w:v) distilled water for another 24 hr and freeze-dried. The extracted collagen was hydrolyzed using papain at optimum temperature, pH and enzyme/substrate ratio [E/S] of 60 °C, 7.0 and 1:50, respectively. CH was found to exhibit tyrosinase inhibitory activity, DPPH radical scavenging and metal ion-chelating assays up to 64, 28, and 83%, respectively, after 8 hr of hydrolysis process. The molecular weight of CH was found <10 kDa consisting of mainly Gly (19.219%), Glu (10.428%), and Arg (8.848%). The UV-visible spectrum analysis showed a major and minor peak at 218 and 276 nm, accordingly. The FTIR spectroscopy confirmed the amide groups in CH. The SEM images demonstrated spongy and porous structure of CH. In the cytotoxicity study, CH has no cytotoxicity against mouse embryonic 3T3 fibroblast cell line with IC₅₀ value >500 µg/ml. Results revealed that the CH generated from this study has a potential to be developed as active ingredient in cosmeceutical application.

Aquaculture and its by-products as a source of nutrients and bioactive compounds

Underutilized marine resources (e.g., algae, fish, and shellfish processing by-products), as sustainable alternatives to livestock protein and interesting sources of bioactive compounds, have attracted the attention of the researchers. Aquatic products processing industries are growing globally and producing huge amounts of by-products that often discarded as waste. However, recent studies pointed out that marine waste contains several valuable components including high-quality proteins, lipids, minerals, vitamins, enzymes, and bioactive compounds that can be used against cancer and some cardiovascular disorders. Besides, previously conducted studies on algae have shown the presence of some unique biologically active compounds and valuable proteins. Hence, this chapter points out recent advances in this area of research and discusses the importance of aquaculture and fish processing by-products as alternative sources of proteins and bioactive compounds.