Effects of pressure on gelatinization of collagen and properties of extracted gelatins

Clean and sustainable extraction of gelatin: Effects of microwave and freeze-thaw on the crosslinking degree and hydrogen bond of fish skin collagen

The traditional gelatin extraction methods (acid-base) may hinder to their green applications due to mass energy consumption and pollution. Herein, we constructed a clean and sustainable gelatin extraction method, investigated the molecular mechanism of microwave treatment (0-360 min) and freeze-thaw on the gelatin extraction from the perspective of the crosslinking degree and hydrogen bonds. Microwave (0-60 min) can improve the hydrolysis degree (DH) and expose more enzyme cleavage sites of collagen by destroying the intramolecular and intermolecular covalent crosslinking. Freeze-thaw loosened the collagen structure mainly by destroying hydrogen bonds, further increased degree of freedom, DH and enzyme cleavage sites, improved the gelatin yield and gel strength. However, the long-term microwave treatment (60-360 min) severely damaged the covalent crosslinking, increased the DH and enzyme cleavage sites. Freeze-thaw further loosened the collagen structure, caused the rapid dissolution and degradation of subunit, improved the gelatin yield and reduced the gels strength.

Valorization of Seafood Waste for Food Packaging Development

Packaging plays a crucial role in protecting food by providing excellent mechanical properties as well as effectively blocking water vapor, oxygen, oil, and other contaminants. The low degradation of widely used petroleum-based plastics leads to environmental pollution and poses health risks. This has drawn interest in renewable biopolymers as sustainable alternatives. The seafood industry generates significant waste that is rich in bioactive substances like chitin, chitosan, gelatins, and alginate, which can replace synthetic polymers in food packaging. Although biopolymers offer biodegradability, biocompatibility, and non-toxicity, their films often lack mechanical and barrier properties compared with synthetic polymer films. This comprehensive review discusses the chemical structure, characteristics, and extraction methods of biopolymers derived from seafood waste and their usage in the packaging area as reinforcement or base materials to guide researchers toward successful plastics replacement and commercialization. Our review highlights recent advancements in improving the thermal durability, mechanical strength, and barrier properties of seafood waste-derived packaging, explores the mechanisms behind these improvements, and briefly mentions the antimicrobial activities and mechanisms gained from these biopolymers. In addition, the remaining challenges and future directions for using seafood waste-derived biopolymers for packaging are discussed. This review aims to guide ongoing efforts to develop seafood waste-derived biopolymer films that can ultimately replace traditional plastic packaging.

Cowhide gelatin peptide as a source of antioxidants for inhibiting the deterioration of pudding quality during storage

To investigate the effect of gelatin peptide on the inhibition of quality deterioration in stored pudding, gelatin peptide with antioxidant properties was added to pudding products. For this purpose, a pudding recipe containing gelatin peptides was created. The gelatin peptides were characterized based on their antioxidant activity and protein structure. It was found that gelatin peptides had better antioxidant properties, lower thermal stability and crystallinity, higher hydrophobic amino acid content, and greater surface hydrogen bond exposure than commercially available peptides. Properties such as the pH, colony growth, and sensory characteristics of the pudding were characterized at 4 °C and 25 °C. The results showed that the addition of 0.5-1.0 % gelatin peptide to pudding was capable of significantly (P< 0.05) slowing down the decline in pH and sensory scores of the pudding and significantly inhibiting colony growth. It could prolong its storage life by five days at 4 °C and three days at 25 °C.

High pressure-assisted enzymatic hydrolysis promotes the release of a bi-functional peptide from cowhide gelatin with dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant activities

The process of generating functional peptides from cowhide gelatin is challenged by inefficient enzymatic hydrolysis. In this study, the researchers attempted to enhance the hydrolysis and potential functional properties of the peptides by subjecting the cowhide gelatin to high-pressure treatment (200, 300, and 400 MPa) for 20 min, followed by enzymatic hydrolysis. The highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2' azinobis(3 ethylbenzothiazoline 6 sulfonic acid) (ABTS) radical scavenging activity, and DPP-IV inhibitory activity of the hydrolysate were obtained at 200 MPa, accompanied with an increase in the content of hydrophobic, acidic, and basic amino acids (P < 0.05). Correspondingly, the high-pressure pretreatment (200 MPa) reduced the thermal stability, particle size, and morphological integrity of cowhide gelatin, with a corresponding increase in the exposure of hydrophobic regions. Altogether, these results indicated that appropriate high-pressure-assisted enzymatic hydrolysis reinforced the release of bi-functional peptides by modifying the structure of cowhide gelatin.

Preparation of Bovine Hides Gelatin by Ultra-High Pressure Technique and the Effect of Its Replacement Fat on the Quality and In Vitro Digestion of Beef Patties

Beef skin gelatin can be used as a good substitute for animal fat in meat patties. In this paper, the effect of different parameters on low-fat beef patties with cowhide gelatin substituted for beef fat (0, 25%, 50%, 75%, 100%) prepared by ultra-high pressure assisted technology was investigated by texture, cooking loss, and sensory scores. The beef patties were also stored at 0-4 °C for 0, 7, 14, 21, and 28 d. The differences and changing rules of fatty acid and amino acid compositions and contents of beef patties with different fat contents were investigated by simulating gastrointestinal digestion in vitro. The optimal process formulation of low-fat beef patties with cowhide gelatin was determined by experimental optimization as follows: ultra-high pressure 360 MPa, ultra-high of pressure time of 21 min, NaCl addition of 1.5%, compound phosphate addition of 0.3%. The addition of cowhide gelatin significantly increased monounsaturated fatty acids, polyunsaturated fatty acids, amino acid content, and protein digestibility of beef patties (p < 0.05). Moreover, with the extension of storage time, the content of saturated fatty acids was significantly higher (p < 0.05), the content of monounsaturated and polyunsaturated fatty acids was significantly lower (p < 0.05), the content of amino acids was significantly lower (p < 0.05), and protein digestibility was significantly lower (p < 0.05) under all substitution ratios. Overall, beef patties with 75% and 100% substitution ratios had better digestibility characteristics. The results of this study provide a theoretical basis for gelatin's potential as a fat substitute for beef patties and for improving the quality of low-fat meat products.

Bone Regeneration of Critical-Size Calvarial Defects in Rats Using Highly Pressed Nano-Apatite/Collagen Composites

Osteo-conductive bone substitute materials are required in dentistry. In this study, highly pressed nano-hydroxyapatite/collagen (P-nHAP/COL) composites were formed by a hydraulic press. Critical-size bone defects (Φ = 6 mm) were made in the cranial bones of 10-week-old Wistar rats, in which P-nHAP/COL and pressed collagen (P-COL) specimens were implanted. Defect-only samples (DEF) were also prepared. After the rats had been nourished for 3 days, 4 weeks, or 8 weeks, ossification of the cranial defects of the rats was evaluated by micro-computed tomography (micro-CT) (n = 6 each). Animals were sacrificed at 8 weeks, followed by histological examination. On micro-CT, the opacity of the defect significantly increased with time after P-nHAP/COL implantation (between 3 days and 8 weeks, p < 0.05) due to active bone regeneration. In contrast, with P-COL and DEF, the opacity increased only slightly with time after implantation, indicating sluggish bone regeneration. Histological inspections of the defect zone implanted with P-nHAP/COL indicated the adherence of multinucleated giant cells (osteoclasts) to the implant with phagocytosis and fragmentation of P-nHAP/COL, whereas active bone formation occurred nearby. Fluorescent double staining indicated dynamic bone-formation activities. P-nHAP/COL is strongly osteo-conductive and could serve as a useful novel bone substitute material for future dental implant treatments.

Valorization of Cattle Slaughtering Industry By-Products: Modification of the Functional Properties and Structural Characteristics of Cowhide Gelatin Induced by High Hydrostatic Pressure

This study investigates the effects of different pressures (200, 250, 300, 350, and 400 MPa) and durations (5, 10, 15, 20, and 25 min) on the functional properties, secondary structure, and intermolecular forces of cowhide gelatin. Our results show that high hydrostatic pressure significantly affected the two, three, and four-level structures of gelatin and caused the contents of the α-helix and β-turn to decrease by 68.86% and 78.58%, respectively (p < 0.05). In particular, the gelatin at 300 MPa for 15 min had the highest gel strength, emulsification, solubility, and foaming of all the treatment conditions under study. The analysis of the surface hydrophobicity, sulfhydryl content, zeta potential, and Raman spectroscopy shows that at a pressure of 300 MPa (15 min), the hydrogen bonds and hydrophobic interactions between collagen molecules are strongly destroyed, leading to changes in the tertiary and quaternary conformation of the protein and unfolding, with the electrostatic repulsion between protein particles making the decentralized state stable. In conclusion, moderate pressure and time can significantly improve the functional and structural properties of collagen, which provides theoretical support and guidance for realizing the high-value utilization of cowhide.

Application of Green Technology in Gelatin Extraction: A Review

Growing demands for green and sustainable processing that eliminates the utilization of toxic chemicals and increases efficiency has encouraged the application of novel extraction technologies for the food industry. This review discusses the principles and potential application of several green technology for gelatin extraction. Several novel technologies and their processing efficiency are discussed in this review. Furthermore, factors that affect the quality of the gelatin produced from different sources are also highlighted. The potential application of ultrasound-assisted extraction (UAE), subcritical water extraction, high-pressure processing, and microwave-assisted extraction (MAE) to improve gelatin extraction are addressed. These technologies have the potential to become an efficient extraction method compared to the conventional extraction technologies. Several combinations of green and conventional technologies have been reported to yield promising results. These combinations, especially using conventional pre-treatment and green technologies for extraction, have been found to be more effective in producing gelatin. Since gelatin could be produced from various sources, it exhibits different characteristics; thus, different approaches and extraction method should be identified for specific types of gelatin. Although these technologies have limitations, such as overhydration and sophisticated systems explicitly designed for large-scale production, they are nonetheless more efficient in the long run to safeguard the environment as they reduce solvent usage and carbon footprint along the way.

INFLUENCE OF THE HYDROTHERMAL TREATMENT TEMPERATURE CONDITIONS ON POULTRY MEAT

The poultry production is growing rapidly every year. Having a rapid pace of development and reproduction, and greater affordability, the poultry products are in high demand from the population. In this regard, the industry is in demand for deep processing of poultry meat, which is not only economically feasible, but also makes it possible to expand the scope of use of this product. The complex morphological structure of the poultry complicates its use as the main raw material for meat products, and poultry meat is mainly sold in the form of natural semi-finished products with a limited shelf life. It is possible to expand the range of poultry products through the production of canned food. A new technology for the production of pasteurized canned poultry meat was developed at the Department of Meat, Fish and Seafood Technology of the Odessa National Academy of Food Technologies. This technology involves hydrothermal treatment of the raw materials, hot boning, mixing of components of the formulation and pasteurization. This article reveals the issue of the first stage of production, namely the establishment of rational meat hydrothermal treatment conditions. The problem of choosing the heat treatment conditions is extremely important, because depending on the process conditions and the final heating temperature, the transformation of the components and the properties of the finished products differ significantly. The paper studies the effect of temperature in the range from 65 to 95°C in 5°C increment on the rate and degree of cooking of collagen, the formation of the required structure of the product (hydrogel base filled with individual muscle fibers), hardness and tenderness of meat. It is established that the optimal processing temperature of poultry meat is 65°C. The meat processed at this temperature had the highest degree of collagen cooking, the highest viscosity of the broth, the lowest shear stress, and the best organoleptic characteristics.

Comparative study on the gel properties and nanostructures of gelatins from chicken, porcine, and tilapia skin

To clarify the feasibility of replacing commercial gelatin with chicken skin gelatin, we investigated the gel properties and nanostructures of chicken skin gelatin (CG), commercial porcine skin gelatin (PG), and tilapia skin gelatin (FG). Compared with PG and FG, CG exhibited the better gel strength, hardness, chewiness, melting point, gelling temperature, and thermostability. The different physicochemical properties of CG might be caused by its higher imino acid content (25.43 residues/100 total residues), which make it more liable to form intramolecular H-bonds (lower amplitude of amide A wave number). In addition, atomic force microscopy (AFM) result was shown that CG contained larger spherical aggregates (483 nm) than PG and FG (334 and 224 nm, respectively), and the lack of chain and ring-like structure promoted the formation of a dense rigid gel. These results revealed that the intramolecular H-bond and the aggregation behavior are the fundamental explanations for the different gel properties of gelatins from three sources. PRACTICAL APPLICATION: This research provides guidance for the application of chicken skin gelatin as a replacer for commercial gelatin. And the results provide a theoretical basis for the modification of chicken skin gelatin.

Effects of single- and tri-frequency ultrasound on self-assembly and characterizations of bionic dynamic rat stomach digestion of pepsin-soluble collagen from chicken leg skin

Chicken feet, aplenty by-products in the chicken industry, are rich in collagen and contain abundant amino acids so that it can be used as an important source for the collagen market. Pepsin-soluble collagen (PSC) was extracted from chicken leg skin and explored the effects of single- and tri-frequency ultrasound on the self-assembly and vitro digestion characteristics. By the diverging and tri-frequency ultrasound reactor, PSC was treated with 20 kHz/270w (C20H5m), 40 kHz/270w (C40H5m), 60 kHz/270w (C60H5m), 20/40/60 kHz/90w × 3 (CtH5m) for 5 min. Results showed that ultrasound could accelerate the process of collagen self-assembly, and 60 kHz/270w was the fastest. Microfiber diameters of C60H5m were 65-89 nm, which was significantly lower than the control without ultrasound (80-161 nm). The digestion results indicated polypeptides with relative molecular weights founded in the range 200-5000 Da were exceeded 85%. The final digested product had the highest content of oligopeptide, consistent rheological properties, and elastic behavior. The cavitation and mechanical of ultrasound have effects on the self-assembly process and collagen gel structure and digestion characteristics, which is of great significance for the development of the chicken industry and collagen market.

A Review on the Effect of High Pressure Processing (HPP) on Gelatinization and Infusion of Nutrients

High pressure processing (HPP) is a novel technology that involves subjecting foods to high hydrostatic pressures of the order of 100-600 MPa. This technology has been proven successful for inactivation of numerous microorganisms, spores and enzymes in foods, leading to increased shelf life. HPP is not limited to cold pasteurization, but has many other applications. The focus of this paper is to explore other applications of HPP, such as gelatinization, forced water absorption and infusion of nutrients. The use of high pressure in producing cold gelatinizing effects, imparting unique properties to food and improving food quality will be also discussed, highlighting the latest published studies and the innovative methods adopted.

Development of chitosan-coated agar-gelatin particles for probiotic delivery and targeted release in the gastrointestinal tract

This study reports the development of a novel and simple formulation for probiotic delivery using chitosan-coated agar-gelatin gel particles. This methodology involves the production of agar-gelatin particles by thermally treating a mixture of agar and gelatin solutions at high temperatures (121 °C) and subsequently coating with chitosan. The particles were able to protect the probiotic strain Lactobacillus plantarum NCIMB 8826 during incubation for 2 h in simulated gastric fluid (pH 2), as no statistically significant loss (P > 0.05) in cell concentration was observed, and also resist dissolution in simulated intestinal fluid (pH 7.2). Interestingly, this protection is related to the fact that the intense thermal treatment affected the physicochemical properties of agars and resulted in the formation of a strong and tight polymer network, as indicated by the X-ray diffraction (XRD) analysis. Using an in vitro faecal batch fermentation model simulating the conditions of the distal part of the large intestine (pH 6.7–6.9), it was demonstrated by quantitative real-time PCR that the majority of L. plantarum cells were released from the agar-gelatin particles within 30 to 48 h. Overall, this work led to the development of a novel methodology for the production of probiotic-containing particles, which is simpler compared with current encapsulation technologies and has a lot of potential to be used for the controlled release of probiotics and potentially other solid bioactives in the large intestine.

Key Points

• Chitosan gel particles is a simple and scalable method of probiotic encapsulation.

• Autoclaving agar-gelatin particles increases their stability at low pH.

• Chitosan gel particles protected L. plantarum during gastrointestinal conditions.

• Probiotics could be controlled release in the colon using chitosan gel particles.

Improvement of the characteristics of fish gelatin - gum arabic through the formation of the polyelectrolyte complex

The aim of this study was to evaluate and characterize the interaction between fish gelatin (FG) and Gum Arabic(GA) and its effects in obtaining optimal atomization conditions. The optimal conditions (D = 0.866) founded in this paper were: Gum Arabic concentration of 33.4% and inlet air temperature of 130 °C. These conditions afforded 6.62 g/h yield, 0.27 a_w and 247 g of Gel Strength, that are considered as suitable characteristics for food grade gelatin. The complex formed (FG-GA) was successfully obtained, as demonstrated by the results of amino acid profile, SDS-PAGE, FTIR spectroscopy, zeta potential and morphology. It was also verified that the formation of FG-GA promotes positive changes, such as higher atomization yield, adequate Gel Strength, low hygroscopicity and high solubility. The technological properties of FG-GA shown high potential to be applied in the food industry as well in other industrial fields like chemical and pharmaceutical areas.

A novel strategy for water disinfection with a AgNPs/gelatin sponge filter

Disinfection of bacteria in water with sustainable and energy-efficient methods is still a great challenge. Herein, a novel gelatin sponge with embedded AgNPs is fabricated via freeze-drying using gelatin as the reducing agent to synthesize AgNPs in situ. UV-vis spectroscopy, HRTEM, XRD, and XPS characterization prove the formation of AgNPs with an average size of 8.55 ± 0.35 nm. TEM and SEM images confirm the even distribution of AgNPs throughout the AgNPs/gelatin sponges. The composite sponge has a low bulk density of 20 ± 3.5 mg/cm³ and a pore size of 6.2 ± 1.5 μm. The AgNPs/gelatin sponges exhibit excellent antibacterial performance to E. coli in water, probably by destroying their cell membranes. The porous AgNPs/gelatin composite sponges are promising filter materials for water disinfection. The removal rate of AgNPs/gelatin composite sponges on E. coli reached almost 100%. Graphical abstract ᅟ.

Analysis of volatile compounds and nutritional properties of enzymatic hydrolysate of protein from cod bone

Hydrolysis of the proteins from cod bone was performed using flavourzyme and trypsin. The nutritional properties of hydrolysates by flavourzyme (HF) and trypsin (HT) were investigated. By comparison, HF exhibits a better degree of hydrolysates (DH) and nitrogen recovery (NR) than HT. The protein content of extract is 97.39% and had a good nutritional value due to the high protein digestibility-corrected amino acid score (PDCAAS) of 0.95 for adults. The content of total amino acids is 942.55 mg/g. The free amino acids content of hydrolysates derived from flavourzyme is 136.82 mg/g after hydrolyzing 3 h, while 17.12 mg/g of such hydrolysates was obtained by using trypsin. The main flavor compounds are alcohols, aldehydes, ketones, acids and alkanes. The molecular weight of predominant peptides ranged from 1000 to 3000 Da in both enzymatic hydrolysates. This study provided a theoretical basis to the preparation of nutritional components with attracting flavor in functional food industry.

Effects of Mixed Bone and Brisket Meat on Physico-Chemical Characteristics of Shank Bone and Rib Extracts from Hanwoo

This study was conducted to investigate the effects of mixed bone and brisket meat on the quality characteristics and nutritional components of shank bone extract and rib extract from Hanwoo. The pH values were influenced by the raw bones, mixed bone, brisket meat and their interactions (p<0.05). The salinity, sugar content, turbidity, and essential amino acid values increased significantly with addition of mixed bone and brisket meat. All attributes of sensory evaluation score were the highest in T6 (Rib 500 g + Mixed bone 500 g + Brisket meat 400 g) (p<0.05). The mixed bone significantly increased the saturated fatty acids of shank bone extract (p<0.001). Thus, the addition of mixed bone and brisket meat had a positive effect on the quality and nutritional components in shank and rib extracts of Hanwoo cattle.

Molecular characteristics and properties of gelatin from skin of seabass with different sizes

Gelatin was extracted from the skin of seabass (Lates calcarifer) with different average sizes (2, 4 and 6 kg/fish), termed G2, G4 and G6, respectively and their characteristics and functional properties were determined. Yields of G2, G4 and G6 were 38.22, 40.50 and 43.48% (based on dry weight), respectively. G2 contained α-chains as dominant component, whilst G4 and G6 comprised α-, β- and γ-chains with a larger content of high MW cross-links. All gelatins had the similar imino acid (hydroxyproline and proline) content. Net charge of G2, G4 and G6 became zero at pH of 6.73, 6.41 and 7.12, respectively. Amongst all gelatin samples, G6 exhibited the highest gel strength (321.5 g) (p<0.05), but had the lowest turbidity (p<0.05). Gels of G6 sample had the lower L*-value but higher a*-, b*- and ΔE*-value, compared with others. Gelling and melting temperatures of all gelatins were 17.09-19.01 and 26.92-28.85 °C, respectively. Furthermore, all gelatins were able to set at room temperature, regardless of size of seabass used. G6 had the shorter setting time at room temperature than others. Therefore, size of seabass, in which skin was used for gelatin extraction, had the impact on yield, composition and properties of resulting gelatin.