Structure and physical properties of gelatin from bovine bone collagen influenced by acid pretreatment and pepsin

Physicochemical and Functional Properties of Yanbian Cattle Bone Gelatin Extracted Using Acid, Alkaline, and Enzymatic Hydrolysis Methods

Yanbian cattle, a high-quality indigenous breed in China, were selected due to their unique biological characteristics, underutilized bone byproducts, and potential as a halal-compliant gelatin source, addressing the growing demand for alternatives to conventional mammalian gelatin in Muslim-majority regions. This study investigates the physicochemical and functional properties of gelatin extracted from Yanbian cattle bones using three different methods: acid, alkaline, and papain enzymatic hydrolysis. The extraction yields and quality of gelatin were evaluated based on hydroxyproline content, gel strength, viscosity, amino acid composition, molecular weight distribution, and structural integrity. Specifically, A gelatin, prepared using 0.075 mol/L hydrochloric acid, achieved the highest yield (18.64%) among the acid-extraction methods. B gelatin, extracted with 0.1 mol/L sodium hydroxide, achieved the highest yield (21.06%) among the alkaline-extraction methods. E gelatin, obtained through papain hydrolysis, exhibited the highest yield (25.25%) among the enzymatic methods. Gelatin extracted via papain enzymatic hydrolysis not only retained better protein structure but also exhibited higher hydroxyproline content (19.13 g/100 g), gel strength (259 g), viscosity (521.67 cP), and superior thermal stability. Structural analyses conducted using SDS-PAGE, GPC, FTIR, XRD, and CD spectroscopy confirmed that papain extraction more effectively preserved the natural structure of collagen. Furthermore, amino acid composition analysis revealed that gelatin extracted via papain hydrolysis contained higher levels of essential residues, such as glycine, proline, and hydroxyproline, emphasizing the mild and efficient nature of enzymatic treatment. These findings suggest that, compared with acid and alkaline extraction methods, enzymatic hydrolysis has potential advantages in gelatin production. Yanbian cattle bone gelatin shows promise as an alternative source for halal gelatin production. This study also provides insights into optimizing gelatin production to enhance its functionality and sustainability.

Effect of acid pretreatments with various acid types on gelling properties and identification characteristics of pigskin gelatin

In order to study the effects of different types of acid pretreatment of pigskin on the gel characteristics and traceability aspects of the extracted gelatin, the molecular weight distribution and gelling properties of pigskin gelatin were studied using SDS-PAGE, texture analyzer, and rheometer. The characteristic peptides digested from pigskin gelatin were studied by HPLC-MS/MS technique. The findings revealed that gelatin extracted from pigskin pretreated with acetic acid showed the most typical bands. The gelatins extracted from pig skin pretreated with acetic acid and hydrochloric acid exhibited the highest gelation-melting transition temperatures (26.81/34.17 °C) and gel strength (605.278 g), respectively. 69 characteristic peptides were the same in all gelatins from pigskin pretreated by various acids. A further comparison of this work with prior studied revealed that 8 were detected under different extraction and processing conditions. These common characteristic peptides could be used as the foundation for pigskin gelatin traceability, boosting accuracy.

Bioactive Properties of Enzymatic Gelatin Hydrolysates Based on In Silico, In Vitro, and In Vivo Studies

This current study aims to analyze the potential bioactivities possessed by the enzymatic hydrolysates of commercial bovine, porcine, and tilapia gelatins using bioinformatics in combination with in vitro and in vivo studies. The hydrolysate with superior inhibition of angiotensin converting enzyme (ACE) activity was used to treat the D-galactose (DG)-induced amnesic mice. In silico digestion of the gelatins led to the identification of peptide sequences with potential antioxidant, ACE-inhibitory, and anti-amnestic properties. The results of in vitro digestion revealed that the <1 kDa peptide fraction of porcine gelatin hydrolysate obtained after 1 h digestion with papain (PP) (PP1, <1 kDa) potently inhibited ACE, acetylcholinesterase, and prolyl endopeptidase activities at 87.42%, 21.24%, and 48.07%, respectively. Administering the PP1 to DG-induced amnesic mice ameliorated the spatial cognitive impairment and Morris water maze learning abilities. The dentate area morphology in the PP1-treated mice was relatively similar to the control group. In addition, PP1 enhanced the antioxidant capacity in the DG-induced amnesic mice. This study suggests that PP1 could serve as a potential treatment tool against oxidative stress, hypertension, and neurodegenerative diseases.

Protein-Based Packaging Films in Food: Developments, Applications, and Challenges

With the emphasis placed by society on environmental resources, current petroleum-based packaging in the food industry can no longer meet people's needs. However, new active packaging technologies have emerged, such as proteins, polysaccharides, and lipids, in which proteins are widely used for their outstanding gel film-forming properties. Most of the current literature focuses on research applications of single protein-based films. In this paper, we review the novel protein-based packaging technologies that have been used in recent years to categorize different proteins, including plant proteins (soybean protein isolate, zein, gluten protein) and animal proteins (whey protein isolate, casein, collagen, gelatin). The advances that have recently been made in protein-based active packaging technology can be understood by describing protein sources, gel properties, molding principles, and applied research. This paper presents the current problems and prospects of active packaging technology, provides new ideas for the development of new types of packaging and the expansion of gel applications in the future, and promotes the development and innovation of environmentally friendly food packaging.

A physicochemical evaluation of ossein-hydroxyapatite within the bovine bone matrix revealed demineralization and making type I collagen available as a result of processing and solubilization by acids

Bovine bone is an animal-origin matrix rich in type I collagen (COL I) and it necessitates prior demineralization and makes COL I available. This study investigated the ossein-hydroxyapatite physicochemical properties evaluation as a result of processing and solubilization by acids and revealed the bone matrix demineralization and making COL I available. The tibia residue from bovine sources was processed, ground, and transformed into bone matrix powder. The bone matrix was solubilized in acetic acid followed by lactic acid. The bone matrix was evaluated as a result of processing and solubilization by acids: ossein and hydroxyapatite percentages by nitrogen and ash content, mineral content, particle size distribution, Fourier-transformation infrared spectroscopy, x-ray diffraction, and scanning electron microscope. For the obtained residual extracts, pH and mineral content were evaluated. The solubilization by acids affected the ossein-hydroxyapatite physicochemical properties, and the bone matrix solubilized by acetic and lactic acid showed the preservation of the ossein alongside the loss of hydroxyapatite. The processing and the solubilization by acids were revealed to be a  alternative to bone matrix demineralization and enabling the accessibility of bone COL I. PRACTICAL APPLICATION: Bovine bone is an abundant type I collagen source, but processing maneuvers and demineralization effect present limitations due to the rigidity of the structural components. Exploring methodologies to process and demineralize will allow type I collagen to be obtained from the bone source, and direct and amplify the potentialities in the chemical and food industries. The research focused on bone sources and collagen availability holds paramount significance, and promotes repurposing agribusiness residues and development of protein-base products.

Investigation of the Structure-Forming Potential of Protein Components in the Reformulation of the Composition of Edible Films

To optimize the functional properties of edible films or coatings, mixtures of several ingredients are used, including food processing by-products. In this way, pectin from fruit pomace, whey proteins from whey as a by-product of rennet cheese production, and gelatin from by-products of the processing of slaughtered animals can be obtained. The aim and scope of the investigation were to verify the hypothesis of the research, which assumes that the addition of beef broth to edible gelatin films will affect the gelation processes of the tested film-forming solutions and will allow for the modification of the edible properties of the films obtained based on these solutions. Measurements were carried out to determine the visual parameters, mechanical strengths, surface and cross-sectional structures, FTIR spectra, thermal degradation rates, and hydrophilicities of the prepared gelatin films. The water content, water vapor permeability, and course of water vapor sorption isotherms of the films were also examined, as well as the course of the gelation process for film-forming solutions. The addition of broth to film-forming solutions was found to increase their opacity and color saturation, especially for the ones that were yellow. The films with the addition of broth were more uneven on the surface and more resistant to stretching, and in the case of the selected types of gelatins, they also formed a more stable gel. The broth increased the hydrophilicity and permeability of the water vapor and reduced the water content of the films. The addition of broth enables the practical use of edible films, but it is necessary to modify some features.

Enhanced hydrophobic interaction between fish (Cyprinus carpio L.) scale gelatin and curcumin: Mechanism study

To enhance the solubility of hydrophobic nutrients, the hydrophobicity of fish scale gelatin hydrolysate (FSGH) was increased with moderate acid or alkali hydrolysis. Acid-induced FSG hydrolysate (AcFSGH) at 3 h showed a superior curcumin loading efficiency (18.30 ± 0.38 μg/mL) among all FSGHs. Compared with FSG, the proportion of hydrophobic amino acids (from 41.1% to 46.4%) and the hydrophobic interaction (from 12.72 to 20.10 mg/mL) was significantly increased in the AcFSGH. Meanwhile, the transformation of the α-helix (from 12.8% to 4.9%) to the β-sheet (from 29.0% to 42.8%) was also observed in the AcFSGH. Based on the observation in the molecular weight and morphological analysis, AcFSGH acquired the best hydrophobic interaction with curcumin, presumably due to the formation of the flexible structure of the linear hydrolyzates. The above results call for an investigation of the role of FSG hydrolysate in the synthesis of nanoparticles loaded with bioactive lipophilic compounds.

Effects of Long-Term Administration of Bovine Bone Gelatin Peptides on Myocardial Hypertrophy in Spontaneously Hypertensive Rats

The research purpose was to investigate the effects and the underlying molecular mechanisms of bovine bone gelatin peptides (BGP) on myocardial hypertrophy in spontaneously hypertensive rats (SHR). BGP relieved myocardial hypertrophy and fibrosis in SHR rats in a dose-dependent manner by reducing the left ventricular mass index, myocardial cell diameter, myocardial fibrosis area, and levels of myocardial hypertrophy markers (atrial natriuretic and brain natriuretic peptide). Label-free quantitative proteomics analysis showed that long-term administration of BGP changed the left ventricle proteomes of SHR. The 37 differentially expressed proteins in the high-dose BGP group participated in multiple signaling pathways associated with cardiac hypertrophy and fibrosis indicating that BGP could play a cardioprotective effect on SHR rats by targeting multiple signaling pathways. Further validation experiments showed that a high dose of BGP inhibited the expression of phosphoinositide 3-kinase (Pi3k), phosphorylated protein kinase B (p-Akt), and transforming growth factor-beta 1 (TGF-β1) in the myocardial tissue of SHR rats. Together, BGP could be an effective candidate for functional nutritional supplements to inhibit myocardial hypertrophy and fibrosis by negatively regulating the TGF-β1 and Pi3k/Akt signaling pathways.

Study on the anti-inflammatory activity of the porcine bone collagen peptides prepared by ultrasound-assisted enzymatic hydrolysis

In this study, the effects of ultrasound-assisted enzymatic hydrolysis on the extraction of anti-inflammatory peptides from porcine bone collagen were investigated. The results showed that ultrasound treatment increased the content of α-helix while decreased β-chain and random coil, promoted generation of small molecular peptides. Ultrasound-assisted enzymatic hydrolysis improved the peptide content, enhanced ABTS+ radical scavenging and ferrous ion chelating ability than non-ultrasound group. At the ultrasonic power of 450 W (20 min), peptides possessed significant anti-inflammatory activity, where the releasing of interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) was all suppressed in lipopolysaccharide (LPS) induced RAW264.7 cells. After the analysis with LC-MS/MS, eight peptides with potential anti-inflammatory activities were selected by the PeptideRanker and molecular docking. In general, the ultrasound-assisted enzymatic hydrolysis was an effective strategy to extract the bioactive peptides from porcine bone, and the inflammatory regulation capacity of bone collagen sourced peptides was firstly demonstrated.

Techno-functional characterization of gelatin extracted from the smooth-hound shark skins: Impact of pretreatments and drying methods

Gelatin derived from marine by-products could be an interesting alternative to classic mammalian gelatin. The pretreatment and extraction conditions could influence the size of the resulting peptide chains and therefore their techno-functional properties. Thus, it is important to optimize the production process to get a gelatin for the appropriate applications. Skin pretreatment was done by microwaves or oven-drying and the extracted gelatin was dried by spray- or freeze-drying. Freeze-dried gelatin extracted from untreated skin (FGUS) had the highest gelatin yield (10.40%). Gelatin proximate composition showed that proteins were the major component (87.12-89.95%), while lipids showed the lowest contents (0.65-2.26%). Glycine showed the highest level (299-316/1000 residues) in the extracted gelatins. Proline and hydroxyproline residues of gelatins from untreated skin were significantly higher than those from pretreated skin-gelatin. FTIR spectra were characterized by peaks of the amide A (3430-3284 cm-1), B (3000-2931 cm-1), I (1636-1672 cm-1), II (1539-1586 cm-1) and III (1000-1107 cm-1). Spray-drying decreased the gelling properties of gelatins, since it reduced gelling and melting temperatures compared to freeze-drying. Skin pretreatment significantly reduced the gel strength of gelatin by about 50-100 g depending on the gelatin drying method. The FGUS showed better surface properties compared to other gelatins. The highest emulsion activity index (39.42 ± 1.02 m2/g) and foaming expansion (172.33 ± 2.35%) were measured at 3% FGUS. Therefore, the promising properties of freeze-dried gelatin derived from untreated skin, gave it the opportunity to be successfully used as a techno-functional ingredient in many formulations.

Intervention Effects of Deer-Tendon Collagen Hydrolysates on Osteoporosis In Vitro and In Vivo

Deer tendon, a deer processing byproduct, is an excellent protein source for the preparation of peptides for improving osteoporosis by its high protein content and high nutritional value. The optimal process of collagen acid extraction was implemented and the results showed that the acid concentration was 7%, the material-liquid ratio was 1:25, and the soaking time was 48 h. DTCHs could promote MC3T3-E1 cell proliferation and increase alkaline phosphatase activities in vitro. In addition, compared with the model group, the DTCHs treatment groups with an oral dosage of 350, 750, and 1500 mg/kg rat/day could significantly improve the shape, weight, bone mechanics, and alkaline phosphatase activities of tail-suspended mice. Bone microstructure and mineralization also recovered significantly in vivo. This result is expected to provide the structural and biological information for DTCHs-based functional foods.

Changes in glycated myofibrillar proteins conformation on the formation of Nε-carboxymethyllysine under gradient thermal conditions

N^ε-carboxymethyllysine (CML), a frequently used marker of advanced glycation end products (AGEs) in food, was generated in food processing easily and caused changes in myofibrillar proteins (MPs) characterization. The relevance between glycosylated MPs structure alternation and CML formation under thermal conditions have been reported. However, the correlation mechanism was not clear yet. In this work, the influence of gradient heating (50℃, 60℃, 70℃, 80℃, and 90℃) on the different degrees of glycated MPs, which determined the correlation with CML formation in protein structural changes of MPs. In the rising stage of the CML level, glycation accelerated the fibrillation and aggregation behavior of MPs during heating and increased surface hydrophobicity and particle size. The protein cross-linking affected the protein modification caused by heating and glycation. This work highlights the substantial influences of glycosylation and thermal treatments on MPs, which transformed the MPs structural characteristics and CML level.

Advanced review on type II collagen and peptide: preparation, functional activities and food industry application

Type II collagen is a homologous super-helical structure consisting of three identical α1(II) chains. It is a major component of animal cartilage, and is widely used in the food industry. Type II collagen can be extracted by acids, salts, enzymes, and via auxiliary methods and can be further hydrolyzed chemically and enzymatically to produce collagen peptides. Recent studies have shown that type II collagen and its polypeptides have good self-assembly properties and important biological activities, such as maintaining cartilage tissue integrity, inducing immune tolerance, stimulating chondrocyte growth and redifferentiation, and providing antioxidant benefits. This review focuses specifically on type II collagen and describes its structure, extraction, and purification, as well as the preparation of type II collagen peptides. In particular, the self-assembly properties and functional activities of type II collagen and collagen peptides are reviewed. In addition, recent research advances in the application of type II collagen and collagen peptides in functional foods, food additives, food coating materials, edible films, and carriers for the food industry are presented. This paper provides more detailed and comprehensive information on type II collagen and peptide for their application.

Preparation of immobilized pepsin for extraction of collagen from bovine hide

In the extraction of collagens from mammalian tissues, the free pepsin used in the acid-pepsin extraction system is hard to recycle, and there is a risk of enzyme protein contamination in the extracted collagen products, which limits their applications. To solve this problem, an immobilized pepsin was successfully prepared via the covalent crosslinking of glutaraldehyde using a 3-aminopropyltriethoxysilane (APTES) surface modified silica clay as the support. The immobilized pepsin was applied for the extraction of collagen from bovine hide. The optimal immobilization process involves incubating pepsin with an initial concentration of 35 mg mL^-1 and glutaraldehyde with 5% activated APTES modified silica clay at 25 °C for 60 min, by which the loading amount of pepsin was 220 mg g^-1 and the activity of the immobilized pepsin was 4.2 U mg^-1. The collagen extracted using acetic acid and the immobilized pepsin method retained its complete triple helix structure. This research thus details an effective separation method using pepsin for extraction of collagen via an acetic acid-enzyme method, where the extracted collagen may be a candidate for use in biomaterial applications.

Bovine Bone Gelatin-Derived Peptides: Food Processing Characteristics and Evaluation of Antihypertensive and Antihyperlipidemic Activities

This study aimed to evaluate the food processing properties of bovine bone gelatin-derived peptides (BGPs) and their effects and mechanisms on hypertension and hypertension complications in spontaneously hypertensive rats (SHRs). BGPs had good acid, high temperature, and NaCl resistance abilities in vitro. Additionally, Maillard reaction of BGPs with low-dose reducing sugar (≤15%) exhibited a free radical scavenging effect. BGPs significantly reduced the blood pressure, triglyceride levels, and the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio in SHRs through downregulated angiotensin converting enzyme (ACE), angiotensin II (Ang II), and Ang II type 1 receptor (AT1R) levels and the upregulated Ang II type 2 receptor (AT2R) level. In brief, BGP could alleviate hypertension and dyslipidemia in SHRs by inhibiting ACE/Ang II/AT1R and activating the Ang II/AT2R signaling pathway. Our study suggests that BGP has good food processing properties and could be a potential nutraceutical for antihypertensive and antihyperlipidemic issues.

Bovidae-based gelatin: Extractions method, physicochemical and functional properties, applications, and future trends

Gelatin is one of the most important multifunctional biopolymers and is widely used as an essential ingredient in food, pharmaceutical, and cosmetics. Porcine gelatin is regarded as the leading source of gelatin globally then followed by bovine gelatin. Porcine sources are favored over other sources since they are less expensive. However, porcine gelatin is religiously prohibited to be consumed by Muslims and the Jewish community. It is predicted that the global demand for gelatin will increase significantly in the future. Therefore, a sustainable source of gelatin with efficient production and free of disease transmission must be developed. The highest quality of Bovidae-based gelatin (BG) was acquired through alkaline pretreatment, which displayed excellent physicochemical and rheological properties. The utilization of mammalian- and plant-based enzyme significantly increased the gelatin yield. The emulsifying and foaming properties of BG also showed good stability when incorporated into food and pharmaceutical products. Manipulation of extraction conditions has enabled the development of custom-made gelatin with desired properties. This review highlighted the various modifications of extraction and processing methods to improve the physicochemical and functional properties of Bovidae-based gelatin. An in-depth analysis of the crucial stage of collagen breakdown is also discussed, which involved acid, alkaline, and enzyme pretreatment, respectively. In addition, the unique characteristics and primary qualities of BG including protein content, amphoteric property, gel strength, emulsifying and viscosity properties, and foaming ability were presented. Finally, the applications and prospects of BG as the preferred gelatin source globally were outlined.

Protein by-products: Composition, extraction, and biomedical applications

Significant upsurge in animal by-products such as skin, bones, wool, hides, feathers, and fats has become a global challenge and, if not properly disposed of, can spread contamination and viral diseases. Animal by-products are rich in proteins, which can be used as nutritional, pharmacologically functional ingredients, and biomedical materials. Therefore, recycling these abundant and renewable by-products and extracting high value-added components from them is a sustainable approach to reclaim animal by-products while addressing scarce landfill resources. This article appraises the most recent studies conducted in the last five years on animal-derived proteins' separation and biomedical application. The effort encompasses an introduction about the composition, an overview of the extraction and purification methods, and the broad range of biomedical applications of these ensuing proteins.

Characterization and functional properties of gelatin from goat bone through alcalase and neutrase enzymatic extraction

Background and Aim:

Gelatin is a dissolved protein that results from partial extraction of collagen, commonly from pig and bovine skin. There was no study on gelatin production from Kacang goat bones through enzymatic extraction. This study aimed to evaluate the chemical, physical, and functional properties of gelatin from bones of Kacang goat using alcalase and neutrase enzymes.

Materials and Methods:

Male Kacang goat bones aged 6-12 months and two commercial enzymes (alcalase and neutrase) were used for this study. Descriptive analysis and completely randomized design (one-way analysis of variance) were used to analyze the chemical, physical, and functional properties of gelatin. Kacang goat bone was extracted with four concentrations of alcalase and neutrase enzymes, namely, 0 U/g (AG-0 and NG-0), 0.02 U/g (AG-1 and NG-1), 0.04 U/g (AG-2 and NG-2), and 0.06 U/g (AG-3 and NG-3) with five replications.

Results:

The highest yield of gelatin extraction with alcalase obtained on AG-3 was 9.78%, and that with neutrase on NG-3 was 6.35%. The moisture content of alcalase gelatin was 9.39-9.94%, and that of neutrase gelatin was 9.15-9.24%. The ash and fat content of gelatin with alcalase was lower than that without enzyme treatment with higher protein content. The lowest fat content was noted in AG-1 (0.50%), with protein that was not different for all enzyme concentrations (69.65-70.21%). Gelatin with neutrase had lower ash content than that without neutrase (1.61-1.90%), with the highest protein content in NG-3 (70.89%). The pH of gelatin with alcalase and neutrase was 6.19-6.92 lower than that without enzymes. Melting points, gel strength, and water holding capacity (WHC) of gelatin with the highest alcalase levels on AG-1 and AG-2 ranged from 28.33 to 28.47°C, 67.41 to 68.14 g bloom, and 324.00 to 334.67%, respectively, with viscosity that did not differ, while the highest foam expansion (FE) and foam stability (FS) were noted in AG-1, which were 71.67% and 52.67%, respectively. The highest oil holding capacity (OHC) was found in AG-2 (283%). FS and OHC of gelatins with the highest neutrase levels in NG-2 were 30.00% and 265.33%, respectively, while gel strength, viscosity, FE, and WHC of gelatins with the highest neutrase levels did not differ with those without enzymes at all enzyme concentrations. B chain was degraded in all gelatins, and high-intensity a-chains in gelatin with alcalase and peptide fraction were formed in gelatin with neutrase. Extraction with enzymes showed loss of the triple helix as demonstrated by Fourier transform infrared spectroscopy.

Conclusion:

Based on the obtained results, the Kacang goat bone was the potential raw source for gelatin production. Enzymatic extraction can increase the quality of gelatin, especially the alcalase (0.02-0.04 U/g bone) method. This can be used to achieve the preferable quality of gelatin with a higher yield.

The physiological activity of bioactive peptides obtained from meat and meat by-products

Meat and meat products constitute an important source of nutrients and play vital roles for growth, maintenance and repair of the body. In addition to the high quality of proteins, meat is also regarded as a major resource to produce bioactive peptides. Meat processing industry also produces by-products such as bones, blood and viscera, which could be further used for the production of bioactive compounds. In the physiological analysis, meat bioactive peptides have been reported to exert antioxidant, anti-hypertensive, anti-inflammatory, anti-microbial and antitumoral activities, which endow nutritional and functional value of meat. With the objective to exert the functional effect, the bioavailability should also be considered due to the degradation by digestion enzymes and the absorption process in intestinal mucosa. In this chapter, the general source, the enzymatic hydrolysis, the physiological effects as well as the bioavailability of bioactive peptides in meat are discussed.

Management of meat by- and co-products for an improved meat processing sustainability

Large amounts of meat by- and co-products are generated during slaughtering and meat processing, and require rational management of these products for an ecological disposal. Efficient solutions are very important for sustainability and innovative developments create high added-value from meat by-products with the least environmental impact, handling and disposal costs, in its transition to bioeconomy. Some proteins have relevant technological uses for gelation, foaming and emulsification while protein hydrolyzates may contribute to a better digestibility and palatability. Protein hydrolysis generate added-value products such as bioactive peptides with relevant physiological effects of interest for applications in the food, pet food, pharmaceutical and cosmetics industry. Inedible fats are increasingly used as raw material for the generation of biodiesel. Other applications are focused on the development of new biodegradable plastics that can constitute an alternative to petroleum-based plastics. This manuscript presents the latest developments for adding value to meat by- and co-products and discusses opportunities for making meat production and processing more sustainable.

Characterization of an intracellular aspartic protease (PsAPA) from Penicillium sp. XT7 and its application in collagen extraction

An intracellular aspartic protease, PsAPA, was identified from Penicillium sp. XT7. This protease was belonged to penicillopepsin and was expressed in Pichia pastoris GS115. The recombinant PsAPA had a specific activity of 4289.7 ± 261.7 U/mg. The pH and temperature maxima of the enzyme were 3.0 and 30 °C, respectively. The PsAPA was stable in the pH range from 3.0 to 6.0 and was completely inactivated after incubation at 50 °C for 15 min. Presence of Mn²⁺ and Cu²⁺ increased the proteolytic activity and β-mercaptoethanol and SDS showed inhibitory effects, whereas 0.05 M pepstatin A strongly inhibited it. PsAPA could effectively hydrolyze animal proteins, including myoglobin, and hemoglobin but not collagens. PsAPA increased the yield of collagen extraction compared to the acid extraction method. The above properties show that the novel low-temperature acidic protease, PsAPA, is comparable to commercial proteases (porcine pepsin) and has great potential for collagen extraction.

Predictive Modeling of Lignin Content for the Screening of Suitable Poplar Genotypes Based on Fourier Transform-Raman Spectrometry

The quick and non-invasive evaluation of lignin from biomass has been the focus of much attention. Several types of spectroscopies, for example, near-infrared (NIR) and Fourier transform-Raman (FT-Raman), have been successfully applied to build quantitative predictive lignin models based on chemometrics. However, due to the effect of sample moisture content and ambient humidity on its signals, NIR spectroscopy requires sophisticated pre-testing preparation. In addition, the current FT-Raman predictive models require large variations in the independent value inputs as restrictions in the corresponding mathematical algorithms prevent the effective biomass screening of suitable genotypes for lignin contents within a narrow range. In order to overcome the limitations associated with the current methods, in this paper, we employed Raman spectra excited using a 1064 nm laser, thus avoiding the impact of water and auto-fluorescence on NIR signals. The optimal baseline correction method, data type, mathematical algorithm, and internal reference were selected in order to build quantitative lignin models based on the data with limited variation. The resulting two predictive models, constructed through lasso and ridge regressions, respectively, proved to be effective in assessing the lignin content of poplar in large-scale breeding and genetic engineering programs.

Comparison of two kinds of peroxyl radical pretreatment at chicken myofibrillar proteins glycation on the formation of Nε-carboxymethyllysine and Nε-carboxyethyllysine

During meat processing, two typical advanced glycation end products (AGEs), N^ε-carboxymethyllysine (CML) and N^ε-carboxyethyllysine (CEL), are generated by free radical induction. However, the impact of peroxyl radicals on myofibrillar proteins (MPs) glycosylation and CML and CEL formation is scarcely reported. In this study, two peroxyl radicals called ROO· and LOO· derived from AAPH (2,2'-azobis (2-methylpropionamidine) dihydrochloride) and linoleic acid were exposed prior to the Maillard reaction (glucosamine incubation at 37 °C for 24 h). Levels of AGEs (CML/CEL), protein oxidation (sulfhydryl/carbonyl), free amino group, surface hydrophobicity, zeta potential, particle size, intrinsic fluorescence intensity and secondary structure were determined. Together with Pearson's correlation, the assumption that free radicals promote MPs oxidation and glycation, alter the aggregation behavior and structure modification, leading to AGEs promotion has been built. In addition, the effect of dose-dependency of peroxyl radical on AGEs has also been established with different effects of peroxyl radical induction.