Isolation and characterization of collagens from the skin of giant grouper (Epinephelus lanceolatus)

ABSTRACT

Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from the skin of giant groupers (Epinephelus lanceolatus) with yields of 39.51 and 19.12%, respectively. ASC and PSC consisted of two different α chains (α1 and α2) and were characterized to be type I collagen with no disulfide bond. The imino acid contents of the ASC and PSC from giant grouper skin were 189 and 181 per 1,000 residues, respectively. The maximum endothermic temperatures (T_max) of ASC and PSC measured by differential scanning calorimetry (DSC) were 31.71 and 31.33°C, respectively. The denaturation temperatures of ASC and PSC measured by viscometry were 29.84 and 29.05°C, respectively. The maximum solubility in 0.5 M acetic acid was observed at pH 5 and pH 6 for ASC and PSC, respectively. A sharp decrease in solubility was observed for both ASC and PSC in the presence of NaCl above 3% (w/v).     

Characterization of Acid-Soluble Collagen From Bone of Pacific Cod (Gadus macrocephalus)

Acid-soluble collagen (ASC) was isolated from Pacific cod (Gadus macrocephalus) bone. The ASC was rich in glycine. The amount of imino acid was lower than that of calf skin collagen, as was the transition temperature (48.6°C). Electrophoresis revealed two different α chains (α₁ and α₂), β-component, and γ-component. Fourier transform infrared spectroscopy measurement showed that ASC was in triple-helix structure. ASC had a solubility greater than 90% in a very acidic pH range (pH 1–4), and the solubility decreased with increasing NaCl concentrations up to 3%. Lyophilized ASC had a network ultrastructure with lace-like fibers, similar to calf skin collagen sponge.     

Characteristics and Select Functional Properties of Collagen from Golden Pompano (Trachinotus ovatus) Skins

Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) from golden pompano skins were extracted and characterized. The molecular weight of ASC was about 130 kDa for α₁ and 115 kDa for α₂, which were slightly higher than those of PSC. Similar amino acid composition and Fourier transform infrared (FTIR) spectra were observed in both collagens, but slight differences were found in the peptide maps of collagen digested by V8 protease and trypsin. The denaturation temperatures (Tds) of ASC and PSC calculated from the reduced viscosity were 31.8 and 30.0°C, while the transition temperature (T_m) of ASC and PSC analyzed by DSC were 33.0 and 32.0°C, respectively. ASC has a lag phase, a growth phase, and a plateau phase in the turbidity–time curve, while PSC does not have similar phenomenon. It was found that the fibril gel of ASC could be formed at 25°C, leading to improved thermal stability.     

Characteristics of Collagen from Rohu (Labeo rohita) Skin

Acid soluble collagen (ASC) and pepsin soluble collagen (PSC) were isolated from rohu skin with the yield of 64.2 and 6.8% (dry weight basis), respectively. Both collagens had glycine as the major amino acid with imino acid content of 196–202 residues/1,000 residues and were characterized as type I collagen with molecular composition of (α1)₂α2-heterotrimer. Fourier transform infrared spectra of both collagens were similar, with no shift in wavenumber of all amide bands. The T_max value of ASC and PSC was 36.40 and 35.48°C, respectively. The zero surface net charge of ASC and PSC was found at pH 5.9 and 5.3, respectively.     

Influence of Water and Glycerol Contents on the aw of Fish Pastes

Abstract

The influence of fish water content on the characteristics of water activity (a_w) of reduced paste was studied. Two fish species were used: a fat species, mackerel (Scomber japonicus marplatensis), and a lean species, Brazilian sandperch (Pseudopercis semifasciata). Glycerol (from 15 to 50%) was used to decrease a_w of the cooked fish paste.(54.12% and 77.89%) in mackerel, two relationships of a_w versus percent added glycerol were obtained, and for Brazilian sandperch one relationship was obtained.     

Physicochemical Properties and Angiotensin I Converting Enzyme Inhibitory Peptides of Freshwater Fish Skin Collagens

ABSTRACT

The objectives of this study were to characterize physicochemical properties of two collagens, tilapia skin (TS) and hybrid catfish skin (HS). Angiotensin-converting enzyme (ACE) inhibitory peptides from extracted TS and HS collagen using pepsin were also determined. HS collagen had a higher amount of imino acid than TS collagen, while TS contained higher amounts of tyrosine (Tyr) and lysine (Lys). Fourier-transform infrared spectra of both collagens showed predominant helix structure. The HS collagen hydrolysate prepared by pepsin was fractionated using sequential ultrafiltration membranes, and the fraction with molecular weight (MW) <5 kDa showed the highest ACE inhibitory activity (p < .05). After cation exchange and two steps size exclusion chromatography, peptides showed ACE inhibitory activity of 72.06%. This study revealed that ACE inhibitory peptides derived from HS collagen could be developed as a functional food with potential antihypertensive properties.     

Encapsulated Spirulina Powder Feed for the Nutritional Enrichment of Adult Brine Shrimp (Artemia salina)

Abstract

Liposomes were prepared in the laboratory with lipids obtained from chicken egg yolk to encapsulate Spirulina powder. Artemia napulii were hatched and fed with lipid-encapsulated Spirulina or Spirulina powder. After 20 days of rearing, the experimental A. salina were harvested and measured for total body length and total content of protein and carbohydrates. Total body length was 45% higher, protein content was 49% higher, and carbohydrate was 35% higher in Artemia fed with liposomes as compared with those fed only Spirulina powder.     

多棘海盘车体壁胶原蛋白的研究

采用两种不同的方法从海盘车体壁中提取出酸溶性胶原蛋白（ＡＳＣ）和胃蛋白酶促溶的胶原蛋白（ＰＳＣ）,得率分别为１０．９０％、６１．４３％。将ＡＳＣ、ＰＳＣ的氨基酸组成、理化性质与脊椎动物及其它无脊椎动物胶原蛋白进行比较,结果表明,ＡＳＣ、ＰＳＣ是典型的胶原蛋白。在此基础上对ＡＳＣ、ＰＳＣ进行了ＳＤＳ－ＰＡＧＥ电泳,进一步表明制品的纯度较高,并且它们在分子大小、构型及性质上没有显著差异。     

Carotenoid Pigments Composition of Two Commonly Discarded Decapod Crustaceans in Grand Sole and the Galician-Northern Portugal Coast Fisheries

ABSTRACT

Carotenoid composition of two commonly discarded decapod crustaceans, Liocarcinus depurator and Munida spp., was assessed in different catching months. Total carotenoid content ranged between 7 ± 1 and 22.4 ± 0.7 μg g^?1. Pigment separation was performed by high-performance liquid chromatography coupled with a diode array detector. Astaxanthin accounted for 21 to 50% of total carotenoids, and the remaining percentage corresponded mainly to esters of astaxanthin. The fatty acid profile of carotenoid extracts for each species was evaluated. Overall total unsaturated fatty acids content ranged from 406 to 1,631 μg g^?1. Both species were rich in omega-3 fatty acids, which on average represented 68% of total unsaturated fatty acids. Therefore, the use of these low value by-catch species as a source of carotenoid pigments and fatty acids (e.g., for aquaculture formulations) is a possible alternative to their disposal at sea.     

Artificial Spawning of African Catfish,Clarias gariepinus

Abstract

The effects of controlled reproduction of African catfish, Clarias gariepinuswere investigated in an experiment with carp pituitary (at the dose 4 mg/kg body weight) or Ovopel (1 pellet/kg body weight) used as ovulation stimulators. The application of the synthetic stimulator led to the significantly (P≤0.01) greater weight of eggs (expressed in grams and as percentage of female body weight) and to the significantly (P≤0.05) higher quality of eggs after 24-hour incubation as compared with the hypophysation effects. Two categories of females were used in the experiment, i.e., light (mean body weight of 3.75 kg) and heavy (mean body weight of 8.86 kg) fish. The results show that a significantly (P≤0.01) greater weight of eggs (expressed in grams) was obtained from heavier females. The quality of eggs expressed as the percentage of live embryos after 12- and 24-hour incubation was significantly (P≤0.01 and P≤0.05, respectively) higher for lighter females. The higher weight of obtained eggs and their better quality after Ovopel stimulation compared to the weight and quality of eggs obtained after hypophysation allow for the recommendation of this ovulation stimulator for the fish species investigated.     

Changes in muscle collagen content during <Emphasis Type="Italic">post mortem</Emphasis> storage of farmed sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>): influence on textural properties

The changes in collagen content and its solubility in sea bream muscle were studied for variable storage times following the death of the fish, and these variables were related to the evolution of physical parameters important for consumer acceptance: firmness and water-holding capacity (WHC). The results show that the collagen content in muscle diminished slightly over storage time and that this variable was directly related to firmness but inversely related to the water-holding capacity. With regard to collagen solubility, a decline was detected in acid-soluble collagen (ASC) in the first few post mortem hours, perhaps related to the end of rigor mortis that occurs at these stages. Pepsin-soluble collagen (PSC) increased, while insoluble collagen (ISC) decreased from 96 h, coinciding with a loss of firmness. This softening can be explained as a result of specific collagenases acting on the insoluble fraction of the collagen.     

Purification and immunochemical detection of a quantitatively major collagen in the dermis of sea cucumber Apostichopus japonicus

Pepsin-solubilized collagen (PSC) was prepared from the dermis of sea cucumber Apostichopus japonicus (green type) by performing pepsin digestion to collagen fiber pretreated with disaggregating solution (0.1 M Tris–HCl, pH 8.0, containing 0.5 M NaCl, 0.05 M ethylenediaminetetraacetic acid (EDTA), and 0.2 M 2-mercaptoethanol) and 0.1 M NaOH. On sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), the PSC clearly showed two alpha bands under phosphate buffer system in the presence of 3.5 M urea. An antiserum was raised against chromatographically purified major molecular species in the PSC, and immunoblot analyses were performed for the soluble fractions at 4 M guanidine hydrochloride treatment and disaggregation as well as the collagen fiber before and after treatment. These fractions and collagen fibers showed quite similar band patterns to that of the PSC, showing mainly two alpha bands. These combined results suggest that the major molecular species of collagen contains at least two distinct alpha components and that the effect of pepsin digestion is relatively small on the structure of this collagen type.

     

Utilization of Shrimp By-Products by Bioconversion with Medical Fungi for Angiotensin I-Converting Enzyme Inhibitor and Antioxidant

ABSTRACT

A liquid fermentation process to bioconvert shrimp by-products was developed with two species of fungi, Boletus edulis and Suillus bovinus. Angiotensin I-converting enzyme (ACE) inhibitory, antioxidant activities of bioconverted products and the deodorization effect of fungal bioconversion were determined. Two species of fungi could grow quickly in shrimp by-products medium and deodorize shrimp by-products. Bioconverted products had higher ACE inhibitory and antioxidant activities than control medium. Water extracts without crude polysaccharides from mycelia of B. edulis had the highest ACE inhibitory activity (IC₅₀ = 0.084 ± 0.011 mg/mL). Crude exopolysaccharides of B. edulis had higher antioxidant activity. Bioconversion with the fungus was proven to be a novel, practicable way to recycle shrimp by-products.     

Preparation of Cookies with Various Native Seaweeds Found on the Korean Coast

ABSTRACT

We investigated the quality characteristics of cookies prepared using different seaweeds native to the Korean coast. Flour made from four different seaweed species (Sargassum fulvellum, Enteromorpha linza, Codium fragile, and Hizikia fusiforme) was used to replace 5% of the regular flour while preparing the cookies. The seaweeds significantly affected solvent retention capacity, thus interfering with gluten network formation. Consequently, the addition of seaweed changed several variables in the cookies, such as moisture content, spread factor, and breaking stress. In sensory evaluation, cookies with Hizikia fusiforme were the most preferred, confirming the possibility of developing cookie products using this seaweed species.     

Influence of Different Hydrolysis Processes by Trypsin on the Physicochemical,Antioxidant, and Functional Properties of Collagen Hydrolysates from Sphyrna lewini,Dasyatis akjei,and Raja porosa

ABSTRACT

Acid soluble collagen hydrolysates from the cartilages of Sphyrna lewini, Dasyatis akjei, and Raja porosa on different hydrolysis conditions by trypsin were prepared and named as S, D, and R, respectively. The hydrolysates (S1, D1, and R1) obtained from hydrolysis in pH 2.5, 3 h, 37°C presented wonderful foaming and emulsifying capacities, caused by their high average molecular weights (AMWs), high degree of Pro and Lys hydroxylation, and imino acid contents (17.1, 15.3, and 14.1%). At the concentration of 0.1% (w/v), the foaming capacities of S1, D1, and R1 were 104.75 ± 2.57, 63.87 ± 2.73, and 76.87 ± 2.02%; and the emulsifying activity indexes of them were 116.07 ± 1.89, 91.04 ± 1.79, and 123.85 ± 2.14 m²/g, respectively. Conversely, hydrolysates (S2, D2, and R2) obtained from hydrolysis in pH 7.8, 3 min, 37°C exhibited strong scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (EC₅₀ 0.568, 0.680, and 1.634 mg/mL), hydroxyl radical (EC₅₀ 0.253, 0.376, and 0.438 mg/mL), and moderate reducing power (0.0465–0.4702 at the concentration of 5 mg/mL), due to their low AMWs. The results indicated that S1, D1, and R1 could be used as emulsifiers and foaming agents, and S2, D2, and R2 could be used as natural antioxidants in food systems.     

Characterization and Cryoprotection of Invasive Silver Carp (Hypophthalmicthys molitrix) Protein Hydrolysates

ABSTRACT

Silver carp (Hypophthalmicthys molitrix) is regarded as an invasive, underutilized freshwater fish causing environmental and economic complications along the U.S. Mississippi River System. In this study, silver carp protein hydrolysates (FPH) were obtained from 30, 60, 90, 120, and 240 min hydrolysis with Protamex®. Amino acid composition showed polar amino acids, including Asp and Glu, and freed hydrophobic residues in FPH-90 and FPH-240. Protein surface hydrophobicity of FPH increased with increasing degree of hydrolysis. Cryoprotection was evaluated using a muscle (mince) food system with 6% FPH (w/w) from each hydrolysis time condition, an untreated mince (CTRL), and 8% (w/w) 1:1 sucrose-sorbitol (SUSO), respectively. After six freeze-thaw cycles (D7), all FPH treatments had lower (p < 0.05) expressible moisture, indicating strong water-holding capacity by the FPH. FPH formulations also imparted antifreeze activity equal to or better than SUSO, with the FPH-90 exhibiting higher (p < 0.05) proportion (43.9%) of unfrozen water at D7. Results from this study provide preliminary evidence for development of effective cryoprotectants using an underutilized, invasive fish species that can be exploited for environmental and economic gain in the form of value-added ingredients and further provide opportunities to understand the fundamental physicochemical properties governing cryoprotection of FPH in a frozen mince system.     

Physicochemical and Functional Properties of Protein Recovered from Fish Waste

ABSTRACT

This work aimed to evaluate the physicochemical and functional properties of proteins recovered from whitemouth croaker (Micropogonias furnieri) and Argentine anchovy (Engraulis anchoita) residues obtained by the process of acid solubilization using HCl at pH = 2 and alkaline solubilization using NaOH at pH = 12 and isoelectric precipitation (pH = 5.5). The proximate composition and functional properties were determined. The solubilization and water holding capacity (WHC) of the recovered protein were studied in the pH range of 3, 5, 7, 9, and 11. The high protein content and lowest lipid reduction presented by the protein recovered from the whitemouth croaker residue and obtained by the acid solubilizing process was 97.1 and 98.4%, respectively. The maximum solubilized protein was at pH 3 and 11, and the minimum solubilized protein was at pH 5 for both species. The greater ability to retain oil was observed for the alkaline solubilization process (8.3 and 7.3). The lower WHC was at pH 5. The acid and alkali residue concentrates of the whitemouth croaker presented higher WHC at pH 3 and 11. These proteins can be used in preparing edible films and have been used to produce bioactive compounds for supplements or functional ingredients.     

Characterization of Flavor Properties from Fish (Collichthys niveatus) Through Enzymatic Hydrolysis and the Maillard Reaction

ABSTRACT

Collichthys niveatus (C. niveatus) is an abundant but underutilized fish species caught in China. In this study, flavor properties of the Maillard reaction products (MRPs) obtained from C. niveatus protein hydrolysates were determined. The optimized fish protein hydrolysates were prepared using commercial Alcalase, and the optimum values of temperature, pH, and enzyme/substrate ratio were 55.6°C, 8.7, and 1.03%, respectively. In addition, the volatile compounds of the MRPs were evaluated using headspace solid–phase microextraction combined with gas chromatography mass spectrometry. A total of 80 volatile compounds were separated and identified. Priazines, alcohols, and aldehydes were the major flavor contributors to the aroma of the MRPs (accounting for 38.86, 9.21, and 8.23%, respectively), while pyrazines were the most abundant group of volatile compounds present, with 2,5-dimethyl-pyrazine, methylpyrazine, and 3-ethyl-2,5-dimethylpyrazine being found in highest quantities (19.83, 5.81, and 5.70%, respectively). Other components—including alcohols, aldehydes, furans, ketones, and esters—were also identified in the MRPs. This study provides a systematic strategy for marine products processing and volatiles characterization. The results point to the information in the volatiles from the MRPs of protein hydrolysis from C. niveatus and pave the way for full utilization of this species.     

Pyridinoline concentrations in muscular and skin collagen of fish and relationship between collagen solubility and pyridinoline concentration in fish muscular collagen

Pyridinoline (Pyr), one of the mature crosslinks of collagen, was determined in muscular collagen of three species of fish. The amounts of muscular Pyr in red sea bream, yellowtail, and tiger puffer were 3.4, 8.8, and 50.3 mmol/mol collagen, respectively, indicating that the Pyr concentration in muscular collagen differs greatly among fish species. The Pyr concentration in tiger puffer muscular collagen was the greatest, but it was only one-fourth that in rabbit muscle. As in mammalian skin collagen, Pyr was not detected in skin collagen of red sea bream and yellowtail. However, tiger puffer skin contained Pyr (3.75 mmol/mol collagen). The presence of Pyr would have a relationship to some features of tiger puffer skin, such as mechanical strength and thickness. Pyr concentrations in acid-soluble collagen (ASC), pepsin-solubilized collagen (PSC), and insoluble collagen (ISC) in muscles of three species of fish were determined. Pyr was found in ISC > PSC > ASC, from the highest to the lowest concentration, and the concentration in ISC was 45–200 times that in ASC. Therefore, Pyr crosslinks that are formed between collagen molecules would have a close relationship to collagen solubility.     

草鱼鱼鳞胶原蛋白的提取及其部分生物学性能

以草鱼鱼鳞为原料, 分别提取鱼鳞中的酸溶性胶原蛋白(ASC)和酶溶性胶原蛋白(PSC), 着重开展了其包括热稳定性、体外酶降解性以及胶原海绵材料特性在内的相关研究, 并与哺乳动物来源的猪皮胶原(PC)相比较。实验结果表明, 制备所得的3种胶原蛋白均为典型的Ⅰ型胶原并具有完整的三螺旋结构; PC的热变性温度(41.6 ℃)明显高于ASC(34.8 ℃)和PSC(35.2 ℃); 3种胶原蛋白的体外酶降解性能受水解酶的种类、胶原蛋白提取方法、胶原蛋白来源、胶原蛋白受热历史以及蛋白的自组装程度影响。胶原蛋白酶、胰蛋白酶和木瓜蛋白酶对淡水鱼胶原均具有不同程度的降解能力, 但胶原蛋白酶的降解能力最强; 相同条件下, 3种胶原蛋白体外酶降解率依次为ASC>PSC>PC; 经热变性处理后胶原蛋白的体外酶降解率明显提高而经体外自组装处理后其体外酶降解率均出现不同程度的降低; 3种胶原样品冻干后得到的胶原海绵材料具有不同的机械性能和组织结构, ASC和PSC海绵是一种多孔但拉伸承受力较弱的海绵材料, 而PC则与之相反。