Physicochemical and Gel Properties of Myofibrillar Protein from Sin Croaker (Johnius dussumieri) Fish During Ice Storage

The physicochemical and gel properties of myofibrillar protein (MFP) from sin croaker fish were studied during ice storage for 18 days. Significant changes in the trends of solubility, Ca²⁺ ATPase enzyme activity, surface hydrophobicity, and water holding capacity of extracted MFP were observed by the 6th day of storage. The Ca²⁺ ATPase enzyme activity reduced significantly (p < 0.05) by the 6th day of storage. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) did not show a remarkable change in the concentration of myosin heavy chain. Surface hydrophobicity increased almost four times from its original value of 18.98 µg; whereas, water holding capacity showed a fluctuating trend during storage. The emulsion capacity of the MFP was in the range of 0.89- to 1.92-mL oil/mg protein during storage. The gel strength value (313.45 g.cm) of heat-induced gel prepared from fresh minced meat decreased significantly (p < 0.05) by the 6th day of ice storage. Texture profile analysis revealed that changes in hardness and gumminess were concurrent to steeply reducing breaking force up to the 6th day. The histological observation showed gradually increasing gaps between muscle fibers. The histological observations and physicochemical quality indicated that the sin croaker fish can be used for producing good quality surimi when stored for up to 6 days in ice.     

Effects of Injection of Protein Solutions Prepared from Fish By-products on Yield and Chemical Properties of Chilled and Frozen Saithe (Pollachius virens) Fillets

Fish gelatine and protein solutions prepared from saithe by-products were injected into saithe fillets. Effects on weight changes, water holding capacity, and chemical composition of the fillets were investigated after chilled (2, 5, and 7 days) and frozen (14 and 49 days) storage. The results showed that higher weight yields were obtained by adding proteins and salt to the fillets in comparison with only salt, especially in chilled fillets. The drawback of the injection was that higher drip losses were found during storage and thawing than for untreated fillets. Effects of injection on water content were only significant after 2 days of chilled storage, but differences leveled out after longer storage time and with freezing and thawing of the fillets. The procedure applied in this study seems to be promising for utilization of by-products such as trimmings as an ingredient in higher value products like fillets, in comparison to mince products.     

Physicochemical and Structural Properties of Recovered Elastin from Jumbo Squid (Dosidicus gigas) By-Products

Physicochemical and structural properties of soluble jumbo squid (Dosidicus gigas) elastin recovered from skin by-products were evaluated. The molecular weight of isolated elastin was ~40 kDa with an isoelectric point (pI) between 9 and 10. Aspartic, glutamic, arginine, proline, glycine, and lysine amino acids were the most abundant in squid elastin, whereas the hydroxyproline absence, ~0.7% cysteine content, and the calculated 0.35 isoleucine/leucine ratio were used as purity index. Total and reactive sulfhydryl contents were similar (247.0 ± 5.1 vs 242.0 ± 7.5 μmol mg^?1 of protein, P ≥ 0.05) in purified squid elastin but surprisingly higher than previously reported in other elastins. On the other hand, the secondary structures of squid elastin analyzed by Fourier transform infrared spectroscopy (FTIR) were ~45% β-sheets, ~15% α-helices, ~10% β-turns, and ~30% undefined structures. In addition, squid elastin experienced glass transition at 82.01 ± 0.01ºC, denaturation temperature at 110.45 ± 0.64ºC, and aggregation at 197.5 ± 0.23ºC. In conclusion, the prevalence of charged amino acids and pI of squid elastin can facilitate its solubilization in hydrophilic systems, whereas the secondary structure profile and thermostability are desirable features in proteins used for biopolymer designs such as food biofilms or barrier systems.     

Functional Properties of White Shrimp (Litopenaeus vannamei) By-Products Protein Recovered by Isoelectric Solubilization/Precipitation

The processing of fish in general entails quantities of by-products, such as exoskeleton and cephalothorax of shrimp, which may reach 70%. Protein recovered from by-products has been investigated in recent years for its ability to offer more nutritious foods and improved functional properties. The objective of the present study was the use of the pH shifting process to recover proteins from solubilization and precipitation that are present in the by-products (heads and shells) of white shrimp (Litopenaeus vannamei). The proximal composition of the by-products presented 58.5% protein (d.b). The isoelectric point used to precipitate the protein was defined at pH 4. The protein concentrate presented 73.1% of protein. The yield of the protein concentrate mass resulted in 47.8% (w.b). The greatest solubility found for the protein concentrate was 51.3% at pH 8. The oil and water retention capacity resulted in values of 8.5 and 2.5 mL/g of protein, respectively, and the highest emulsifying capacity was found at pH 8. The by-products and concentrate amino acids profiles confirmed the presence of 16 amino acids. In general, the shrimp protein concentrate obtained showed the potential to be included as an ingredient in food formulations.     

Stability of Fish Powder Made from Saithe (Pollachius virens) as Measured by Lipid Oxidation and Functional Properties

ABSTRACT

Lipid oxidation and functional properties were monitored in spray dried fish powder made from saithe (Pollachius virens) by-products. The fresh powder exhibited slight antioxidant activity in a model system of linoleic acid emulsion. The freshly made powder had low lipid extract-ability in polar solvents and over 30% free fatty acids (FFA). Further lipid oxidation took place during storage, independent of storage temperatures. Functional properties measured by color changes, water-binding capacity, apparent viscosity and protein solubilty changed more during storage at 30°C than 0°C.     

Functional and Biochemical Characterization of Proteins Remaining in Solution After Isoelectric Precipitation

ABSTRACT

The resulting supernatant from the isoelectric precipitation of “sawdust” from Cape hake portioning and blue whiting muscle was concentrated by ultrafiltration and the retentate spray-dried. Two main peaks corresponding to molecular weights of 15 kDa and 65 kDa were detected in the supernatant from both raw materials; in the retentate the main proteins had approximately 18 kDa and 73 kDa, and some proteins with 59 kDa were detected in the permeate. The protein content was 74.0% and 70.0% for hake by-products and blue whiting, respectively. Dried proteins had relatively low emulsifying and foaming capacity but high foaming stability and were whitish in color. Hydrophobicity and sulphydryl content were similar to those from other protein sources.     

Evaluation of Physicochemical and Sensory Properties of Sausages Made with Washed and Unwashed Mince from Nile Tilapia By-products

This study evaluates the effects of inclusion level (60 to 100%) and washing cycles (0 to 2) of minced fish from Nile tilapia fillet by-products on proximate composition, mineral contents, color, hardness, and sensory acceptance of sausages. A complete 2² factorial experimental design was used. Regression models for protein, fat, moisture, minerals, color, and hardness were developed. The optimum combinations for the independent variables are sausages made with 100% non-washed minced fish, which represents a better use of by-products without generating washing residues, leading to less expensive sausage with higher nutritional value.     

Fish Protein Isolates Recovered from Silver Carp (Hypophthalmichthys molitrix) By-Products Using Alkaline pH Solubilization and Precipitation

ABSTRACT

Fish protein isolates (FPI) were produced from silver carp processing by-products by means of the isoelectric solubilization-precipitation method, and the quality was evaluated. The alkali-aided process led to significantly more lipid reduction (p < 0.05) compared with the acid-aided process. Similar protein types were extracted for the acid and alkali solubilization, and most protein types can be recovered from the raw materials, as observed in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The FPI was higher in total amino acids and essential amino acids (EAAs) compared with the original by-products (p < 0.05). The alkali-aided process yielded a higher nutritional and color quality than the acidic process. Furthermore, we found that alkali-aided protein had higher oxidative stability than the acid-aided protein. Our study indicates that high-quality fish proteins can be efficiently recovered from low-value silver carp processing by-products using isoelectric solubilization/precipitation, particularly the alkali-aided process, and subsequently be used in value-added human foods.     

Protein Hydrolysate from Visceral Waste Proteins of Bolti Fish (Tilapia nilotica): Chemical and Nutritional Variations as Affected by Processing pHs and Time of Hydrolysis

The main objective of the current work was to evaluate the proximate chemical composition and nutritional quality of amino acids of protein hydrolysates from viscera of Tilapia nilotica fish. The results of amino acid composition showed that all hydrolysates contained sufficient and/or excessive amounts of both essential and nonessential amino acids, with appreciable values of essential amino acid/nonessential amino acid ratio (0.77 to 1.59) and essential amino acid/total amino acid ratio (43.35 to 61.35). All protein hydrolysates had a high content of the flavor enhancer amino acids. The lowest values of essential amino acids were found for phenylalanine and methionine with chemical scores ranging from 0.04 to 0.77 and 0.09 to 1.06, respectively, except for 18 h hydrolysates. The protein efficiency ratio had values greatly exceeding 2.0, which is considered a high quality. On the other hand, the levels of sugar and ash contents ranged from 2.69 to 3.32 g L^?1 and 0.48 to 2.1%, respectively, with 9.2 to 14% dry matter. Mineral composition showed that sufficient amounts of calcium, sodium, potassium, magnesium, and iron were present. The results suggest that the studied hydrolysates are appropriate for use in balanced human or animal diets.     

防止白鲢鱼糜蛋白质冷冻变性的研究

用正交试验Ｌ９（３＾３）法研究了白链鱼糜蛋白经漂洗后，添加食品磷酸盐和蔗糖作为抗冻剂对防止冷冻变性的影响。结果显示：漂洗液的盐分浓度越低，鱼糜中蔗糖含量越高，蛋白质冷冻变性程度越小。添加食品磷酸盐对漂洗和未漂洗鱼糜的影响有所不同。此外，在无抗冻剂条件下冷冻，漂洗鱼糜蛋白质的变性程度大于未漂洗鱼糜，而抗冻剂在提高漂洗鱼糜蛋白质抗冷冻变性的效果比未漂洗鱼糜要明显。     

Characteristic and Functional Properties of Gelatin from the Bones of Alaska Pollock (Theragra chalcogramma) and Yellowfin Sole (Limanda aspera) with Papain-Aided Process

Fish gelatin was extracted from the bone of Alaska pollock (Theragra chalcogramma) and yellowfin sole (Limanda aspera) using papain-aided process and the characteristic and functional properties were analyzed. The bones of Alaska pollock and yellowfin sole yielded 9.07% and 7.15% gelatin, respectively. Protein was the main component (84.67–91.76 g/100 g) in both gelatins. There was no significant difference in whiteness between the two gelatins. The absorption peak of Alaska pollock bone gelatin (ABG) and yellowfin sole bone gelatin (YBG) in ultraviolet-visible (UV-vis) spectra was 209 nm and 211 nm, respectively. Scanning electron microscope (SEM) and Fourier transform infrared (FTIR) investigations indicated the existence of helical arrangements and uniform network structures in the two gelatins. The gel strength of ABG (105.64 g) was significantly lower than that of YBG (187.39 g), possibly due to the presence of shorter chains as indicated by the degradation of α-, β-, and γ-chains. ABG also had lower emulsibility and foamability than YBG, which was associated with relatively lower hydrophobic amino acids. Therefore, yellowfin sole would be a better potential marine source of gelatin obtained from fish processing by-products.     

海洋鱼虾中功能因子的研究现状

目前,世界水产品年总产量已超过1.0×108t,然而每年因变质而丢弃的水产品约占10%,还有约30%的低值水产品被加工成动物饲料,真正提供人类食用的水产品并不富裕。就我国而言,由于海洋资源变化,近几年来,我国海洋中上层鱼类和低值鱼的产量呈上升趋势,占有较大的比重。随着人们生活     

Textural and Sensory Properties of Fish Sausage from Rainbow Trout

The aim of this study was to determine the textural and sensory properties of fish sausage which were prepared from refrigerated and frozen rainbow trout (Onchorynchus mykiss) and stored for 14 days at 0?4 °C. These two groups of sausages were compared for texture, physical, and sensory properties by carrying out texture profile analysis (TPA), shear test, water holding capacity (WHC), cook loss, color, and sensory analyses. According to TPA and shear test, sausages prepared from frozen fillets exhibited a texture significantly (p < 0.05) weaker than those prepared from refrigerated fillets, but no difference in overall liking was observed.     

鱼蛋白的综合利用途径2.酸贮液体鱼蛋白

酸贮液体鱼蛋白是开发低值鱼及水产加工废弃物中鱼蛋白的有效途径之一,本文就酸贮液体鱼蛋白的生产和使用状况进行了分析和讨论,并将鱼粉和酸贮液体鱼蛋白二者进行了比较。     

鱼蛋白的综合利用途径1.鱼粉

就有关低值鱼及水产加工废弃物中鱼蛋白的开发研究及应用情况做系列介绍,本文就低值鱼蛋白主要利用形式即鱼粉进行了分析和讨论。     

Chemical Compositions and Functional Properties of Protein Isolated from By-Product of Triangle Shell Pearl Mussel Hyriopsis cumingii

Hyriopsis cumingii is a freshwater mussel widely cultured in China to produce cultured pearls. However, after the pearls are harvested, the mussel is discarded. To make effective utilization of pearl production wastes, proteins were recovered from the pearl mussel meat using pH shift technology. The protein recovery conditions, chemical compositions, and functional properties of the recovered protein were investigated. Results show that the proteins could be well extracted from the meat by 5 volumes of alkali water (pH 11, 20°C, 1 h) followed by acidic precipitation (pH 5.2). The recovered product contained 94.7% of protein with high levels of essential and semiessential amino acids (48.9%). The most abundant essential amino acid was sulfur-containing amino acids (12.82%), followed by lysine (8.89%), phenylalanine (4.69%), and threonine (4.37%). Compared with soybean protein isolate and egg protein, the recovered protein had better water/oil absorption capability, better foaming ability, and similar emulsion capability. These results suggest that the protein isolated from the pearl mussel meat might be utilized as ingredients for the food industries.     

低值鱼蛋白挤压组织化模拟产品质构特性的研究

运用栅栏技术,合理设置栅栏因子,通过栅栏因子间交互作用,形成有效的防止食品腐败变质的栅栏,研发出感官、品质良好的中间水分组织化模拟食品。采用二次旋转组合试验设计方法进行试验设计,以山梨糖醇、蔗糖和食醋为栅栏因子调节参数,以产品最大剪切力为响应参数,建立3个调节参数与产品最大剪切力的回归拟合方程,同时分析感官评定值咀嚼感与仪器测定值最大剪切力之间相关性。研究结果表明,山梨糖醇、蔗糖和食醋对产品最大剪切力显示出不同影响趋势,拟合方程相关系数r2=0.8504,拟合模型具有较高的可信度;感官评定值咀嚼感与仪器测定值最大剪切力之间存在极显著的线性相关关系,可以用仪器测定值最大剪切力来判断感官评定值咀嚼感。     

Effect of Temperature and Alkaline pH on the Physicochemical Properties of the Protein Isolates Extracted from the Whole Ungutted Lanternfish (Benthosema pterotum)

The aim of this study was to evaluate functional properties of the protein extracted from lanternfish (Benthosema pterotum). Extraction of the fish protein was performed in alkaline pHs (10 and 12) followed by precipitation at its isoelectric pH. The effects of different extraction temperatures (0, 4, 11, 25, and 30°C) were also studied. The results showed that the protein recovery yield was higher when extracted at pH 12 compared to pH 10. Furthermore, some functional properties including water holding capacity, oil holding capacity, emulsifying capacity, foaming capacity, and solubility of the protein isolated at pH 12 were higher than that isolated at pH 10 (p < 0.05). The color evaluation (L*, a*, and b*) of the samples showed protein isolated at pH 12 was lighter (higher L*) than protein isolated at pH 10, but redness (a* value) declined in both samples. Evaluation of different extraction temperatures showed that protein recovery yield and functional properties were improved with increasing temperature. Fish protein isolate can be used in the formulation of value-added products because of their distinctive functional properties.     

Fish Processing By-Products as a Potential Source of Gelatin: A Review

ABSTRACT

The current practice of fish processing generates large amounts of by-products, which can account for up to three-quarters of the total fish weight. Despite the presence of several valuable components in the fish processing discards, the latter are usually dumped into landfills or at sea, having potentially harmful environmental effects or end up as low commercial value products (e.g., white fish meal). Still, fish processing by-products can be considered as an alternative raw material for the preparation of high-protein ingredients, especially for the production of food grade gelatin due to the presence of large amounts of collagen in fish skins, scales, and bones. Although fish gelatin is an alternative to the commercially available mammalian gelatins, its production on a large commercial scale has been hampered, mainly, due to the inferior quality characteristics compared to its mammalian counterparts. This review article summarizes and highlights the potential utilization of by-products generated during fish processing for gelatin extraction. Furthermore, several technical challenges and directions of ongoing research are discussed.     

赤水河流域鱼类物种、功能和分类多样性研究

淡水鱼类多样性格局研究目前大多集中在物种层面,通过结合不同层面的多样性指数对长江上游珍稀特有鱼类资源保护具有重要意义与生态价值。基于2019年和2020年对赤水河流域30个样区的鱼类调查数据,对鱼类物种丰富度(Richness)、Shannon-Weiner指数(H)、功能丰富度(FRic)、功能均匀度(FEve)、功能离散度(FDiv)、平均分类差异指数(Δ⁺)和分类差异变异指数(Λ⁺)等多样性指数的空间分布格局及其相关性进行了分析。结果显示,调查期间共采集到鱼类125种(亚种),隶属于7目、20科、80属;其中,土著鱼类112种(亚种),隶属于6目、17科、71属;外来鱼类13种(亚种),隶属于5目、6科、11属。7个多样性指数均呈显著的纵向梯度分布格局,上游到下游也呈增加趋势,但FEve、FDiv和Δ+指数在河段间的增量相对较小。不同生物多样性指数之间的相关性差异较大,从不显著到显著正相关。研究表明,与传统的物种多样性相比,功能和分类多样性指数能够反映河流鱼类纵向空间格局的不同信息。综合使用3种层面的多样性指数有助于更好地理解淡水鱼类分...