Physicochemical Properties and Bioactivity of Extracts from the Roe of New Zealand Hoki and Southern Blue Whiting

ABSTRACT

Various physicochemical properties of New Zealand hoki and southern blue whiting (SBW) roes and the biological activities of their extracts were investigated. Protein, moisture, and ash contents in both roes were similar; however, the lipid content of hoki roe was higher (p < 0.05) than SBW roe (11.0 ± 0.9 and 2.5 ± 0.1, respectively). Both fish roe extracts contained active protease inhibitors toward trypsin and papain. Neither of the roe extracts agglutinated erythrocytes, indicating the absence of lectins. Both fish roe extracts at 5 mg/mL concentration exhibited slight inhibitory effects on the proliferation of breast cancer cells, but neither of the roe extracts exhibited RNase or antifungal activity.     

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.     

Gel Forming Ability of Tropical Tilapia Surimi as Compared with Alaska Pollock and Pacific Whiting Surimi

Abstract

Setting and thermal treatment effects on texture and color of tropical tilapia surimi gels were compared to Alaska pollock and Pacific whiting gels. Heat treatments that most favored intrinsic gelling factors of a fish species exhibited strong gel formation. Whiteness values increased as total thermal inputs increased, which reflect the increasing opacity of the gels. Pollock gels were generally the strongest and whitest. Tilapia gel quality was generally second to pollock gels, however, in heat treatments using setting temperatures ≥ 40 °C, tilapia gels were comparable (60 °C setting) or superior (40 °C setting) to pollock gels. The optimum heat treatment for tilapia surimi appeared to be a 40° C setting for 1 hr followed by a 90 °C cook for 15 min. SDS-PAGE patterns of gels prepared with 60°C setting followed by 90 °C cooking elucidated the various degree of protein degradation depending upon the species in a descending order of whiting, tilapia, and pollock.     

Characterization of New Zealand Hoki and Southern Blue Whiting Surimi Compared to Alaska Pollock Surimi

Representative commercial lots of surimi produced from the New Zealand fish species hoki (Macruronus novaezelandiae) and Southern blue whiting (Micromesistius australis) were compared to that of Alaska pollock (Theragra chalcogramma) on the basis of functional properties and composition. Parameters studied included gelling response to preincubation and cooking for various times and to the addition of water and starch as well as frozen stability at -8°C. There were few species-related differences in response to the various treatments, although differences in absolute values of rheological parameters were noted. Surimi from the three species should be interchangeable with few or no modifications needed in the operating procedures of food manufacturers.     

Characterization and Functional Properties of Gelatin Extracted from Chinese Giant Salamander (Andrias Davidianus) Skin

The characteristics and functional properties of gelatin obtained from Chinese giant salamander (Andrias davidianus) skin were investigated. After alkaline and acetic acid pre-treatment, yield of the gelatin by hot water extraction (60°, 8 h) was 17.63 g/100 g (wet basis), and the gelatin contained 89.46 g/100 g protein, 0.3 g/100 g fat, and 0.41 g/100 g ash (dry basis). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results of the gelatin showed clear band pattern for collagen subunits,β- and α-chains. The gelatin contained 18.85% imino acids, 28.62% hydrophobic amino acids, and 19.68% essential amino acids, which is slightly lower than porcine skin gelatin (PSG). The gelatin exhibited thermo-reversible properties, with gel strength of 192.50 ± 11.47 g, rupture distance of 10.17 ± 0.20 mm, gelling temperature of 4.98°, and melting temperature of 18.04°, Emulsifying activity index (EAI) of the gelatin diminished with increasing concentrations from 10 to 40 mg/mL (p < .05), whereas the emulsifying stability index (ESI) improved significantly (p < .05). Higher concentrations (30 and 40 mg/mL) could significantly enhance the gelatin’s foam expansion (FE) and foam stability (FS) (p < .05). Water absorption ability and oil absorption ability of the gelatin were 7.1 g water/g gelatin and 9.8 g oil/g gelatin, respectively. These results imply that the gelatin with good interfacial properties could potentially be used as a novel ingredient in food emulsion systems.

Abbreviations: CGSS, Chinese giant salamander skin; CSG, Chinese giant salamander skin gelatin; PSG, porcine skin gelatin; EAI, emulsion activity index; ESI, emulsion stability index; FE, foam expansion; FS, foam stability; WAC, water absorption capacity; OAC, oil absorption capacity.     

自由基化学改性氧化石墨烯对亚甲基蓝的吸附性能

氧化石墨烯（Graphene Oxide,GO）拥有较大的比表面积和较高的稳定性,可用来吸附水体中的多种污染物,其潜在功能稳定性具有规模化应用前景。考虑到GO在高级氧化体系中结构和形貌会发生改变,探究了经UV/H2O2和UV/过硫酸盐(Persulfate, PS)产生强氧化性自由基的体系处理后所得GOs对亚甲基蓝(Methylene Blue, MB)的吸附性能。氧化性自由基体系光源为300 W中压汞灯,30 mL GO储备液(1 mg/mL)在2种氧化体系下反应1、2、4 h后制得GOs。实验考察了不同反应条件对GOs吸附动力学的影响,傅里叶变换红外光谱(FTIR)研究了GOs氧化前后表面官能团的变化。结果显示,经UV/H2O2, UV/PS氧化1 h后,GOs表面的含氧官能团数量开始明显减少;吸附动力学过程更符合准二级动力学模型（R2>0.999）;吸附热力学过程更符合Langmuir模型,MB饱和吸附量(经UV/H2O2和UV/PS氧化1、2、4 h后分别记G1-1, G1-2, G1-3, G2-1, G2-2, G2-3)依次为580.26, 591.80, 598.63, 521.77, 554.91, 568.00 mg/g。研究表明,GO可以快速吸附较大浓度范围内的MB,且对低浓度染料表现出更好的去除效果;GO对MB的吸附量随着pH值的增加逐渐增大,且在碱性条件下的增加得更明显;经氧化处理后,GOs的吸附性能随着氧化时间的增长,性能减弱,尤其在UV/PS体系中更为显著。     

不同盐度条件下饥饿及恢复摄食鲈稚鱼脂肪酸的组成

采用气相色谱法测定和分析了15.00、7.50及淡水3个盐度条件下鲈稚鱼在饥饿时及其恢复摄食后的脂肪酸变化。结果显示,在3个盐度条件下,饥饿的鲈稚鱼均首先消耗饱和脂肪酸,随后才会消耗不饱和脂肪酸;恢复摄食后的鲈稚鱼,其不饱和脂肪酸也优先得到补充。在3个盐度条件下,以淡水组饥饿稚鱼的多不饱和脂肪酸的消耗量最大,但在恢复摄食后,其EPA、DHA的含量又为最高,这可能与不同盐度条件下鲈稚鱼的生物转化能力不同有关。     

Influence of Dietary Lipid and Protein Sources on the Sensory Quality of Organic Rainbow Trout (Oncorhynchus mykiss) After Ice Storage

The influence of dietary protein and lipid sources on the quality of organic rainbow trout (Oncorhynchus mykiss) was studied. The protein and oil sources were fishmeal, fish oil, and organic vegetable protein and oils. Sensory profiling was performed during 3 to 14 days of ice storage along with lipid analyses of the fillet. Overall, the results showed that the sensory characteristics of the trout were affected in different ways during ice storage. The source of lipid seemed to affect the sensory quality at the beginning of the storage period, while the protein source seemed to have a more pronounced impact at the end of the storage period.     

温度对浒苔降解过程中溶解有机物释放及其组成的影响

2007~2019年浒苔(Ulva prolifera)绿潮在我国南黄海连续13年大规模暴发,每年上百万吨浒苔来不及打捞而沉降至海底。在浒苔绿潮消亡期,大量来不及打捞的浒苔藻体在微生物降解作用下释放丰富的碳、氮等生源要素。本研究探讨了温度对浒苔降解向水体释放溶解有机物(主要包括溶解有机碳和溶解有机氮)及其组成的影响。结果显示,不同温度(15℃、20℃和25℃)对0~7 d浒苔降解过程中溶解有机碳(DOC)的释放有显著影响(P<0.05)：20℃条件下,DOC浓度显著高于15℃和25℃条件下,而7~30 d不同温度下水体的DOC浓度没有显著差异(P>0.05)。对于溶解有机氮(DON)而言,温度对0~7 d浒苔释放DON的影响不显著(P>0.05),而7~30 d不同温度下,DON浓度呈现显著差异。其中,25℃条件下,DON浓度显著低于15℃和20℃(P<0.05),这主要是由于在实验中后期,微生物将浒苔释放的DON部分转化为无机氮形式,而25℃条件下,微生物丰度较高,进而导致较多的DON发生转化。另外,利用三维荧光光谱—平行因子分析技术(EEMs-PARAFAC)对浒苔降解过程中荧光溶解有机物(FDOM)的组成和荧光特性进行探究,共鉴别出3个荧光组分：类色氨酸组分(C1和C2)和类腐殖质组分(C3)。不同温度下,3个组分的相对含量表明,温度对FDOM的组成并没有显著影响(P>0.05),而对C2和C3组分的荧光强度具有显著影响(P<0.05),这可能由不同温度下微生物的分解速率不同所导致。     

丁鱥不同生长阶段肌肉脂肪酸和微量营养元素的比较

对丁鱥不同生长阶段鱼体肌肉中脂肪酸组成及微量营养元索含量进行了比较。结果表明：丁鱥不同生长阶段肌肉中的脂肪酸含量及组成有明显差异。脂肪酸总量、不饱和脂肪酸总量和饱和脂肪酸总量，亲鱼均高于幼鱼和成鱼，成鱼均高于幼鱼；不饱和脂肪酸／饱和脂肪酸总量，成鱼和亲鱼均高于幼鱼；同时，成鱼和亲鱼肌肉中高度不饱和脂肪酸花生三烯酸、花生四烯酸、二十二碳五烯酸和EPA、DHA含量明显高于幼鱼肌肉。成鱼和亲鱼肌肉中微量营养元素Fe和Mn含量显著低于幼鱼（P〈0．05）；亲鱼肌肉中Zn含量显著低于成鱼和幼鱼（P（0．05），成鱼显著高于幼鱼（P（0．05）；亲鱼肌肉中Cu含量显著低于成鱼和幼鱼（P〈0．05）。     

The Forms of Fluoride in Antarctic Krill (Euphausia superba) Oil Extracted with Hexane and its Removal with Different Absorbents

Krill oils (KOs) were prepared using different extraction methods (hexane and supercritical carbon dioxide), different materials (heat-dried krill powder, freeze-dried krill powder, and freeze-dried krill tail meat powder), and different standing times during hexane extraction. The fluoride concentrations in the KOs were positively correlated with the protein concentrations. Absorbents were employed to remove fluoride from KO. Activated clay achieved the highest fluoride removal rate (70.66%), followed by calcium oxide (14.49%), activated carbon (11.97%), calcium chloride (9.32%), activated alumina (0.94%), and chitosan (0.52%). Meanwhile, the protein removal rates of the above absorbents were positively correlated with the fluoride removal rates.     

Characterization of Sardine Minced Flesh (Sardinella aurita) Washed with Different Solutions

Abstract

Minced sardine was washed with sodium bicarbonate (0.5%) and water to evaluate their effectiveness in removing components such as protein, fat, ash and non-protein nitrogen. Mince washed with NaHCO₃ showed greater reductions in protein and nitrogen compounds and had a lighter color, while water washed mince showed highest reductions in ash and lipid components. Moisture and pH increased with the number of washing exchanges. Centrifugation after each washing cycle did significantly reduce the components compared to a one step centrifugation dewatering process.     

混合植物蛋白添加晶体氨基酸替代鱼粉的饲料对花鱼种生长和免疫指标的影响

在水温25.0±3.0℃下,在以不同比例的玉米蛋白、棉籽粕和豆粕为蛋白源、部分替代鱼粉的饲料中,按鱼粉的必需基酸组成添加晶体赖氨酸、蛋氨酸和精氨酸,配制成5种等蛋白(37.0%)和等脂类(11.0%)的饲料,在60cm×60cm×120cm的微流水网箱中饲养平均体质量14.84g,平均体长12.06cm的花鱼种。实验饲料分别含鱼粉28.0%(F0,对照)、21.0%(F1)、14.0%(F2)、7.0%(F3)和0%(F4)。100d的饲养中,花成活率变化在98.67%-100%之间,各组之间差异不显著(P0.05),但对生长和饲料利用率却有显著影响。花特殊增重率随饲料中鱼粉替代比例的增加而降低,用植物蛋白替代25%(F1)的鱼粉,添加晶体氨基酸,鱼特殊增重率、免疫力和消化率最高,显著高于对照组(P0.05),用植物蛋白替代50%(F2)和75%(F3)的鱼粉组鱼的特殊增重率与对照组差异不显著(P0.05),但用植物蛋白全部替代(F4,100%)鱼粉,鱼的特殊增重率显著低于F2和F3组(P0.05)。根据Excel趋势预测曲线的二次曲线计算,当最大特殊增重率为0.585%时,相对应的鱼粉含量为22.77%,可以替代18.69%的鱼粉。植物蛋白替代鱼粉对鱼肌肉中水分和灰份含量无显著影响(P0.05),但蛋白质、总氨基酸、必需氨基酸和脂肪的含量高于对照鱼。     

Partial replacement of fish meal with plant protein sources using organic acids to practical diets for juvenile yellowtail,Seriola quinqueradiata

An experiment was conducted to investigate the effects of phosphorus (P), citric acid (CA) and formic acid (FA) supplementation on growth and loading of nitrogen (N) and phosphorus (P) in juvenile yellowtail fed fish meal (FM) and alternate plant protein (APP) diets. Six diets designated as F49 (490 g kg^?1 FM‐based), F49 + P (490 g kg^?1 FM with 5 g kg^?1 inorganic P), F31 + CA (310 g kg^?1 FM containing 200 g kg^?1 APP with 5 g kg^?1 CA), F31 + FA (310 g kg^?1 FM having 200 g kg^?1 APP with 4 g kg^?1 FA), F23 + CA (230 g kg^?1 FM containing 300 g kg^?1 APP with 5 g kg^?1 CA) and F23 + FA (230 g kg^?1 FM having 300 g kg^?1 APP with 4 g kg^?1 FA) were formulated. Yellowtails were fed one of the diets for 12 weeks under on‐site conditions at water temperature 22.0–27.0 °C. F49 + P gave the best growth, while F23 + CA the lowest. Specific growth rate and feed conversion ratio of F31 + CA were similar with control group. Addition of CA to APP diets significantly increased retention of P; hence, its excretion was lowered. The results of this study suggest that FM could be replaced up to 70% with the addition of 5 g kg^?1 CA to a low P‐containing plant protein sources diet without inorganic P supplementation in juvenile yellowtail diets, which in turn would enable a reduction in environmental pollution from aquafeeds.     

Extraction and Characterization of Phospholipid-Enriched Oils from Antarctic Krill (Euphausia Superba) with Different Solvents

Krill oils (KOs) were extracted from Antarctic krill using ethanol, hexane, or their mixture (1:2, v/v) with yields of 21.32%, 8.50%, and 18.75%, respectively. The total nitrogen content of the aforementioned oils was 2.76%, 1.06%, and 1.87%, respectively, indicating the presence of lipoprotein. All KOs contained a high proportion of phospholipid (PL) (30.20–64.82% of total lipids) and polyunsaturated fatty acids (PUFA) (30.00–34.94% of total FAs). Among PL, phosphatidylcholine was dominant (89.81–90.60 mol %). In contrast, KO extracted with the mixed solvent had the highest amount of glycerophosphocholine species containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).     

The Growth Performance and Nutrient Quality of Asian Swamp Eel Monopterus albus in Central Java Indonesia in a Freshwater Aquaculture System with Different Feeds

The Asian swamp eel (Monopterus albus) is a high protein content fish with delicious taste that can survive for 6–8 months. The growth performance and nutrient quality of Asian swamp eels in a freshwater aquaculture system in Central Java, Indonesia was studied using a completely randomized design. Golden snails, snails, silkworms, and earthworms were the feeding treatments at 5% of total body weight. The test animals weighed 5.68 ± 0.35 g after a 60-day culture, and the density was 36 eels/m². Providing different types of feed had significant effects (P < 0.05) on relative growth rate (RGR), feed intake, and survival rate (SR) but did not significantly affect the protein efficiency ratio (P > 0.05). The best final weight, RGR, and SR results were 11.80 g, 2.64%, and 80.95% during a 60-day culture with silkworms used as feed. The nutrient quality in a similar treatment found with the best proximate composition was 76.90% protein, 3.24% fat, 25.19% palmitic acid, 15.41% oleic acid, 15.9% glutamic acid, 8.2% isoleucine, and 8.9% lysine.     

Removal of cadmium from scallop processing waste by washing with weak acid solution and utilization of useful constituents for organic fertilizer manufacturing

ABSTRACT:   Hepatopancreases were washed four times with 2% acetic acid solution. In both the washed hepatopancreases and the supernatant of the washing solution, the residual cadmium (Cd) concentration was in accordance with the required standard for organic fertilizers. Hepatopancreases do not naturally contain high levels of nitrogen, but they do contain several amino acids which are useful for cultivation, and these were retained during the washing process. Although the condensed precipitate of the washing solution contained a considerable amount of Cd, Cd elution levels at the time of final disposal met judgment standard for special management industrial waste as a result of kneading and immobilizing with chelating adsorbent for treatment of contaminated soil. The volume of the precipitate of the washing solution was one-fifth of the original hepatopancreas, and the solid waste was suitable for burial at a final disposal site without further treatment.