Fish Protein Concentrate (FPC) from Bombay Duck Isolated by Radiation-Heat Combination Procedure: Functional and Nutritional Properties

A process involving gamma-irradiation (200 Krad) and heat treatment (60°C, 10 min), for the preparation of fish protein concentrate (FPC) from a tropical fish Bombay duck (Harpodon nehereus) is described. The procedure enabled the precipitation of 75% of proteins from Bombay duck muscle which accounted for 80% of myofibrillar proteins. The solubility of FPC was 3% in water and 15% in 5% NaCl. However, the preparation could be solubilized by treatments with alkali (0.2N NaOH) or proteolytic enzymes. Among the enzymes tested for FPC solubilization, pronase was Pound to be the most effective both with respect to the extent and the rate of hydrolysis. The FPC displayed good functional properties in terms of emulsifying capacity and wettability. The PER was better than that obtained for casein when fed to rats at 11% protein level.     

脱皮大豆等温吸水模型与复水磨浆工艺参数优化

目的:探讨脱皮大豆复水磨浆工艺参数对钝化大豆脂肪氧化酶及蛋白得率的影响,为高品质豆奶产品的研制提供理论与技术支持。方法:通过构建脱皮大豆的等温吸水模型来探讨吸水率与大豆蛋白得率的关系;以浸泡液温度、pH及浸泡时间为因子,大豆蛋白得率及脂肪氧化酶活性钝化指数为指标,优化脱皮大豆磨浆吸水工艺参数。结果与结论:脱皮大豆的等温吸水模型符合M=115.693-e^-(at2+bt+c),a、b、c为与温度有关的常数,磨浆大豆的复水吸水率达到90%以上时,大豆蛋白提取利用趋于最大值。影响大豆蛋白质得率的主次顺序为浸泡时间 > 浸泡温度 > 浸泡液pH,影响钝化脂肪氧化酶活性的主次顺序为浸泡温度 > 浸泡液pH > 浸泡时间,综合考虑脂肪氧化酶活性钝化及蛋白得率,选优处理组合为浸泡液温度80 ℃、pH9,浸泡时间60 min,蛋白质得率可达90.76%,脂肪氧化酶活性钝化指数达92.78,脱去豆腥味效果显著。     

The removal of fat, skin and viscera from sand eel flesh by incubation above ambient temperature

An incubation process for the selective removal of skin, viscera and lipid from the small pelagic species sand eel ( Ammodytes tobianus) has been evaluated. The fish were cut transversely into portions (2–3 cm) and then incubated at 40°C and pH 7.0 or pH 4.0 for 60 min with vigorous agitation. The separated flesh, off white in colour and free of skin and viscera was recovered in yields of 20% at pH 7 and 30% at pH 4. The oil content was reduced from 7.3 to 4.1% (pH 7) and to 5.3% (pH 4). Proximate analyses of the final products showed that the process resulted in an increased protein content and a decreased lipid content when compared with whole sand eel flesh. Analyses of the released oil showed only slight losses in some more unsaturated fatty acids during the process. The separated flesh obtained at pH 4 and pH 7 had water-holding capacities of 2.19 and 2.78 g water/g protein respectively while intact sand eel flesh had a value of 2.62 g water/g protein.     

FISH PROTEIN CONCENTRATE AS AN EMULSIFIER

The emulsifying property of solubilized 10% fish protein concentrate (FPC) adjusted to pH 4, 6 or 8 was tested by substituting it for log liquid whole egg in a mayonnaise-type formula. Adjusting the pH to either 6 or 8 favored firmness and fineness and stability of emulsions. Regardless of pH, the emulsions made with 20g of solubilized 10% FPC were significantly (P < 0.05) more stable than those made with 10 or with 30g.     

Volatile Constituents of Fish Protein Concentrate

SUMMARY— Progress in an investigation of the chemistry of flavor in fish protein concentrate (FPC) prepared by extraction of red hake ( Urophycis chuss ) with iso -propanol is described. Lyophilization of slurries of FPC yielded condensates from which a neutral fraction and a mixture of amine hydrochlorides were isolated. The quantity of amine mixture present was dependent on processing conditions used in the FPC preparation and was related to the flavor intensity observed. The contribution of neutral components to flavor was not determined. Based on chromatographic separations and direct investigation of components by mass spectrometry, dimethylamine, trimethylamine, ammonia, ethylamine, diethylamine, n -propyl-amine and a butylamine were identified. The probable presence of methylamine, methylethylamine and iso -propylamine was indicated.     

鱼鳞冻水法制备工艺及性质的研究

以草鱼鱼鳞为原料,研究了鱼鳞冻水法制备工艺及其性质。以提胶温度、提胶时间、提胶用水pH、料水比为考察因素,以胶原蛋白提取率、冻力、灰分提取率为考察指标,采用正交实验得到鱼鳞冻最佳工艺条件为:提胶料水比1∶4,提胶用水pH为6,在100℃水浴中提胶2h。在该条件下制备的鱼鳞冻,胶原蛋白提取率为54.06%±2.38%,灰分提取率为0.76%±0.05%,冻力为(48.98±2.45)g,黏度为(1.87±0.05)mPa·s,胶凝温度为(14.73±0.31)℃,熔化温度为(23.33±0.30)℃,质构特性表明鱼鳞冻比普通果冻软且弹性更佳。综上,鱼鳞冻是一种有潜力的健康休闲食品。      

Evaluation of Corn Protein Concentrate: Extrusion Study

Functional properties of corn protein concentrate were evaluated after extrusion with a laboratory Brabender and a Wenger X-25 extruder. Bulk density, water content and hardness after rehydration were used as criteria for textural comparison among extrudates. Results indicated that corn protein concentrates resulting from either aqueous (CPC-A) or ethyl acetate (CPC-E) extraction were more suitable for extrusion applications than the one resulting from hexane extraction. A blend containing corn protein concentrate and soy flour at the ratio of 15:85 was good for chunks and granules extrusion in the pH range 7.0 - 7.3. In a dry spinning process which requires a dough with high cohesiveness for fiber formation, a blend containing 21% of corn protein concentrate, 20% soy isolate, and 59% soy concentrate at a natural pH was satisfactory.     

Studies on fish protein concentrate and fish meal from river Nile bolti fish (Tilapia nilotica)

Fish protein concentrate (FPC) from river Nile bolti fish (Tilapia nilotica) was prepared and compared with commercial FPC and fresh bolti fish flesh. Fish meal (FM) from bolti fish offals was prepared and compared with commercial FM and also fresh bolti fish flesh. FPC from bolti fish showed a higher crude protein content but less fat, ash, calcium and sand than the commercial sample, while FM from bolti fish showed a higher content of ash and phosphorus than commercial FM but was nearly similar in crude protein, fat, calcium and sodium chloride. FPC from bolti fish had a higher content of lysine, arginine, aspartic acid, glycine and glutamic acid and a lower content of the other free amino acids. The bolti fish FM had a lower content of total amino acids and the contents of the free amino acids cysteine, glycine, aspartic acid, serine, alanine, valine, and methionine increased slightly. The yield was 12% for FPC and 19.5% for FM. Coliform bacteria were not present in both FPC and FM from bolti fish. Low moisture contents of FPC and FM were essential for preventing microbiol growth and to attain a good keeping quality. The FPC and FM from bolti fish reached moisture equilibrium and stopped increasing in weight within 144 to 192 h.     

PRODUCTION OF A LOW-CHOLESTEROL SHRIMP USING SUPERCRITICAL EXTRACTION

A low‐cholesterol shrimp was produced using supercritical extraction. The processing sequence included freeze drying, cholesterol extraction and rehydration. The shrimp was freeze dried, kept under vacuum until an experimental central composite rotatory design was applied using Response Surface Analysis for the supercritical extraction process. Three variables at five levels each were tested during the experiment (pressure, volume and temperature). After the extraction procedure, various rehydration and cooking conditions were applied to obtain a processed product with characteristics similar to those of the natural shrimp. Two sensory analyses were performed: one which compared the attributes of fresh shrimp with those of the freeze‐dried and rehydrated products, and another one which compared the acceptability between fresh shrimp and low‐cholesterol shrimp after freeze drying, supercritical extraction and rehydration. Under the conditions of 310 bar, 1875 L of carbon dioxide and 37C, it was possible to obtain a low‐cholesterol shrimp with acceptable organoleptic properties.     

水分活度降低剂在罗非鱼片干燥加工中的应用

采用单因素试验以及四因素三水平L9(34)正交试验,研究了丙二醇、丙三醇、NaCl和乙醇对干燥罗非鱼片水分活度、复水率和色差的影响。结果表明:丙二醇、丙三醇、NaCl和乙醇均能有效降低罗非鱼片的水分活度;用综合加权评分法对干燥罗非鱼片水分活度、复水率和色差值进行分析,影响综合加权评分值的主次顺序为:NaCl>丙三醇>丙二醇>乙醇,最佳组合为丙二醇添加量3%,丙三醇添加量5%,NaCl添加量1%,乙醇添加量3%。     

SPRAY DRIED PROTEIN POWDER FROM THREADFIN BREAM: PREPARATION, PROPERTIES AND COMPARISON WITH FPC TYPE-B

Mechanically deboned threadfin bream (Nemipterus japonicus) meat was repeatedly washed in cold water and homogenized in equal amounts of water. The myofibrillar proteins in the homogenate were converted into a gel by the addition of acetic acid to lower the pH. The diluted gel was spray dried to get a colorless, odorless powder containing 93% protein, 1% lipid, 2.6% ash and 5% moisture. The functional properties of the powder including solubility, moisture absorption, and water holding and emulsifying capacities were superior as compared with those of FPC type-B obtained after cooking and hot air-drying of the fish meat. The spray dried powder had a protein efficiency ratio of 3.52 ± 0.27 and was digestible up to 80% by trypsin and pepsin. Unlike the FPC-type B, the spray dried powder did not undergo significant browning suggesting its superior storage stability.     

洋葱皮总黄酮纤维素酶法提取及抗氧化研究

采用中心组合试验设计研究纤维素酶法辅助提取洋葱皮中总黄酮的工艺条件,并对洋葱皮总黄酮的抗氧化活性进行测定。结果表明：洋葱皮总黄酮最佳提取工艺为纤维素酶用量0.52%、pH5.0、提取温度48℃、提取时间105min、料水比(g/mL)1:40,在此条件下,提取率为2.32%。洋葱皮总黄酮清除DPPH自由基和羟自由基的IC50分别为3.751、4.267μg/mL;同时洋葱皮黄酮还原能力较强,高于茶多酚。洋葱皮总黄酮抗氧化性强,是一种天然有效的抗氧化剂。     

多肋藻(Costaria costata)渣可溶性膳食纤维提取工艺研究

采用乙醇沉淀法、氯化钠活化法、褐藻酸转化法3种方法从多肋藻(Costaria costata)渣中提取可溶性膳食纤维(SDF),以SDF的提取率为指标,通过正交试验优化了乙醇沉淀法的提取条件,由SDF提取率及膨胀力分析结果确定了氯化钠的活化法的最优活化浓度和活化时间。实验结果表明氯化钠活化法优于乙醇沉淀法与褐藻酸转化法,其提取率为55.41%,SDF的膨胀力为55.06mL/g,持水力为2391%,吸脂力为269%,在pH值为2与pH值为7的条件下吸收胆固醇的能力分别为18.21mg/g和13.25mg/g。     

球等鞭金藻多糖的微波萃取工艺

采用微波法,通过单因素试验研究pH值、微波功率、萃取温度和萃取时间对球等鞭金藻多糖提取的影响。在此基础上,通过正交试验进一步优化多糖的微波提取工艺。最后,比较微波提取法和热水浸提法制备的球等鞭金藻多糖样品的红外光谱,并测定样品中蛋白质和多糖含量。单因素试验结果表明,pH值、微波功率、萃取温度和萃取时间均能显著影响球等鞭金藻多糖的提取。正交试验结果表明,微波法提取球等鞭金藻多糖的最佳工艺为pH9、微波功率600W、萃取温度90℃、萃取时间20min。微波提取法和热水浸提法制备的多糖产率分别为96.8mg/g和47.7mg/g。其中,前者蛋白质和多糖含量分别为1.08%和43.6%,后者中蛋白质和多糖含量依次为1.18%和22.1%。微波法与热水浸提法制备的多糖具有相似的红外光谱,表明微波提取法并不会破坏多糖结构。综上所述,在球等鞭金藻多糖提取过程中,微波法明显优于热水浸提法。     

鲢鱼内脏油提取方法的比较研究

为建立鲢鱼内脏油的最佳提取方法及工艺,充分利用鲢鱼资源,以鲢鱼内脏为原材料,分别采用淡碱水解法-钾法和酶解法进行鱼油提取,以鱼油提取率和理化性质进行比较研究。结果表明,钾法提取鲢鱼内脏油的最佳工艺条件为液固比1.5∶1（mL/g）、硝酸钾用量5%、温度70℃、pH7.5、水解时间40min和盐析时间15min,鱼油提取率为87.49%;酶解法提取的最佳工艺条件为pH7、温度50℃、酶解时间2.5h、酶添加量1.5%和液固比1.5∶1,鱼油提取率为90.33%。钾法与酶解法提取的鱼油理化指标分别为:酸值14.58、9.23mg KOH/g,过氧化值3.82、3.47mmol/kg,碘值123.93、127.48g I2/100g,水分及挥发物0.48%、0.32%,不溶性杂质0.13%、0.34%。除不溶性杂质外,其他指标酶解法均优于钾法。酶解法是鲢鱼内脏油提取的较好方法。      

鱼鳞冻热处理工艺优化及性质的研究

采用正交试验法,研究了未经前处理、酸处理、酶处理3种不同前处理方式制备草鱼鱼鳞冻的热处理优化工艺。以胶原蛋白提取率和冻力作为考察指标,确定鱼鳞冻热处理工艺最佳条件的提胶温度都为100℃,提胶时间都为2 h,除酸处理鱼鳞冻提胶料水比为1∶5外,其余均为1∶4,未前处理鱼鳞冻的提胶用水pH值为6。但由于原料中胶原蛋白含量不同,需要调整料水比以满足冻力要求。优化工艺制备的3种鱼鳞冻冻力相当,质构上都要比普通果味型果冻松软、爽滑,更有弹性。酶处理鱼鳞冻胶原蛋白浓度最高,未前处理鱼鳞冻黏度最高、质构特性最好,酸处理鱼鳞冻产量最高。胶凝温度和熔化温度表明鱼鳞冻适合在10℃以下凝冻,在20℃以下保存。     

Effects of fish meals on rumen bacterial fermentation in continuous culture

Effects of various forms of fish meal on microbial metabolism were investigated in continuous cultures of rumen contents. Five diets were formulated to contain 12% ruminally degradable protein and 47 to 48% nonstructural carbohydrate. Soybean meal was the major protein source in the control diet, whereas in the other four diets, various fish meals were substituted for 6% of total diet DM. Fish meals were: fish meal containing 34.4% FFA, fish meal containing 34.4% FFA with CaCl2 added, fish meal containing 65.6% FFA, and fish meal defatted using 1:1 ethanol:ether extraction. The five treatments were fermented with pH either held constant at 6.2 or not controlled. When pH was maintained at 6.2, the inclusion of any fish meal except defatted fish meal reduced the acetate:propionate ratio, decreased protein digestion, and reduced microbial N produced/per kilogram DM digested when compared with the soybean control. When not controlled, pH decreased after feeding to 6.0 or lower. Under these conditions, the soybean control had a lower acetate:propionate ratio and lower NDF digestion than all diets containing fish meal. In this study, oil-containing fish meal affected microbial metabolism more negatively when the fermentation pH was held at 6.2 than when the pH was 6.0 or lower.     

盐含量对草鱼片冰温腌干特性的影响

腌干能够显著延长水产品的储藏期,盐含量与水产品腌干特性密切相关。本实验通过添加不同含量的盐探究其对草鱼片冰温(-0.5±0.4) ℃腌干特性及4 ℃常规冷链储藏品质的影响。结果表明:草鱼片盐含量越高腌制过程中含水率下降速度越快,腌制平衡后含水率越低。同时盐含量影响草鱼片干燥时间、复水率、挥发性盐基氮的生成等。盐含量增加干燥时间延长、复水率增大、有效抑制挥发性盐基氮生成。综合各种指标变化草鱼片冰温腌干4 ℃储藏加盐量9%较为适宜。     

酶解小球藻保健饮品工艺研究

小球藻是高蛋白含量的营养较全面的可食藻类,含有细胞生长因子。以小球藻粉为原料,经60℃热浸复水,30MPa高压均质,小球藻细胞可有效破壁。纤维素酶和果胶酶可一定程度提高细胞蛋白抽提率;进一步用碱性蛋白酶:中性蛋白酶(3万U:3万U/g小球藻粉)在pH8.0、65℃作用4h,可有效降解蛋白质并得到稳定的可调配的酶解液。该酶解液用活性炭可完全脱腥,过滤后可用于配制澄清型小球藻口服液和保健饮料。     

Ability of flaxseed and soybean protein concentrates to stabilize oil-in-water emulsions

The ability of flaxseed protein concentrate (FPC) to stabilize soybean oil-in-water emulsion was compared with that of soybean protein concentrate (SPC). The stability of emulsions increased with increase in protein concentration. The FPC-stabilized emulsions had smaller droplet size and higher surface charge, but worse stability at the same protein concentration compared to SPC-stabilized emulsions. Oil-in-water emulsions stabilized by both proteins were diluted and compared at different pH values (3–7), ionic strength (0–200 mM NaCl) and thermal treatment regimes (25–95 °C for 20 min). Considerable emulsion droplet flocculation occurred around iso-electric point of both proteins: FPC (pH 4.2) and SPC (pH 4.5). FPC and SPC-stabilized emulsions remained relatively stable against droplet aggregation and creaming at NaCl concentration below 100 and 50 mM, respectively. The emulsions stabilized by both proteins were fairly stable within these thermal processing regimes. FPC appears to be less effective as an emulsifier compared to SPC due to its lower emulsion viscosity. Hence, FPC could be more effective in emulsions that are fairly viscous.