Elution and internal migration of free amino acids in fish meats by soaking in sodium chloride or sorbitol solution

ABSTRACT:   Elution and internal migration of free amino acids (FAA) in fish meats by soaking were investigated when the meat strips were soaked in various concentrations of sodium chloride (NaCl) or sorbitol solution. Rapid decrease of FAA in an earlier phase of soaking was followed by a mild one, irrespective of the kind and the concentration of soaking solution. The loss of FAA by soaking in NaCl solution was slightly larger than that in sorbitol solution. However, regardless of the kinds of soaking solution, the elution of FAA from fish meats by soaking was only dependent on the soaking time, independently of the concentration, namely osmotic pressure of the soaking solution. Conversely, sluggish migration of FAA from the inside to the surface of the meat strips proceeded by soaking. These results suggested that the elution of FAA from fish meats by soaking was driven by a simple diffusion from the surface of the meats to soaking solution, but it was regulated by sluggish migration rate of FAA in fish meats.     

罗非鱼片在食盐溶液中的渗透脱水规律研究

研究了质量分数(10%、20%、30%)、温度(10、20、30℃)及厚度(3、5mm)对罗非鱼片在食盐溶液中的渗透脱水和盐吸收量随渗透时间而变化的影响规律。试验结果表明,鱼片的脱水量及盐的吸收量均随渗透温度的升高而增加。食盐的质量分数是决定鱼片是否脱水的关键因素,鱼片在10%的食盐溶液中表现为吸水,而在质量分数超过20%的食盐溶液中表现为脱水,质量分数越高,则鱼片失水量越多,同时溶质获得量也越高。较薄鱼片的渗透脱水和溶质获得量均高于较厚鱼片。     

Different effects of ionic and non-ionic compounds on the freeze denaturation of myofibrils and myosin subfragment-1

The effects of non-ionic (sorbitol, maltose, trehalose) and ionic compounds (Na-glutamate, Na-acetate, Na-sulfate, ammonium sulfate) on freeze denaturation of myosin subfragment-1 (S-1) and of myofibrils were compared. Sugars, Na-glutamate and Na-acetate well suppressed the freeze denaturation of myofibrils as well as S-1 in a concentration dependent manner. Although sulfate suppressed freeze denaturation of S-1 irregularly, it accelerated myofibril denaturation. It was concluded that sulfate salts were useless as cryoprotectant for myofibrils. Stabilization extent by F-actin in frozen storage was much less than that in heating.     

Effect of sorbitol on moisture transportation and textural change of fish and squid meats during curing and drying processes

SUMMARY: Atka mackerel (Am) and Japanese common squid (Sq) meats were cured in 0.5–1.5 M sorbitol solutions (pH 7.0) and dried at 30°C (relative humidity, 60%), and the effect of sorbitol on the moisture transportation and textural change during the curing and drying processes was investigated. With an increase in sorbitol permeated through samples, the moisture contents decreased by 52% (Am) and 42% (Sq) by curing in 1.5 M sorbitol solution. When the cured meats were dried, slow moisture vaporization occurred at the initial drying period, and the critical moisture content significantly decreased with an increase in the sorbitol content of the cured meats. Further, the hardening of the dried products was effectively suppressed by sorbitol curing. These effects of sorbitol would contribute to the reduction of drying time and particularly the elimination of the excess hardening of dried fish products.     

Assessing the end-point temperature of heated fish and shellfish meats

ABSTRACT: Attempts have been made to assess the end-point temperature (EPT) of heated fish and shellfish meats by using the coagulation method together with sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis and enzyme activity determination. Unfrozen and frozen fish and shellfish meats were heat-treated at different selected temperatures with 0, 15 or 30 min holding times. Proteins were extracted with NaCl solution. The coagulation method was able to determine EPT of heated fish and shellfish meats between 60 and 67°C. SDS-PAGE patterns of the filtrates from heated meats were closely related to the results of the coagulation method and enzyme activity determination. Two proteins responsible for producing coagulum of fish meat extracts seem to be lactate dehydrogenase (LDH) and glyceraldehyde phosphate dehydrogenase (GAPDH). End-point temperatures determined by these methods were not significantly different between unfrozen and frozen samples. On the contrary, a highly thermostable protein with a molecular mass of 35 kDa was detected in heated shellfish meats up to 108°C. In scallop adductor muscle, this highly thermostable protein was found to be the tropomyosin subunit from its amino acid composition and their partial sequences. Tropomyosin could be used as an EPT indicator up to 108°C for heated shellfish meats.     

Stabilization of myosin by ionic compounds as affected by F-actin

ABSTRACT:   Suppressive effects of non-ionic (sorbitol, maltose, and trehalose) and ionic (Na-glutamate, Na-acetate, Na-sulfate, and ammonium sulfate) compounds on the thermal inactivation of myosin subframgent-1 (S-1) and myofibril Ca²⁺-ATPase were compared. All compounds suppressed S-1 denaturation. When myofibrils were used (at 0.1 M KCl), sugars and sugar alcohol (non-ionic compounds) suppressed denaturation similar to S-1, while Na-glutamate, Na-acetate, and Na-sulfate weakly suppressed them. Ammonium sulfate accelerated denaturation, but suppressed denaturation when heated in 2 M KCl, at which myosin lost protection by F-actin. It was thus concluded that ionic compounds affected the denaturation of myofibrils in two ways; suppression as established with S-1, and acceleration as a result of loss of protection by F-actin caused by increase in ionic strength.     

Reduction of the Phosphate Soaking Time Required for Shrimp Products Using Pulsed Vacuum Condition

Pulsed vacuum (PV) was used to reduce the phosphate soaking time for raw and cooked shrimp, without reducing its quality. The shrimp was soaked in a phosphate solution under cycles of vacuum pressure (15 kPa, 7 min) and atmospheric (ATM) pressure (101 kPa, 3 min). PV-soaked shrimp reached stable absorption faster than ATM-soaked shrimp. At equilibrium absorption, no differences in moisture or phosphate contents were observed between PV- and ATM-soaked shrimp. After cooking, PV-soaked and ATM-soaked shrimp showed no differences in product yield or texture. Therefore, PV soaking reduces soaking time but does not affect the yield of cooked shrimp, increasing production capacity. Moreover, this study suggests that to maximize the yield of raw-soaked shrimp, shrimp should be soaked until the moisture content reaches equilibrium. In contrast, cooked shrimp should be soaked until the phosphate content stabilizes, to produce the highest yield with the lowest soaking time.     

Effect of organic salts on setting gels and their corresponding acids on kamaboko gels prepared from squid Todarodes pacificus mantle muscle

The present study evaluated the quality of setting gels prepared by adding sodium acetate, sodium gluconate, sodium citrate, and sodium succinate to Todarodes pacificus mantle muscle meat, and of the acid-induced kamaboko gels produced by soaking the setting gels in their corresponding acid solutions. The breaking strength was the lowest for the setting gel treated with sodium acetate. The pH values of the acid-induced kamaboko gels decreased when soaked in acid, whereas their moisture contents, whitenesses, and breaking strengths increased. The citric acid-induced kamaboko gel had the highest whiteness index and breaking strength among the gels. The sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) patterns did not show large differences among the gels, except for a low-intensity polymer band in the gluconic acid-induced kamaboko gel. Sodium citrate combined with citric acid yielded the best-quality acid-induced kamaboko gel among all the combinations, so this condition was used to study the effect of organic salt levels. The breaking strength increased when a sodium citrate level of up to 3% was used for the sodium citrate-treated setting gel, and 10% for the citric acid-induced kamaboko gel. The SDS-PAGE patterns did not differ among the sodium citrate levels. Egg white and microbial transglutaminase were necessary for citric acid-induced kamaboko gel production.     

A study of the dynamics of volume changes during the period of active motility in carp, Cyprinus carpio L., spermatozoa

Carp, Cyprinus carpio L., spermatozoa swelling in NaCl hypotonic solutions (18.8, 37.5, 75, 100 mM) was studied by the methods of photometry and resistance impulses spectroscopy (RIS). The possibility of application of the value of relative optical density of cell suspension, as a qualitative characteristics of the extent of spermatozoa swelling in the period of their movement, was demonstrated. It has been noted, that the moment when swelling starts coincides with the moment of the start of sperm motility. Movement duration, extent and time of swelling depend on the osmotic pressure of the activation solution and moreover the maximum motile period is observed during the activation by 75 mM NaCl solution.     

Comparative nutritional evaluation of differentially processed mucuna seeds [Mucuna pruriens (L.) DC. var. utilis (Wall ex Wight) Baker ex Burck] on growth performance, feed utilization and body composition in Nile tilapia (Oreochromis niloticus L.)

A fish feeding trial was conducted in a warm‐water recirculating system for 8 weeks to assess the nutritive value of processed mucuna seeds as a dietary protein replacement for fish meal in practical diets of tilapia. Diets 2–6 contained mucuna seeds processed as follows: raw, soaked in water, soaked in sodium bicarbonate solution (0.07%), soaked in ascorbic acid solution (0.1%) or soaked in water containing 3% of freeze‐dried moringa leaf powder, followed by autoclaving. The mucuna seed meals were then used to replace 25% of the total dietary protein in each diet. The performance of fish fed these diets was compared with fish fed a fish meal‐based control diet (diet 1), which contained 35% protein. All diets were prepared to be isonitrogenous and isoenergetic. Each treatment had three replicates, using seven fish per aquarium, with a mean initial body weight of 3.9 ± 0.06 g. Fish were fed five times about their maintenance level (3.0 g feed × body weight (kg)^?0.8 day^?1), and no mortality was observed during the experiment. The growth rate, feed conversion ratio and protein productive value of fish fed diets 1, 3, 4, 5 and 6 were similar. However, with regard to energy retention and apparent net lipid utilization, the values observed in fish fed diet 1 were similar to those of fish fed diets 5 and 6, and diet 6, and significantly higher than other dietary groups. Fish fed diet 2 showed a significantly (P < 0.05) reduced growth performance, higher carcass moisture and ash contents, and lower levels of lipid and energy compared with all other dietary groups. Fish fed diet 2 had a significantly lower plasma cholesterol level compared with other diets. However, no significant variation of muscle cholesterol was found between the dietary groups. Even though the hepato‐somatic index of the fish fed diets 3, 4, 5 and 6 was significantly lower than diet 1, these values appeared to be significantly higher compared with fish fed diet 2. The present study indicates that the inclusion of mucuna seed meal (replacement of 25% of total dietary protein of feed) after soaking in any one of the tested solutions followed by autoclaving significantly improved the growth performance and feed utilization of tilapia compared with that of the raw seeds. Moreover, these values were similar to the performance obtained with the fish meal‐based control diet 1. This might be due to the relative reduction of anti‐nutrients, particularly the non‐protein amino acid 3, 4‐dihydroxyphenylalanine, and increased palatability and nutrient availability of processed beans.     

史氏鲟（Acipenser schrenckii）鱼肉冻藏过程中的质量变化

为探讨适宜的冷冻鲟鱼片防冻剂,将鲟鱼肉分别浸泡于三种不同溶液后冻藏,每月测定其冻藏过程中挥发性盐基氮、自由液滴损失及加热液滴损失的变化,并测定了冻藏一年前、后的鲟鱼肉质地特性,经一年跟踪检测查明生产冷冻鲟鱼片以12%氯化钠＋0.2%三聚磷酸钠的混合液浸渍为佳,5%的让水量为宜。     

Gel forming ability of fish meat oxidized during washing

ABSTRACT: In order to examine the effect of meat oxidation on the gel forming ability before grinding the meat with salt, fish meat was washed with CuCl₂ solution, and the gel strength as well as total sulfhydryl (SH) groups and sodium dodecylsulfate–polyacrylamide gel electrophoresis (SDS-PAGE) patterns were analysed. Washing with CuCl₂ solution resulted in a decrease in the total SH content of fish meat and the formation of myosin heavy chain (MHC) dimer through disulfide bonding. The plot of logarithmic gel strength versus protein concentration after heating the washed meat at 80°C in the presence of 3% NaCl to form a gel illustrated that the gel forming ability of meats washed with CuCl₂ solution was weaker than the control meat. The gel of meat washed with CuCl₂ showed the polymerization of MHC and MHC dimers through disulfide bonding much more than the control meat gel, although a small decrease in the SH group content after heating. Further washing with ethylene diamine tetra-acetic acid (EDTA) solution to remove CuCl₂ from the CuCl₂-washed meat also resulted in similar behavior for MHC polymerization and SH content as the CuCl₂-washed meat, and the gel was still weaker than the control gel. It was found that the oxidation of SH groups during washing with CuCl₂ solution accompanied by MHC dimer formation in the meat results in the weakening of its gel forming ability.     

The apparent total and nutrient digestibility of sal seed (Shorea robusta) meal in rohu, Labeo rohita (Hamilton), fingerlings

The apparent digestibility of both raw and treated (16 h soaked in water) deoiled salseed (Shorea robusta) meal by Labeo rohita (Hamilton) fingerlings was evaluated at 20, 30, 40, 50 and 60% levels of incorporation for each, using fish meal based feed as the reference diet. The tannin content from salseed meal could be reduced from 3.4% (in raw salseed meal) to 1.1, 0.9, 0.8 and 0.7% by soaking in water at room temperature for 30 min, 1 h, 2 h and 16 h, respectively. The digestibility of dry matter, protein, lipid and ash declined with increasing levels of inclusion of raw and soaked salseed meal. The diets containing soaked salseed meal resulted in better digestibility of nutrients at all levels of inclusion as compared to those obtained with diets that incorporate raw salseed meal. The results indicate that deoiled salseed meal can be incorporated upto a level of 30% in processed (16 h soaking in water) condition by reducing tannin.     

环境因子和生物自身因子对中国明对虾渗透浓度和离子浓度的影响

本文检验了环境因子和生物自身因子对中国明对虾渗透浓度和离子浓度的影响。研究结果表明:①盐度变化对中国明对虾血淋巴渗透浓度有极显著影响;对血淋巴中钠、氯离子浓度有显著影响,而对钾离子浓度影响不显著。②在同一生长期,性别、体长、体重等自身因子对中国明对虾血淋巴渗透浓度和钠、钾、氯离子浓度均无显著影响。③水温对中国明对虾血淋巴离子调节能力有显著影响,但对血淋巴中钠、氯离子浓度的影响还受到盐度的制约。     

海带_江蓠浸渍光合细菌菌液后喂养九孔鲍的效果

使用海带、江蓠浸渍光合细菌的不同浓度和时间对大小两种不同规格九孔鲍的生长效果进行试验.结果表明,光合细菌促进养成鲍的生长效果,因海带、江蓠浸渍光合细菌的浓度和时间而异,浸渍浓度越大,浸渍时间越长,则其促进生长作用越明显;海带、江蓠浸渍光合细菌的浓度和时间分别为150×10-6(V/V)和3h～4h或200×l0-6(V/V)和2h～3h的试验组鲍的平均壳长增长率都比对照组提高了5%以上,最高提高11.5%左右(P＜0.05).     

美国金鳟和日本鳗鲡精浆的化学组成和渗透压

本研究采用原子吸收分光光度法(AAS)和气相渗透压仪测定了人工养殖美国金鳟和日本鳗鲡精浆的化学组成和渗透压。研究结果表明,Na+、K+是精浆中的主要离子,可能在维持精浆渗透压和精子活动能力中有重要的作用。人工养殖美国金鳟与日本鳗鲡相比,精浆离子含量各项指标除K含量较高之外(P<0.01),其它各项指标均无显著性差异。本实验的两种鱼与其它种类海淡水鱼类比较,各种离子含量均较高;美国金鳟精浆渗透压值与其它鱼类相似,均保持在300 mOsm/kg的水平。     

Global Diversity of Aquatic Food Products

In this work, water activity (a_w), moisture loss, and salt uptake as mass transfer in osmotic dehydration (OD) of Cyprinus carpio fillets were analyzed. Two highly concentrated solutions were used for the OD: binary (NaCl-water) and ternary (NaCl-sucrose-water) solutions at 20°C. Both solutions had the same NaCl concentration, but the second also had sucrose (2:1) which improved water loss and reduced NaCl gain. Among the OD models analyzed, Peleg's equation presented the best fit with the ternary solution (R² > 0.900), while the Zugarramurdi and Lupín did so for the binary solution treatment (R² > 0.950). Page's model presented good fit for water release in both cases (R² > 0.950).     

The effect of high salt diet on the direct transfer of Oreochromis mossambicus,O. spilurus and O. aureus/O. niloticus hybrids to sea water

The effect of feeding a high salt diet on the survival rates of some fresh water Oreochromis (formerly Sarotherodon) species in marine culture was experimentally investigated. High salt diet (10% NaCl) was fed to O. mossambicus, O. spilurus and O. aureus/O. niloticus hybrids for a period of 4 weeks and the survival rates were estimated after each week by directly transferring the species to various salinity levels. Feeding of dietary sodium chloride considerably enhanced the survival rates of O. mossambicus up to 84%, and the O. aureus/O. niloticus hybrids and O. spilurus up to 62% and 50%, respectively, in sea water. Best survival rates were recorded after 2 weeks of feeding the salt diet for O. mossambicus and O. aureus/O. niloticus hybrids, whereas in O. spilurus best survival was not achieved until 3 weeks. Contrary to the sudden increase in plasma osmotic concentration recorded in the fish transferred directly from fresh water to 60% sea water, high salt diet feeding prior to the transfer resulted in only a slight increase in the plasma osmotic concentration in sea water.     

Comparison of taste components in cooked meats of small abalone fed different diets

ABSTRACT: Differences in taste preference and the levels of extractive components and glycogen were compared between cooked meats of small abalone Haliotis diversicolor fed either gracilar (G-small abalone) or an artificial diet (A-small abalone). Using sensory tests, taste preference of cooked meats was significantly higher for A-small abalone than for G-small abalone. Results of clustering analysis and principal component analysis of chemical data also revealed that the two cooked meats differed from each other in terms of their measured constituent compositions irrespective of sampling periods. Compared with G-small abalone, A-small abalone meats were lower in taurine and arginine, but higher in glycine (Gly), glutamic acid (Glu), alanine, serine, proline, adenosine monophosphate (AMP), and glycogen. It is concluded that the discrepancy in the levels of taste-active components of abalone, such as Gly, Glu, and AMP, is likely to be responsible for the differences in taste preference between G- and A-small abalone cooked meats.     

Susceptibility of Nile tilapia (Oreochromis niloticus) fed with dietary sodium chloride to nitrite toxicity

Juvenile Nile tilapia (Oreochromis niloticus) were fed with diets supplemented with 0 or 6% NaCl for 10 weeks. Tilapia were exposed to approximately 21 mg/l nitrite-N after 5 and 10 weeks of feeding to determine the effect of dietary NaCl supplementation on resistance to nitrite toxicity. Fish were sampled before (baseline, pre-exposure) and after 24 h nitrite exposure to determine the effects of dietary NaCl on mortality, hematology (hematocrit, hemoglobin, and methemoglobin), and plasma electrolyte dynamics (nitrite, chloride, sodium, and potassium). After 10 weeks of feeding, tilapia were also challenged with Streptococcus iniae to determine the effect of sodium chloride on immunity. Tilapia fed with the NaCl-supplemented diet had significantly higher weight gain compared with the control group, which was associated with a significant increase in feed intake in the NaCl group. Mortality from nitrite exposure was lower in tilapia fed with the NaCl-supplemented diet compared with the control group at 5 and 10 weeks, but the differences were not significant. However, dietary NaCl supplementation caused a significant decrease in plasma nitrite levels after nitrite exposure. The dietary reduction in nitrite may be related to the increase in plasma chloride in the 6% NaCl-supplemented fish. A direct link between the effects of dietary NaCl supplementation on methemoglobin (MetHb) could not be established. Tilapia in this study were subjected to acute nitrite toxicity. Dietary sodium chloride may be more effective in protecting against nitrite toxicity at lower levels of nitrite, but the conditions at which it proves to be effective may be limited and requires further investigation. Feeding NaCl to tilapia did not affect susceptibility to S. iniae or immune function, but nitrite exposure cause a stress-related reduction in non-specific immune function. This is the first study to examine the effects of dietary salt on nitrite toxicity in tilapia.