Biochemical and Microbiological Assessment of Crucifix Crab (Charybdis feriatus) Stored at 4°C

Charybdis feriatus is a highly prized crab in the local and international markets of East Asian countries. In local markets, crabs are sold live, iced, or refrigerated at 2°C – 4°C. The present study was carried out to determine the shelf life of whole crab stored at 4°C for 192 h using a set of biochemical, microbiological, and sensorial parameters. Biochemical indicators such as the total volatile base nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) increased significantly during storage and within an acceptable limit up to 144 h. Regarding the biogenic amines, cadaverine and spermidine increased significantly (p < 0.05) during the storage period. Among them, cadaverine could be proposed as a useful spoilage indicator for this crab species. The mesophilic and psychotropic bacterial count exceeded the limit of acceptance after 144 h of storage. Sensory attributes were gradually diminished with the storage time. Sensory scores were found to correlate well with both mesophiles and psychrotrophs. Based on the results of this study, the meat quality of Charybdis feriatus can be maintained up to 144 h when properly stored at a temperature of 4°C ± 1°C.     

Effects of High Pressure Treatment on Physicochemical Quality of Pre- and Post-Rigor Palm Ruff (Seriolella Violacea) Fillets

Fish and fish products are characterized for having a short shelf life. Nonthermal processing techniques such as high hydrostatic pressure (HHP) have increasingly been employed to extend shelf life of food products. The aim of this study was to evaluate changes on flesh physicochemical spoilage parameters (pH, total volatile bases (TVB-N), trimethylamine (TMA), thiobarbituric acid (TBA), and color) of palm ruff (Seriolella violacea) fillets in pre- and post-rigor conditions, subjected to two different HHP conditions: 450 MPa and 550 MPa, for 3 and 4 min each. Unpressurized and pressurized fillets were kept in chilled storage (4 ± 1°C) for 26 days to assess the effect of HHP on shelf life. pH and TBA values increased after HHP treatment and with storage time for both unpressurized and pressurized samples. This is attributable to pressure-induced lipid oxidation. Lightness (L*) values increased with pressure, where fish fillets had a cooked appearance. TMA and TVB-N values decreased after HHP treatment compared to the unpressurized samples, showing that HHP treatment is an efficient method to maintain the quality of palm ruff fillets. There was no clear difference between pre- and post-rigor in the parameters evaluated.     

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.     

Effect of Microbial Transglutaminase,Dietary Fiber,and Low-Salt Levels Upon Heat-Induced Meagre (Argyrosomus regius) Gels

The effects of microbial transglutaminase (MTGase; 5 g/kg, w/w) and dietary fiber (40 g pea fiber/kg product and 20 g carrageenan + 20 g konjac flour/kg product) on heat-induced meagre (Argyrosomus regius) gels with 25 and 10 g salt/kg, w/w were analyzed.

MTGase addition increased the magnitude of texture variables. Inner pea fiber had an increasing effect on gel texture. The combination of carrageenan and konjac hardened meagre gels (from 22.2 ± 1.4 to 47.3 ± 4.5 N) and enhanced water-holding capacity. Salt reduction with MTGase ensured a gelling quality similar to that of gels from Alaska pollock surimi.     

添加圆苞车前子壳粉的鲢鱼糜凝胶工艺优化及其凝胶特性

圆苞车前子壳粉(psyllium husk powder, PHP)是一种富含膳食纤维的食品亲水胶体。为了解其在鱼糜制品中的作用,本实验以冷冻鲢鱼糜为研究对象,以凝胶强度和持水性(water holding capacity, WHC)为考察指标,研究了PHP的添加量、凝胶化温度和凝胶化时间3个因素对鱼糜凝胶特性的影响。在单因素试验的基础上,进行了三因素三水平的正交试验和验证试验。正交试验结果得到最佳工艺条件:PHP添加量0.1%,凝胶化温度45°C,凝胶化时间2 h。单因素试验结果表明,添加适量PHP (0.1%～0.3%)能够增加鱼糜凝胶的硬度和WHC,但对破断距离有不利影响;根据验证试验中蒸煮损失率、SDS-聚丙烯酰胺凝胶电泳(SDS-polyacrylamide gel electrophoresis, SDS-PAGE)和扫描电镜(scanning electron microscopy, SEM)分析,PHP的添加降低了较高凝胶化温度时凝胶的蒸煮损失,PHP或许可以促进肌球蛋白重链(myosin heavy chain, MHC)分子间交联,减缓蛋白质降解,形成更加致密的凝胶结构。本研究对PHP作为一种新型食品原料应用于开发优质健康鱼糜制品进行了初步的探究,以期为丰富亲水胶在影响鱼糜凝胶特性中的应用研究提供一定的参考。     

Growth compensation in juvenile tongue sole,Cynoglossus semilaevis (Güther, 1873): responses to thermal stress and feed restriction

Responses of compensatory growth to high temperature and feed restriction in juvenile tongue sole, Cynoglossus semilaevis (Güther, 1873), were investigated during a 56‐days experiment. Fish were divided into seven groups including three high‐temperature treatments which were reared at 28°C for 1, 2 and 3 weeks, respectively, then returned to 22°C (recorded as T1, T2 and T3), three feed‐restricted treatments which were fed 25% satiation for 1, 2 and 3 weeks, respectively, then fed ad libitum (recorded as R1, R2 and R3) and a control (continuously reared at 22°C). The results showed that juvenile tongue sole exposed to thermal stress for 1 week exhibited overcompensatory growth. However, complete compensation occurred in T2, T3 and R1 fish, while partial compensation occurred in R2 and R3 fish. The body composition and energy content of fish were not significantly different among all treatments (P > 0.05). The specific growth rate and feed efficiency of fish in T1 were significantly higher than other treatments during the whole experiment period (P < 0.05). Higher feed efficiency and apparent digestion rate during recovery might account for the compensatory growth in tongue sole in the present study. Hyperphagia played an important role in compensatory growth for feed‐restricted fish, but was not involved in the compensatory response in thermal stressed fish in the present study. The results from the present study suggested that a suitable thermal stress could be more feasible to elicit compensatory growth than feed restriction in juvenile tongue sole.     

Passing times of two types of feeds in wels (Silurus glanis) at three different temperatures

Passing times of two different types of feeds were determined in cases of wels (Silurus glanis) by measuring the body weight at three different temperatures. Fingerlings, 38.03 ± 8.04 g, were fed by an artificial dry feed (commercial catfish feed) or forage fish. The treatments were carried out (11 fish/aquaria) in 3 replicates. Fish were individually tagged by pit tags. Temperatures applied were the following: 15, 20 and 24 °C. The appetite of fish highly depended on temperature. At 15 °C, only 42.4 % of the experimental fish accepted the granulated feed, while this ratio was 90.9 % in the forage fish fed group. At higher temperatures, 100 % of the experimental fish accepted feed in both feeding groups. The daily mean value of consumed feed at 15 °C was 3.20 % of body weight in the case of forage fish and 1.36 % in the case of dry feed. At 24 °C, this ratio was 10.68 % of body weight in cases of forage fish and 4.46 % in cases of artificial feed. At low temperature (15 °C), the quantity of consumed feed met the measurement’s error threshold, which made the determination of passing time uncertain. At 20 °C, the evacuation started 20 h after feeding and lasted for 18 h, while at 24 °C, it started 11 h after feeding and lasted for another 16 h.     

Replacement of Rice Flour by Meat Flour Mechanically Separated from Tilapia on the Technological,Nutritional, and Sensory Quality of Salted Gluten-free Cookies

ABSTRACT

This work evaluated the technological, bacteriological, and sensorial quality of cookies produced with increasing levels (0%, 10%, 20%, 30%, and 40%) of mechanically separated meat flour from tilapia (MSMF) to replace rice flour (RF) in order to identify the optimal level without compromising the overall quality of the product. The cookies were analyzed for expansion index (EI), specific volume (SV), hardness, color, water activity (a_w ), coagulase-positive staphylococci, coliforms at 45°C, Salmonella spp., and sensory acceptance. The inclusion of MSMF affected (P < .05) some characteristics such as EI, SV, a_w , hardness, and color (L*, a*, b*), but all formulations met the legal bacteriological standards. Cookies with 20% substitution of RF by MSMF presented 58.82% carbohydrates, 18.53% proteins, and 11.31% lipids, and was the most accepted (P < .05); 51% of consumers rated it with a score of six or higher (above I liked slightly). It is concluded that the substitution of 20% of RF by MSMF can be used for nutritional enrichment of widely consumed conventional products.     

Effect of Traditional and Liquid Smoke on the Quality of Sea Catfish Sausages (Sciades herzbergii,Bloch, 1794)

ABSTRACT

Smoking is a technique used to improve the sensory attributes and increase the shelf life of fish. The objective of the present study was to evaluate the nutritional, physicochemical, microbiological, and sensory characteristics of sausages made with sea catfish (Sciades herzbergii) fillets subjected to the traditional and liquid smoking processes. The traditionally smoked sausages showed lower (p < .05) moisture content and higher protein, fat, and mineral levels, higher weight loss during processing, higher pH, higher a* (red intensity), and lower L* (luminosity) values. The percentage of shrinkage, water holding capacity, water activity, hardness, cohesiveness, and elasticity were not influenced (p > .05) by the smoking methods tested. The microbial counts of both treatments were in compliance with the current Brazilian legislation. The sensory acceptance of the liquid smoked sausages was higher (p < .05) when compared to the traditionally smoked sausages for the attributes of color, aroma, texture, flavor, and overall acceptance, with scores ranging from 6 (liked slightly) to 7 (liked moderately). Between the two smoking methods tested, liquid smoking presented better sensory acceptance, easier execution, greater process control, and less environmental impact; thus, it is a viable alternative to the traditional smoking of sea catfish (Sciades herzbergii) sausages.     

Measurement of Morphometric Dimensions and Mechanical Properties of Rohu Fish for Design of Processing Machines

Indian major carps (IMC) viz. rohu, catla, and mrigal are the most important fresh water species. They are marketed locally without post-harvest processing and value addition because of the lack of suitable processing machines. The present study was undertaken to measure the morphometric and mechanical properties of rohu fish for the development of fish processing machinery, and the same can be adjusted for the other IMC. Twenty-five samples of rohu fish (Labeo rohita) were caught, with weight ranging from 290 to 2,100 g (harvestable size). The measured morphometric dimensions were the body depth (10.14 ± 1.63 cm), thickness (5.9 ± 0.85 cm), head length (9.35 ± 1.04 cm), standard length (37.54 ± 4.17 cm), total length (45.89 ± 5.68 cm), and fish backbone thickness (11.2 ± 4.91 mm). Mechanical properties including the angle of repose over steel surface (20°–22°) and plastic surface (18°–20°) were recorded. The maximum power consumption for slicing the fish lengthwise was recorded as 460 W. The measured morphometric and mechanical properties are useful in limiting the adjustments, design of conveyors, capacity, and power requirement of fish processing machines for rohu fish.     

Combined effects of photoperiod and temperature on growth and survival of African catfish (Clarias gariepinus,Burchell 1822) larvae under laboratory conditions

ABSTRACT

The effect of photoperiod (24L:00D, 12L:12D, and 00L:24D) and temperature (22 ± 1°C and 28 ± 1°C) on performance of Clarias gariepinus larvae was tested. Larvae weighing 3.2 ± 0.24 mg were cultured in aquaria at a stocking density of 20 fish L^?1 and fed twice a day on catfish starter diet (40% CP) at 10 % BW day^?1. Highest mean weight gain (31.00 mg), SGR (7.56% day^?1), and survival (83%) were achieved at photoperiod and temperature combination of 00L:24D and 28 ± 1°C. Percent survival of larvae differed significantly (p < .05) among treatments with optimal survival of (83%) in treatment combination of 28 ± 1°C and 00L:24D, while lowest survival (40%) in treatment combination of 22 ± 1°C and 24L:00D.     

3种改性方法对琼胶理化性质的影响

文章采用羧甲基化、过氧化氢氧化和羟丙基化3种方法对琼胶进行改性,通过比较表征改性前后琼胶的溶解性能、色泽、凝胶透明度、凝胶质构特性、IR分子结构和热稳定性,探究不同改性方法对琼胶理化性质的影响。结果显示,羧甲基化和羟丙基化后琼胶的溶解温度、凝胶温度、凝胶再溶温度和凝胶强度显著降低(P<0.05),琼胶凝胶软弹性和持水性增强;氧化改性显著提高了琼胶凝胶强度(P<0.05),由984 g·cm^-2提高至1463 g·cm^-2;氧化改性和羟丙基化改性显著提高了琼胶的白度(P<0.05),而羧甲基化改性显著降低了琼胶白度(P<0.05);3种改性方法均显著提高了琼胶凝胶的透明度(P<0.05);羧甲基化改性降低了琼胶的热稳定性,氧化和羟丙基化改性提高了琼胶的热稳定性。由此证明3种改性方法可不同程度地改变琼胶的理化性质。     

Improving the Quality of Silver Carp Fish Fillets by Gamma Irradiation and Coatings Containing Rosemary Oil

The objective of this work was to study the combined effect of gamma irradiation and coatings containing 0.5% rosemary (Rosmarinus officinalis) essential oil (RO) on the chemical, microbiological, and sensorial qualities of silver carp (Hypophthalmichthys molitrix) fish fillets (SFF) during cold storage (4°C). SFF were divided into three groups: uncoated (control), coated with edible coating (without additives), and γ-irradiated (0, 1, 3, and 5 kGy) coated with coating containing 0.5% rosemary. Gamma irradiation at 1, 3, and 5 kGy with coating reduced the initial total bacterial count, psychrophilic bacteria, and lactic acid bacteria and prolonged shelf life of the samples. Coated samples irradiated at 1 kGy reduced the counts of Enterobacteriaceae, Staphylococcus aureus, and Bacillus cereus, as well as eliminating Vibrio spp. and Salmonella spp., while coated samples irradiated at 3 and 5 kGy completely eliminated these bacteria. Combined treatment showed a slight increase in thiobarbituric acid-reactive substances postirradiation during cold storage but had no effect on the total volatile basic nitrogen and trimethylamine contents, while a gradual increase in these chemical quality indices was observed during cold storage. Combined treatment had no adverse effects on the sensory properties of SFF. The increase in the bacterial inhibitory effect is caused by both rosemary oil and irradiation.     

Effects of olive pomace on growth performance,digestibility, body composition and fatty acid profile in yearling Siberian sturgeon,Acipenser baerii (Brandt 1896)

Replacement of olive pomace (OP) with wheat flour in diet was studied in diet of yearling Siberian sturgeon (Acipenser baerii). Fish (165 ± 6.8 g) were randomly allocated to 15 fibreglass tanks (15 fish/tank, in triplicate). Fish were assigned to one of five dietary treatments at 19.1 ± 1.5°C for 8 weeks: control diet (crude protein and crude lipid at 514.6 and 188 g/kg_, respectively) and four experimental diets with 20, 50, 75 and 100 g/kg OP to replace wheat flour in the experimental diets. No significant difference was observed in the final weight, feed conversion ratio, specific growth rate, hepatosomatic index, viscera‐somatic index and survival rate among the treatments (p > 0.05). No change was seen in digestibility of protein and lipid in diets containing 20 g/kg and 50 g/kg OP compared to control group, while these values decreased with increasing in OP above 50 g/kg. Digestibility of dry matter and gross energy among the treatments demonstrated no significant difference (p > 0.05). Polyunsaturated fatty acids, especially C22:6n3 (DHA), in the muscle of the fish fed 75 g/kg and 100 g/kg OP in diets were significantly higher than control group (p < 0.05). These data show that OP could be recommended as a substitute for wheat flour in diet of S. sturgeon but its utilization for other species warranted future works.     

Effects of a superoptimal temperature on aquacultured yellowtail <Emphasis Type="Italic">Seriola quinqueradiata</Emphasis>

This study aimed to investigate the effects of a superoptimal temperature on growth, body composition, body size heterogeneity, and relationships among these factors in juvenile yellowtail. Fish (mean body weight?=?24 g) were tagged individually and reared for 70 days under two different water temperature regimes [optimal (25 °C) and superoptimal (30 °C)]. After rearing, fish reared at 30 °C showed lower survival, less food, feed and protein utilization, significantly lower growth performance, and a lower hepatosomatic index than fish raised at 25 °C. Variations in body indices among individuals were larger for fish reared at 30 °C than for fish reared at 25 °C. Mean whole body protein content was significantly lower in fish reared at 30 °C than fish reared at 25 °C. In addition, several glucogenic and/or aromatic amino acids were lower in fish reared at 30 °C than in fish reared at 25 °C. Whole body lipid levels tended to be lower in fish with lower body weight reared at 30 °C. These results suggest that fish raised at 30 °C will have lower growth performance, and lower concentrations of specific amino acids. Moreover, heterogeneity in body size and body lipid content is expanded by a superoptimal temperature.     

Treatment Method Affects Color,Chemical, and Mineral Composition of Seabream (Sparus aurata) Fish Bone Powder from by-Products of Fish Fillet

ABSTRACT

Seabream fish bone powder was produced using different chemical methods and tap water. The effect of different chemical procedures (sodium hydroxide (NaOH); NaOH + citric acid; NaOH + sodium hypochlorite (NaOCl); NaOH + ethanol (EtOH); and NaOH + hydrogen chloride (HCl)) and tap water on proximate composition, yield, mineral composition, color, and sensorial odor was investigated. Despite its high bone powder yield (59.39%), tap water treatment was not an efficient method due to low calcium (Ca²⁺, 232.13 g/kg) and phosphorus (P, 111.63 g/kg) concentration and heavy fish odor. Sensorial odor analysis of seabream fish bone powder showed that tap water received the lowest scores (1.71/5), while chemically treated samples received sensorial odor scores higher than 4.00, with an average of 4.61, indicating that they had a very slight odor. The best fish bone powder yield was obtained using NaOH treatment (21.46%), where Ca²⁺ (276.73 g/kg) and P (147.23 g/kg) content was also high. The utilization of chemicals in combination with NaOH did not increase the sensorial odor score of seabream fish powders but resulted in a decrease in powder yield. Moreover, the mineral composition of all chemical processing techniques was comparable. Processing by-products of seabream fillet production with 8% NaOH will contribute to daily Ca²⁺ and P intake of individuals.     

Effects of Freezing and Frozen Storage on Protein Functionality and Texture of Some Cephalopod Muscles

The aim of this study was to investigate the effects of freezing and frozen storage on protein functionality and texture of squid (Loligo vulgaris), octopus (Octopus vulgaris), and cuttlefish (Sepia officinalis) muscles. Squid, octopus, and cuttlefish samples were cut into pieces of 4 × 4 cm. These pieces were packed in polyethylene bags. The bags were frozen in a blast freezer at ?45°C until the thermal center reached ?18°C. Frozen samples were stored in a deep freezer at ?18°C for 30 days. After freezing and during frozen storage, total soluble protein and water holding capacity decreased and total free amino acid and cooking loss increased in all cephalopod muscles. According to instrumental texture analysis results, freezing and frozen storage affected textural characteristics of squid and cuttlefish but not of octopus. Sensory hardness and chewiness values of all cephalopods increased after freezing, but elasticity values did not change. There were no significant differences between storage days in hardness values of squid and octopus. However, significant differences in hardness values of cuttlefish were observed between the 1st day of storage and the last day.     

Preslaughter Anesthesia with Lippia alba Essential Oil Delays the Spoilage of Chilled Rhamdia quelen

This study evaluated whether anesthesia with essential oil (EO) of Lippia alba (300 mg L^?1 for 4 min) prior to electronarcosis (128 V m^?1 × 300 Hz for 5 s) or hypothermia (ice/water slurry) could delay fish spoilage during chilled storage of whole fish. Silver catfish (Rhamdia quelen) were subjected to two different pre-stunning treatments (water or anesthesia with EO of L. alba) followed by two different stunning procedures (hypothermia or electrical stunning), yielding four groups (n = 32/group): water (control) + hypothermia, water (control) + electrical stunning, EO of L. alba + hypothermia, and EO of L. alba + electrical stunning. After stunning, fish were slaughtered by percussion and stored in ice. Preslaughter anesthesia with the EO of L. alba extended fish shelf life by delaying the loss of freshness (nucleotide degradation), growth of Enterobacteriaceae, and fish deterioration (sensory evaluation). Such preservative effect was most remarkable for fish that were subsequently submitted to electrical stunning, as they had the lowest demerit scores and greatest shelf life in the sensory evaluation. Our results showed that preslaughter anesthesia with EO of L. alba followed by electrical stunning can delay the loss of freshness and extend fish shelf life during chilled storage.     

Performance of Advanced Juvenile Cobia,Rachycentron canadum,Reared Under Different Thermal Regimes: Evidence for Compensatory Growth and a Method for Cold Banking

ABSTRACT

Two trials were undertaken to examine the growth response of juvenile cobia, Rachycentron canadum, at varying temperatures. The initial trial was conducted to determine the effect of various temperatures (18, 23, and 29°C) on weight gain and feed efficiency. The second trial investigated the effect of elevating water temperature in which fish maintained at 18°C and 23°C to a temperature close to their optimum (29°C). The latter study was undertaken in order to determine the effect of thermal shifts upon subsequent growth response of the species. Such information will assist commercial producers in developing various culture guidelines. As anticipated, differences (P < 0.01) in weight gain were recorded among all treatments, although remarkably, feed efficiency did not differ for cobia held at 23°C and 29°C. Following thermal shift, cobia subjected to the largest temperature change (18–29°C) illustrated an immediate growth response, but specific growth rates (SGR) did not exceed that of cobia held at 29°C for the duration of the trial. Nevertheless, when SGR were examined using fish of similar size (i.e., derived from different time points during the study) evidence for growth compensation was obtained. This study illustrates that cobia can be held at reduced temperatures, without detrimental impact on future performance, as a means of maintaining animals at smaller size for production and experimental purposes: “Cold banking.”