Purification and properties of digestive lipases from Chinook salmon (<Emphasis Type="Italic">Oncorhynchus tshawytscha</Emphasis>) and New Zealand hoki (<Emphasis Type="Italic">Macruronus novaezelandiae</Emphasis>)

Lipases were purified from delipidated pyloric ceca powder of two New Zealand-sourced fish, Chinook salmon (Oncorhynchus tshawytscha) and hoki (Macruronus novaezelandiae), by fractional precipitation with polyethylene glycol 1000, followed by affinity chromatography using cholate-Affi-Gel 102, and gel filtration on Sephacryl S-300 HR. For the first time, in-polyacrylamide gel activity of purified fish lipases against 4-methylumbelliferyl butyrate has been demonstrated. Calcium ions and sodium cholate were absolutely necessary both for lipase stability in the gel and for optimum activity against caprate and palmitate esters of p-nitrophenol. A single protein band was present in native polyacrylamide gels for both salmon and hoki final enzyme preparations. Under denaturing conditions, electrophoretic analysis revealed two bands of 79.6 and 54.9 kDa for salmon lipase. It is proposed that these bands correspond to an uncleaved and a final form of the enzyme. One band of 44.6 kDa was seen for hoki lipase. pI values of 5.8 ± 0.1 and 5.7 ± 0.1 were obtained for the two salmon lipase forms. The hoki lipase had a pI of 5.8 ± 0.1. Both lipases had the highest activity at 35°C, were thermally labile, had a pH optimum of 8–8.5, and were more acid stable compared to other fish lipases studied to date. Both enzymes were inhibited by the organophosphate paraoxon. Chinook salmon and hoki lipases showed good stability in several water-immiscible solvents. The enzymes had very similar amino acid composition to mammalian carboxyl ester lipases and one other fish digestive lipase. The salmon enzyme was an overall better catalyst based on its higher turnover number (3.7 ± 0.3 vs. 0.71 ± 0.05 s⁻¹ for the hoki enzyme) and lower activation energy (2.0 ± 0.4 vs. 7.6 ± 0.8 kcal/mol for the hoki enzyme) for the hydrolysis of p-nitrophenyl caprate. The salmon and hoki enzymes are homologous with mammalian carboxyl ester lipases.     

Characterization of vitamin B12 compounds from commercially available fish roe products

Although fish roes (or the egg-laden ovary) are seafood products with high nutritional value and are considered abundant in vitamins including vitamin B₁₂, nevertheless, the detailed properties of vitamin B₁₂ have not been fully elucidated in fish roe products. Vitamin B₁₂ content was determined using C18-reversed-phase high-performance liquid chromatography after purification of samples from immunoaffinity columns. Salmon egg-laden ovary products (sujiko), salmon roe products (ikura), dried mullet roe products (bottarga), and white sturgeon roe products (caviar) were found to contain substantial levels of vitamin B₁₂ (more than approximately 15 µg/100 g wet weight). Interestingly, high levels of vitamin B₁₂ per 100 g wet weight have been measured in pollack roe products (tarako) and flying fish roe products (tobiko). Liquid chromatography–electrospray-ionization/tandem mass spectrometry analysis revealed that vitamin B₁₂ was the predominant corrinoid in the evaluated fish roe products examined, while no inactive corrinoid compounds were identified. These results suggest that commercially available fish roe products could be an important source of vitamin B₁₂ for use as a dietary product for humans.

     

Seasonal Changes in Hoki (Macruronus novaezelandaie)

Abstract

Biological condition factors and proximate composition of hoki (Macruronus novaezelandaie) white muscle, dark muscle and liver vary considerably between individual fish and with season. Seasonal changes in the gonads and liver were correlated with concomitant changes in proximate composition of white muscle, dark muscle and liver. In white muscle there was an inverse relationship between protein and moisture content, while in dark muscle and the liver the inverse relationship was between lipid and moisture. These seasonal changes in proximate composition can be related to hoki's breeding cycle and have a direct effect on yields, quality and storage stability of products made from hoki.     

A Preliminary Study of the Nuclear Basic Proteins from Hoki [Macruronus novaezelandiae (Hector) (Merlucciidae)] Milt,an Underutilized Resource

ABSTRACT

Hoki (Macruronus novaezelandiae) (Hector) (Merlucciidae) were collected on six occasions from the fishing grounds off the west and east coasts of New Zealand. Light and electron micrographs showed that gonads were at different stages of maturity while the yields of the crude nucleoprotein extracts of the gonads from the different collection dates were similar. The crude extracts were purified by ion exchange chromatography. The molecular weights and amino acid composition of purified fractions indicated that the sperm nuclear basic proteins in hoki gonad were more like histones than protamines and were tentatively identified as histones H2A, H3, and H4.     

Amino acid composition of edible parts of three-year-old experimental scaly crossbreds of common carp (Cyprinus carpio, Linnaeus 1758)

The aim of this study was to compare the amino acid (AA) composition of edible parts of three experimental groups of carp, i.e. a pure line of Přerov scaly carp (PS), a hybrid line of Přerov scaly carp and Northern mirror carp (PS × M72), and a hybrid line of Přerov scaly carp and Ropsha scaly carp (PS × ROP), with the quality of the edible parts of control hybrids of Hungarian and Northern mirror carp (M2 × M72) in harvest size (K₃). A comparison between the controls (M2 × M72) and experimental carp (PS, PS × M72, PS × ROP) showed that their muscle tissues contained the same amounts of 10 AA [essential amino acids (EAA): Thr, Val, Leu, Phe, Lys, His; non‐essential amino acids (NEAA): Asp, Gly, Ala, Tyr] of the 16 AA determined. Glu, Asp, Lys and Leu were the AA with the highest muscle concentrations. The total EAA_sum and NEAA_sum contents in the fastest‐growing PS × ROP hybrid, in spite of specific differences found (P<0.05: Arg, Met; P<0.01: Pro), were practically identical to those found in the control group of M2 × M72 mirror carp. PS × ROP hybrid female and male muscle tissues differed (P<0.05) only in Met and Ala levels. Hard roes of experimental female carp (PS, PS × M72, PS × ROP) contained the largest quantities of Glu and Val, and that of control female carp (M2 × M72) the largest quantities of Glu and Gly. Hard roes of PS × ROP hybrids contained the largest quantities (P<0.01) of EAA_sum (52.44±0.19%). Compared with hard roes, soft roes from all groups of carp contained more EAA_sum (PS × ROP: 55.03±0.26%). The two most abundant AA in soft roes were Lys and Arg. The most abundant AA in the hepatopancreas in all carp groups were Glu, Asp, Leu and Arg. Hepatopancreas EAA_sum levels in experimental carp (PS, PS × M72, PS × ROP) were significantly (P<0.05) lower than those in controls (M2 × M72).     

Immunomodulatory effect of Guavarine®, aqueous guava leaf extract,on ornamental Koi carp Cyprinus carpio var. koi L. 1758

The leaves and bark of guava (Psidium guajava) have a long history of medicinal uses. The immunomodulatory effect of Guavarine®, an aqueous guava leaf extract, was investigated on Cyprinus carpio var. koi L. The fish (8.33 ± 1.02 g) were injected with guava leaf extracts (10 or 100 µg/fish) intraperitoneally, and the innate immune parameters were monitored for 28 days. In fish injected with guava leaf extracts, the lymphocyte proliferation, nitric oxide production, and respiratory burst activity increased until the 14th day and decreased thereafter. The results indicated an elevation in the innate immune status of fish, possibly due to the presence of flavonoids in the leaf extracts.     

Effects of the total fish meal replacement by soybean meal on growth parameters,serum biochemistry,and hepatic and intestinal histology of juvenile blunt snout bream (Megalobrama amblycephala)

ABSTRACT

Fish meal is the main protein source in fish diet, but due to its unsustainability, it has to be replaced with more sustainable protein sources, such as soybean meal (SBM), in fish feeds. As SBM often produces negative effects on fish growth and health, we conducted an eight-week trial of complete fish meal replacement with SBM in the diet of juvenile (48.2 ± 0.55 g) blunt snout bream (Megalobrama amblycephala), a herbivorous cyprinid fish native to the Yangtze basin (China). SBM-fed fish exhibited: a worsened growth performance; improved survival rate (P > 0.05); elevated serum triglycerides and total cholesterol but reduced low-density lipoprotein in plasma (P < 0.05); mild lipid droplet accumulation and swelling of the liver; elevated goblet cell counts and mild signs of enteritis in the intestines. With negligible effects on growth and mild effects on health, M. amblycephala appears to be comparatively tolerant of SBM, but total fish meal replacement is not recommended. Future studies should aim to identify the SBM tolerance threshold in long-term growth trials.     

Evaluation of Growth and Disease Resistance of USDA103, USDA303, USDA102, and USDA102 × USDA103 Strains of Channel Catfish, Ictalurus punctatus

USDA103, USDA303, USDA102, and USDA102 × USDA103 strains of channel catfish (27.7 ± 0.7 g/fish) were fed daily for 6 wk. Feed consumption and weight gain were highest (P < 0.001) in USDA103, USDA303, and USDA102 × USDA103 fish. USDA102 fish exhibited the poorest (P < 0.01) feed conversion ratio. Fillet and whole‐body content were similar (P > 0.05) among strains when final weight was used as a covariate. USDA103, USDA303, and USDA102 × USDA103 strains had higher (P < 0.01) protein efficiency ratios compared to USDA102. In a second study, the four groups of catfish (22.2 ± 1.9 g/fish) were challenged with Edwardsiella ictaluri and mortality was recorded for 3 wk postchallenge. Survival was higher (P < 0.02) for USDA303 and USDA102 × USDA103 fish. Results of these studies demonstrate that the USDA103 and USDA303 strains of catfish were superior in growth performance. Results of the bacterial challenge show that the USDA303 and USDA102 × USDA103 strains of fish exhibited increased survival. Continued selection of the USDA103 line and crossing this line of fish with lines of fish such as the USDA102 strain may produce fish with desirable growth and disease characteristics.     

Evaluation of Cuphea Meal as an Ingredient Replacement in Channel Catfish,Ictalurus punctatus,Diets

ABSTRACT

Cuphea meal is a new, alternative feedstuff that has potential as a sustainable, economical replacement for wheat, rice, and corn ingredients in channel catfish, Ictalurus punctatus, diets. Channel catfish fingerlings were fed a control diet containing wheat or two experimental diets containing 7.5% cuphea meal, or 12.5% cuphea meal for eight weeks to determine if cuphea meal could replace wheat products in catfish diets. Mean (±SE) weight gains were 317.8 ± 28.8 g, 407.0 ± 36.9 g, and 372.8 ± 29.8 g for fish fed the control diet, the 7.5% cuphea meal diet, and the 15% cuphea meal diet, respectively, and there were no significant differences (P < 0.05) among treatments. Mean (±SE) whole-body protein of fish fed the cuphea diets (13.3 ± 0.66 and 14.5 ± 0.21%) was significantly (P < 0.05) higher than that of fish fed the wheat diet (12.7 ± 0.44%). Cuphea meal enhanced body composition of juvenile channel catfish without affecting growth or survival. Therefore, cuphea meal is a promising candidate for replacement of wheat bran at the levels tested.     

Determination of Fatty Acid Composition and Phospholipid Molecular Species of Large Yellow Croaker (Pseudosciaena crocea) Roe from China

The aim of this study is to investigate the composition of the fatty acids and phospholipids derived from large yellow croaker (Pseudosciaena crocea) roe. The composition of the total lipids and the molecular species of phospholipids were determined by gas chromatography–mass spectroscopy (GC–MS) and high performance liquid chromatography–evaporative light scattering detector (HPLC–ELSD), respectively. The results showed that large yellow croaker roe had high levels of the total lipid (19.6% ± 1.32%, w/w) and phospholipid (61.2% ± 1.22% of the total lipid). The phospholipid was rich in docosahexaenoic acid (31.0% ± 0.19% of the total phospholipids), and the major phospholipid molecular species was phosphatidylcholine (PC, 61.06% ± 0.02% of the total phospholipids, w/w). It was concluded that large yellow croaker roe is expected to be a good resource of phospholipids with a high content of PC.     

Determination of Lipid Peroxidation and Fatty Acid Compositions in the Caviars of Rainbow Trout and Carp

In this study, roes obtained from carp (Cyprinus carpio carpio) that were caught in Keban Dam Lake (Turkey) and cultured rainbow trout (Oncorhynchus mykiss) were processed as caviar, and the products were stored at + 4 C°. Lipid peroxidation and the compositions of fatty acids of these products were assessed during production and storage period. The result of fatty analyses showed that palmitic acid (16:0), stearic acid (18:0), palmitoleic acid (16:1), oleic acid (18:1), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), which are all essential fatty acids, were determined in the caviars of the roes obtained from rainbow trout and carp. According to results of chemical analyses, there were no significant differences in thiobarbituric acid reactive substances (TBARs) between rainbow trout and carp caviars (p > 0.05), but malondialdehyde (MDA) levels were found to be statistically significant (p < 0.01). It can be concluded that caviars obtained from both rainbow trout and carp roes are rich in fatty acids and take a part in a balanced and healthy diet.     

Chemical Characterization,Temperature Stability,and Enzymatic Studies on Edible Marine Algae Kappaphycus alvarezii (Doty)

Antioxidant activity of the marine alga Kappaphycus alvarezii was investigated. Methanol, acetone, petroleum ether, aqueous methanol, ethyl acetate, and chloroform extracts (1 mg/mL) of K. alvarezii were tested for their 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. The values were compared with those of Vitamin C and butylated hydroxytoluene (BHT). Extracts showing positive results, when tested for DPPH free radical scavenging, were examined for dose effect, in-vivo hydrogen peroxide (H₂O₂) and hydroxyl radical scavenging assays. All extracts showed dose-dependent DPPH scavenging and significant hydroxyl radical scavenging activities (> 82.6%). The acetone, aqueous methanol, and methanol extracts of K. alvarezii showed the highest scavenging activity. Ethyl acetate extract showed a moderate activity of 62.9%. In the DPPH method, petroleum ether and hexane extracts showed less activity with IC₅₀ values of 118.58 ± 8.94 and 116.25 ± 7.14 μg/mL, respectively. Acetone, methanol, and ethyl acetate extracts exhibited IC₅₀ values of 57.32 ± 1.07, 61.31 ± 0.67, and 79.50 ± 1.59 μg/mL, respectively. K. alvarezii showed higher antioxidant activity in both in vitro and in vivo studies. Proton NMR studies revealed signals in the region 0.5 to 2.0 ppm suggesting the presence of steroidal identity in the extracts.     

Dietary supplementation of L-tryptophan: Effect on growth and survival of Pabda,Ompok bimaculatus (Bloch) fry

ABSTRACT

A 30-day experiment was conducted to assess the effect of tryptophan-supplemented diets on growth and survival of Pabda, Ompok bimaculatus fry. Fifty pabda fry (0.114 ± 0.02 g; 2.45 ± 0.13 cm) were stocked into each aerated aquarium following a completely randomized design consisting of four treatments with triplicate each. Four iso-proteinious purified diets were prepared with different levels of tryptophan—0%, 1%, 2%, and 3%—of the dry diet and were designated as Control, TRP1, TRP2, and TRP3 respectively. Fishes were fed with the experimental diet ad libitum four times a day. The results showed that fish fed with tryptophan-supplemented diets exhibited significantly (P < 0.05) lower cannibalism and higher survival than the control diet. Further, the tryptophan-supplemented groups showed a significantly lower coefficient of variation (%) and size heterogeneity (P < 0.05). However, the growth as measured by body weight gain, length increment, and specific growth rate of fry in tryptophan-supplemented groups was significantly lower than the control group (P < 0.05). Moreover, maximum survival (52.67 ± 1.76%) and minimum cannibalism (21.33 ± 5.70%) coupled with higher growth and performance index (0.38 ± 0.01) were recorded in the 2% tryptophan-supplemented group compared to other tryptophan-fed groups. Overall interpretation from the present study concludes that the dietary supplementation of 2% tryptophan is recommended for better survival of pabda fish, although growth was compromised.     

Production Characteristics of Channel Catfish,Ictalurus punctatusStocked at Two Densities in the Partitioned Aquaculture System

Abstract

This study was conducted to determine if channel catfish could be cultured at an increased density in the Partitioned Aquaculture System (PAS) without significantly affecting performance. Channel catfish fingerlings (36.53±6.76 g; mean ±SD) were initially stocked into six 9.15 m³ sections at 3,461±317 fish per section, twice the designed carrying capacity, and fed twice daily to satiation. After 75 days, the density of three units was reduced by approximately 50% and all six units were fed for another 97 days. There was no significant difference (P > 0.05) in mean growth rate, feed conversion ratio, or production between fish grown at the low- and high-density treatments. Also, length variation (CV) and condition factors (K) were similar (P > 0.05) between fish grown at the low and high-density. Increasing density by twice the designed carrying capacity did not affect performance of channel catfish in the PAS.     

Production Characteristics of Rainbow Trout,Oncorhynchus mykiss and Brook Trout,Salvelinus fontinalis Under Seasonal Pond Conditions

Abstract

The production characteristics of juvenile rainbow trout, Oncorhynchus mykiss and brook trout, Salvelinus fontinalis were compared under winter pond conditions. Juvenile rainbow trout (55.1 ±1.5 g) and brook trout (28.9 ±0.4 g) were stocked at a density of 8,750 fish/ha into six 0.04-ha ponds. After 163 days, survival, growth, and feed conversion were similar (P >0.05). The results of this study suggest that brook trout may attain growth rates similar to rainbow trout under winter pond conditions in temperate regions of North America.     

Comparison of Four Commercial Diets and Three Feeding Rates for Black Sea Bass,Centropristis striata,Fingerlings

Abstract

A new demand for live black sea bass, Centropristis striata L., is emerging in the fish markets of the northeast United States and Canada. Aquaculturists need to know suitable commercial diets and feeding rates for growing black sea bass to increase profitability. In these experiments, four commercial diets and three feeding rates were compared for juvenile black sea bass (0.8-1.3 g). The diet experiment compared growth rates for fish fed four commercial diets, Rangen Trout and Salmon Starter (R), Nelson and Son's Silver Cup Trout Crumbles (SCT), Nelson and Son's Silver Cup Salmon Crumbles (SCS), and Zeigler Salmon Starter (Z). The feeding rate experiment compared growth rates for fish fed Zeigler Salmon Starter, at 2.5%, 5.0%, and 7.5% levels (dry weight of food/wet weight of fish). At the end of the diet experiment (18 weeks), Tukey's studentized range test (? = 0.05) showed that fish fed diet Z (14.5±0.92 g) were significantly larger than fish fed diet R (11.4±0.93 g). Diets Z and R both produced significantly larger fish than diets SCS (7.3±0.85 g) and SCT (4.5±0.29 g). At the end of the feeding rate experiment (10 weeks), Duncan's multiple range test (? = 0.05) showed that fish fed a 7.5% (4.61±0.24 g) rate and a 5.0% (4.49±0.24 g) rate were not significantly different in weight. Both of these treatments produced significantly larger fish than a feeding rate of 2.5% (3.59+0.21 g).     

Comparison of the amino acid contents of roe, whole body and muscle tissue and their A/E ratios for largemouth bass Micropterus salmoides (Lacepéde, 1802)

Nutritional amino acid requirements of varying size classes of largemouth bass were estimated using A/E ratios. Nutrient and amino acid contents of roe and carcass of the different size classes were determined and compared to results of selected, classic works related to the concept of ideal protein and relationship between the contents of individual, essential amino acids and the total contents of essential amino acids – A/E ratios. Protein content in the roes of the largemouth bass were higher in comparison to the carcass, but the content of lipids of the roes and of the carcass didn’t present significant difference (P<0.05). Largemouth bass showed higher muscle protein content in comparison to other species. Although some authors report variation in the contents of some amino acids in the carcass of selected species, differences observed in this study regarding carcass amino acid contents of tilapia, speckled catfish and largemouth bass were not significant (P<0.05), values of the ratio A/E followed the same trend. Results, herein presented, indicate that the amino acid profile of largemouth bass could be used as complementary tool for balancing amino acids in formulated feed for the species, and in the validation of amino acid requirements determined in performance studies.     

Effects of Sodium Alginate and Chitosan Coating Combined with Three Different Essential Oils on Microbial and Chemical Attributes of Rainbow Trout Fillets

ABSTRACT

Meat products, such as fish meat, are known to be susceptible to undesirable chemical and microbial reactions that characterize spoilage. In this study, the effect of a sodium alginate and chitosan coating incorporated with Mentha piperita, Artemisia dracunculus, and Zataria multiflora essential oils on chemical and microbial attributes of rainbow trout meat was evaluated during storage at 4°C. Chemical and microbial assays were performed on rainbow trout fillets with alginate and chitosan coatings and 0.2% concentration of test essential oils. The results showed that the alginate coating with essential oils significantly decreased production of thiobarbituric acid (TBA) and total volatile basic nitrogen (TVBN) and reduced the growth of foodborne spoilage bacteria during storage at 4ºC. At day 12, the best results were obtained in chitosan coating + Z. multiflora, with 5.96 ± 0.12, 4.93 ± 0.12, and 3.83 ± 0.2 for total viable counts, psychrotrophic bacterial count, and lactic acid bacteria count, respectively. Moreover, the lowest amounts of chemical analysis were observed in chitosan coating + Z. multiflora at the final day (0.54 ± 0.03 and 20.31 ± 0.1 for TBA and TVBN, respectively). Our study revealed that essential oils can be used as effective natural components against undesirable chemical and microbial reactions in fish meat.     

Species identification of Alaska pollock,Gadus spp., and Micromesistius spp. in cod roe products using a PCR-based method

Fish species identification techniques for authentic food labeling were developed using species-specific PCR primers for cod roe products. A salted, seasoned fish roe product, karashimentaiko (chilli cod roe), is produced from the eggs of Alaska pollock, Theragra chalcogramma, according to the fair trade competition agreement authorized by the Fair Trade Commission of the Japanese government. To examine whether Alaska pollock ovaries or those of other fish species are being used as raw materials for the fish roe products, we developed species identification techniques using PCR amplification of a 255-bp fragment encoding the mitochondrial ATP synthase Fo subunit 6 (ATP6) gene with a species-specific primer set for Alaska pollock mitochondrial DNA. We also designed two species-specific primer sets corresponding to the mitochondrial ATP6 and cytochrome b (cytb) for Gadus spp. and Micromesistius spp. by PCR amplification of 332- and 223-bp fragments, respectively. We examined the species specificity of these PCR-based methods among nine commercially important Gadidae species.     

Antioxidant Activities of Citrus Albedo and Flavedo Fragments Against Fish Lipid Oxidation

ABSTRACT

This research aimed to inhibit the oxidation of fish lipid by adding the ethanol extracts of albedo and flavedo fragments of grapefruit, sour orange, and bergamot. The samples were stored at 25°C, and analyses were performed on weekly intervals. The albedo fragments of sour orange extract had the highest antioxidant activity (0.342 ± 0.002 µM Trolox) and total phenolic content (5.29 ± 0.00 g GAE/100 g dry matter). Lipid oxidation increased rapidly in control samples compared to the extract treatments. The lowest scores for thiobarbituric acid reactive substances (TBARS), para-anisidine value, peroxide value, and UV absorbance values were determined in sour orange albedo extracts as 5.21 mg MDA/kg, 17.81 and 4.78 meq O₂/kg, 2.24, and 0.403, respectively, at the end of the storage. More successful results were obtained with the peels of grapefruit and bergamot in supressing the lipid oxidation. Bergamot extract was the most preferred citrus in terms of sensory analyses.