Simultaneous Extraction and Fractionation of Fish Oil from Tuna By-Product Using Supercritical Carbon Dioxide (SC-CO2)

ABSTRACT

Fish oil was extracted and simultaneously collected into six fractions based on molecular weight and the chain length of triglycerides in terms of fatty acid constituents without splitting of the triglycerides, using supercritical carbon dioxide (SC-CO₂) at optimized conditions of 40 MPa, 65°C, and a flow rate 3 mL min^?1. In each type of fractionation, the first fraction (F1) was rich in saturated fatty acids (SFA; 52.57 to 61.26%), followed by monounsaturated fatty acids (MUFA; 22.17 to 23.22%) and polyunsaturated fatty acids (PUFA; (0.54 to 20.37%); the sixth fraction (F6) was rich in PUFA (48.93%), followed by MUFA (33.59%) and SFA (13.61%). It was obvious that short-chain fatty acids were extracted at an earlier fraction; therefore, the latter fractions were dominant in long-chain fatty acids, especially MUFA and PUFA. Thus, omega-3 fish oil (last three fractions) was successfully separated to be used as a value-added health product.     

Effects of Delayed Processing of Pink Salmon (Oncorhynchus gorbuscha) By-products on Fishmeal Quality

The effects of storage temperature and time on raw pink salmon by-products were evaluated in relation to the fishmeal produced. Chemical analyses were performed on the raw and processed by‐products at two temperatures. Total volatile base nitrogen values indicated substantial spoilage by day 2 at 15.4 ± 1.4°C and day 6 at 6.0 ± 0.8°C. For most biogenic amines in raw by-products stored at 15.4°C, there were many significant differences from the fresh by-products by day 2. For by-products stored at 6.0°C, significant changes in biogenic amine were evident by day 2 and continued to increase. The thiobarbituric acid reactive substances (TBARS) values of the raw material stored at 15.4°C started showing significant changes from fresh on day 3 and at 6.0°C on day 4. The lipid oxidation (TBARS) was significantly different from fresh by day 2. Biogenic amines in fishmeals suggested some changes occurred between day 0 and day 3 at 15.4°C and by day 7 at 6.0°C.     

Digestibility of dietary components and amino acids in plant protein feed ingredients in striped catfish (Pangasianodon hypophthalmus) fingerlings

The apparent digestibility (AD) of dietary components, energy and essential amino acids (EAA) of selected locally available plant protein feed ingredients in striped catfish (Pangasianodon hypophthalmus) fingerlings was studied. The AD of the test ingredients (ADi) differed (P < 0.05) and ranged from 66.2 to 89.6% for ADi_DM, from 63.6 to 91.3% for ADi_CP, from 65.4 to 85.3% for ADi_OM and from 69.8 to 89.3% for ADi_GE. The highest ADi_DM, ADi_OM and ADi_GE in the test ingredients was obtained for broken rice, maize meal and soybean meal, while the lowest values were obtained for duckweed meal. Soybean meal and duckweed meal had the highest ADi_CP, while there were no differences (P > 0.05) between the other test ingredients. The AD of total and individual EAA was higher in soybean meal, duckweed meal and broken rice than in the other test feed ingredients (P < 0.05). The lowest AD of individual EAA was found in maize meal, followed by cassava leaf meal and sweet potato leaf meal (P < 0.05). The low AD of individual plant feed ingredients may limit their potential to be used as replacement for fish meal in the feed.     

Digestibility of dietary components and amino acids in animal and plant protein feed ingredients in striped catfish (Pangasianodon hypophthalmus) fingerlings

The apparent digestibility (AD) of dietary components, energy and essential amino acids (EAA) of selected locally available animal and plant protein feed ingredients in striped catfish (Pangasianodon hypophthalmus) fingerlings was studied. The AD of the test ingredients (ADi) differed (P < 0.05) and ranged from 81.1% to 90.8%, for ADi_DM, from 84.0% to 95.0% for ADi_CP, from 78.4% to 86.9% for ADi_OM and from 79.0% to 87.8% for ADi_GE. The highest ADi_DM, ADi_CP and ADi_OM in the test ingredients were found for shrimp head meal, catfish by‐product meal, golden apple snail and groundnut cake, while the lowest values were obtained for earthworm meal and rice bran. The highest ADi_GE was found in rice bran, followed by golden apple snail and catfish by‐product meal, while there were no differences (P < 0.05) between the other test ingredients, except for earthworm meal. The AD of total and individual EAA was high in catfish by‐product meal and shrimp head meal, followed by decreasing AD in golden apple snail, groundnut cake, rice bran and earthworm meal ingredients (P < 0.05). The low AD of earthworm meal may limit its potential to be used as replacement for fish meal in the feed.     

Effects of replacing fish meal with soybean meal on growth,body composition and digestive enzyme activities of juvenile Chinese sucker,Myxocyprinus asiaticus

Six isonitrogenous diets (420 g kg^?1 crude protein on dry matter basis) with six levels of soybean meal (SBM) inclusion (0, 112, 225, 336, 449 and 560 g kg^?1) in substitution of fish meal (0%, 20%, 40%, 60%, 80% and 100%) were evaluated in Chinese sucker of 1.81 ± 0.01 g initial weight for 8 weeks. There existed a significant difference (P < 0.001) in fish weight gain, feed conversion ratio, feed intake, protein efficiency ratio and specific growth rate when the replacement level for fish meal protein was increased from 40% to 60%, indicating that up to 40% of fish meal protein could be replaced with SBM protein without causing reduction in growth and protein utilization. Lipid contents in the Chinese sucker body decreased significantly (P < 0.001) as dietary SBM increased. Digestive enzyme activities in the intestine and hepatopancreas of the fish were significantly different (P < 0.001) as the SBM protein replacement level was increased. Results of the present study appear to indicate that 40% FM can be replaced by SBM in practical feeds of Chinese sucker.     

Effect of Season on Vitamin E,Fatty Acid Profile,and Nutritional Value of Fish By-Products from Cod,Saithe, Ling and Haddock Species Caught in Southern Irish Coastal Waters

ABSTRACT

The value of fish is largely dependent on fillet size and species but greater value could be obtained by finding commercial uses for the remaining fish frame, particularly fish by-products. Vitamin E and polyunsaturated fatty acids, particularly docosahexaenoic acid (DHA) and eicosapentaenoic (EPA), are of economic importance to the food and pharmaceutical industries and are available for extraction from fish waste. The objective of this study was to compare α-tocopherol levels and the fatty acid profile from several demersal species (cod, ling, saithe and haddock, n = 15) caught in Irish coastal waters over a one-year period (2001). α-Tocopherol levels in samples of liver, viscera and cut-off (any residual flesh from belly flap) were extracted and subsequently measured by high performance liquid chromatography (HPLC). Total fatty acids were extracted and determined by gas chromatography (GC). Results indicated that a-tocopherol levels in liver were higher (P < 0.05) than those in viscera or cut-off. Regardless of species, α-tocopherol levels were found in the following order: liver > viscera > cut-off. In general, α-tocopherol levels were highest in autumn and lowest in spring. Overall, percent free fatty acid levels recorded in liver and viscera samples were higher (P < 0.05) than those in cut-off samples. Percent free fatty acid varied significantly (P < 0.05) with each season, and was generally greater in autumn samples. An inverse relationship was observed between percent fat and moisture levels recorded in this study. The major fatty acids identified in each fish species and each by-product were 16:0 (palmitic), 18:0 (stearic), 18:1 (oleic) 20:5n-3 (eicosapentaenoic acid, EPA) and 22:6n-3 (docosahexaenoic, DHA). The highest percent of total identified fatty acids were reported in the autumn catch, including the highest EPA and DHA levels. Overall, liver samples had the highest levels of EPA and DHA.     

Consequences of connectivity alteration on riverine fish assemblages: potential opportunities to overcome constraints in applying conventional monitoring designs

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Economic feasibility for producing Imperial Zebra pleco (Hypancistrus zebra) in recirculating aquaculture systems: An alternative for a critically endangered ornamental fish

Abstract

The L46 (Hypancistrus zebra) stands out as one of the most valuable Amazonian species in the international market for ornamental fish and faces a notable problem: the risk of extinction versus the demand for new specimens for aquariums. Considering that breeding in captivity can be a conservational tool for aquatic species and an alternative source for generating income, the objective of the present paper was to verify the economic feasibility of producing H. zebra in recirculation aquaculture systems (RAS), in different scenarios of rearing: residential breeding (S1), mid-size store production (S2) and large-scale production as a supplier (S3). The main profitability indicators used were: net present value (NPV), internal rate of return (IRR) and payback period (PP). The selling price per unit was fixed in US$260.15 (S1/S2) and US$156.09 (S3). The largest investments were made with the acquisition of broodstocks (S1/S2) and property (S3), while the highest costs were with labor (S2/S3) and taxes (S1). Only S1 demonstrated economic profitability (NPV 8.50%?=?US$28,187.85; IRR?=?74.71%; PP?=?1.80?years). Conclusion: the production in this study appeared to be profitable on smaller scales, however the profitability of large-scale production depends upon reducing expenses and increasing the selling price.     

EFFICIENCY OF RESOURCE USE AMONG POND FISH FARMERS IN CENTRAL UGANDA: A STOCHASTIC FRONTIER PRODUCTION FUNCTION APPROACH

This article presents the use of a stochastic frontier production function to examine the efficiency of resource utilization in pond fish farming in Uganda. The study draws on data from a field survey administered to 200 small-scale fish farmers in three major fish farming districts in Central Uganda: Mukono, Mpigi and Wakiso. The districts were part of a large aquaculture development project funded by the United States Agency for International Development-Aquaculture and Fisheries Collaborative Research Support Program. Productive efficiency was analyzed using stochastic frontier analysis with a translog production function while assuming a truncated-normal distribution for the inefficiency term. The output variable was total quantity of fish produced, while input variables were quantity or value of inputs used in the production process, namely labor, pond size, stocking density, capital and feeds. The estimated index of resource-use efficiency revealed that small-scale farmers were inefficient in resource allocation by over-utilizing labor with an estimated allocative efficiency index of ?0.94 and grossly under-utilized pond size, feeds and fingerlings with allocative efficient indices of 1.15, 1.64, 3.71, respectively. The results suggest that there is considerable scope to expand output and also productivity by increasing production efficiency at the relatively inefficient farms and sustaining the efficiency of those operating at or closer to the frontier.     

Economies of scale for juvenile production of common snook (Centropomus undecimalis Bloch)

Abstract

Construction and operating costs for three common snook (Centropomus undecimalis) hatcheries in Florida, USA, are illustrated. Hypothetical capacities and targets of the three hatcheries (Scenarios I, II and III respectively) were 615, 000 juveniles (8 ‐ 10 g in weight) for stock enhancement, and 1, 275, 000 and 3, 000, 000 juveniles (1‐g in weight) for commercial grow‐out. Estimated production costs were lower than for many marine finfish species. The 20‐year mean costs per 1, 000 juveniles were estimated to be $324, $215, and $159, for hatcheries I, II, and III respectively, and the initial capital investments were $731, 660, $1, 162, 460, and $1, 896, 030¹, respectively. Major cost items of annual production were labor (22 ‐ 33%), supplies (14 ‐ 20%), fixed costs (15 ‐ 17%), and interest (13 ‐ 15%). The most profitable hatchery was the 3 million 1‐g juvenile hatchery due to the hatchery size effect, with a net present value (NPV) of $1, 760, 000, an internal rate of return (ERR) of 81%, a payback period of 3.6 years, and a profitability index of $2.86 for every dollar invested. Possible cost reductions to increase financial profitability were discussed.