Search

Three composite samples of whitefish meals, each representing samples over 4 mo from plants in eastern Canada were analyzed for proximate composition, minerals, vitamins, amino acids, available lysine, and pepsin digestibility. Protein quality was evaluated biologically in feeding trials with chicks. The composite samples were similar in chemical composition with respect to both macro- and micronutrients. In vitro pepsin digestibility was 95–96% and chemically estimated available lysine 6.5–6.9 g/16 g N, or 87–96% of the total lysine present. The growth response to the meals, when they were fed to supply either 4 or 8% of supplementary protein in diets containing a total of 14.5 or 18.5% of protein, respectively, indicated that the supplementary protein value was high.

Three fish protein sources and milk by-products were used in milk replacers. Thirty Holstein heifer calves were fed five different milk replacers as follows: all-milk nitrogen control, and four with 65% of the nitrogen supplied by steam-dried herring meal and the remaining nitrogen from milk as: (a) skim milk powder, (b) skim milk and acid whey powders; and (c) acid whey powder partially neutralized with NaOH or (d) Ca(OH)2. Body weight gains were greater for calves fed the control milk replacer; from birth to 26 wk of age, calves weaned from this milk replacer gained 822 g/day, compared with 662, 731, 741 and 699 g/day, respectively, on diets a to d noted above (P 2, compared with 81% when it was neutralized with NaOH. Three milk replacers containing 62% of the total nitrogen from herring meal, isopropanol-extracted fish protein concentrate (FPC), or predigested FPC were compared using six Holstein bull calves in two 3 × 3 latin squares. Apparent digestion of dry matter and energy by the calves was similar for the three diets. Nitrogen digestibility was 82% in the herring meal and 86% in the predigested FPC diet (P

Studies of the effect of treatment of haddock (Melanogrammus aeglefinus) with solutions of sodium salts of ethylenediaminetetraacetic acid (EDTA) have shown that a 1% solution of tetrasodium EDTA used as a dip can extend the storage life in ice (0 C) for 11 days over that of untreated controls. The texture of these fillets remained acceptable for the whole of their storage lives.Fillets treated with 0.5 and 0.75% tetrasodium EDTA had a storage life extension of 5 days and those treated with 1% disodium EDTA had a storage life of 6 days longer than the untreated control fillets. Fillets treated with 0.5 and 1.0% disodium calcium EDTA solution showed 0- and 1-day storage life extension respectively.Increase in trimethylamine (TMA) during storage was reduced by treatment with EDTA with the tetrasodium EDTA-treated fillets having the lowest rate of increase. Samples were rejected by the taste panel as spoiled with TMA values of between 3 and 9.5 mg TMA nitrogen (TMA-N) per 100 g.Although treatment of fillets with EDTA extended the storage life in ice and suppressed the increase in TMA, there was little or no effect on the growth of the bacterial population.

Excellent quality fish protein concentrate can be prepared from a variety of raw materials. In this study, the use of whole cod, headed, eviscerated cod, cod trimmings, cod press cake and whole herring was studied as a source of raw material for the production of fish protein concentrate. The process previously described by Power for use with cod fillets was satisfactory for use with all material studied with the exception of herring. Final fat contents were between 0.018–0.056%. For use with herring a modification to the process was required to increase the efficiency of the second extraction. The second extraction, which used a 70:30 isopropanol + water mixture was changed to 99% isopropanol. With this modification a final fat content of 0.17% was achieved. The corrected Protein Efficiency Ratio values for all fish protein concentrates, with the exception of those produced from cod trimming press cake, were higher than that for casein. Lysine values, determined microbiologically were between 9.1 and 15.03% of the protein. The available lysine values were between 6.1 and 10.4% of the protein.

Storage studies of iced irradiated scallops (Placopecten magellanicus Gmelin) have shown that treatment with a dose of 75,000 rads of gamma radiation increases the useful storage life at 0 °C with negligible changes in odour and texture. The raw scallops remained acceptable for 28 days, while the scallops assessed after cooking remained unchanged for 35 days and did not become unacceptable until 43 days storage. Doses of gamma radiation greater than 75,000 rads caused undesirable changes in texture and odour with a consequent loss of quality. Neither irradiated nor fresh iced scallops rated as high organoleptically as frozen control scallops which had been rapidly frozen in a pre-rigor condition and immediately stored at −26 °C.

The efficiency of candling cod fillets was studied using various values and colours of light transmitted through the cod flesh and various values of incident light. It was found that there was no advantage gained in using other than white light for transmission through the fillet. It was also found that a low level of incident light was desirable if the maximum number of parasites is to be detected.

Slicing cod fillets longitudinally into slices [Formula: see text] inch (13 mm) thick can increase the efficiency of candling cod fillets for codworms to over 95%. The increase is greater in the larger fillets than in the smaller fillets if sliced. If fillets are not sliced the candling efficiency decreases with increasing size of fillets.

A high quality fish protein concentrate can be produced from cod fillets by extraction with suitable isopropanol–water mixtures. A process has been developed, on a pilot plant scale, for the production of high quality fish protein concentrate from skinned cod fillets by this method. It is white in colour and of soft texture and for all practical purposes tasteless and odourless. The analysis on a moisture-free basis, of a typical sample shows the following protein (N × 6.25), 96%; ash, 5%; lipids, 0.033%. The moisture remaining in the product after drying is approximately 4%. The yield of protein concentrate (approx. 4% moisture) is between 12 and 15%.

not available

The seasonal variation in the oil content of cod livers is shown to affect the liberation of free fatty acids (FFA) when the "sun-rotted" method for producing cod-oil is used under laboratory conditions. Since lean livers produce an oil with a high FFA content, oil of this type would most likely be produced in April–June after the fish have spawned. An antibiotic, chlortetracycline, was found to have little effect on the liberation of FFA and cannot be used as a liver preservative without an enzyme inhibitor added. Isopropanol at suitable concentrations inhibits both the liberation of oil from the livers and the formation of FFA in the oil.

Studies of the storage life of iced haddock (Melanogrammus aeglefinus) fillets after treatment with doses of gamma radiation of 75,000, 150,000, and 250,000 rads, have shown that a useful extension of the storage life is made possible by irradiation. The fillets irradiated with the 75,000-rad dose and assessed after cooking became unacceptable after about 25 days at 0 °C. The unirradiated control became unacceptable after 12 days. Fillets irradiated at the two higher levels were of lower quality initially than the fillets irradiated at the 75,000-rad level but showed no significant decrease in acceptability up to 27 days storage in ice. Raw fillets developed an objectionable odour and appearance just prior to becoming unacceptable to the taste panel.

Two experiments were carried out with Holstein heifer calves to determine the effect of supplying a major portion of the protein in milk replacers by isopropanol-extracted protein concentrate from whole herring (FPC) or a mixture of FPC and soybean protein concentrate (SPC). Milk replacers were compared with whole milk in experiment 1. All calves were abruptly weaned when consuming 0.5 kg starter/day, or by 5 weeks of age. Calf performance was similar when the pre-weaning liquid diet was whole milk, or milk replacers containing either milk protein or 50% of the protein from FPC. Average daily gains to weaning and to 26 weeks of age for all calves were 377 and 692 g/day, respectively. Calves in experiment 2 were fed either an all-milk protein milk replacer or one containing 98% of the protein equally from FPC and SPC. Both milk replacers were fed once daily either six or seven times per week. Calf growth to weaning was lower on the FPC–SPC formula (283 vs. 364 g/day, P

The isopropyl alcohol residues in fish protein concentrates prepared with this solvent can be determined by a hot extraction technique employing methyl acetate as the solvent and gas–liquid chromatographic analysis of the extract. Studies on vacuum stripping of fish protein concentrates and analysis of various samples suggest that the isopropyl alcohol is trapped mechanically inside particles because of formation of an impervious shell during drying.

Irradiation of cooked lobster (Homarus americanus) meat with a dose of gamma radiation of 75,000 rads extended the storage life, in ice, to between 28 and 35 days for both tail and claw meats from 14 to 21 days for unirradiated iced samples. Higher irradiation levels caused an immediate loss of quality due to toughening and loss of flavour. The growth of trimethylamine-producing bacteria was inhibited 10 days longer on irradiated samples than on the unirradiated iced control.

The fluoride content of fish protein concentrate prepared by the Halifax isopropanol process and also of several possible raw materials was determined by distillation without fusion. The concentration of fluoride in this dry material ranged from 20 to 760 ppm and was dependent upon the raw materials. The major source of the fluoride was the bones which were incorporated in the product to a variable extent. The levels in fresh fillets ranged between 2·3 and 5·4 ppm while whole eviscerated fish contained 3·6-57 ppm fluoride.

not available