Effects of Heat Treatment on Composition and Nutritive Value of Herring Meal

1. The effect of heat treatment on quality of herring meal has been investigated using a rotating autoclave operated under variable conditions (meal moisture: 1.1% - 41%; meal temperature: 96° C – 132° C; heating time: 0-2 hrs). 2. In terms of proximate chemical analyses all heat treated meals, containing 82.5-85.0% protein on a dry weight basis, would be considered of a very high grade. 3. Short heat treatments at about 125° C appeared to stabilize the lipid phase towards oxidation during storage: After four weeks an unheated reference meal had a carbonyl number of 323 mmol CO/kg fat whereas heat treated meals had values in the range of 74-91 mmol CO /kg fat. Corresponding iodine numbers were on the average 100 g I2/100 g fat for the unheated meal and 120 g I2/100 g fat for heat treated meals. 4. Analyses indicated some slight decrease in amino acids of the herring meals resulting from the heat treatments. 5. No clear correlation was found between available lysine and conditions of heat treatment, but there was a tendency for availability to decrease with increasing moisture content during prolonged heating of meals. 6. During the heat treatments, pepsin digestibility for dry meals dropped to 66% while that for wet meals dropped at most to about 33% with reference to freeze dried meals. 7. Pepsin digestibility was well correlated with values for nutritive criteria obtained in animal feeding tests. 8. Apparent indigestibility of individual amino acids In two selected meals showed some increase due to heat treatment

Effect of BHT (Butylated Hydroxytoluene) on the protein value of herring meal for the young rat

The effect of BHT (butylated hydroxytoluene) on the protein quality of herring meal was studied in nitrogen balance experiments with young rats. BHT at the 0.03% level in the meal improved the protein quality of meals produced from small summer herring when it was added after the drying process but was without any effect when it was added before the drying process. BHT had only little effect on the protein quality of meals produced from winter herring. Different production methods of the meals had little effect on the protein quality. Pelleting of the meals seemed to be no advantage, there were indications that the protein quality might be adversely affected by this process

Protein value of cod and coalfish and some products for the young rat

The protein quality of cod muscle protein and of some products of cod and coalfish was determined in nitrogen balance experiments with young rats. In most of the experiments spray dried egg albumin was used as a standard of reference. All the fish proteins showed as expected a lower utilization than egg albumin, but the results indicated that the preparations tested had high biological values. There was no appreciable difference between raw cod fillets, acetone dried cod fillets, or acetone dried fillets which had been boiled before drying. Two pilot plant fish flours from cod fillet waste showed high biological values. There was no difference in the utilization values between freeze dried coalfish fillet pastes containing different amounts of residual bones. Stockfish flours showed utilization values of about the same magnitude as the acetone dried fillets. There was no difference in the utilization values for stockfish and paste made from stockfish soaked in NaOH or NaC03 («lutefisk»). A comparison between acetone dried cod and herring fillets and meat from porbeagle and basking shark showed the elasmobranchs to be less well utilized than the teleosts

Effect of BHT (Butylated Hydroxytoluene) on the protein value of herring meal for the young rat

The effect of BHT (butylated hydroxytoluene) on the protein quality of herring meal was studied in nitrogen balance experiments with young rats. BHT at the 0.03% level in the meal improved the protein quality of meals produced from small summer herring when it was added after the drying process but was without any effect when it was added before the drying process. BHT had only little effect on the protein quality of meals produced from winter herring. Different production methods of the meals had little effect on the protein quality. Pelleting of the meals seemed to be no advantage, there were indications that the protein quality might be adversely affected by this process

Protein value of herring meal and some other protein concentrates of marine origin for the young rat

Protein concentrates, mainly of marine origin, were tested in nitrogen balance experiments with young rats. Commercial herring meals produced by several methods showed only small differences in protein utilization values. In most cases when differences in nitrogen balance values were found they were mainly due to corresponding differences in the protein digestibility. Press cake meals were slightly better utilized than whole meals, this difference was not accounted for by a corresponding difference in digestibility. Steam drying did not produce meals of better protein value than flame drying. No effect on the protein quality of herring meals was found of the preservatives sodium nitrite or formalin used during the storage of the raw material. Extraction of a whole meal with light petrol did not improve the protein quality wheras extraction of another whole meal with ethyl alcohol, ethyl ether and acetone improved the quality. Four foreign fish meals were of about the same protein value as Norwegian herring meal, whereas one was decidedly better. A sand-eel press cake meal was better than a whole meal produced from this raw material. The whole meal was of about the same protein quality as the herring meals. A flash dried whale meat meal was of about equal protein value as herring meals, but decidedly better than a slowly dried whale meal. A squid meal, a spray dried herring solubles meal and two fish off-fall meals were of decidedly poorer protein quality than the herring meals. Rennet casein was of about the same protein value as the herring meals, whereas the reference protein source, spray dried egg albumin, was better than all the other protein sources tested. Acetone dried samples of herring fillets and whole herring were of moderately better protein value than commercial herring meals. Acetone dried male herring was of poorer protein value than a corresponding sample of female herring. Acetone dried herring roe was of good protein value whereas the corresponding sample of herring milt was of poor protein value

The Effect of Some Marine Oils and Squalene on the Plasma Cholesterol in Chicks

The effect of some fish oils on the plasma-cholesterol level of chicks were studied in eleven experiments. Soya- bean oil, margarine fat and squalene were also included in the study. Arachis oil was used as a reference in all experiments. In experiments with added cholesterol, cod liver oil usually showed lowered values compared with arachis oil and no fat added, but the effect varied greatly. Thus no final conclusions could be drawn. Soya-bean oil did not show any effect compared with arachis oil, whereas basking shark liver oil, dogfish liver oil and squalene lowered the cholesterol level. Methyl ester fractions of cod liver oil with iodine numbers ranging from 78 to 254 were without effect. In experiments without added cholesterol, cod liver oil in most cases gave significantly lower cholesterol levels than did arachis oil. This effect was also observed for herring oil, dogfish liver oil, basking shark liver oil and squalene