Composição em nutrientes e caracterização das proteinas de file de pacu (Colossoma mitrei, Berg 1895)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1989

RESUMO

The present work was undertaken with the aim of obtaining some information about pacu (Colossoma mitrei, Berg 1895) in terms of its chemical composition, protein characterization and nutritional evaluation. This fish is visualized as a very interesting species in Brazilian aquaculture programs. The proximate composition of the edible portion of pacu, based on 6 samples collected at different periods from the Pirassununga Fish Culture Research Station (SP) and from a local fish wholesale distributor was: moisture, 67.7 :I:: 0.9; protein, 13.0 :I:: 0.3; lipids, 17.2 :I:: 0.6 and ash, 1.3 :I:: 0.1. Phosphorus, potassium and calcium averaging 121.5, 118.4 and 55.2 mgj100g filet were the predominant mineral components. Fatty acids were detected by gas chromatography of which the principal components were oleic (42.85%), palmitic (22.68%), linoleic (10.30%), palmitoleic (8.95%), stearic (8.15%), miristic (2.72%) and linolenic (1.76%). The aminoacid composition determined by ion exchange chromatography revealed that pacu is a good source of histidine (2.24gj16gN), lysine (10.05gj16gN), leucine (8.75gj16gN), isoleucine (4.25gj16gN), threonine (3.82gj16gN), phenylalanine (4.29gj16gN) and methionine (2.79gj16gN). The extraction and fractionation of the proteins of the edible portion with a 5% N aCI solution allowed the extraction of 92.0% soluble protein. From this portion myofibrillar fraction and sarcoplasmatic fraction accounted for 64.3% and 25.0%, respectively, in relation to the total muscle protein. In vitro digestibility of the muscle proteins was determined by hydrolysis with pepsin and pancreatin and was found to be 84.3%. The electrophoresis of the sarcoplasmatic proteins of the muscle in polyacrylamide gel and the electrophoresis with SDS showed patterns of 8 bands with molecular weights estimated in the range of 4 to 15 Kd. The protein nutritive value was determined by PER and nitrogen balance using rat assays. The rats were fed ad libitum and the diets were prepared to contain 10% protein of the freeze-dried edible portion of the fish in its integral form and defatted. The integral fiour gave the following results: PER, 2.94; apparent protein digestibility (AD), 90.0%; biological value (BV), 82.8% and net protein utilization (NPU), 74.6%. For defatted fiour, results of the same determinations were: 3.00; 84.3%; 82.5% and 69.5%, respectively. From these results we are able to conclude that pacu can be considered as a protein and energy rich food and relatively poor as a source of mineraIs. The lipid fraction presents as main components oleic, palmitic and linoleic acids. The ratio of insaturated to saturated fatty acids is 1.9. This pattern is characteristic of fresh water fish. The protein fraction was high in lysine and methionine. Rat assays showed that (considering a significance leveI of 5%) the PER values were not different for diets prepared with casein, integral fiour and defatted fiour obtained from the freeze-dried edible portion of the fish. When compared to casein, integral fiour showed lower biological value, but apparent protein digestibility and net protein utilization were not significantly different. For these determinations defatted fiour presented lower values compared to caseln

ASSUNTO(S)

peixe - pesquisa peixe - alimentação

ACESSO AO ARTIGO

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