Aproveitamento do resíduo do beneficiamento da Tilápia do Nilo (Oreochromis niloticus) para obtenção de silagem e óleo como subprodutos. / Utilization of fish waste from the processing of nile tilapia (Oreochromis niloticus) to obtain fish silage and fish oil as by-products.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

One third of the world fishing produce is not directly applied in human consumption. Instead, it is used in the elaboration of feed or wasted as residue. It would be ideal to use the raw material thoroughly and to recover by-products, preventing the generation of residues. With the objectives of increasing the income and the production of the industry, as well as minimizing environmental and health problems from fish residues, chemical silage from Tilapia processing residues was produced. The Nile tilapia (Oreochromis niloticus) is the most popular species in Brazil today. Tilapia is cultivated in 22 Brazilian states and its annual production is between 30 and 40 thousand tons. Tilapia was one of the first aquaculture species to be processed after harvesting, being currently commercialized in the form of frozen fillets, however, with a yield of about 30%. Thus, there is a need for transforming the residues generated by the fillet processing into by-products, minimizing the environmental impact. The silage was elaborated after cutter-homogenization and acidification of the biomass with 3% formic acid: propionic, 1:1, addition of antioxidant BHT and maintenance of pH at about 4.0. Analyses for the determination of the moisture, protein, lipids and ash were carried out. The amino acids were examined in an auto analyzer after acid hydrolysis, except for the triptophane which was determined through colorimetry. The tilapia silage presented contents that were similar to or higher than the FAO standards for all essential amino acids, except for the triptophane. The highest values found were for lysine and leucine. The results indicate a possible use of the silage prepared from the Nile tilapia processing residue as a proteic source in the manufacturing of fish feed. However For the use of the silage, oil-removing techniques are necessary in order to increase the stability of the product as well as its commercial value. Lipid oxidation may cause peroxide formation, which can produce complex proteins with a consequent destruction of amino acids. The present work tried to determine the best form of extracting the oil from the acid silage of Nile tilapia (Oreochromis niloticus) and to caracterize the silage oil. The lipid fraction was extracted by three extraction methods: centrifugation (3500 × G·30 min-1), Soxhlet (AOAC, 1990) and Bligh &Dyer (1969). The results for yield and peroxide value were, respectively, 65.53% and 0.00 mEq·1000g-1 of O2, 44.27% and 25.00 mEq·1000g-1of O2, 46.87% and 0.00 mEq·1000g-1 of O2. The lipid fraction showed 28,60; 16,30 and 3,10mg·1000g-1 of oleic, linoleic and linolenic acids, respectively. Centrifugation proved to be the best extraction methodology due to the preservation of the physical-chemical characteristics of the oil and greater yield. The lipid content of the tilapia silage, on a fresh matter basis, was 3.99g·100g-1. With the removal of the lipid fraction by centrifugation, only 1.54 g·100g-1of lipids could be found in the sample, which is considered an acceptable level for its inclusion in animal feed.

ASSUNTO(S)

silage subproduto animal resíduo animal nile tilapia animal by-product óleo de peixe animal residue tilápia-do-nilo fish oil silagem

ACESSO AO ARTIGO

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