Elaboração e caracterização química, funcional e nutricional de ensilados de resíduos de pescado da família Lutjanidae

Abstract

The objective of this research work was to provide both data and information about the chemical, functional and nutritional characteristics of the fish waste silage (FWBS) of the Lutjanidae family (red snappers, yelIow-tail snappers, dentex, bastard snappers, etc.) The silage was prepared by using fish waste from local fish industries and fish markets and was classified into three categories: abdominal flange scraps (minced fish), frames (head and skeleton containing muscle scraps) and guts. The experiment outlining consisted of three treatments denominated A (minced fish), B (frames) and C (guts) wich were submited to silage by mixing of 81,5% ground fish waste, 10% yogurt inoculating (Lactobacillus bulgaricus and Streptococcus thermophylus), 7,5% sugar-cane syrup, and 1% salt (NaCI). The experiment was accomplished in two different trials within a thirty-day lapse, by using the same fish waste and silage process. The mixture was disposed in open buckets and fermentation occurred at room temperature of about 28°C - 32°C. The following determinations were performed: a) dry silage yield (23,3% for minced fish, 38,7% for frames and 31% for guts) in relation to the liquid silage; b) silage pH which was maintained at nearly 4.0 for the three treatments; c) acidity expressed in lactic acid, as measured at the end of the fermentation and varying from 4.0% to 4.1% for the three treatments; d) proximal chemical composition which did not show any significant diference (P ≤ 0.05) among the liquid silages in the three treatments for moisture, protein, lipids, ashes and carbohydrates. With respect to the protein content in the dry silages, there was a significantly higher difference (P ≤ 0.05) in treatment A than in treatments B and C; e) water activity (aw) of the dry silages which measured 0.232, 0.220 and 0.223 respectively for treatments A, B and C; f) functional properties study which suggested that FWBS could be used as a proteic supplement incorporated to animal food, due to its wetability, solubility, suspended solids and emulsification characteristics; g) nutritional characterization, through the arnino acid determination, which indicated that FWBS contained alI the essential amino-acids, nutritional value with respect to mineral and essential fatty acids; h) microbiological analysis which indicated the absence of pathogenic bacteria in the product. It case concluded that the process for obtaining silages is technically practicable and it is suggested that FWBS be used as an alternative proteic supplement to those traditionalIy used (fish meal and meat and bone meal) by being incorporated to animal food.