Microbial count, chemical composition and fatty acid profile of biological silage obtained from pacu and spotted sorubim fish waste using lactic acid bacteria fermentation

Abstract

With the increasing production and processing of fish, managing the generated waste is a growing concern. Fish processing by-products, like viscera, are rich in energy and nutrients and can be transformed into valuable raw materials, including fish silage, which represents an alternative to fishmeal. This study evaluated the quality of biological silage obtained from the fermentation of the waste of two fish species, pacu and spotted sorubim, by seven lactic acid bacteria inoculants. Cultivations were conducted using either 100% fish viscera or mixture of 90% fish viscera and 10% sugarcane molasses as the substrate at 30 or 35 °C, for 120 h, with an inoculum concentration of 6% (v/w) in the bioreactors. Results showed variations (P < 0.05) in microbiological count, chemical composition, and fatty acid profile in the silages after 5 days of fermentation. Spotted sorubim-based media supported better lactic acid bacteria growth, and the silages exhibited varying fatty acid profiles, depending on the formulation. Media inoculated with Lactobacillus brevis NRRL-B 4527 containing 90% spotted sorubim viscera and 10% sugarcane molasses at 30 °C had the highest protein content (44.6 ± 0.7% dry basys). Oleic (C18:1n-9), palmitic (C16:0), and stearic (C18:0) acids were the most abundant fatty acids. The LAB/MES ratio of 0.96 and pH final of 4.21 underline the microbial quality of this silage.