Physicochemical Characterization and Potential Applications of Biodiesel Produced from Industrial Fish Waste

Biofuels are gaining significant global attention as renewable and alternative energy sources, produced from various materials through different extraction methods and conversion processes. Food industry generates not only substantial organic waste, presenting economic and ecological challenges but also potential opportunities for valorization. This study focuses on recovering industrial fish waste from the manufacture of canned tuna, specifically targeting non-food and abundant fish co-products such as heads, bones, skin, and viscera, which constitute nearly 50% of the fish body. The process involves several steps: oil extraction using Soxhlet extraction, purification, and conversion into biodiesel via transesterification, followed by physicochemical analysis. The experiments revealed that 32.41% of fish waste was in the liquid phase (a mixture of hexane and oil), and the extracted oil accounted for 26.56% of the total fish waste weight (from 1.012 kg of waste, approximately 268.78 g of oil was extracted, equivalent to 280.36 mL). The fatty acid composition influenced the cetane number of the biodiesel. Two types of biodiesel (methyl and ethyl esters) were produced from the extracted fish oil through transesterification with methanol or ethanol and sulfuric acid (H₂SO₄). The analysis showed that the produced biodiesels possess properties similar to conventional diesel, indicating their suitability for use in diesel engines. This research highlights the potential of fish waste valorization to reduce fossil fuel consumption and promote sustainable energy solutions.