
The global seafood industry generates substantial amounts of waste each year, with up to 50% of a fish's weight classified as by-products, including heads, viscera, skin, and fish bones. Previously regarded as mere waste, these by-products are now increasingly recognised as valuable resources, thanks to recent technological advancements.
One such breakthrough is Subcritical Water Hydrolysis (SWH), a state-of-the-art and sustainable process with the potential to revolutionise the management and reuse of fish by-products. This innovative technique heats water to temperatures between 100°C and 374°C under high pressure, transforming it into a highly effective solvent and catalyst.
For instance, fish byproducts, which contain between 10% and 20% crude protein, can be converted into protein hydrolysates with extraordinary properties, such as antioxidant, antihypertensive, and antidiabetic effects. Notably, fish viscera hydrolysates produced via Subcritical Water Hydrolysis have demonstrated an impressive oxygen radical absorbance capacity, underlining their potential as potent antioxidant agents.
Unlike conventional hydrolysis methods, Subcritical Water Hydrolysis is environmentally friendly, requiring no harmful chemicals and generating minimal waste. By reducing the dielectric constant of water from 80 to 27 at 250°C, the process significantly enhances the water’s ability to dissolve and extract valuable compounds, making it not only efficient but also highly sustainable.
Furthermore, protein hydrolysates created through this technique have shown great promise across a range of industries, including pharmaceuticals and functional foods. For example, fish peptides derived using Subcritical Water Hydrolysis have demonstrated antihypertensive properties comparable to conventional treatments.
The applications of Subcritical Water Hydrolysis extend well beyond human health. In the aquaculture sector, hydrolysates produced by this method have been successfully incorporated into animal feed, improving growth rates and immune resilience in livestock and fish. Additionally, studies have shown that broiler chickens fed diets enriched with fish viscera hydrolysates experience improved intestinal health and nutrient absorption. This reduces dependence on traditional fishmeal, supporting a circular economy by creating high-value products from waste.
The cosmeceutical and pharmaceutical industries are also beginning to tap into the potential of Subcritical Water Hydrolysis. Fish-derived peptides have proven effective as natural moisturisers and UV-protection agents, while their antioxidant and anti-inflammatory properties make them valuable for managing chronic conditions such as hypertension, diabetes, and oxidative stress-related diseases. The versatility of Subcritical Water Hydrolysis also lies in its ability to produce natural bioactives that can replace synthetic additives, offering safer and more sustainable alternatives for consumers.
Despite its many benefits, Subcritical Water Hydrolysis faces some challenges, including the high initial investment required for equipment and the need to optimise processes for large-scale production.
However, its long-term advantages—such as reducing environmental pollution, minimising waste, and generating high-value bioactive compounds—position it as a game-changer for the seafood industry. With further refinement and broader exploration of its applications, Subcritical Water Hydrolysis could redefine how the world views fish waste, transforming it from an environmental burden into an opportunity for innovation and sustainability.