OXITEST as a Screening Method to Evaluate Antioxidant Agents: A Study of Oxidative Stability of Fishmeal

Oxidation in fishmeal (FM) can generate sufficient heat to potentially trigger combustion, making it essential to assess its risk of self-ignition before transport to prevent fires. Ethoxyquin, commonly used to mitigate this risk, has been banned in some markets due to its genotoxicity, driving the search for alternative antioxidants. The traditional method to evaluate this risk, the SW-846 1050 test, is costly and time-consuming. We used the simpler and cheaper OXITEST method to assess the oxidative stability of FM by comparing oxygen consumption in FM with and without antioxidants. Fresh FM without antioxidants was used, which was stored at -30°C for 6 months. FM contained 7.2% moisture, 18.8% ash, 64.3% protein, and 9.7% crude fat; of the lipids, 75% were neutral, and 25% were phospholipids. The fatty acid profile of the lipids revealed high levels of EPA and DHA, with a DHA/EPA ratio greater than 1, which makes the FM more prone to oxidation compared to anchovy oil. Initial results demonstrated oxygen consumption in FM samples, although the inflection point (IP) was not detected. In a second step, after optimizing the sample volume (50 g), temperature (80°C), and time (4 h), oxygen consumption was evaluated by OXITEST in FM samples with increasing concentrations of ethoxyquin, demonstrating an inverse correlation between concentrations of ethoxyquin and oxygen consumption (Pearson's linear). Finally, we evaluated FM samples with various commercial antioxidants and compared the area under the curve for oxygen pressure versus time using FM alone as a negative control and FM with 750 ppm of ethoxyquin as the positive control. OXITEST measurements revealed differences in the rate of oxygen pressure loss among the studied agents, offering a comparative measure of antioxidant efficiency. The OXITEST method can be employed as a rapid and cost-effective method to evaluate oxidative stability and the effectiveness of antioxidants in FM.