Effect of high hydrostatic pressure processing on quality of antioxidant-enriched Tenebrio molitor paste

Several studies have shown that high hydrostatic pressure (HHP) processing may induce lipid oxidation in fat-rich foods. Antioxidants are widely used in the food industry to prevent oxidation and extend the shelf life of products. Therefore, this study aimed to evaluate the effectiveness of antioxidants in controlling the oxidation in insect paste. Two commercially available antioxidant mixtures (Loxidan 303 and Loxidan E Ros Liquid +) were separately added to fresh mealworm paste, and one set of samples was then subjected to HHP treatment (600 MPa, 5 min). Both HHP-treated and untreated samples were subsequently stored for 15 days at 5 °C and evaluated for quality parameters. Results showed that HHP was able to significantly reduce microbial counts, browning index, acid value, peroxide value and TBARs. Synergistic effects between HHP and natural antioxidants were detected in terms of microbial reduction and prevention of microbial regrowth during storage. No clear lipid oxidation was observed during the HHP treatment. However, a reduction in the browning index and pH, along with an increase in microbial counts, were detected during storage. Peroxide values remained constant in samples without antioxidants, while they decreased in pastes containing Loxidan E Ros Liquid + and increased in pastes containing Loxidan 303 during 15 days of refrigerated storage. TBARs values were stable in pastes without antioxidants, while they increased in pastes containing Loxidan E Ros Liquid + and decreased in pastes with Loxidan 303 during storage. However, HHP appeared to be effective in keeping their levels low. Fluorescence analyses revealed the reversible unfolding of the proteins, leading to protein oxidation. Overall, the study suggested that HHP may extend the shelf life of mealworm paste, with low lipid oxidation expected when vacuum packaging is applied. However, the application of appropriate antioxidant blends should be tested in future studies to achieve a stable product with a longer shelf life.