Evaluation of Interactions of Added Soybean Peroxidase with Other Nutrients Present in Fish Feeds Using an In Vitro Digestive Simulation

SIMPLE SUMMARY: Peroxidase (PO) is effective at mitigating or eliminating mycotoxins in fish feeds. However, the literature does not describe how the free radicals produced during oxidation by PO can interact with other nutrients and active compounds present in such feeds, affecting their bioavailability and modifying both the metabolism of the species and the quality of the final product. The objective of this study was to evaluate the impact of using PO as a treatment against mycotoxins on the nutritional quality of the fatty acids and polyphenols present in a fish feed. The results demonstrate that applying PO may have unwanted side effects on long-chain polyunsaturated fatty acids and the digestive bioaccessibility of polyphenols. ABSTRACT: Peroxidase (PO) has been applied in different areas of industrial biotechnology, including the control of contaminants like aflatoxin B(1) in fish feeds. However, its potential negative interactions with the macro and micro components of feeds have not been evaluated. The aim of this study was to evaluate the impact of PO’s addition to a feed on compounds like fatty acids and polyphenols using an in vitro simulation of the digestive tract of the tilapia. The influence on fatty acids was determined by changes in the peroxide index, with the feed including PO presenting values four times higher than those of the control feed. On the other hand, the in vitro digestive simulation also evidenced an effect of PO on the bioaccessibility of polyphenols significantly influenced by the total digestion time and temperature. The bioaccessibility of polyphenol ranged from 2.09 to 16.23 μmol of the total Trolox equivalent antioxidant capacity for the combinations evaluated in the study. The greatest bioaccessibility was observed at the central point under the following conditions of digestive hydrolysis: pH of 7, 30 °C, 4.5 h of digestive hydrolysis and an absence of PO.