ARTICLE 66 FEED & ADDITIVE MAGAZINE September 2025 Lipid oxidation refers to the chemical degradation of lipids, particularly unsaturated fatty acids, and it plays a crucial role in food spoilage, biological aging, and disease processes. There are three main forms of lipid oxidation, autoxidation, enzymatic oxidation and photooxidation. Autoxidation (also Free Radical Oxidation) is the most common form and occurs spontaneously in the presence of oxygen. It consists of three phases: initiation, where lipid radicals are formed, propagation where a chain reaction lipid peroxides are formed, and termination where radicals combine to non-radical products. The breakdown products of lipid peroxides are responsible for the rancid smell and consist of aldehydes, ketones and alcohols. Enzymatic oxidation occurs in living organisms and involves the presence of lipoxygenase, cyclooxygenase or cytochrome P450. Lipoxygenase can be present in feed ingredients of vegetable origin, such as soybean meal, and catalyze the reaction between free fatty acids and oxygen, with formation of lipid peroxides. Photooxidation involves the presence of photosensitizers, such as chlorophyll or riboflavin, that after excitation by light, can transform triplet oxygen to singlet oxygen. Singlet oxygen can react directly with fatty acids with the formation of lipid peroxides. Substantial evidence indicates lipid oxidation detrimentally impacts aquatic animal health. Lipid levels in aquafeeds, particularly for carnivorous species, commonly reach 15-16%. They exceed 30-35% in formulations for cold-water fish like Atlantic salmon. Consequently, lipid freshness is paramount for optimal aquatic animal growth and health. Regrettably, commercially available lipid sources (animal fats, vegetable oils) have been found to be of inconsistent quality and freshness frequently. Present study investigates the efficacy of various antioxidants on fish oil, soybean oil and poultry meal. MATERIALS AND METHODS Three liquid antioxidant samples of product BC, product DBX, product YZD and two powder antioxidants of product ATY and product KYB were collected from two feed mills from Zhuhai city and Wuhan city, Antioxidation management of aqua feed raw materials is essential to prevent lipid oxidation in fish oil, soybean oil, and poultry meal, which can harm aquatic animals. Various antioxidants were tested at different dosages, showing differing efficacy in prolonging stability and reducing MDA formation. Results indicate that proper antioxidant selection can significantly improve raw material freshness, though effectiveness varies among oils and meals, encouraging further evaluation of optimal formulations. ANTIOXIDATION MANAGEMENT OF AQUA FEED RAW MATERIALS Richard Liu Global Project Manager Kemin AquaScience
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