Nutritional, functional and bioactive properties of protein isolates from edible insects for pet food applications

Abstract

The global pet food industry is undergoing rapid transformation driven by sustainability requirements, rising raw material costs, and increasing demand for nutritionally optimised and functional ingredients. Insect-derived proteins have gained signi cant attention as a sustainable alternative due to their e cient feed conversion, low environmental footprint, and high nutritional value, making them particularly attractive for premium and functional pet food formulations. Among insect-based ingredients, protein isolates ofer improved functionality, and bioactive potential compared to whole insect meals. This study evaluated protein isolates (PI) obtained from Acheta domesticus (AD), Tenebrio molitor (TM), and Zophobas morio (ZM) for their applicability in pet food production. Insects were reared on wheat meal with carrots and cabbage, thermally inactivated, vacuum-dried at 70 °C, defatted with hexane, and subjected to alkaline extraction (pH 11) followed by isoelectric precipitation (pH 3). Lyophilized protein isolates were analysed for protein content (cf 5.6), amino acid composition, antioxidant activity, water- and oil-binding capacity, and antimicrobial activity. Enzymatic hydrolysis was performed to obtain protein hydrolysates (PH) and assess their bioactivity against Escherichia coli and Staphylococcus epidermidis. The highest protein content was observed in ZM PI (76.55%), followed by TM (45%) and AD (42%). Valine, leucine, isoleucine, and lysine were the dominant essential amino acids, while methionine was the limiting amino acid in all isolates. Aspartic and glutamic acids were the most abundant non-essential amino acids. All PI showed high antioxidant activity and contained low-molecular-weight proteins and peptides (<14 kDa) associated with bioactive functionality. Favourable water- and oil-binding capacities con rmed their suitability as functional pet food ingredients. Protein hydrolysates exhibited inhibitory efects against both bacterial strains, with stronger activity against S. epidermidis. In conclusion, insect protein isolates and their hydrolysates represent a promising sustainable and functional ingredient for the global pet food industry, while economic feasibility will determine their large-scale implementation.