Combined effects of pretreatment and type of protease on the chemical and bioactive properties of edible bird’s nest glycopeptides

Edible bird’s nest (EBN), rich in glycoproteins, is valued for its nutritional content. Broken EBN pieces contaminated with fine feathers are often discarded. This study examines the combined effects of different pretreatments (boiling, ultrasound, autoclave) and proteases (Alcalase^®, Flavourzyme^®, Neutrase^®, papain) on the chemical and bioactive properties of EBN hydrolysate (EBNH). Initially, 4%(w/v) of EBN underwent boiling, ultrasound, and autoclave treatments, with untreated EBN as the control. Pretreated EBN was then hydrolysed using Alcalase^®, Flavourzyme^®, Neutrase^®, papain. The effects on EBNHs were evaluated based on viscosity, degree of hydrolysis (DH), total soluble protein (TSP), total free sialic acid (TSA), FTIR, and bioactivities (ABTS, FRAP, anti-lipoxygenase activities). Boiling was the most efficient pretreatment, resulting in EBNH with the highest DH (2.5–2.7%), TSP (11–13 mg/mL), ABTS activity (43–57%), anti-lipoxygenase activity (78–82%), and low viscosity (< 2.0 mPa.s). EBNHs from boiled EBN hydrolysed with Neutrase^® exhibited the most prominent antioxidant and anti-inflammatory activities. This study suggests combining boiling with Neutrase^® hydrolysis for optimal EBNH bioactive properties, emphasizing the need to tailor enzymatic processes to enhance EBNH functionality.