Fortifying milk and whey-based probiotic beverages with bioactive peptides: Effects of concentration and molecular weight on fermentation, bioactivity and sensory properties

Cardiovascular diseases are the leading cause of death today. Enhancing yoghurt, a globally consumed product, with targeted peptides and probiotics offers a convenient functional-food approach to improve health without altering dietary habits. Aim: The study examined the impact of adding bioactive peptides to milk and whey-based substrates (WBS) on fermentation behaviour and product properties, intending to create a functional food. Methods: Milk and WBS were supplemented with 1, 3 and 5% of whey protein hydrolysate obtained using proteinase k (PKH), as well as peptide fractions of this hydrolysate obtained through ultrafiltration with a 3 kDa pore-size membrane (PK3). These mixtures were then fermented with ABY6 culture. Fermentative ability, pH, titratable acidity, probiotic viability, antioxidant and antihypertensive capacity, and sensory properties of the beverages were evaluated. Major Findings: PK3 addition significantly affected probiotic viability in WBS. The addition of PKH and PK3 increases the metabolic activity of the culture in both substrates. The ACE-inhibitory activity of milk and WBS was significantly increased by the addition of bioactive peptides (PK3 and PKH) before fermentation. The antioxidant activity of the product was significantly increased in all samples (more pronounced in WBSs) with the addition of whey peptides and further increased by fermentation, with the expected highest increase in the samples with the addition of 5% peptides in both substrate and 3% PK3 in the WBS. Bioactive peptides did not affect sensory properties. Sensory attributes are the primary driver of consumer choice, with participants favouring yoghurt over a WBS unless the health benefits of the latter are significantly greater. Scientific Implications: This research shows that adding specific whey-derived bioactive peptides to milk and whey-based drinks can enhance their health benefits without changing taste. These findings could help develop new functional dairy products that support cardiovascular health and are appealing to consumers.