Rheological alteration in W/O emulsions using controlled aggregation and heteroaggregation of cellulose ethers with protein and polysaccharide in aqueous phases

Despite the potential benefits of using cellulose ethers and their combination with other polysaccharides and proteins in the creation of reduced-fat water-in-oil (W/O) emulsions, research in this specific area is currently limited. Further studies are needed to explore the optimal combinations and concentrations of these materials to achieve emulsions with desired texture and higher rheological properties. To address this research gap, seven W/O emulsions with a 40 wt% water phase at pH 3.5 are prepared. The water phase consisted of 2 wt% methylcellulose (MC) or hydroxypropyl methylcellulose (HPMC) combined with 10 wt% whey protein isolate (WPI) and/or kappa-carrageenan (kC). The oil phase, comprising 60 wt%, contained 8 wt% polyglycerol polyricinoleate (PGPR) in soybean oil . The emulsions were initially prepared at room temperature and subsequently subjected to a heating process at an elevated temperature of 90 °C for a duration of 30 min. Following this heating step, the emulsions were then cooled back to room temperature. This sequential temperature treatment was employed with the intention of inducing aggregation and gelation within the emulsions. The temperature oscillation measurements (G* versus temperature) provide further evidence for the role of covalent and noncovalent bonding in the rheology and gelation of WPI-based emulsions. The viscosity and moduli of unheated and heated emulsions containing combinations of HPMC were found to be higher compared to those containing MC combinations. This behavior can be attributed to the stronger intermolecular interaction between HPMC, WPI, and/or kC, as well as their attachment with PGPR. These interactions lead to the formation of a more viscous and firmer W–O interface in emulsions.