Effect of Salivary Flow Rate, Particle Size, and Concentration on Sensations and Liking for Fiber-Fortified Beverages

Xerostomia (perceived oral dryness) is a common problem in older adults, often due to hyposalivation, which can cause difficulty in eating and swallowing, resulting in insufficient dietary fiber intake. Recent work shows salivary flow rate, particle size, and concentration are major factors for particle perception in beverages. Given that disliking drives non-consumption, here we explore how particle size, concentration, and salivary flow rate may affect liking in a fiber-fortified model beverage. Beverages made with 2 particle sizes of wheat brans (D₉₀ = 976 μm and 209 μm) in 3 concentrations (5%, 7.5%, 10% w/v) were compared to a control beverage (no fiber added) and 2 commercial fiber-fortified beverages (Detoxifiber, ARG Cellulose) at 7.5% w/v concentration. Under controlled laboratory conditions, 90 adults (30% men, 58% women; age range = 18-79 years) rated beverage liking and the intensity of particles remaining in the mouth/throat. Individuals were divided into low and high salivary flow groups; rinsing time and rinse water weight were also recorded following consumption. As expected, higher particle concentration reduced liking, but particle size showed no main effect on liking. Surprisingly, no significant difference was found between salivary flow groups on liking and remaining particles perception. However, we saw a significant negative correlation (r = -0.93) between liking and particles remaining ratings. Collectively, higher concentration reduced liking, but finer particles have less impact on liking at moderate concentrations. Product developers should avoid formulating highly concentrated fiber supplement beverages and consider using finer particles to prevent beverage unacceptability.