Temperature-driven kinetics and storage stability of allulose syrup for beverages

Allulose is an emerging sugar substitute, yet stability data for concentrated, industrial-grade syrup remain limited. Here, we systematically evaluated the storage stability of allulose syrup (70.4%) over 16 weeks at 4-60 °C to support beverage applications. At ≤25 °C, attributes were essentially unchanged. At ≥40 °C, color intensified whereas pH and viscosity decreased; °Brix increased, allulose declined, and 5-HMF/organic acids/esters accumulated-evidence of degradation. Kinetic profiles were biphasic, showing near zero-order behavior in the early phase (0-8 weeks) followed by late-stage acceleration (8-16 weeks). The acceleration factor (k₈-₁₆/k₀-₈) was greatest for A₄₂₀ and moderate for 5-HMF and TPC, while early-phase Arrhenius fits (40-60 °C) indicated temperature sensitivity of A420 > 5-HMF > TPC > ABTS. Accordingly, storage at ≤25 °C is recommended, and hot holding (≥40 °C) should be minimized to limit browning and increased aftertaste intensity, which coincided with elevated 5-HMF at higher storage temperatures. These results establish essential industrial guidelines for maintaining allulose quality, facilitating its broader application across the food and beverage sectors.