Rheological and physicochemical properties of pasteurized and sterilizedbambangan (Mangifera pajang) fruit puree

This study examines the effects of thermal processing on the rheological and physicochemical properties of bambangan fruit puree (BFP). Three thermal treatments were applied: sterilisation (121°C for 3 mins), low temperature long time (LTLT) pasteurisation (65°C for 15 mins), and high temperature short time (HTST) pasteurisation (90°C for 1 min). Rheological characterisation was performed using a rheometer under shear rates ranging from 1 to 250 s⁻¹ and temperatures between 5°C and 70°C. The rheological behaviour was described by the Herschel-Bulkley model, with the LTLT process showing the most suitable thermal processing with a high correlation coefficient (R² = 0.9999). The Herschel-Bulkley parameters for LTLT-treated BFP were determined as follows: flow behaviour index (n) = 0.43, consistency coefficient (K) = 5.88 Pa·sⁿ, and yield stress = 8.47 Pa. Viscosity measurements for LTLT-treated BFP exhibited temperature-dependent behaviour, with values of 19.76, 15.85, 9.96, and 7.45 Pa·s recorded at 5°C, 20°C, 40°C, and 70°C, respectively. Furthermore, the LTLT process effectively preserved the physicochemical properties of BFP, as reflected by its moisture content (87.05%), vitamin C content (175.18 mg/100 g), total soluble solids (14.03°Brix), pH (3.19), and colour parameters (L* = 64.21, a* = 20.25, b* = 65.99). These findings highlight the importance of selecting appropriate thermal processing conditions to ensure both the safety and quality of BFP, with LTLT emerging as a particularly effective method for maintaining desirable rheological and physicochemical attributes.