Steady and dynamic shear rheology of Indian Jujube (Ziziphus mauritiana Lam.) fruit pulp with physiochemical, textural and thermal properties of the fruit

Abstract

Indian jujube (Ziziphus mauritiana Lam.) is a globally underutilized fruit and is well-known for being a good source of total phenolics and a rich source of ascorbic acid with essential minerals such as calcium, phosphorus and iron. A rheometer was used to investigate the rheological characterization of Indian jujube pulp. It was found that Indian jujube pulp exhibit a shear thinning behaviour as viscosity (η) and shear stress (σ) of pulp significantly (p < 0.05) decreased as the shear rate (γ̇̇) increased. Pulp's behaviour was characterized efficiently by correlating Power-law, Carreau-Yasuda, and Cross models with flow curve. The Cross model was found more efficient (R2:0.99775) than the Power-law (R2:0.85995) and Carreau-Yasuda model (R2:0.97291). Dynamic shear rheology test of the Indian jujube pulp presented weak gel behaviour as storage modulus (G') surpassed loss modulus (G") value. The frequency dependency of both the storage G′ and loss G′′ moduli was evaluated using a power Law model with a determination coefficient (R2) greater than 0.9. The tan(δ) values (0.020 to 0.535) suggested that the Indian jujube pulp is elastic in nature. Textural properties of Indian jujube fruit like hardness, percentage deformation at the hardness and peak stress of Indian jujube fruit were 32.76 ± 5.00 N, 7.15 ± 1.06% and 17780.80 ± 3185.47 N/m2. DSC curve showed glass transition phase of unprocessed Indian jujube fruit flesh at (98.29°C), and specific heat (Delta Cp) was found 193.96 J/g. The findings of this study will aid in the development of handling and processing machinery for the commercial manufacture of Indian jujube pulp.