Harnessing the effect of pectin addition in enhancing the structural properties of date syrups

Date syrup is a widely utilised natural sweetener in the Middle East, yet its conventional production involves high temperature, often leading to undesirable browning, HMF formation, and nutrient degradation. This study examined the effect of incorporating low-methoxyl pectin (LMP, DE 31%) and high-methoxyl pectin (HMP, DE 85%) into syrups extracted at 25, 50, 75 and 90°C. Pectin addition (LMP and HMP) retained higher moisture (40–50%) and reduced °Brix to 47–54 due to water entrapment by pectin gel network when compared to control syrups. Colour stability was improved, with L* values increasing from 9-15 (control) to 18–24 in pectin-containing syrups. Pectin addition reduced browning index in 50°C and 75°C (289 for LMP, 268 for HMP) extracted syrups when compared to control (312) highlighting pectin’s protective effect in limiting the formation of brown pigments during thermal processing. Viscosity dropped from 12.58 Pa·s (25°C control) to 6.37 Pa·s (90°C control), but pectin, mainly HMP, raised viscosity especially in 75°C extracted syrup. Storage modulus (G′) of controls decreased from 0.0925 MPa (25°C) to 0.0099 MPa (90°C), whereas LMP addition enhanced gel strength especially when added in samples extracted at 50°C (0.0441 MPa) and 75°C (0.0267 MPa). DSC revealed improved thermal stability, with HMP-enriched syrup showing a higher peak (∼191°C) compared with 122°C in control at 75°C. Microstructure characterisation also confirmed these findings, where LMP produced compact fibrillar networks and HMP produced smoother, sheet-like structures, both contributing to improved gel smoothness and structural improvements. Overall, LMP demonstrated superior water-binding and gelation, while HMP contributed to improved thermal property, confirming pectin as a valuable hydrocolloid to enhance syrup quality and processing efficiency.