Investigating a galactomannan gel obtained from Cassia grandis seeds as immobilizing matrix for Cramoll lectin

• The galactomannan gel with immobilized Cramoll 1–4 has stable physical properties.
• The system presented constant pH and color parameters, and no microbial counting.
• The galactomannan gel maintained the biological lectin activity for up to 30 days.
• The galactomannan gel may improve the quantity of Cramoll 1–4 available for promisor applications.

Characterization, with emphasis on the rheological properties, of Cassia grandis seeds galactomannan gel containing immobilized Cramoll 1–4 is presented. The gels, with and without immobilized Cramoll 1–4, were evaluated along time by rheometry, pH, color, microbial contamination and lectin hemagglutinating activity (HA). Rheological determinations confirmed the gels to be very stable up to 30 days with variations occurring after this period. Rheological data also showed that the gel/Cramoll 1–4 immobilizing matrix loses its elastic modulus substantially after 60 days. Both gels presented no microbial contamination as well as a pH close to neutral. Colorimetric parameters demonstrated the gels transparency with occasional yellowness. The opacity of the galactomannan gel did not change significantly along the study; the same did not occur for the gel with immobilized Cramoll 1–4 as a statistically significant reduction of its opacity was observed. In what concerns immobilized Cramoll 1–4 HA, up to 90% of its initial HA was maintained after 20 days, with a decrease to 60% after 60 days. These results combined with the thickening and stabilizing characteristics of the galactomannan gel make this gel a promising immobilizing matrix for Cramoll 1–4 that can be further exploited for clinical and cosmetic applications.