EFFECT OF INTERNAL AND EXTERNAL IONIC GELATION ON THE RHEOLOGICAL PROPERTIES OF ALBUMEN, PECTIN, AND BURITI OIL EMULGELS

Emulgels based on protein-polysaccharide complexes are promising matrices for the food industry. This study focuses on the combination of egg albumen (ALB) and amidated low-methoxyl pectin (PEC), which together create a synergistic system for structuring and protecting vegetable oils. The aim was to develop and characterize emulgels stabilized by the ALB:PEC combination, using buriti oil as the lipid phase, while evaluating the impact of different ratios and crosslinking methods on their rheological properties. Emulgels were formulated using 10% albumen and 2% pectin solutions, incorporating 8% oil. Samples were prepared in two ratios: 80:20 and 60:40 (ALB:PEC), using two different ionic gelation methods. For external gelation, the network was crosslinked with a calcium chloride solution (2% w/v). In contrast, for internal gelation, calcium carbonate (2% w/v) and acetic acid were used. Viscoelastic properties were analyzed through oscillatory rheological tests. After conducting an amplitude sweep at a 1% strain, frequency sweeps were performed. The results showed that all formulations exhibited typical gel behavior, characterized by a storage modulus (G') higher than the loss modulus (G'') and low frequency dependence. It was found that the gelation method influenced the strength of the samples. External gelation produced more rigid and dense matrices, with G' values ranging from 52 kPa to 62 kPa, due to intense crosslinking. In contrast, internal gelation led to the formation of weaker matrices, with G' values between 8 kPa and 15 kPa, attributed to the slower ionic crosslinking process. Furthermore, in the case of external gelation, the 80:20 ratio resulted in a more structured network compared to the 60:40 ratio, indicating that a higher protein content favored three-dimensional packing around the oil droplets. In conclusion, the properties of these emulgels can be effectively modulated by choosing the appropriate crosslinking method and biopolymer ratio. The external gelation technique is recommended for applications requiring high mechanical firmness, while the internal gelation technique is more suitable for producing softer structures.