Novel neutral pH, low concentration gelling property of macambo (Theobroma bicolor L.) pulp soluble fiber

Macambo ( Theobroma bicolor L.) is a fruit native to the Amazon region that belongs to the same species as cocoa. Farmers in the Peruvian Amazon are increasingly interested in growing macambo due to its resistance to pests and growing market potential. Producers in the region solely sell the seeds, the only fraction of the fruit currently used, representing 35% of the total mass of the fruit, while the remaining pulp and husk are considered waste. The macambo pulp is rich in total dietary fiber and has the potential to be used as a food ingredient. This study focused on the macambo pulp soluble fiber (MPSF) as it was observed to be capable of forming a gel at low concentration under neutral pH. Rheological properties were analyzed at different concentrations in aqueous solutions to determine its gelling potential. The MPSF hydrogels displayed a shear-thinning behavior across all the studied concentrations, characterized by a reduced apparent viscosity with increasing shear rate. An increase in concentration was accompanied by an increase of pseudoplasticity, shown by a decrease in the flow behavior index value ( n' ). Meanwhile, the consistency coefficient ( m' ) presented increasing values with increasing concentration. The hydrogel prepared at 4.5% MPSF showed the highest elasticity, tolerance to deformation, and recovery capacity. This study reveals the potential of an edible soluble fiber extracted from macambo waste to be used as a neutral pH, sugar-free gelling hydrocolloid, which may be utilized in the food industry as structural support matrix or textural enhancement agent.