CAUIM: Amazonian Cassava-Based Programmable Biocolloid

Biological materials offer a sustainable and biocompatible alternative to silicon-based electronics, yet their application in computing remains constrained by material variability and limited functional control. Here, we demonstrate that \textit{cauim}, a traditionally fermented cassava beverage from South America, functions as a programmable biological colloid with memristive properties, making it suitable for logic operations. The system exhibits non-pinched hysteresis, voltage-dependent conductance modulation, and stable resistance switching that can be described using a hybrid memristor model incorporating parallel memristance and capacitive elements. Microscopy analysis reveals a hierarchically porous starch network with submicron cavities, and FTIR spectroscopy confirms the presence of polysaccharide components critical for electrical functionality. By modulating the input frequency, the colloid performs reconfigurable Boolean logic operations, including AND, OR, and complex logic expressions, without requiring physical alterations to the substrate. Input pulse durations from 10 to 200~ms enable transitions from simple conjunctions to higher-order disjunctions, demonstrating frequency-controlled logic programmability. These results position fermented biological colloids as functional substrates for unconventional computing, with potential applications in neuromorphic systems and soft bioelectronic devices.