Sapote gum (SG), tunta (TS), and bitter potato starches (PS) are promising Peruvian biopolymers that have not been studied in coatings for fruit preservation. The present work aimed to study the influence of the composition of the coating based on tunta and potato starch and sapote gum on the characteristics of the baby banana in storage. Ten formulations were obtained according to a simplex-lattice mixture design (SLMD), and coating forming solution (CFS) and bananas coated were analyzed. CFS were analyzed according to turbidity, light transmission barrier, color, and viscosity. Bananas coated with CFS were analyzed according to weight loss, color index, and firmness. A total of 100% PS and 50% TS:50% PS CFS presented the higher viscosities (8873.85 and 7874.34 mPa.s, respectively), which generated thick coatings, and did not cover the banana surface homogeneously, affecting the preservation process. On the other hand, 100% TS and 100% SG, with intermediate and low viscosities (4047.68 and 58.62 mPa.s, respectively), generate thin coatings that preserved the banana characteristics after 12 days of storage (color index: −6.6 (green) and firmness ~63 N). 100%TS also presented the lower weight loss (16.53%) being the best formulation. Results were confirmed by the modeling option of SLMD, although high model fits were not achieved.