Bioplastics from lucuma seed starch containing microencapsulated lemon verbena essential oil: physicochemical, mechanical and optical properties

ABSTRACT Agro-industrial residues represent a valuable source of biopolymers for sustainable packaging applications. Lucuma seed starch was obtained through acid and alkaline extraction, yielding a high-purity starch with elevated amylose content and predominantly oval to polyhedral granules. Starch-based bioplastics incorporating microencapsulated lemon verbena essential oil (EOM) were prepared by the casting method. Response surface methodology was applied using transparency and elastic modulus as optimization responses, identifying an optimal formulation containing 5.94 g starch, 2.00 mL glycerol, and 598.29 mg EOM. To evaluate the effect of microencapsulation, bioplastics containing free essential oil (EO) and control formulations without EO/EOM were also analyzed. EOM formulations maintained tensile strength while modulating stiffness and flexibility relative to EO-containing bioplastics and exhibited controlled optical properties and enhanced UV-barrier performance. Thermal analyses indicated that microencapsulation partially preserved thermal stability by limiting direct oil–starch interactions. Antioxidant analyses confirmed retention of antioxidant functionality in EO- and EOM-containing bioplastics. All formulations exhibited rapid disintegration under laboratory soil burial conditions, reaching near-complete degradation within 18 days. These results highlight the potential of lucuma seed starch incorporating EOM for biodegradable bioplastic applications.