Development and characterization of bioplastics based on different varieties of corn starch (Zea mays L.): Morphological, thermal and mechanical properties

In response to the growing demand for sustainable packaging alternatives, this study aimed to develop and characterize edible, biodegradable biofilms produced from starches extracted from five corn varieties (Zea mays L.): yellow, white, colorado, purple-husk, and purple. The starches from the varieties were evaluated for extraction yield, amylose content, and presence of bioactive compounds, while the resulting biofilms were characterized in terms of morphological, barrier, thermal, and mechanical properties. Starch extraction yield ranged from 18.31 % (yellow corn) to 30.40 % (white corn), with the latter showing highest efficiency. The average amylose content was 26.87 %, with purple corn presenting the highest value (27.80 ± 0.22 %) and purple-straw corn the lowest (25.90 ± 0.05 %). Bioactive compounds such as lutein, zeaxanthin, gallic acid, and cinnamic acid were identified in all varieties, with purple corn exhibiting the highest concentrations of lutein (2.53 μg/g) and zeaxanthin (10.14 μg/g). The films showed thickness between 0.056 and 0.060 mm and water solubility ranging from 27.08 ± 4.31 % (white corn, least soluble) to 37.22 ± 0.40 % (purple corn, most soluble), as well as significant color differences (ΔE from 1.80 to 27.57). Thermal analysis revealed maximum gelatinization temperatures between 95 °C and 110 °C, while storage modulus (E') varied from 800 to 1400 MPa. These results highlight the potential of starches from different corn varieties, particularly purple corn, for developing functional bioplastics. The films exhibited suitable physical, thermal, and bioactive properties for use as edible coatings and biodegradable packaging, representing sustainable, value-added alternatives for the food industry.