Development and characterization of starch films extracted from avocado (Persea americana mill) seeds incorporated with avocado (Persea Gratissima) essential oil.

The extraction of oil and starch from avocado pulp and seeds represents an efficient way to add value to an abundant but low-value byproduct. The integration of these components in the production of films for use as bioactive and biodegradable packaging is an innovative strategy to reduce the generation of agricultural waste and the use of conventional plastics, which are directly associated with serious environmental problems. In this context, the objective of this work was to develop and characterize biodegradable films using starch extracted from avocado seeds at different concentrations (2, 3, 4, 5 and 6 g/100 mL) and glycerol (30 % w/w starch) with subsequent incorporation of avocado essential oil (20 %). The films were characterized according to their physicochemical, barrier, mechanical, thermal and antimicrobial properties. The films produced were homogeneous and flexible to handling, except for the formulation with 6 g of starch, which was brittle. Increasing the starch concentration from 2 g to 5 g/100 mL in the film resulted in an increase in thickness (from 0.139 to 0.185 mm), opacity (3.069 to 3.283 %), water solubility (from 22.43 to 23.44 %), water vapor permeability (0.439 to 0.443 g.mm/kPa.h.m), increase in elongation (from 363.50 to 104.29 %) and decrease in tensile strength (from 6.12 to 4.28 MPa). The starch concentration significantly influenced (p < 0.05) the thickness values, without influencing opacity, solubility and permeability. Thermogravimetric analysis showed that 63 % of the film mass loss occurred around 270 °C. The incorporation of avocado oil into the 4 g starch/100 mL formulation did not significantly (p > 0.05) alter the physical, barrier and mechanical properties of the film. Avocado oil showed a minimum inhibitory concentration of 16 % for Staphylococcus aureus, although this effect was not confirmed in the halo test.