Physical properties of chitosan films with lemon essential oil added and their impact on the shelf life of tomatoes (Lycopersicon esculentum l.)

Chitosan forms a structural matrix that adheres to the fruit surface and combines with lipids to strengthen its water barrier and mechanical properties. In this research, films consisting of chitosan, oleic acid/beeswax and lemon essential oil were made. The fracture stress, percent elongation, and water vapor permeability of the preformed films were determined. The coatings were applied by immersion in two maturity stages (green-ripe and red-ripe) of Cuauhtemoc tomatoes; they were stored at two temperatures (25 ± 2 and 10 ± 2 °C) and the parameters of firmness, TSS, color, weight loss, CO2 and ethylene were evaluated. The chitosan-oleic acid-lemon film showed higher fracture stress than the chitosan-beeswax-lemon film (18.68 and 12.50 mPa, respectively) and lower water vapor permeability (5.08x1010g m1 s1 Pa1). Weight loss was lower in fruits treated with chitosan-oleic acid-lemon (7.9%). The fruits in a green-ripe maturity stage produced lower CO2 content in the last week of storage compared to red-ripe fruits (14.32 mg kg-1 h-1and 16.05 mg kg-1 h-1, respectively).

Keywords: mechanical properties, permeability, maturation, chitosan, Lycopersicon esculentum L.