Biopolymer films have several industrial applications because they are environmentally sustainable. Cassava starch is a biopolymer that is easily available, but has limitations: it is hydrophilic, poorly resistant and degradable. The improvement of these properties was proposed in this research from the use of bentonite clay (BT) as a filling material. The compatibilization of this in the polymer matrix was obtained by ion exchange with an organic anionic surfactant. The formation of intercalated or exfoliated starch nanocomposites in the presence of natural or modified clay was characterized by XRD, FTIR, AFM and SEM. The improvement of water vapor, thermal and mechanical properties was investigated by WVP, solubility, TGA and tensile test. The starch nanocomposites in the presence of modified clay showed a better result than those of natural clay. There was no significant difference in the color of the starch film in the presence of the natural or modified clay.

Coatings technologies with biopolymeric films are effective in maintaining the chemical and sensory characteristics of several fruits. Cassava starch is an attractive biopolymeric because of its renewable characteristics and low cost, but it has a high transfer rate of water vapor. Hydrophilic compounds of organically modified montmorillonite clay by ion exchange can be used to improve the limiting properties of starch in exchange for additives such as lipids. The solutions prepared with 5% m/v starch / 5% m/m cationic / anionic clay and uncoated were applied in caja fruit, harvested at physiological maturity, selected for absence of defects and color uniformity. The experimental design was performed with four storage times (0, 3, 6 and 9 days). For the maturation index, there was an isolated effect of the type of coating and storage time, showing the composite films of modified cationic clay with greater MI of the fruits in comparison to the control fruits.

Films and edible coatings of natural polymers have been proposed as an attractive alternative for conventional plastic packaging because of their excellent biodegradability and biocompatibility. However, natural polymers, like chitosan, are hydrophilic and present poor water barrier properties. The addition of wax or other hydrophobic substances decreases water permeability of natural polymers but can increases their opacity.The objective of this work was to produce biofilms based on chitosan and different concentrations of carnauba wax and analyze their optical and barrier properties. The films were obtained by dissolving chitosan in acetic acid. Carnauba wax was incorporated into film-forming solutions at0, 15, 30, 40 and 50% (w/w). The opacity increased with higher concentrations of wax, the film with 50% of wax showed the highest value with an increase of 10.5% compared to the control film. The water vapor permeability decreased from 2.73 g.mm/kPa.m2.h (0% of wax) to 0.77 g.mm/h.kPa.m2 (40% of wax). The solubility decreased to about 60% over the control films, and the contact angle increased from 53º to 83º, in film with 0 and 50% of wax, respectively.