Use of biopolymeric coating hydrophobized with beeswax in post-harvest conservation of guavas.

Biopolymeric coatings are effective in maintaining the chemical and sensory characteristics of fruits and vegetables because they preserve innumerable nutrients effectively for long periods of storage. Coatings based on cornstarch (3%), cassava starch (2%) and gelatin (5%) were synthesized. Beeswax (BW) was added as a hydrophobic agent in the polymeric network at different concentrations relative to the dry base of biopolymer. The biofilm containing 10% BW presented the best results in the water vapor transmission rate (WVTR) and the effect of the BW incorporation was also evaluated from surface roughness and SEM. An 80% increase in elasticity and 15% decrease in solubility indicated resistance against unfavorable environmental conditions. Physical-chemical analysis showed that its use minimized weight loss, guaranteeing adequate ripening of the fruits during 15 days in a regulated environment: 15 °C ±â€¯2 °C, 90% ±2% RH. The sensorial attributes indicated better acceptability of these fruits, demonstrating the potential of this coating.

Incorporation of bentonite clay in cassava starch films for the reduction of water vapor permeability.

Complete factorial planning 23 was applied to identify the influence of the cassava starch(A), glycerol(B) and modified clay(C) content on the water vapor permeability(WVP) of the cassava starch films with the addition of bentonite clay as a filler, its surface was modified by ion exchange from cetyltrimethyl ammonium bromide. The films were characterized by X-ray diffraction(XRD), fourier transform by infrared radiation(FTIR), atomic force microscopy(AFM) and scanning electron microscopy(SEM). The factorial analysis suggested a mathematical model thats predicting the optimal condition of the minimization of WVP. The influence of each individual factor and interaction in the WVP was investigated by Pareto graph, response surface and the optimization was established by the desirability function. The sequence of the degree of statistical significance of the investigated effects on the WVP observed in the Pareto graph was C>B>A>BC>AC. Interactions AB, BC and AC showed that the modified clay was the factor of greater significance.