Use of solid lipid nanoparticles (SLNs) in edible coatings to increase guava (Psidium guajava L.) shelf-life

The objective of this work was to prepare solid lipid nanoparticles (SLNs) based on the hot lipid dispersion method using a rotor-stator device in order to obtain a submicronic system and evaluate the effect of SLN-xanthan gum coatings on the guava shelf life. Candeuba (R) wax was used as a component of SLN. The coating was formulated with xanthan gum (4 g/L) and polyethylene glycol (5 g/L) in order to form a continuous film retaining the SLN. The SLN concentrations were varied from 60 to 80 g/L and were compared with the control and xanthan gum. These were evaluated (n = 3) every third day. The film-forming dispersion was applied by dipping the guavas and storing them under refrigeration at 10 degrees C and 85% RH for 30 days. Every 5 days guava samples were transferred to room temperature (25 degrees C) in order to assess the effect of maturation on the changes in weight loss, chemical quality, texture and color. It was established that Candeuba (R) wax as a SLN maintained the quality of guavas, and that the SLN concentration in the film formation depends on the characteristics of the fruits. The best results were obtained with SLN concentrations of 60 and 65 g/L since at these concentrations, guavas showed the lowest range of weight loss and preserved the best quality compared to the fruits processed at concentrations above 70 g/L In addition high contents of SLN cause physiological damage and also delay the maturation which can be observed by the greenness color without changes. (C) 2013 Elsevier Ltd. All rights reserved.