The effect of nano-coatings with α-tocopherol and xanthan gum on shelf-life and browning index of fresh-cut Red Delicious apples

The objective of this study was to prepare nanoparticles and nanocapsules using the emulsification-diffusion method, and then evaluate the effectiveness of several systems made with DL-alpha-tocopherol on the browning index and firmness in fresh-cut apples. Poly-epsilon-caprolactone was used as a biopolymer to form the membrane of nanocapsules and the matrix of nanospheres. To provide greater functionality to the coating, xanthan gum was added to some of the systems tested. Changes in the treated fruit were monitored during 18 days of cold storage. The micrographs obtained give evidence of the presence of capsular entities. Particle size was 174 to 240 nm, and the zeta potential was -44 to -56 mV, which indicates that the systems were stable. With respect to the browning index, nanocapsules proved to be the most effective system, followed by nanospheres. Firmness changes were reduced by applying nanocapsules and nanospheres, both of which limited variations in firmness to below 15% (6.1 and 63 N, respectively). These results confirm that the use of nanoparticle systems does indeed help maintain the quality of fresh-cut apples. Industrial relevance: This study shows the advantages of using edible coatings containing nanosystems to preserve fresh cut fruits in particular the apple. The results show clearly that nanotechnological coatings decrease the browning index and preserve the firmness by longer times compared with the xanthan gum and control. Nanocapsules containing DL-alpha-tocopherol were the best system followed by nanoemulsions and nanospheres. The systems were prepared by the emulsion-diffusion method from acceptable food materials. This process is efficient, versatile and of simple implementation to industrial level. On the other hand, the nanosystems can be easily applied by dipping or spraying as conventional coatings in production lines, and they do not require special equipment. Apparently the effect of nanosystems is attributed to their high superficial area and the modification of membrane permeability due to their lipophilic nature. Furthermore, the food industry is continuously growing, so that the application of antioxidants in a nanocapsule form is a choice of easy application, in accordance with current systems of conservation of fresh-cut fruit, helping to increase the shelf life of apples and other products of high marked demand, thereby reducing product losses (C) 2013 Elsevier Ltd. All rights reserved.