ABSTRACT
The demand for natural orange juice with a high quality in terms of nutritional value, physicochemical properties and sensory characteristics, and processed with a minimum of heat treatment, is presently increasing. The shelf-life of orange juices now marketed is short due to rapid microbial growth in them, even when refrigerated. The objective of this study was to determine the potential of ZnO-and Ag-filled LDPE [low-density polyethylene] nanoparticle packaging, as a new packaging method, for preserving the maximum nutritional value, freshness and shelf-life of orange juice. Nanocomposite LDPE films containing Ag and ZnO nanoparticles were prepared by melt-mixing in a twin-screw extruder. Packages prepared from these films were then filled with fresh orange juice and stored at 4°C. Microbial stability, ascorbic acid [AA] content, browning index, color value, and sensory characteristics of the juices were determined immediately after packaging and after 7, 28, and 56 days of storage. Microbial growth rate significantly decreased as a result of using the nanocomposite packaging up to 28 days of storage [p<0.05]. Reduced degradation of AA and development of brown pigments were also observed [p<0.05] in the orange juice packaged in nanocomposite packages containing 0.25% of nano-ZnO. Moreover, odor, taste and overall sensory attributes ranked highest for the orange juice packed after 28 days of storage [p<0.05]. Packages containing nanosilver increased the shelf-life of fresh orange juice to 28 days, although parts of its sensory attributes weres lost. Nanocomposite packaging containing 0.25% nano-ZnO can extend the shelf-life of natural orange juice for up to 28 days at 4°C, without any undesirable effects on its sensory characteristics