| چکیده انگلیسی مقاله |
Background and objectives: Thirty percent of agricultural products are annually wasted in Iran, 7 to 8 percent of which are due to improper packaging. In this study, the effects of seven types of nanofilms with low a permeability to oxygen and water vapor on organoleptic and microbial properties of bread were investigated. Materials and methods: Voluminous (i.e., non-flat) bread samples packaged in nanofilms were stored at 5°C, 20°C and 35°C and tested for organoleptic properties on days 1, 3, 5, 7, 14, and 21of storage. Also microbial counts in the samples kept at the 3 temperatures were made on day 14. Results: The three main factors affecting significantly staling of the bread samples were type of nanofilm, temperature, and length of storage. The effects of combination of each 2 factors were also statistically significant (p< 0.01 and 0.05). The lowest and highest amounts of staling on day 14 occurred in bread packaged in a 3% composite film (500ppm silver and 450ppm clay) and in the control package sample (with no nano-particles), respectively. The total microbial count decreased with increasing silver nano content of the film, such that the 2% (1000ppm) silver film had the lowest count. In addition, the control packaging at the 3 storage temperatures showed the highest counts for coliform and moulds. The lowest and highest counts for coliform and moulds were found in nano-packaging samples kept at 5°C and 35°C, respectively. Conclusion: In conclusion, the nano composite film with 3% nano-particles (SC3) was judged to be the best film due to lower cost and longer conservation of bread freshness. Key words: Bread, Nanofilms, Organoleptic properties, Microbial properties. Temperature, Storage |