Effects of nanofilms packaging on organoleptic and microbial properties of bread

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. 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. 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. 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.