Authors:H. Hosseini, M. Ghorbani, A. Mahoonak and Y. Maghsoudlou
It is believed that lipids are the most important factor affecting nuts shelf-life. In the present study, an accelerated shelf-life testing by means of elevated temperatures 62, 72, and 82 °C was conducted to predict the oxidation stability of walnuts over a long-term storage. Peroxide value (PV) was employed to monitor the lipid oxidation progression in the walnuts. A range of 74.01–79.57 kJ mol−1 K−1 energy was required for formation of primary oxidation products. The reaction changes followed an apparent first-order kinetic. Formation of hydroperoxides in walnut kernels was found to be a temperature-dependent reaction with Q10 of 2.1. Walnut kernels were also kept in normal condition (temp: 20–30 °C; relative humidity (RH): 35–45%) for 12 months to validate the shelf-life estimation approach. The results showed that PV could provide a proper estimation for oxidative stability of the walnuts stored in ordinary condition.
Authors:N. Samadi Ghorbani, M. Mazaheri Tehrani, M.H. Haddad Khodaparast and R. Farhoosh
The aim of the current paper was to elucidate the influence of temperature and time on acrylamide formation and physico-chemical characteristics of bread. Additionally, the effect of asparaginase addition to bran was evaluated. With increasing baking time and temperature, the amount of acrylamide (µg kg−1) increased. The results indicated that the acrylamide concentration in treated samples with asparaginase was significantly less than those without asparaginase treatment. Based on Pearson’ test, it was found that there was a significant correlation between baking temperature and acrylamide concentration (R=0.99, P=0.025; and R=0.98, P=0.026 for the samples prepared by baking for 2.5 min and 3 min, respectively). The firmness of bread samples increased with increasing baking temperature (P>0.05), while asparaginase addition did not significant affect the textural characteristics of the final product. Breads baked at 320 °C for 3 min were more acceptable by the sensory panel in terms of their texture and chewiness, whereas the samples baked at 370 °C for 2.5 min had the lowest score in comparison to other evaluated samples.