effect of contact surface area and two common storage temperatures on the oxidative stability of walnut

oxidative stability of walnut (juglansregia l.) was evaluated over a period of 1 year storage in various conditions. the whole walnuts, walnut kernels, walnut chopped kernels, walnut kernels packaged in polyethylene (pet) under vacuum and poly propylene (pp) contain of co2 were kept in a normal condition (temperature, 19-30˚с and relative humidity (rh), 35-45%). the whole walnuts and walnut kernels were also kept in refrigerator (4˚с, rh 75%). some quality parameters for the oil extracted from walnut kernels were measured throughout the storage. peroxide value of whole walnuts, walnut kernels and walnut chopped kernels pass over 2 meq o2/kg after 12, 10 and 8 months storage, respectively. peroxide value of the packaged nuts and the nuts stored at cold storage were increased only 1 meq o2/kg over a period of 1 year storage. according to the statistically analysis results, the effect of storage condition and storage time on oxidative stability of walnuts were significant (p packaging > walnuts shell > contact surface of walnut kernels with environment were defined to maintain the quality of walnut kernels during long term storage.