Survey shelf life of whole kernel and powdered almond at different temperature and packaging condition

Background and objectives: Tree nuts and their oils contain bioactive materials which have vital roles in improving human’s health. Degradation and decreasing the quality of the nuts especially in almond which have high fat is related to the oxidation. The quality of stored almond depends mainly on the kernel moisture and fat , storage temperature, relative humidity, oxygen level, type of packaging, the form of stored nut (in-shell or shelled, peeled, roasted, etc).
Materials and methods: In this research, the stability of Mamaei variety almond) Prnus amygdolus Batsch cv. Mamaei) in two physical shape (kernel and powdered) was evaluated by conjugated dienes (K232), thiobarbituric acid (TBA), index for primary and secondary oxidation products of lipid oxidation, respectively and refractive index (RI) for 10 months in the three different storage conditions, included: to expose in the direct environment air, packaging under vacuum, packaging under CO2 at ambient and refrigeration temperature in dark condition.
Results: The effect of temperature, type of atmosphere and physical shape of almond ( kernel and powder ) was significant (P≤0.05) on conjugated dienes value ( K232) and thiobarbituric acid index ( TBA ), contents. The refractive index of fresh almond obtained 1.4671 and all samples was not showed any changes during10 months of storage significantly ( P≤0.05 ). conjugated dienes value (K232) range was obtained 3.795 µmol/g in fresh almond and 11.95 µmol/g in powdered almond in the environment air exposition and in the ambient temperature. Moreover, the amount of thiobarbituric acid index (TBA) was between 0.024 mg to 0.193 mg malonaldehydes/kg almond oil for fresh almond and pow dered almond in the temperature and exposition the environment air, respectively. Packaging under vacuum and CO2 had more protective effect on the kernel than powdered on the conjugated dienes value ( K232 )and thiobarbituric acid index ( TBA ). However, at least of changes in the conjugated dienes value ( K232) and thiobarbituric acid index ( TBA) was related to the almond kernel under vacuum packaging and the refrigeration temperature storage.
Conclusion: According to the results, these factors were affected in delaying of the oxidation as well as low temperature had higher effect than packaging and the packaging had higher effect than physical shape, respectively. also, storaging in low temperature with packag under vacuum according conjugated dienes value (K232) and thiobarbituric acid index ( TBA ) most effect on delay oxidation (increase shelf life) of almond kernel and powder.