Effects Of Modified Atmosphere Storage On The Quality Of Walnut Kernels And Processed Products

Juglans regia L. is one of the world's four major dried fruits, and its kernel has great nutritive and economic value. The fat content of walnut is above 60%, which turns the walnut into a very sensitive product owing to rancidity. Modified atmosphere storage is one of the most important methods in the storage of fruits and vegetables. But the research on the modified atmosphere storage of walnut was not found. This paper studied the effects of different oxygen and carbon dioxide concentration and packaging materials on walnut kernel's storage quality, to explore the appropriate gas composition and packaging materials. On the other hand, the effect of different storage conditions on the preservation of walnut kernel was observed and the change of amber walnut's quality was discussed.The research contents and the results are as follows:1. The effects of different gas composition and packaging materials on the storage quality of walnut kernelThe experiment was carried out to evaluate the effects of gas composition on walnut kernels. The walnut kernels were stored under the conditions of air temperature at (2±1)℃with the concentration of oxygen was 3% and carbon dioxide was 20%,30%,40%, 50%, respectively. The nano was packaged with nano packaging material.The control was stored directly at (2±1)℃. Peroxide value (POV), acid value (AV), and relative humidity (RH) were investigated regularly. The experimental results showed that, different carbon dioxide concentrations had some effect on the preservation of walnut kernels under hypoxic condition, but the difference between treatment groups was not significant. The nano-packaging had significant effect on the preservation of walnut kernels. Hypoxia can inhibit the oxidative deterioration of walnut kernel and extend the storage period.The walnut kernels were stored under the conditions of air temperature at (2±1)℃, KNY17||CPE80 packaging material and with the concentration of oxygen was 3% and carbon dioxide was 0,20%,30%,40%,50%, respectively. Peroxide value (POV), acid value (AV), water content, and relative humidity (RH) were investigated regularly. The experimental results showed that, the package of nitrogen, and the one of low O2 and high CO2 concentration were consistent with the preservation of walnut kernel. The effect of different concentrations of carbon dioxide on the preservation of the walnut was not significant.The walnut kernels were stored under the conditions of KNY17||CPE80 packaging material, air temperature at (2±1)℃with the concentration of oxygen was 3% and carbon dioxide was 0,3%,7%,10%, respectively. The control was packaged with KNY17||CPE80 material. Peroxide value (POV), acid value (AV), water content, and relative humidity (RH) were investigated regularly. The results showed that, the KNY17||CPE80 packaging had significant effect on the preservation of walnut kernels, but the groups of 3%CO2,7%CO2, and 10% CO2 didn't have significant difference.2. The effects of different gas composition and packaging materials on storage quality of amber walnutWhen the storage finished, the walnut kernel was processed into amber walnut. And the amber walnut was stored at 37℃for one month and its quality indicators were detected periodically. The results showed that, the peroxide value of 1+20%CO2,1 +30%CO2, 1+40%CO2,1+50%CO2 and nano-packaging group were lower than other groups, and their fresh-keeping effect was obvious.