Analysis of the effect of temperature and packing method on the quality and oxidative stability of walnuts in storage

Walnuts are rich in a variety of nutritional components. However, due to their high content of unsaturated fatty acids (UFAs), the quality of walnuts tends to decline during storage, which adversely affects the development of the walnut industry. This study was aimed to investigate the impacts of temperature and packaging methods on the storage quality and oxidative stability of walnuts. The Wen 185 walnut variety was selected, and the physical-chemical and nutritional indexes of walnuts stored for 42 weeks under different temperatures (−18 ​°C, 4 ​°C, and room temperature) and packaging methods (vacuum light-exposed, vacuum light-proof, vacuum-radiation light-exposed, vacuum-radiation light-proof, nitrogen-filled light-exposed, nitrogen-filled light-proof) were measured. The results showed that low temperatures, especially −18 ​°C, in combination with vacuum lightproof packaging, could effectively suppress the increase in oxidative stability indicators such as acid value (AV) and peroxide value (PV), and maintain high retention rates of nutritional indicators like tocopherol and phytosterol. This study has elucidated that low temperatures and appropriate packaging methods play the crucial roles in maintaining the quality and oxidative stability of walnuts during storage. It has provided comprehensive and valuable data support and theoretical basis for the scientific storage of walnuts, contributing to the development of the walnut industry and the guarantee of product quality.