Effects of Different Storage Methods on the Contents of Polycyclic Aromatic Hydrocarbons in Lactuca sativa

The main purpose of this study was to research the change tendency of PAHs contents in vegetables under different storage temperatures (H₂O₂ treatment, oxalic acid treatment, fresh bag treatment, untreated) and different preservation measures (25, 15, 4 ℃). In this study, the Lactuca sativa with vigorous metabolism and short storage period was used as the experimental samples, and they were respectively stored in eight ways. The changes of PAHs contents in different treatments were analyzed and compared. The results showed that the PAHs contents of untreated Lactuca sativa decreased significantly with the increasing of storage time and temperature under the conditions of normal temperature storage 25, 15 and 4℃, and the 15 ℃ cold storage treatment group decreased the most. Under the storage conditions of 25 ℃, 15 ℃ and 4 ℃, the contents of PAHs increased on the first day of storage due to the loss of water by transpiration. The PAHs content of the packaged Lactuca sativa increased in the early stage of storage, and the growth rate was negatively related to the temperature, and the PAHs content was mainly changed by low ring PAHs. Under the 15 ℃ cold storage, the final PAHs contents in Lactuca sativa after different preservation treatments compared with the initial PAHs content decreased in order of H₂O₂ treatment > no treatment > oxalic acid treatment > fresh bag treatment. Under different storage conditions, the PAHs content of 2-ring and 3-ring changed most significantly (P＜0.05), followed by 4-ring, and 5-ring and 6-ring were least. This study would have important significance for the systematic analysis of PAHs residues in vegetables during storage and the improvement of safety and health evaluation of vegetables.