Changes in Quality Characteristics and Metabolite Composition of Low-Temperature and Nitrogen-Modified Atmosphere in Indica Rice during Storage

A low temperature (LT) is used to delay grain deterioration effectively. In practical applications, a nitrogen-modified atmosphere (N₂) is also an effective way of preventing grain pests and delaying grain deterioration. However, there are few studies on grain quality changes using a combination treatment of an LT and N₂ during storage. In this study, the storage quality, processing characteristics, and metabolites of rice under conventional storage (CS), LT (20 °C), N₂ (95%), and LT+N₂ treatments were analyzed for 180 days, under a controlled humidity of 65% ± 2%. The results showed that compared to the CS, LT, and N₂ treatments, the LT+N₂ treatment had the best effect in retarding the increase in MDA and electrical conductivity and deferring the decrease in CAT activity. In addition, the LT+N₂ treatment maintained the color of the rice better and sustained a better processing quality. Non-targeted metabolomics analysis further confirmed that the LT+N₂ treatment maintained the vigor of the rice and retarded its spoilage by activating the metabolisms of amino acids, carbohydrates, and flavonoids. These results suggest a favorable practice for preventing storage deterioration and increasing the processing quality for rice storage. They provided new insights into the mechanisms of rice quality changes using the combination treatment of an LT and N₂.