Different processing methods on anthocyanin composition and antioxidant capacity in blueberry juice: Based on metabolomics and DFT analysis

Abstract Blueberry juice is one of deep‐processed products of blueberries, anthocyanins are main bioactive substance in blueberry juice. However, anthocyanins have poor stability. Thermal, high pressure, electric field, magnetic field and cobalt source irradiation were used to treat blueberry juice, and then the treated blueberry juice composition and antioxidant capacity were determined to explore ways to better protect anthocyanins. Metabolomics was used to qualitatively and quantitatively analyze the anthocyanins in blueberry juice, a total of 54 anthocyanins were identified. Different processing methods of treatment did not significantly change the types of anthocyanins in blueberry juice. Their effects were mainly focused on the changes in content. By determining the antioxidant capacity of blueberry juice, it was found that there is more than a simple linear relationship between the total anthocyanin content of blueberry juice and its antioxidant capacity. Therefore, the structural parameters of the four main anthocyanin monomers of blueberry juice were calculated using density functional theory to predict the antioxidant capacity and the antioxidant capacity of the monomers was determined for validation. The effect of different treatments on the change of antioxidant activity of blueberry juice due to anthocyanin occupancy was explained using equivalent antioxidant. The results showed that the 1 kGy irradiation treatment had a better protective effect on the anthocyanins, whereas the change in the percentage of anthocyanins due to this treatment was the key factor for the change in their antioxidant capacity.