Widely targeted metabolomics provides insights into the effect of parboiling treatment on the nutritional quality of black rice based on its improved cooking characteristics

Little is known about the cooking characteristics and the overall changes in nutrient metabolites in economically valuable and nutritious black rice (BR) under parboiling treatment. Here, we reported parboiling treatment could promote water absorption while cooking, thus shortening the cooking time and leading to a softer texture of cooked BR. On this basis, we compared metabolites between untreated BR (UBR) and parboiled BR (PBR) through widely targeted metabolomics. Compared with UBR, PBR had significant increases in 129 differential metabolites, such as six tricin derivatives (5.8-1941-fold changes). KEGG analysis revealed that these changes in metabolites may be related to variations in the metabolism of phenylalanine, tyrosine and various secondary metabolites. indicating that parboiling can improve the nutrition of BR. More importantly, the nutritional advantages of 78 differential metabolites were still maintained in PBR after cooking, despite of a certain loss of anthocyanins possibly due to degradation into aglycones and phenolic acids. These results suggest that parboiling treatment is a good strategy to improve the cooking characteristics and nutrition of BR.