Effects of enzymolysis and fermentation on the antioxidant activity and functional components of a coarse cereal compound powder based on principal component analysis and microstructure study

ABSTRACT: In this study, a coarse cereal compound powder (CCCP) was prepared through enzymolysis, fermentation, and joint treatment with 10 coarse cereal types as raw materials. Using 10 evaluation indices, namely the scavenging capacity of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH•), 2,2′‐azino‐bis‐(3‐ethylbenzthiazoline‐6‐sulfonic acid) (ABTS(+)), hydroxyl (OH•) and superoxide anion (O(2) (–)), the Fe(2+) chelating capacity, the content of anthocyanin, flavone, soluble dietary fiber, reducing sugar and protein, antioxidant activity, and functional components of CCCP prepared by different methods were compared. Principal component analysis (PCA) was performed to establish a quality evaluation model of CCCP. Then, the effects of different treatments on the microstructure of CCCP were investigated. Two principal components (PCs) were extracted from PCA, with a cumulative contribution rate of 97.014%. In addition, the analysis of thermodynamic properties indicated that the initial gelatinization temperature of CCCP decreased after enzymolysis and fermentation and that it was easier to gelatinize. Particle size analyses revealed that different treatments could reduce the sample particles to different degrees. The average particle size in the three study groups decreased. Scanning electron microscopy (SEM) revealed that after different treatments, the samples were destroyed to different extents, which facilitated easy dissolution of active substances. Fourier‐transformed‐infrared spectroscopy (FTIR) revealed that the changes of CCCP functional groups after fermentation and joint treatment were more significant than those after enzymolysis. PRACTICAL APPLICATION: In this study, enzymolysis and fermentation techniques were used to improve the antioxidant activity and functional components of CCCP, and the effects of different treatments on the microstructure of CCCP were investigated. The bioavailability and nutrient composition of CCCP could be significantly improved by pretreatment, provide useful reference for the development of beneficial ingredients in cereal meal products and the application of different pretreatment methods.