No abstract

The analytical method for the metabolomics of the 60 rice seeds from two main rice origins in Heilongjiang Province was developed based on gas chromatography coupled with mass spectrum. The specific differential metabolites between two rice origins were identified, and the distinguish of the two main origins was illustrated by using the R software platform with XCMS software package for gas chromatography coupled with mass spectrum data processing, combined with multivariate statistical analysis software. The result indicated that the 173 peaks were detected, and 54 of which were structurally identified, covering amino acids, aliphatic acid, sugar, polyols, and so on. By comparing the data of Wuchang and Jiansanjiang origins, it was found that there were 9 special metabolites in Wuchang origin and 8 special metabolites in Jiansanjiang origin. The 10 differential metabolites with significant changes (P<0.05, VIP ≥ 1) were filtrated. It is indicated that the differential metabolites of rice carry information of their origin and there are the differences in the metabolites of rice in two main origins. The proposed method is expected to be useful for the metabolomic researches of rice.

Background and objectives Health benefits of cereals depend not only on the intake levels but also on their processing methods and conditions. In this work, effects of processing treatments, including steaming, cooking, and roasting on the free and bound phenolics content and antioxidant properties of mung bean, were investigated. Findings The free phenolics content of mung bean significantly decreased (p < .05), while the bound phenolics content significantly increased after processing. The loss in the free phenolics content was found to be greater after cooking, followed by steaming, and roasting. However, cooked mung bean samples showed greater bound phenolics content than that of steamed or roasted ones. Antioxidant activity of mung bean phenolics retained or even enhanced after processing depending processing method, duration, and temperature as well as phenolics type, that is, free and bound. Furthermore, a positive correlation was found between the free or bound phenolics content and antioxidant activity of mung bean. Conclusions The processing of whole mung bean grain resulted in the change of the composition content of phenolics and changed the antioxidant activity. It was feasible to maintain the active by adjusting the processing mode and conditions of grain. Significance and novelty The antioxidant activity modification promoted by the processing treatment could increase the potential applications of mung bean.

BackgroundStorage is an essential part of brown rice circulation. During the storage process, the metabolic activity of brown rice is still ongoing, and long‐term storage leads to the deterioration of brown rice. Metabolomics analysis was performed using gas chromatography–mass spectrometry to investigate the changes in metabolites of brown rice after storage at 18 °C for 12 months.ResultsIn terms of quantity, sugar, fatty acids, and other metabolites in brown rice decreased after storage, and alcohols, aldehydes, phenols, and amines increased. A total of 34 differential metabolites were screened. In terms of contents, carbohydrates, amino acids, and fatty acids of brown rice decreased after storage, while those of sugar alcohol, amines, and aldehydes increased after storage. Cluster analysis of the samples at zero storage time revealed that the metabolites expressed least became highly expressed after storage and those expressed highly became low after storage. Metabolic pathway analysis showed that storage significantly influenced the lipid metabolism in brown rice. Palmitoleic acid, cholesterol, linoleic acid, and lauric acid are four key metabolites in lipid metabolism during storage of brown rice.ConclusionSignificant changes occurred in quantity and type of brown rice metabolites after storage. Storage has the greatest effect on lipids. Storage caused a ‘reverse change’ in the metabolites content of brown rice. The results obtained may help in understanding the changes in metabolites profile and delaying of the quality deterioration of brown rice during storage.

Metabolomic studies were carried out using gas chromatography and mass spectrometry (GC‐MS) on Daohuaxiang variety rice (Oryza sativa L.) from the Wuchang Geographical Indication Rice Protection Area in Heilongjiang Province, to investigate the effects of storage on brown rice metabolism. The data were subjected to principal component analysis (PCA), orthogonal partial least squares‐discriminant analysis (OPLS‐DA), and cluster analysis using software such as SIMCA. Analysis of the samples led to the identification of a total of 160 metabolites. No significant differences were found in the amount of metabolites before and after storage. A total of 31 differential metabolites were screened, and the changes in metabolite content showed a “reverse change” overall. Storage significantly changed the content of various metabolites in rice, with fatty acids impacted most significantly. Metabolic pathway analysis revealed that fatty acid biosynthesis is a key metabolic pathway in rice storage. The degradation of brown rice quality caused by storage is closely related to the composition and content of its metabolites, and that change in lipid content significantly affects brown rice quality during storage.