Analysis of the Fruit Quality of Pear (Pyrus spp.) Using Widely Targeted Metabolomics

Xenia Effect on Nutritional and Flavor Components of 'Jingbaili' Pear

The 'Jingbaili' pear is a national geographical indication product of China, featuring an oblate shape and being rich in nutrients. But the quality of the 'Jingbaili' pear is unstable. Xenia can cause changes in the quality of pears, but the effect of xenia on the 'Jingbaili' pear is unknown, and its mechanism is still unclear. In order to clarify the effect of pollination on the fruit quality of the 'Jingbaili' pear, this research pollinated 'Jingbaili' pear flowers with the pollen of 'Yali' (JY), 'Suli' (JS) and 'Huangli' (JH). The results indicated that the mass, transverse diameter and longitudinal diameter of the JY group were significantly higher than the JS group and JH group. On the other hand, the pears of the JY group and JS group obtained higher soluble sugar content. The aroma content of characteristic compounds was higher in the JY group than in the JS group and JH group. Multivariate analysis revealed significant differences in the nonvolatile metabolites among the JY group, JS group and JH group, potentially explaining the variations in the nutritional and flavor compounds of the pears. Furthermore, this research investigated metabolic changes in the pears during development and ripening under the three types of pollination. The results showed that amino acid metabolism differed among these pollination types during development. These differences may be the cause of the observed variations in the pears. This research clarified the effect of xenia on the nutritional components and flavor substances in the 'Jingbaili' pear and could provide data support for improving the quality of the 'Jingbaili' pear.

Application of a metabolomics method in the study of pear fruit storage

The entire transportation process of 'crown' pears from harvest to consumption is primarily refrigerated. However, the impact of refrigeration time and temperature on fruit quality remains unclear. In this study, metabolites of 'crown' pears were analyzed using UHPLC-Q-Exactive and GC-MS/MS techniques under cold storage, at room temperature, and at different cold storage durations. A total of 372 substances were identified, including sugars, amino acids, and flavonoids, among others. Among these substances, 27 were identified as significant biomarkers affecting pear quality. An accurate quantitative method for amino acids was established to systematically verify the change trend of L-aspartic amide, glycine, glutamic acid, and other amino acids. The results indicated that after 30 days of storage at 0 °C, there was a relatively small change in the quality and substance content of 'crown' pears with little effect on their nutritional value. These findings could serve as a reference for optimizing the refrigeration time and temperature for pear fruit.

Widely targeted metabolomics reveal the distribution of primary and secondary metabolites in pomegranate fruit

The pomegranate fruit is valued for its nutritional and medicinal properties, and the composition and content of primary and secondary metabolites are the main factors impacting its nutritional and medicinal properties. However, a deep understanding of metabolites in different parts of fruit is still lacking. Here, the peel, aril, and seed of mature pomegranate fruits were analyzed separately to compare metabolic component differences using UPLC/MS-MS. A total of 858 metabolites belonging to 11 classes were identified, of which flavonoids, such as delphinidin-3-O-glucoside and cyanidin-3-O-glucoside; tannins, such as ellagic acid and punicalin; and terpenoids, such as corosolic acid and madasiatic acid, were upregulated in the peel. Lipids, such as punicic acid, methyl linolenate, and linoleic acid; alkaloids, such as indole and choline; nucleotides and derivatives mainly including 2-deoxyribose-1-phosphate and 9-(arabinosyl)-hypoxanthine, were upregulated in seeds. Phenolic acids, such as 1-O-galloyl-4,6-(S)-HHDP-β-D-glucose and 1,7-di-O-galloyl-D-sedoheptulose, and flavonoids, such as cyanidin-3-O-glucoside, cyanidin-3-O-(2″-O-xylosyl) galactoside, and delphinidin-3-O-glucoside, were upregulated in aril. The flavone and flavonol biosynthesis (ko00944) pathways were significantly enriched between the peel and seed, as were the anthocyanin biosynthesis (ko00944) pathways between the aril and seed and the flavonoid biosynthesis (ko00941) pathways between the peel and aril. Additionally, functional antioxidants, such as 10,16-dihydroxypalmitic acid, 3-O-methylellagic acid, and 3,3'-O-dimethylellagic acid, were first identified in pomegranate fruits. Our results revealed the composition and abundance of primary and secondary metabolites in pomegranate fruit, which can lay the foundation for further elucidation of its nutritional and medicinal properties.

The dynamic changes in pigment metabolites provide a new understanding of the colouration of Pyracantha fortuneana at maturity

The type, content and accumulation characteristics of pigments are the material basis for fruit colour and the evaluation basis of the fruit maturity and nutritional value of P. fortuneana. However, little information is available on the changes in carotenoids, anthocyanins, procyanidins and major flavones during the ripening process of P. fortuneana fruits. Thus, this study investigated the colour conversion characteristics, the main changes in the above four metabolites and the association landscape with those metabolites. The results showed that thirty-nine kinds of carotenoids and derivatives, eighteen anthocyanins, five procyanidins and five flavone compounds were identified in the fruits of P. fortuneana. The total content and contents of most individual carotenoids, anthocyanins, procyanidins and flavones reached the highest values at the TS2, TS4, TS1 and TS1 stages, respectively. Among the variations, the contents of β-carotene and lutein increased first and then decreased, cyanidin-3-galactoside and cyanidin-3-glucoside accumulated, the concentrations of procyanidin C1 and procyanidin B2 decreased, and the contents of rutin and quercetin-3-O-glucoside also decreased; these changers were responsible for the main changes in carotenoids, anthocyanidin, procyanidins and flavones, respectively. For the correlation analysis results, there might be two modes of action that together affected the colour conversion of P. fortuneana fruits during ripening, i.e., (E/Z)-phytoene communicated with the carotenoid metabolic pathway that might promote the accumulated ABA content, which might cause the increased anthocyanidin (primarily through cyanidin-3-(6-malonyl-beta-d-glucoside) (C3MG)) at the final stage; most of the decreased flavone and procyanidin metabolites produced by the flavonoid metabolic pathway were another important factor affecting the accumulation of C3MG.

Metabolic Variations among Three New Tea Varieties Cultivated in Shandong, China

Cultivar identification is a necessary step in tea breeding programs. Rapid identification methods would greatly improve these breeding processes. To preliminarily identify the three new Lucha tea varieties (LC6, LC7, and LC17) cultivated in Shandong, we measured their main agronomic characters and biochemical components. Then, we analyzed the metabolic profiles of these tea varieties and Fuding Dabaicha (FD) using a UPLC-ESI-MS/MS system. Their biochemical components indicated that the Lucha varieties had excellent varietal characteristics, with higher amino acid contents. Furthermore, secondary metabolism changed a lot in the Lucha tea varieties compared with that in the FD, with their accumulations of flavonoids and phenolic acids showing significant differences. These differential flavonoids were dominated by flavones and flavanone, flavonols, flavonoid carbonosides, and flavanols monomer. Flavanols especially, including epicatechin glucoside, epicatechin-3-(3″-O-methyl)gallate, epigallocatechin-3-O-(3,5-O-dimethyl)gallate, and epitheaflavic acid-3-O-Gallate, showed higher levels in the Lucha varieties. The phenolic acids containing caffeoyl groups showed higher levels in the Lucha varieties than those in the FD, while those containing galloyl groups showed a reverse pattern. Nitrogen metabolism, including amino acids, also showed obvious differences between the Lucha varieties and FD. The differential amino acids were mainly higher in the Lucha varieties, including 5-L-glutamyl-L-amino acid, N-monomethyl-L-arginine, and N-α-acetyl-L-ornithine. By using these approaches, we found that LC6, LC7, and LC17 were excellent varieties with a high yield and high quality for making green teas in Shandong.

Changes in the Primary Metabolites of ‘Fengtang’ Plums during Storage Detected by Widely Targeted Metabolomics

Plums are one of the most popular stone fruits worldwide owing to their high nutritional value. After harvest, plum fruit quality and flavor change during storage; however, little is known about the changes in metabolites during this period. A comprehensive comparison of primary metabolites in ‘Fengtang’ plum fruits during storage is performed using widely targeted primary metabolomics. A total of 272 primary metabolites were identified by means of ultra-performance liquid chromatography and tandem mass spectrometry (UPLC-MS/MS) in the plums at different storage periods. There was a significant increase in the relative amounts of twenty-eight lipids, twenty amino acids and their derivatives, thirteen organic acids, ten saccharides and alcohols, six nucleotides and their derivatives, and two vitamins. A Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of differential metabolites revealed that glucosinolate biosynthesis, starch and sucrose metabolism, ascorbate and aldarate metabolism, lysine degradation, and other metabolic pathways were significantly enriched; therefore, changes in these metabolic pathways may be key to the quality and flavor change in ‘Fengtang’ plum fruits during storage. Our results provide a theoretical foundation and technical support to evaluate ‘Fengtang’ plum fruit quality.