Studying the metabolic patterns underlying the key quality traits during the growth and development of melon is very important for the quality improvement and breeding of melon fruit. In this study, we employed transcriptomics and metabolomics to analyze the primary metabolic changes occurring in melon ('Xizhoumi 25') across five growth and development stages. We identified a total of 666 metabolites and their co-expressed genes, which were categorized into five different metabolic and gene modules. Through the analysis of these modules, the main metabolic pathways during the growth and development of melon were demonstrated from a global perspective. We also discussed the contribution of sucrose accumulation, the TCA cycle, and amino acid metabolism to the quality and flavor of melon. Enzymes related to amino acid metabolism were proposed, including Amine oxidase (AOC), aldehyde dehydrogenase (ALDH), tryptophan synthase (TRPB), etc. These results and data can provide new insights for further study on the metabolic regulation of melon quality and improve fruit quality.

Not from concentrate (NFC) fruit juice is the crucial clean label ingredient for new-style tea-making due to its pleasant color and fresh aroma. Here, we compared the effects of mild heating (MH) and high pressure processing (HPP) on physicochemical characters and phytochemicals in NFC spine grape juice based on metabolomics analysis. Similar compound profiles were observed between HPP-treated and fresh juices. The richer phytochemical compounds comprised malvidin-3-O-glucoside, malvidin-3,5-di-O-glucoside, quercetin-3-O-rhamnoside, quercetin-3-O-glucuronide, catechin, caffeic acid, ferulic acid, procyanidin B1, procyanidin B2 were obtained after MH treatment. Nine marker phenolics and two marker tripeptides (i.e., Glu-Val-Phe and Leu-Leu-Tyr) were identified to differentiate MH from HPP treatment, of which higher contents occurred in the MH group. Storage time experiments showed that the Glu-Val-Phe could serve as potential markers for monitoring storage of spine grape juice. These results provide new insights into the effects of processing on individual phytochemical changes and the guide for commercial application of production of spine grape NFC juice.

Plant seeds from the Fabaceae (Leguminosae) family are commonly edible. However, little has been done to study the phytochemicals of red clover (Trifolium pratense) seeds. Our study aims to obtain comprehensive and novel findings on red clover seeds and supercritical fluid extraction (SFE)-extracted oil, with the purpose of exploring their potential as a new source of functional ingredients for food and health care products. In our study, red clover seed oil was extracted by supercritical CO2. Forty-four phytochemical compounds were preliminarily identified in red clover seeds and the extracted oil by UPLC-ESI-MS/MS metabolomics method. These compounds mainly belong to lipids, phenolic compounds, terpenoids and phytosterols. Red clover seeds contain fatty acids (4,676.1 mg/100 g dried seeds) and bioactive components such as phenolic compounds (228.4 mg/100 g) and tocopherols (94.9 mg/100 g). In red clover seed oil, unsaturated fatty acids are over 83% and are rich in linoleic acid (54.7 g/100 g oil) and oleic acid (14.0 g/100 g oil). These findings provide important guidance for introducing red clover seed oil into pharmaceutical products or as functional foods.

Lily bulbs are valued for their health benefits, and drying is a common method for their preservation. This study employed untargeted metabolomics using UHPLC-QTOF-MS to analyze the phytochemical profiles of lily bulbs dried by hot air (HD), microwave (MD), and vacuum freeze (FD) methods. In terms of appearance, FD samples exhibited minimal browning and wrinkling, while HD bulbs showed the most severe changes. Nineteen potential markers were identified, with HD samples showing higher levels of bitter amino acids, peptides, and N-fructosyl phenylalanine. The markers of FD samples were glutamine, coumarin, and p-coumaric acid. Notably, eleutheroside E was detected in lily bulbs for the first time and confirmed as an MD marker, with levels 1.51-fold and 6.19-fold higher than in FD and HD samples, respectively. MD method shows promise for enriching bioactive compounds in dried lily bulbs.