# Untargeted Metabolomics Reveals the Effect of Carbon Dots on Improving the Shelf Life of Postharvest Goji Berries (Lycium barbarum L.)

## TL;DR

This study uses metabolomics to show how carbon dots help preserve goji berries by altering their metabolism and extending shelf life.

## Contribution

The study reveals the global metabolic reprogramming induced by carbon-dot-mediated photodynamic treatment in postharvest goji berries.

## Key findings

- CD-PDT significantly altered the metabolic profile of goji berries, with 17,603 differentially expressed metabolites identified.
- The treatment activated the phenylpropanoid biosynthesis pathway, enhancing antioxidant capacity through compounds like kaempferol derivatives.
- CD-PDT also induced the tricarboxylic acid cycle, providing energy to support metabolic pathways involved in preservation.

## Abstract

Lycium barbarum L. (goji berry) undergoes rapid quality deterioration after harvest owing to its high water activity and abundant reactive oxygen species (ROS). Carbon-dot-mediated photodynamic treatment (CD-PDT) has recently been shown to extend shelf life by modulating ROS-scavenging and defense enzymes, yet the global metabolic reprogramming that supports this protection remains unresolved. Here, we applied ultra-high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS)-based untargeted metabolomics to decode the metabolic footprint of CD-PDT in freshly harvested goji berries. Our results revealed a total of 17,603 differentially expressed metabolites between the treatment and control groups under both positive- and negative-ion modes. Principal component analysis indicated that CD-mediated PDT significantly altered the metabolic profile of fresh goji berries. The treatment activated the phenylpropanoid biosynthesis pathway, promoting the accumulation of compounds such as kaempferol-3-sophoroside, kaempferol-3-O-β-D-glucoside, and galactoside, thereby enhancing the antioxidant capacity of the fruit. Furthermore, CD-mediated PDT induced the tricarboxylic acid cycle, providing sufficient energy to support the phenylpropanoid biosynthesis pathway. In conclusion, these findings provide the systems-level evidence that CD-PDT orchestrates a coordinated activation of primary and secondary metabolism in postharvest goji berries, establishing a mechanistic framework for preservation of horticultural products.