Widely targeted metabolomics analysis unveils the underlying mechanism of starch/carboxymethyl cellulose-based photodynamic antimicrobial packaging in delaying quality deterioration of snap beans

Snap beans ( Phaseolus vulgaris L.) have high nutritional value but are susceptible to senescence and spoilage after harvest. Previously, a carboxymethyl cellulose/starch-based photodynamic film (CCPF) was shown to delay the senescence process and maintain the storage quality of snap bean pods (SBPs). However, the mechanism of the CCPF effect on the preservation of snap beans remains unclear. This study first confirmed the beneficial effects of CCPF packaging on the appearance and nutritional quality of SBPs and microbial growth inhibition. Then, the regulatory mechanism by which CCPF packaging impacts the physiological metabolism of postharvest SBPs was investigated via widely targeted metabolomics. The results revealed 1802 metabolites in total SBP samples, among which 464 metabolites were significantly different between SBPs packaged with the CCPF and those packaged with a pure carboxymethyl cellulose/starch-based film (CCF) in the dark. It was found that CCPF packaging could delay the deterioration of the quality of SBPs by regulating the synthesis and decomposition of phenolic acids, flavonoids, lipids, amino acids and derivatives in postharvest SBPs. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that compared with CCF packaging, CCPF packaging delayed the postharvest senescence of SBPs by affecting three potential metabolic pathways (isoflavone biosynthesis, flavonoid biosynthesis and nicotinate and nicotinamide metabolism), maintaining the storage quality of snap beans. This study revealed the possible mechanism by which CCPF packaging maintains the postharvest storage quality of snap beans.