Background: Aroma is an important organoleptic quality for fruit and has a large influence on consumer preference. Kiwifruit esters undergo rapid and substantial changes contributing to the flavor during fruit ripening. Part of enzymes and their coding genes have been indicated potential candidates for flavor-related esters synthesis. However, there still exist obvious gaps in the biosynthetic pathways of esters and the mechanisms regulating ester biosynthesis in kiwifruit remain unknown. Results: Using gas chromatography-mass spectrometry (GC-MS), volatile compounds of kiwifruit were quantified in response to ethylene (ETH, 100 μl/l, 24 h, 20 °C) and 1-methylcyclopropene (1-MCP, 1 μl/l, 24 h, 20 °C). The results indicated that esters showed the most substantial changes enhanced by ethylene and were inhibited by 1-MCP. Correlations between RNA-seq results and concentrations of esters, constructed using Weighted Gene Co-Expression Network Analysis (WGCNA) indicated that three structural genes (fatty acid desaturase, AdFAD1; aldehyde dehydrogenase, AdALDH2; alcohol acyltransferase, AdAT17) had similar expression patterns that paralled the changes in total ester content, and AdFAD1 transcripts exhibited the highest correlation. In order to search for potential regulators for ester biosynthesis, 14 previously reported ethylene-responsive transcription factors (TFs) were included in the correlation analysis with esters and their biosynthetic genes. Using dual-luciferase assay, the in vivo regulatory activities of TFs on ester biosynthetic gene promoters were investigated and the results indicated that AdNAC5 and AdDof4 (DNA binding with one finger) trans-activated and trans-suppressed the AdFAD1 promoter. Conclusions: The present study advanced the molecular basis of ripening-related ester biosynthesis in kiwifruit by identifying three biosynthetic related genes AdFAD1, AdALDH2 and AdAT17 by transcriptome analysis, and highlighted the function of two TFs by transactivation studies.

This study aimed to investigate that rapid high-temperature treatment (RHT) at an appropriate temperature could accelerate callus formation by effectively promoting the necessary metabolic pathways in sweet potato callus. In this study, the callus of sweet potato was treated with heat shock at 50, 65, and 80 °C for 15 min. The callus formation was observed within 1, 3, and 5 days, and the accumulation of intermediates in the metabolism of phenylpropane and reactive oxygen species and changes in enzyme activities were determined. The results showed that appropriate RHT treatment at 65 °C stimulated the metabolism of reactive oxygen species at the injury site of sweet potato on the first day, and maintained a high level of reactive oxygen species production and scavenging within 5 days. The higher level of reactive oxygen species stimulated the phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase and cinnamate-4-hydroxylase activities of the phenylpropane metabolic pathway, and promoted the rapid synthesis of chlorogenic acid, p-coumaric acid, rutin, and caffeic acid at the injury site, which stacked to form callus. By Pearson’s correlation analysis, catalase (CAT), PAL, and chlorogenic acid content were found to be strongly positively correlated with changes in all metabolites and enzymatic activities. Our results indicated that appropriate high-temperature rapid treatment could promote sweet potato callus by inducing reactive oxygen species and phenylpropane metabolism; moreover, CAT, PAL, and chlorogenic acid were key factors in promoting two metabolic pathways in sweet potato callus.

Introduction: Traditional modified atmosphere packaging (MAP) cannot meet the preservation requirements of winter jujube, and the high respiration rate characteristics of winter jujube will produce an atmosphere component with high CO₂ concentration in traditional MAP. Micro-perforated MAP is suitable for the preservation of winter jujube due to its high permeability, which can effectively remove excess CO₂ and supply O₂. In this study, a microporous film preservation system that can be quickly applied to winter jujube was developed, namely PMP-MAP (precise micro-perforated modified atmosphere packaging). An experiment was designed to store winter jujube in PMP-MAP at 20°C and 2°C, respectively. The quality, aroma and antioxidant capacity, etc. of winter jujube at the storage time were determined.Methods: In this study, the optimal micropore area required for microporous film packaging at different temperatures is first determined. To ensure the best perforation effect, the effects of various factors on perforation efficiency were studied. The gas composition within the package was predicted using the gas prediction equation to ensure that the gas composition of the perforated package achieved the desired target. Finally, storage experiments were designed to determine the quality index of winter jujube, including firmness, total soluble solids, titratable acid, reddening, and decay incidence. In addition, sensory evaluation, aroma and antioxidant capacity were also determined. Finally, the preservation effect of PMP-MAP for winter jujube was evaluated by combining the above indicators.Results and discussion: At the end of storage, PMP-MAP reduced the respiration rate of winter jujube, which contributed to the preservation of high total soluble solids and titratable acid levels, and delayed the reddening and decay rate of winter jujube. In addition, PMP-MAP maintained the antioxidant capacity and flavor of winter jujube while inhibiting the occurrence of alcoholic fermentation and off-flavors. This can be attributed to the effective gas exchange facilitated by PMP-MAP, thereby preventing anaerobic stress and quality degradation. Therefore, the PMP-MAP approach is an efficient method for the storage of winter jujube.

Introduction: Sweet cherries (Prunus avium L.) are highly valued for their taste and nutrients but are prone to decay due to their delicate skin and high respiration rate. Traditional chemical preservatives have drawbacks like residues and resistance, prompting the search for natural alternatives. Phenylactic acid (PLA) has shown promise due to its antibacterial and antioxidant properties, making it a potential natural preservative to extend cherry shelf life.Methods: 'Stella' sweet cherries were treated with varying concentrations of PLA (0, 2, 4, 8, 16 mmol·L^-1) and stored at 4°C. Key quality indicators, including firmness, total acidity, total soluble solids, weight loss, decay index, and antioxidant activity, were assessed over time. Additionally, HPLC, GC-MS, GC-IMS, colony counts, in vivo inhibition analyses were conducted to evaluate phenolic content, aroma compounds and antifungal ability.Results and Discussion: PLA at 8 mmol·L^-1 effectively maintained cherry quality by reducing weight loss and decay of cherries, delaying the decline of firmness, while enhancing antioxidant capacity, flavor stability, and antifungal ability. Higher concentrations (16 mmol·L^-1) provided stronger antimicrobial effects but caused slight surface wrinkling. Thus, 8 mmol·L^-1 was optimal, balancing preservation and appearance, making it a promising natural preservative for extending cherry shelf life.