Effects of 1-MCP treatment on sprouting and preservation of ginger rhizomes during storage at room temperature

Cooperative effects of three preservatives on physiological quality, endophytic bacterial community and volatile organic compounds of postharvest Codonopsis pilosula var. modesta roots

BACKGROUND

Codonopsis pilosula var. modesta (CPVM) is a famous medicinal and edible plant of Campanulaceae. However, fresh CPVM roots (FCPVR) are prone to softening, browning and spoilage after concentrated harvesting in the main production area of Gansu Province, China in autumn, which poses great challenges to their large-scale storage and modern processing. In this study, effects of chitosan (CS), natamycin (NA) and modified atmosphere agent (MA) on the postharvest quality of FCPVR were first investigated. The roots after different treatments were stored at 4 °C and relative humidity of 75 ± 5% for 100 days. Their overall quality changes were evaluated from three perspectives: physiological quality, endophytic bacterial community and volatile organic compounds.

RESULTS

The clustering heatmap and principal component analysis results indicated that CS (2 g kg-1), NA (0.5 g kg-1) and MA (5 g) had a synergistic effect on physiological quality. The roots in the CS + NA + MA group maintained better physiological state, effective components and antioxidant capacity throughout the storage process. On this basis, compared with room temperature storage, the relative abundance of the main spoilage bacterium Pseudomonas in the CS + NA + MA group roots decreased by 44% on the 100th day of storage. Furthermore, after CS + NA + MA composite treatment, the roots produced richer esters with fruit aroma during low-temperature storage.

CONCLUSIONS

The CS + NA + MA composite treatment could maintain the physiological quality and flavor of FCPVR, inhibit spoilage by microbial contamination and maintain the optimal quality during low-temperature storage for up to 100 days. © 2024 Society of Chemical Industry.

Exploration of Postharvest Conditions for Codonopsis pilosula Nannf. var. modesta (Nannf.) L. T. Shen Roots Based on Sensory Quality, Active Components, Antioxidant Capacity and Physiological Changes at Different Storage Temperatures

The promotion of industrial-mode production of Codonopsis pilosula Nannf. var. modesta (Nannf.) L. T. Shen (C. pilosula) has expanded the demand for the postharvest storage of fresh roots. Further research is needed to establish comprehensive methods to evaluate the impact of storage conditions. This study simulated the storage process of roots at near-freezing temperature [NFT (-1 °C)] and traditional low temperatures (-6 °C, 4 °C and 9 °C) for 40 days. At different storage stages, correlation analysis was conducted using quantitative data on 20 parameters, including sensory quality, active components, antioxidant capacity and physiological changes. Appearance and principal component analysis could distinguish between fresh and stored samples, while NFT samples on the 40th day of storage were similar to fresh ones. Correlation analysis indicated that NFT storage could maintain the sensory quality by increasing the antioxidant enzyme activity and active components, reducing the accumulation of reactive oxygen species and malondialdehyde and reducing the activity of browning-related enzymes and cell-wall-degrading enzymes. These findings highlight the importance of the overall quality evaluation of fresh roots and emphasize the potential to improve fresh root and dried medicinal material quality by regulating storage conditions such as temperature.

Transcriptomic and physiological analyses reveal changes in secondary metabolite and endogenous hormone in ginger (Zingiber officinale Rosc.) in response to postharvest chilling stress

Storing postharvest ginger at low temperatures can extend its shelf life, but can also lead to chilling injury, loss of flavor, and excessive water loss. To investigate the effects of chilling stress on ginger quality, morphological, physiological, and transcriptomic changes were examined after storage at 26 °C, 10 °C, and 2 °C for 24 h. Compared to 26 °C and 10 °C, storage at 2 °C significantly increased the concentrations of lignin, soluble sugar, flavonoids, and phenolics, as well as the accumulation of H2O2, O2-, and thiobarbituric acid reactive substances (TBARS). Additionally, chilling stress inhibited the levels of indoleacetic acid, while enhancing gibberellin, abscisic acid, and jasmonic acid, which may have increased postharvest ginger's adaptation to chilling. Storage at 10 °C decreased lignin concentration and oxidative damage, and induced less fluctuant changes in enzymes and hormones than storage at 2 °C. RNA-seq revealed that the number of differentially expressed genes (DEGs) increased with decreasing temperature. Functional enrichment analysis of the 523 DEGs that exhibited similar expression patterns between all treatments indicated that they were primarily enriched in phytohormone signaling, biosynthesis of secondary metabolites, and cold-associated MAPK signaling pathways. Key enzymes related to 6-gingerol and curcumin biosynthesis were downregulated at 2 °C, suggesting that cold storage may negatively impact ginger quality. Additionally, 2 °C activated the MKK4/5-MPK3/6-related protein kinase pathway, indicating that chilling may increase the risk of ginger pathogenesis.

Effects of 1-MCP Treatment on Physiology and Storage Quality of Root Mustard at Ambient Temperature

Root mustard is plentiful in vitamins and minerals but shrivels and molds easily. In this study, freshly harvested root mustard was fumigated with various concentrations of 1-Methycyclopropene(1-MCP) (1 µL L⁻¹, 1.5 µL L⁻¹, and 2.0 µL L⁻¹) for 24 h and stored at ambient temperature (17 ± 1 °C) for 35 d. Our data showed that 1-MCP fumigation had a striking preservation effect on maintaining weight loss, fruit firmness, lignin, Vc content, and moisture content, inhibiting respiratory intensity and ethylene release rate, as well as decreasing cell permeability and malondialdehyde (MDA) accumulation and maintaining cell membrane integrity of root mustard. In addition, lipoxygenase (LOX), pyruvate dehydrogenase (PDH), and polyphenol oxidase (PPO) activities were significantly reduced throughout the storage period. In contrast, the activities of succinate dehydrogenase (SDH), superoxide dismutase (SOD), ascorbate peroxidase (APX), phenylalanine deaminase (PAL), and peroxidase (POD) remained at high levels. Results showed that 1-MCP treatments were effective in maintaining the quality of root mustard, and the preservation effect of 1.0 μL·L⁻¹ 1-MCP was better than other concentrations of 1-MCP. This study could serve as a theoretical reference for root mustard preservation.

Starch branching enzymes as putative determinants of postharvest quality in horticultural crops

Starch branching enzymes (SBEs) are key determinants of the structure and amount of the starch in plant organs, and as such, they have the capacity to influence plant growth, developmental, and fitness processes, and in addition, the industrial end-use of starch. However, little is known about the role of SBEs in determining starch structure-function relations in economically important horticultural crops such as fruit and leafy greens, many of which accumulate starch transiently. Further, a full understanding of the biological function of these types of starches is lacking. Because of this gap in knowledge, this minireview aims to provide an overview of SBEs in horticultural crops, to investigate the potential role of starch in determining postharvest quality. A systematic examination of SBE sequences in 43 diverse horticultural species, identified SBE1, 2 and 3 isoforms in all species examined except apple, olive, and Brassicaceae, which lacked SBE1, but had a duplicated SBE2. Among our findings after a comprehensive and critical review of published data, was that as apple, banana, and tomato fruits ripens, the ratio of the highly digestible amylopectin component of starch increases relative to the more digestion-resistant amylose fraction, with parallel increases in SBE2 transcription, fruit sugar content, and decreases in starch. It is tempting to speculate that during the ripening of these fruit when starch degradation occurs, there are rearrangements made to the structure of starch possibly via branching enzymes to increase starch digestibility to sugars. We propose that based on the known action of SBEs, and these observations, SBEs may affect produce quality, and shelf-life directly through starch accumulation, and indirectly, by altering sugar availability. Further studies where SBE activity is fine-tuned in these crops, can enrich our understanding of the role of starch across species and may improve horticulture postharvest quality.