Postharvest Biology and Technology最新文献

Energy status of cells is a key factor in switching on the senescence process of horticultural crops. Extracellular ATP (eATP) and its receptor DORN1 play pivotal roles in responding to energy deficit signals and are involved in multiple biological processes, yet their mechanisms remain unclear. A total of 17 LcDORN1 genes were identified in the genome of litchi. During storage of litchi fruit, eATP gradually acummulated with the upregulated expression of LcDORN1s. However, this trend was delayed by the application of exogenous ATP, ultimately leading to delayed senescence of the litchi fruit. LcDORN1.2 and LcDORN1.6, which were verified to be localized in the endoplasmic reticulum, were specifically targeted and modulated by LcmiR3627f and LcmiR159b, respectively. The expression of LcPLD was upregulated, whereas the expression of LcAPY1 was downregulated in LcDORN1.6 silenced litchi fruit. This research provides novel insights into the roles of eATP and its receptor, LcDORN1s, in the ripening and senescence of litchi fruit.

This study aimed to develop a postharvest quality index for strawberry (Fragaria ananassa Duch.) based on Vis-NIR reflectance, using a portable handset spectrometer to assess fruit quality and establish maximum shelf life. Fresh strawberries were stored at different temperatures (5, 15, 25 and 35 °C) and at 60 % relative humidity for up to 15 days. Various quality parameters were evaluated, including colour, firmness, weight loss, appearance, and microbial quality, every three days during storage. Kinetic models were used to describe the changes in weight loss, appearance, colour, and firmness of strawberries during storage under different temperatures. Vis-NIR spectroscopy was employed to establish a Reflectance Quality Index (RQI) for determining fruit quality during storage. This index helped to reduce the high number of wavelengths to a lower set of representative independent variables. Calibration and prediction models were created using the partial least squares (PLS) regression method, incorporating cross-validation, to predict quality indicators of strawberries. These models were developed for predicting appearance, weight loss, L*, a*, b* colour parameters, and firmness. A very good fit was obtained (R² = 0.95), demonstrating the feasibility of both the RQI and PLS for evaluating strawberry quality. This study presents a novel approach for assessing the shelf life of strawberries based on storage time and temperature using a portable spectrophotometer. This method can be a valuable tool for the food industry to ensure optimal fruit quality and minimize food losses.

Color is the most intuitive indicator to determine the appearance quality of citrus. There are large differences in the color transition rate and color transition initiation region between mandarin fruit colored on-tree or during postharvest storage. Here, we obtained CcbHLH66, a transcription factor that could be related in the controlling of mandarin fruit coloration, from the transcriptome data of mandarin fruit colored on-tree and colored during postharvest storage. And verified its function in the regulation of mandarin fruit coloration by transient overexpression system of Nicotiana benthamiana and mandarin peel. The results showed that CcbHLH66 is localized in the nucleus with transcriptional activation activity. Overexpression of CcbHLH66 could promote yellowing of Nicotiana benthamiana and green ripe mandarin, and significantly reduce the amounts of chlorophyll and its metabolites in tobacco leaves and mandarin fruit peels. However, it had no significant effect on the amounts of carotenoids and their metabolites in mandarin fruit peels. Meanwhile, it could promote the expression of tobacco chlorophyll degrading genes NbSGR, NbNYC and NbRCCR, while repressing the expression of chlorophyll synthesizing gene NbCAO. The expression levels of chlorophyll metabolism-related genes CcNYC, CcPAO, CcRCCR, CcSGR, and CcChlase-2 were significantly up-regulated and the expression of CcChlase-1 was inhibited in mandarin fruit peel. EMSA and DLR experiments further showed that CcbHLH66 directly binds to and activates the key chlorophyll degradation genes CcRCCR and CcNYC. In summary, CcbHLH66 is an important coloration-related transcription factor in mandarin fruit, which accelerates the coloration process of mandarin by regulating the degradation of chlorophyll in the peel.

The postharvest fragrance quality of aromatic cut flowers is crucial, yet efficient and rapid detection methods are lacking. To develop a rapid and accurate method for evaluating the fragrance quality during the senescence of aromatic cut flowers, this study first utilized HS–SPME–GC–MS to analyze the fragrance of six Hedychium cultivars cut flowers at different stages postharvest (bud, semi-open, full bloom, and senescence), identifying 69 compounds. Multivariate statistical analysis revealed significant during full bloom, with monoterpenoids predominant in ‘ZS’, ‘EM’, ‘Gaoling’, and ‘Jin’, and benzenoids/phenylpropanoids in ‘MH’. Concurrently, PTR–ToF–MS detected 68 masses consistent with GC–MS results. PLS–DA analysis identified eucalyptol, benzyl acetate, linalool, (E)-β-ocimene, methyl benzoate, and masses m/z 91.057, m/z 137.134, m/z 81.07, m/z 102.096, m/z 31.019 as potential markers for distinguishing Hedychium varieties. Additionally, PLS analysis identified masses m/z 58.078, m/z 103.076, and m/z 155.144 as predictors of agarospirol content; m/z 73.065, m/z 74.069, m/z 151.151 for eucalyptol, and m/z 27.021, m/z 31.019, m/z 41.039, m/z 43.054, m/z 55.054, m/z 57.033, m/z 70.077, m/z 72.056, m/z 88.079, m/z 91.057, m/z 92.065, and m/z 108.089 for benzyl acetate. The results provide new methods for efficient fragrance evaluation during the postharvest senescence of aromatic flower.

Cucumber (Cucumis sativus L.) fruit is susceptible to chilling injury (CI) during low-temperature storage; however, the mechanism behind the chilling response of cucumber fruit is not fully understood. Cellular responses to low-temperature conditions should be determined to identify the factors behind CI occurrence and chilling tolerance in postharvest fruit. In this study, the CI incidence in cucumber fruit stored at 13 °C (non-chilling temperature) and 2 °C (chilling temperature) were compared to determine the key factors involved in the chilling response. Transcriptome analysis revealed that different metabolite and phytohormone signalling pathways were activated in the two storage temperatures. Thus, metabolites and phytohormones were profiled to gain a deeper understanding of their roles in the chilling response. Sucrose and amino acids such as isoleucine, serine, valine, and threonine significantly accumulated in the fruit stored at 13 °C compared with those stored at 2 °C. Among the analysed phytohormones, more abscisic acid accumulated at 13 °C than at 2 °C as an early response to non-chilling temperature. Meanwhile, salicylic acid levels and expressions of its signalling genes increased with persistent exposure to 2 °C as a response to chilling stress. Phytohormones such as brassinolide, ethylene, indole-3-acetic acid, jasmonic acid did not significantly accumulate at 2 °C. However, their signalling genes were upregulated in the fruit stored at 2 °C compared to 13 °C. These results suggest that the transcriptional activation of phytohormone signalling pathways, rather than their biosynthesis, plays a crucial role in the chilling response. These findings provide insights into chilling response and complex interplay of various molecular components during the low-temperature storage of cucumber fruit.

Environmental and instrumental factors can cause variations in sample temperature, which may affect the predictive performance of models that use online Vis/NIR spectroscopy to predict the soluble solids content (SSC) of fresh fruit, an important quality indicator that influences their price. This study proposed a knowledge-guided (KG) temperature correction method based on one-dimensional convolutional neural network (1D-CNN) to reduce the impact of sample temperature on the SSC prediction model. First, a 1D-CNN was developed for prediction of temperature from spectra, and gradient-weighted class activation mapping was used to identify features related to temperature. These features, which were sensitive to temperature variations, were used to suppress temperature-sensitive bands and generated new spectra that were less affected by temperature. Subsequently, these new spectra were utilized to construct the partial least squares (PLS) model to predict SSC. To validate the efficacy of the proposed method, it was compared with the external parameter orthogonal method (EPO), competitive adaptive reweighted sampling (CARS) and successive projection algorithm (SPA) in terms of SSC prediction performance. The results indicated that while KG-PLS does not enhance the performance of local models on local (a specific temperature) testing sets, it can improve their performance on external (temperatures other than the specific temperature) testing sets. The root mean square error of cross validation (RMSECV) for SSC of local model at 15 ℃ using KG-PLS was 0.415 %, which was 0.196 %, 0.166 %, 0.169 %, and 0.065 % lower than the RMSECV obtained by PLS (0.611 %), CARS-PLS (0.581 %), SPA-PLS (0.584 %), and EPO-PLS (0.480 %), respectively. In general, the proposed KG method can effectively mitigate the impact of temperature interference on spectral modeling, providing a reference for high-precision online non-destructive sorting of fruit quality.

Cut-surface browning significantly impacts the quality of sliced products, even when stored at cold conditions. Cinnamic acid (CA) is a natural browning inhibitor for fresh-cut produces, yet the molecular mechanisms underlying its inhibitory effects remain undisclosed. In this study, the application of CA effectively inhibited the browning progression of sliced taro and downregulated the expression levels of genes associated with membrane lipid degradation or peroxidation. Comparative transcriptome and weighted gene co-expression network analysis revealed that the downregulated differentially expressed genes (DEGs) were significantly enriched in the flavonoid biosynthesis and lipid metabolism pathways, while the upregulated DEGs were enriched in the glutathione metabolism pathway. Molecular docking analysis showed that CA could bind with the active center of PAL3 and 4CL1 proteins through hydrophobic interactions and hydrogen bonding. These results suggested that CA treatment inhibits sliced taro browning by reducing flavonoid biosynthesis and lipid metabolism, and enhancing glutathione metabolism. Overall, this study confirms the efficacy of CA on browning inhibition and provides novel lights into the mechanisms of CA-mediated browning mitigation in fresh-cut taro.

Postharvest internal browning (PIB) in pineapple fruit is induced by low-temperature storage. The characteristic brown color associated with PIB is likely due to enzymes catalyzing substrates released from the cold-induced damage of organellar membranes. However, the regulation of these processes is unclear. To understand the mechanisms behind PIB in pineapple fruit, we compared browning-related genes, enzyme activities, calcium transporter genes, and cell structure in three cultivars: the susceptible ‘Trat Sri Thong’ (TST), the tolerant ‘Pattavia’ (PTV), and the resistant ‘MD2’. In response to the initial chilling stress, PM-ATPase3 expression, which is responsible for pumping Ca²⁺ to the apoplast, increased in the tolerant PTV and resistant MD2 cultivars, but not in the susceptible TST cultivar. Additionally, V-type-(H⁺)-ATPase and CAX3-like, which transport Ca²⁺ to the vacuole, were upregulated in all three cultivars. As chilling stress progressed, an upregulation of polyphenol oxidase 1 (PPO1) expression and an increase of PPO activity were observed in all three cultivars. However, the lowest PPO1 expression and activity were observed in the tolerant PTV cultivar. The ascorbic acid/H₂O₂ ratio was highest in the MD2 cultivar across storage durations, coinciding with intact cell and tonoplast membranes in MD2 during chilling stress, as observed with transmission electron microscopy and electrolyte leakage analysis. Consequently, no PIB symptoms were observed in MD2 despite high PPO activity. These findings suggest that different cultivars undergo distinct regulatory mechanisms at the subcellular level in response to cold stress. The details of potential mechanisms are discussed.

Green bell peppers (Capsicum annuum L.) are susceptible to chilling injury (CI) under low temperatures. The study examined the effect of a 20-minute immersion of green bell peppers in 1.6 g L⁻¹ papain (a naturally occurring cysteine protease), followed by storage for eight days at 4 ℃ and then three days at 20 ℃ to simulate market shelf life. Results indicated that the papain treatment delayed the onset of CI symptoms and, relative to the control, more effectively preserved firmness, chlorophyll, and ascorbic acid content, while decreasing relative conductivity, and levels of malondialdehyde and reactive oxygen species. Additionally, papain treatment not only reduced the activity and gene expression of LOX enzyme in pepper fruit, but also enhanced the enzyme activity of CAT, POD, SOD, APX, and the expression of their encoding genes. These results indicate that treating green bell peppers with papain could mitigate CI and membrane lipid peroxidation, and bolster antioxidant capacity. This study provides a practical and eco-friendly approach to enhancing the postharvest quality of green bell peppers. Future research should be directed at elucidating the molecular mechanisms underlying the effect of the papain treatment.

The ozone assisted hydro cooling (OAHC) process is introduced for simultaneous disinfection and pre-cooling of fresh produce. This study was conducted to examine the effect of different ozone concentrations (0.3, 0.7, and 1.5 ppm) on hydrocooling process and postharvest qualities of amla and tomato. The investigation included post-harvest qualities characteristics assessment between OAHC and cold room cooling. It was observed that the integration of ozone into hydrocooled water did not negatively impact cooling kinetics, while an ozone concentration of 1.5 ppm reduced E. coli count by 2.4 and 3.1 log cycles from tomato and amla, respectively. SEM analysis revealed no significant changes in amla and tomato pericarp microstructure during the OAHC process. In addition, OAHC-treated amla and tomato demonstrated lower weight loss, ascorbic acid, and higher phenolic compounds. The study outcomes concluded that OAHC technology did not adversely affect the cooling process and quality characteristics during the hydrocooling process and preserved the quality of fresh produce during storage.