Postharvest Biology and Technology最新文献

This study reports on a linear-rail, dual-laser scanning system for high-speed, non-destructive detection of internal quality of fruit. The system was used to detect internal browning of ‘Scilate’ apples. A sample of 200 ‘Scilate’ apples with four different (healthy, slight, moderate, and severe) levels of browning was investigated. The new system’s performance was compared to that of a bench-top near infrared spectroscopy (NIRS) system. Apples with moderate and severe browning were easily detected by both systems. A comprehensive binary classification was made between healthy apples and those with slight browning. The classification results showed that the dual-laser scanning system performed very well for classifying apples with slight internal browning, achieving high accuracies of around 90 % compared to that of 82 % with the NIRS method. The dual-laser system operated successfully while fruit were moving at high speeds of 1.125 m/s and was able to identify small or localised defects.

As a sign of mushroom maturity, spore discharge continues accelerating in postharvest Lentinula edodes. However, the relationship between spore discharge quantity and both physiological quality and energy metabolism remains unclear. In this study, spore discharge intensity, the number of spores discharged per unit mass of fruiting body per unit time, was introduced to analyze the variations in physiological quality attributes and energy metabolism associated with spore discharge in harvested Lentinula edodes. The results demonstrated a correlation between increased spore discharge intensity and deteriorating weight loss, firmness, and browning of the fruiting bodies. Moreover, a positive relationship was observed between spore discharge intensity and mannitol, an osmotic substance released alongside spores. Mannitol metabolism is linked to glycolysis, suggesting that the accumulation of mannitol may enhance spore discharge. Significant correlations were identified between the total amount of spore discharge and H⁺-ATPase activity, as well as energy charge, which proved that higher levels of energy metabolism may promote spore discharge. Energy depletion was responsible for the deterioration in the physiological quality during this period. Collectively, a substantial amount of spore discharge needs to be supported by adequate osmotic substances and energy levels, and this result may provide a new perspective on the preservation of edible mushrooms. Delaying the peak of spore release and inhibiting the spore discharge intensity may be directions for maintaining the postharvest storage quality of edible mushrooms.

Blackberry fruit is rich in various nutrients and has strong antioxidant activity. However, these fruit are soft, juicy, prone to decay and spoilage, and not suitable for storage. To ensure the quality of blackberry fruit and extend its shelf life, this study used methyl jasmonate (MJ), salicylic acid (SA), or MJ+SA to treat mature blackberry fruit after harvesting. And measure the fruit appearance indicators, antioxidant contents, antioxidant enzyme activities, and related gene expression levels stored at 4 °C for different durations. The results showed that the MJ, SA, and the combination of MJ+SA treatments could slow fruit softening by increasing antioxidant contents and antioxidant enzyme activities, with MJ+SA having the greatest effect on the postharvest treatment of blackberry. Compared with those in the control, the DPPH radical scavenging capacity, total phenol and flavonoid contents, and antioxidant enzyme (POD, GSH, and SOD) activities were increased in three hormone treatment groups. Moreover, the expression levels of key genes involved in flavonoid and phenol compound synthesis were upregulated in all the postharvest treatment groups. There was a positive correlation between the contents of total phenol and flavonoid and between their related structural enzyme-encoding genes and transcription factors. This study lays the foundation for further exploration of hormone application for prolonging the shelf life and changing in the antioxidant activity of blackberry fruit.

Bitter pit causes significant losses to apple producers, packers, and retailers each year. While bitter pit is often associated with calcium deficiency, this postharvest disorder is still not fully understood. Some studies have demonstrated positive effects of preharvest sprays with prohexadione and abscisic acid. To evaluate the effects of these phytohormones as postharvest dips, ‘Granny Smith’ apples were dipped after harvest in prohexadione-Ca, abscisic acid, or CaCl₂. Undipped and water dipped fruit were included as controls. Bitter pit incidence and severity were evaluated on fruit stored at 0 °C and >90 % RH for 68–75 d. Postharvest prohexadione-Ca and abscisic acid treatments did not reduce bitter pit incidence over two years of testing. However, there was an increase in bitter pit incidence in control fruit dipped in water and surfactant compared to undipped control fruit in the first year of testing. This increase (7.5–14 %) was observed again in water dipped control fruit in each of the following 2 years of experimentation. Inclusion of 1 % calcium chloride in the dip solution eliminated this increase in bitter pit incidence. Applying calcium with a surfactant increased the apoplastic calcium concentration and reduced bitter pit development compared to water dipped fruit. Results indicate that the increase in bitter pit induced by water dips may be due to removal of residual calcium on the fruit’s surface from preharvest calcium treatments. Ethylene production was higher in bitter pit fruit compared to healthy fruit. Reduced and total ascorbate were decreased in pitted fruit compared to healthy calcium dipped fruit. Dichlorofluoresceine diacetate fluorescence was higher in tissue adjacent to pits compared to healthy tissue from healthy fruit, indicating accumulation of reactive oxygen species. However, no consistent trend was observed in antioxidant enzyme activity. These results indicate that bitter pit shares some, but not all, of the oxidative metabolic trends observed in other fruit calcium deficiency disorders.

Auxin is the earliest discovered class of endogenous plant hormones, widely distributed in higher plants, and plays a key role in regulating plant growth and development. However, the molecular mechanism by which auxin affects postharvest leaf senescence in pak choi (Brassica rapa subsp. chinensis) remains unclear. In this study, we found that exogenous application of 2 mg L⁻¹ of the auxin analog indoleacetic acid (IAA) could delay postharvest leaf senescence in pak choi. Importantly, we isolated an R2R3-MYB transcription factor (TF), BrMYB108, which was highly expressed in senescent leaves and whoes expression was suppressed by IAA treatment. Molecular evidence confirmed that BrMYB108 can bind to the promoter region of the chlorophyll metabolism gene BrSGR2 to activate its expression. Heterologous expression of BrMYB108 in Arabidopsis accelerated leaf senescence, while silencing BrMYB108 in pak choi using virus induced gene silencing (VIGS) delayed leaf senescence. In addition, we found that BrMYB108 is a direct target gene of the auxin response factor 17 (ARF17) homolog gene, BrARF17, in Arabidopsis. Our study reveals a model in which BrARF17 regulates postharvest leaf senescence in pak choi by targeting the expression of BrMYB108. These molecular insights into the auxin-mediated regulation of postharvest leaf senescence in pak choi have positive implications for manipulating BrMYB108 to improve the postharvest shelf life of vegetables.

This study aimed to develop an intelligent capacitive system to measure the moisture content of date fruit and to recognize fruit characteristics, such as variety, size, and ripeness. A cost-effective and fast non-contact measurement solution using the capacitive method was employed to create a platform with a variable oscillator to measure the dielectric properties of date fruit after harvest. Different date varieties, namely Zahedi, Ghasb, Mazafati and Medjool, representing dry, semi-dry and wet date fruit, respectively, were selected to model and calibrate the proposed system. Samples of date fruit of each variety were selected at three different ripening stages (Khalal, Rutab and Tamr), ranging from high to low moisture content. Additionally, five distinct moisture contents were determined using the oven method. The moisture content of the date fruit samples ranged from 8.6 % to 86.9 % owing to the selection of four varieties, three ripening stages and five stepwise thermal treatments. After acquiring electronic information, 80 % of the dataset was allocated for training purposes, while the remaining 20 % was reserved for evaluating the final regression model. The results showed that of all the trained machine learning models, Support Vector Regression (SVR) had the highest potential for predicting moisture content at the specified frequencies. The SVR model was fine-tuned by fitting 1824 combinations of hyperparameters over 6 folds. The tuned model's prediction for 20 % of the assigned test data resulted in a coefficient of determination of 88 % compared to the actual moisture content, with a Root Mean Square Error (RMSE) of 9.4 %. Furthermore, the dielectric-based system classified the ripening stages using a Multilayer Perceptron (MLP) model, achieving F1 scores of 87 %, 60 % and 68 % for the Khalal, Rutab and Tamr stages, respectively. The MLP regression model also predicted the geometric mean of the date fruit with a coefficient of determination of 0.82 and an RMSE of 3.05 mm.

Pulp breakdown is one of the primary symptoms of quality deterioration in postharvest longan fruit. As a pivotal pathogen, Phomopsis longanae Chi (P. longanae) leads to the spoilage of fresh longan. This work aimed to elucidate the influences of P. longanae infection on the metabolisms of energy and respiration in relation to longan pulp breakdown. Longan fruit were infected for 5 min with P. longanae at 10⁴ spores mL⁻¹, while the fruit dipped in distilled water were served as the control. These longans were stored for five days under the conditions of 28 °C and 90 % relative humidity. The results showed that, compared with the control longans, P. longanae-infected longans displayed a higher index of pulp breakdown, lower levels of ATP, ADP and EC, and lower activities of H⁺, Ca²⁺ and Mg²⁺-ATPase in the membranes of mitochondria, plasma and vacuoles. Besides, P. longanae-infected longans presented a higher respiration rate, higher activities of PGI, SDH, CCO, AAO, PPO and AOX, and higher levels of NAD and NADH, while showing lower activities of G-6-PDH + 6-PGDH and NADK, and lower levels of NADP and NADPH. These findings suggest that P. longanae infection aggravated the development of pulp breakdown in fresh longan, which was related to the reduced energy status and the enhanced respiratory metabolism.

The sprout of potatoes during storage threatens the post-harvest potato market supply chain. To reduce the massive economic losses in potato production industry, herein, the exogenous nicotinamide (NAM) was taken into consideration to maintain the potato quality. This study focused on the role of NAM on potato sprout development and revealed the possible mechanisms from the perspectives of energy and pyridine nucleotides metabolism. It was found that NAM delayed the sprouting and quality deterioration by down-regulating respiration rate and energy charge. Additionally, NAM stimulated the synthesis of nicotinamide adenine dinucleotide (NAD⁺) and nicotinamide adenine dinucleotide phosphate (NADPH) in pyridine nucleotides cycle, which maintained redox balance and reduced the burst of reactive oxygen species (ROS) at the sprouting site. Our findings provide a novel perspective on the possible strategies of NAM for improving the quality of fresh produce.