To investigate the regulatory effect of nitric oxide (NO) fumigation combined with hypobaric treatment (HYT) on the postharvest quality of Xiaobai apricots, ‘Luntai’ apricots were treated with exogenous NO under hypobaric conditions (HYT + NO). NO fumigation at normal pressure (NO group) and single hypobaric treatment (HYT group) were used as controls for comparison. During 10 days of storage at (25 ± 2) ℃ and (85 ± 5)% relative humidity, changes in fruit firmness, mass loss, decay incidence, antioxidant capacity, and key indicators related to glutathione and polyamine metabolism were measured. Correlation analysis was also performed. The results showed that HYT + NO treatment significantly enhanced the antioxidant capacity of the fruit, maintained higher firmness, and suppressed the increase in mass loss and decay incidence. Meanwhile, HYT + NO up-regulated the expression of genes involved in polyamine and glutathione metabolism, leading to increased activities of arginine decarboxylase, ornithine decarboxylase, spermidine synthase, spermine synthase, S-adenosylmethionine decarboxylase, γ-glutamylcysteine synthetase, glutathione reductase, glutathione peroxidase, and glutathione S-transferase, while decreasing the activities of diamine oxidase and polyamine oxidase. Moreover, this treatment maintained the contents of spermidine (Spd), spermine (Spm), and reduced glutathione (GSH) and mitigated the accumulation of oxidized glutathione and hydrogen peroxide. Correlation analysis revealed that Spd, Spm, and GSH were significantly positively correlated with total antioxidant capacity and firmness, but significantly negatively correlated with mass loss and decay incidence. Spd and Spm were also significantly positively correlated with GSH. In conclusion, HYT + NO treatment enhances the antioxidant capacity and maintains the postharvest storage quality of Xiaobai apricots through the synergistic regulation of the polyamines (PAs) and GSH metabolic pathways.

In order to study the effect of BioSuee film and silicate materials on the rate of color change of fresh apricot fruit produced in Xinjiang during storage and transportation in e-commerce logistics packaging, Xiaobai, Saimaiti and Liguang apricot fruit were commercially packaged with PE film (control), BioSuee film (T1) or BioSuee film combined with microporous crystal silicate preservative (T2). After simulated transportation at (10 ± 1) ℃, the fruits were stored at (25 ± 1) ℃. The concentration of O₂/CO₂ in the packaging box, ethylene release, the activities of the enzymes related to ethylene synthesis and metabolism, and the contents of pigments, flavonoids and total phenols were determined during storage. The results showed that T2 resulted in a high CO₂ contents and low O₂ contents packaging environment, delayed the onset of the peak of ethylene production as well as decreased its peak value, slowed down chlorophyll degradation in fresh apricot peel and flesh, and inhibited the synthesis and accumulation of carotenoids, flavonoids and anthocyanins and total phenols. T2 significantly delayed the color change of ‘Saimaiti’ apricots from green to yellow to red, inhibited its yellowing and senescence, maintain its physiological quality during storage and transportation. The results of this study may provide technical support for the storage and transportation of fresh apricot fruit grown in Xinjiang in e-commerce logistics.

The application of sulfur dioxide (SO₂) treatment to dried apricots causes many problems such as bleaching, off-odor and high SO₂ residues. In order to address these issues, the effect of nitric oxide (NO) fumigation before or after drying on the quality of dried apricots was studied. In this experiment, Xinjiang-grown Diaogan apricots were used to prepare dried apricots. The changes in physiological indexes, NO residue and sensory quality of dried apricots stored at (25 ± 1) ℃ were determined. The results showed that NO fumigation maintained moisture content, water activity (a_w), color and nutritional quality well, inhibited the increase in browning degree and total color difference, delayed the decrease in the levels of total soluble solids (TSS), titratable acidity (TA), ascorbic acid (vitamin C, VC) and reducing sugars (Rs), and inhibited microbial growth. NO fumigation followed by drying and NO fumigation again was more effective in maintaining the storage quality of dried apricots. Both the residues of NO₃^- and NO₂^- in dried apricots were lower than the limits of the national standard (GB 2762-2017). This study may provide theoretical and technical support for the industrial application of NO fumigation in the preservation of dried apricots.

In order to investigate the regulatory mechanism of exogeneous calcium chloride (CaCl₂) on postharvest energy metabolism and ascertain the association between energy metabolism levels and color change in ‘Xiaobai’ apricots, ‘Xiaobai’apricots from Xinjiang were fumigated with 3 g/100 mL CaCl₂ solution or distilled water (control) before being stored at (10 ± 1.0) ℃ and relative humidity of (80 ± 5)%. Changes in chlorophyll, carotenoid, adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) contents and energy charge (EC) levels in the peel and pulp of apricots and changes in enzyme activities and gene expression related to energy metabolism were determined during the storage period. The results showed that compared with the control group, CaCl₂ treatment delayed chlorophyll degradation, inhibited carotenoid synthesis, maintained ATP and ADP contents and energy charge levels, enhanced the activities of H⁺-ATPase, Ca²⁺-ATPase, succinate dehydrogenase (SDH) and cytochrome c oxidase (CCO), and induced the expression of the PaH⁺-ATPase1, PaCa²⁺-ATPase10, PaSDH and PaCCO6 genes in both peel and pulp. Chlorophyll content in the peel and pulp was positively correlated with ATP, ADP and EC levels, but negatively correlated with carotenoid contents. There was a significantly positive correlation between chlorophyll and ADP levels in the peel and pulp (P < 0.01). It was suggested that exogenous CaCl₂ could delay postharvest color change and maintain high energy charge by regulating energy metabolism, therefore prolonging the shelf life of ‘Xiaobai’ apricots.

Hydrogen sulfide (H₂S) is a key intermediate in sulfur metabolism. In order to investigate the role of sulfur metabolism in the effect of sulfur dioxide (SO₂) on maintaining the post-harvest quality of table grapes, as well as the potential function of H₂S in this process, ‘Munage’ grapes (Vitis vinifera L.) were treated with 500 μL/L SO₂ alone or in combination with 0.5 mmol/L DL-propargylglycine (PAG) as a H₂S inhibitor. PAG was sprayed on grapes 24 h before harvest and distilled water was used as a control. Grapes were stored at (0 ± 1) ℃ and 80%–90% relative humidity. Fruit firmness, berry shatter, decay incidence, sulfur metabolites, enzymatic activities and gene expression levels were evaluated every 10 days, and correlation analysis was performed. The results showed that SO₂treatment maintained fruit firmness and inhibited the increase of berry shatter and decay incidence. At the end of storage, the fruit hardness of the SO₂ treatment group was 36.9% higher than that of the control group, and the grain drop rate and decay rate were 70.5% and 83.7% lower than those of the control group, respectively. Additionally, SO₂ promoted the accumulation of the sulfur metabolites SO₃^2-, H₂S, cysteine and glutathione (GSH), and improved the activities of sulfite reductase, serine acetyltransferase, O-acetylserine(thiol)lyase, D-cysteine desulftosylase, L-cysteine desulfhydrylase, cystathion β-synthase and 3-mercaptopyruvate sulfur transferase by up-regulating the expression of sulfur metabolism pathway-related genes. These indicated that SO₂ had a positively regulatory effect on sulfur metabolism. Correlation analysis revealed that SO₃^2-, H₂S, and GSH were positively correlated with fruit firmness and negatively with shatter and decay rates. The combination of PAG and SO₂ weakened the regulatory effect of SO₂ on sulfur metabolism and thereby the preservation effect of SO₂ by inhibiting the synthesis of H₂S. In conclusion, SO₂ can effectively maintain the postharvest quality of grapes by enhancing sulfur metabolism.