During fresh-cut processing, potatoes lose their inherent protective cellular structure, leading to enzymatic browning that compromises sensory and edible quality. Tea polyphenols (TPs), natural preservatives with potent reducing properties, are hypothesized to impact this browning process. However, their influence and regulatory mechanism on the enzymatic browning of fresh-cut potatoes remain poorly understood. This study used the “Holland Seven” potato as the research material to explore the effects of a treatment with different TP concentrations (0.1 g L⁻¹, 0.2 g L⁻¹, and 0.3 g L⁻¹) on the browning phenomenon and quality of fresh-cut potatoes during storage. The results showed that appropriate concentrations of TP treatment had a good preservation effect on the appearance and edible quality of fresh-cut potatoes. Furthermore, exogenous TP treatment reduced the content of enzymatic browning substrates (caffeic acid, p-coumaric acid, and ferulic acid) by regulating phenylpropanoid metabolism. Meanwhile, TP treatment augmented the activities of antioxidative enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase), maintained higher levels of ascorbic acid (Vc), and reduced glutathione (GSH). Consequently, the TP treatment could inhibit enzymatic browning by regulating reactive oxygen species (ROS) metabolism and the Vc-GSH cycle in fresh-cut potatoes.

Fungal decay is one of the most significant causes of postharvest losses of blueberries, with Botrytis rot caused by Botrytis cinerea and Alternaria rot caused by Alternaria alternata being the two most destructive fungal diseases. Plant essential oil has attracted the extensive attention of scholars due to its natural antifungal and anti-corrosion effects. In this study, the effects of fumigation treatment with plant essential oils on the growth of pathogenic fungi in blueberry fruits in vitro and the activity of defense-related enzymes of fungi-inoculated blueberry were evaluated. The results showed that, of the six natural plant essential oils of cinnamon, oregano, clove, tea tree, pomelo peel, and rosemary, oregano essential oil had the most efficient inhibitory effect on Botrytis cinerea and Alternaria alternata in PDA. After fumigating inoculated blueberry fruits with concentration gradients of 0, 30, 60, and 90 μL/L of oregano essential oil, it was found that the activity of defense-related enzymes such as phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), peroxidase (POD), chitinase (CHI), and β-1,3-glucanase (GLU) in the inoculated blueberry fruits was induced and enhanced to varying degrees throughout the entire storage period, effectively enhancing the resistance of blueberry fruits to pathogenic fungi and reducing the postharvest decay caused by Botrytis cinerea and Alternaria alternata. The optimal concentration for the fumigation treatment with oregano essential oil is 60 μL/L. This study provides a theoretical basis for the postharvest application of oregano essential oil in blueberries and other fruits and vegetables.

Fresh-cut pumpkins refer to fresh pumpkin that has been graded, cleaned, peeled, sliced, preserved, and packaged. It has the qualities of freshness, nutrition, convenience, and being 100% edible. However, mechanical damages during the cutting processing can accelerate the quality deterioration, aging, and loss of nutritional values of fresh-cut pumpkins. Nisin, a natural preservative, has been widely used in fruits and vegetables with good preservation effects. To investigate the effect of different concentrations (0, 0.2, 0.4, and 0.6 g/L) of nisin on the quality of fresh-cut pumpkins, the critical indexes involved in weight loss, firmness, color, respiration intensity, reactive oxygen species (ROS) metabolism, ascorbate (AsA)—glutathione (GSH) cycle, and antioxidant capacity were monitored for fresh-cut pumpkins during storage at 4 °C for 10 days. The results showed that 0.4 g/L nisin was the best preservation concentration. Compared with 0 g/L nisin, 0.4 g/L nisin reduced the weight loss rate and whitening rate of fresh-cut pumpkins by 13.53% and 13.61%, inhibited respiration rate by 45.83%, and maintained hardness by 1.18 times. Meanwhile, 0.4 g/L nisin increased the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) and maintained higher contents of GSH and AsA. It prevented the rapid increase in ROS levels by improving antioxidant capacity, including DPPH, ABTS free radical scavenging rate, and T-AOC (total antioxidant capacity). The collected results showed that nisin has an obvious influence on the quality by regulating physiological and antioxidant activity metabolism. It is envisaged that the combination of nisin and physical and chemical preservation technology will further enhance the quality of fresh-cut pumpkins during storage in the future.

Fresh-cut cucumbers (Cucumis sativus L.) are appreciated by consumers for their convenience and freshness. In the process of home cooking and in the food industry, different cutting methods for cucumbers are needed. In order to explore the effect of cutting methods on the quality of fresh-cut cucumbers, cucumbers were cut into slices, pieces, and strips and whole cucumbers were used as the control. The results indicate that the vitamin C content of the sliced, pieced, and stripped cucumbers was gradually reduced, while the glutathione content increased significantly (p < 0.05) compared with the whole cucumbers. Furthermore, this study reveals that the fresh-cutting operation induced the production of ROS (O₂⁻· and H₂O₂). Simultaneously, cutting activates phenylalanine ammonia-lyase and peroxidase activity, which enhanced the total phenol content by 1.35 times, 1.51 times, and 1.78 times in the pieced, stripped, and sliced cucumbers, respectively. This combines with the enhancement in the ascorbate peroxidase, glutathione reductase, superoxide dismutase, and catalase activity, contributing to the antioxidant capacity increasing by 1.14–1.95 times compared with the control. In conclusion, the degree of quality indexes was sliced > pieced > stripped. Therefore, this study provides useful information to illuminate the mechanism of the quality change in fresh-cut cucumbers subjected to different cutting methods and makes suggestions on the appropriate cutting style for the commercial or home use of cucumbers.

When subjected to a certain degree of mechanical damages, a systematic responsive mechanism of fresh-cut cucumber is activated. Among them, the lignin produced in the secondary metabolism will make the fresh-cut cucumber lignified, which will increase the hardness and whiten the cutting surface of the fresh-cut cucumber, seriously affecting the taste and appearance quality. In order to further understand the mechanism of lignin synthesis, transcriptome analysis was carried out on two cutting types of fruit samples from the slices treatment (P) and shreds treatment (S) stored for 24 h. Compared with the whole fruit (CK), 2281 and 2259 differentially expressed genes (EDGs) were identified in the slices and shreds treatments, respectively; 1442 up-regulated genes and 839 down-regulated genes were expressed as 2281 in the slices treatment; 1475 significantly up-regulated genes and 784 significantly down-regulated genes were expressed as 2259 in the shreds treatment; and 1582 DEGs were commonly detected between the slices treatment and shreds treatment, indicating that these DEGs were related to lignin synthesis. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that compared with the whole fruit, the metabolic pathways of amino acid metabolism, lipid metabolism, and secondary metabolism were affected by mechanical damages. This study revealed that JA biosynthesis was activated by mechanical damages, and the up-regulation of phenylalanine metabolism and phenylalanine, tyrosine, and tryptophan metabolism affected phenylpropanoid biosynthesis, which may promote lignin synthesis. Fifteen DEGs were selected for qRT-PCR validation, and the reliability and accuracy of transcriptome data were confirmed.