Effect of vaporized ethyl pyruvate as a novel preservation agent for control of postharvest quality and fungal damage of strawberry and cherry fruits

Synergistic Microbial Inhibition and Quality Preservation for Grapes through High-Voltage Electric Field Cold Plasma and Nano-ZnO Antimicrobial Film Treatment

To ensure their quality and safety, harvested grapes should be protected from microbial contamination before reaching consumers. For the first time, this study combined high-voltage electric field cold plasma (HVEF-CP) and nano-ZnO antimicrobial film to inhibit microbial growth on grapes. Using the response surface method, the optimal processing parameters of HVEF-CP (a voltage of 78 kV, a frequency of 110 Hz, and a time of 116 s) were identified to achieve 96.29% sterilization. The effects of co-processing with HVEF-CP and nano-ZnO antimicrobial film on the quality and safety of grapes during storage were explored. When stored at 4 °C and 20 °C, the co-processing extended the shelf life of grapes to 14 and 10 days, respectively. The co-processing increased the sterilization rate to 99.34%, demonstrating a synergistic effect between the two methods to ensure not only the safety of grapes but also their nutrient retention during storage. This novel approach is promising for the efficient, safe, and scalable preservation of grapes as well as other foods.

Quality and Stability Equivalence of High Pressure and/or Thermal Treatments in Peach-Strawberry Puree. A Multicriteria Study

A bottom-up approach identifying equivalent effects of high-pressure processing (HPP—600 MPa, 20 °C, 10 min), thermal treatment (TT—70 °C, 15 min) and high pressure-mild thermal processing (HPMT—600 MPa, 50 °C, 10 min) on quality and stability of peach–strawberry puree was applied during refrigerated storage. TT and HPP ensured 3-log aerobic bacteria inactivation at first, while HPMT reduction was below the detection limit. After 21 days all samples had equivalent microbiological stability. A 2.6-fold increase in the residual activity of PPO and POD was found in the HPP sample compared to TT and HPMT samples (1st day); after 21 days PPO, POD and TPC were equivalent for TT and HPP peach–strawberry purees. Equivalent volatile profile and rheology behavior was observed after 21 days of all samples’ storage. Meanwhile, the color of the HPP, TT and HMPT samples remained significantly different (p < 0.05) throughout the whole storage period, with the lowest browning index registered for HPP samples.

Ethyl pyruvate inhibits glioblastoma cells migration and invasion through modulation of NF-κB and ERK-mediated EMT

Background

Glioblastoma is a grade IV glioma with the highest degree of malignancy and extremely high incidence. Because of the poor therapeutic effect of surgery and radiochemotherapy, glioblastoma has a high recurrence rate and lethality, and is one of the most challenging tumors in the field of oncology. Ethyl pyruvate (EP), a stable lipophilic pyruvic acid derivative, has anti-inflammatory, antioxidant, immunomodulatory and other cellular protective effects. It has been reported that EP has potent anti-tumor effects on many types of tumors, including pancreatic cancer, prostate cancer, liver cancer, gastric cancer. However, whether EP has anti-tumor effect on glioblastoma or not is still unclear.

Methods

Glioblastoma U87 and U251 cells were treated with different concentrations of EP for 24 h or 48 h. CCK8 assay and Colony-Formation assay were performed to test the viability and proliferation. Wound-healing assay and Transwell assay were carried out to measure cell invasion and migration. Western blot was not only used to detect the protein expression of epithelial-mesenchymal transition (EMT)-related molecules, but also to detect the expression and activation levels of NF-κB (p65) and Extracellular Signal Regulated Kinase (ERK).

Results

In glioblastoma U87 and U251 cells treated with EP, the viability, proliferation, migration, invasion abilities were inhibited in a dose-dependent manner. EP inhibited EMT and the activation of NF-κB (p65) and ERK. With NF-κB (p65) and ERK activated, EMT, migration and invasion of U87 and U251 cells were promoted. However the activation of NF-κB (p65) and ERK were decreased, EMT, migration and invasion abilities were inhibited in U87 and U251 cells treated with EP.

Conclusion

EP inhibits glioblastoma cells migration and invasion by blocking NF-κB and ERK-mediated EMT.

Postharvest application of pectic-oligosaccharides on quality attributes, activities of defense-related enzymes, and anthocyanin accumulation in strawberry

BACKGROUND

The postharvest application of pectic-oligosaccharides (POS) as an elicitor to improve the postharvest shelf-life and nutritional quality by stimulating natural defense mechanisms in strawberries was studied. Strawberries (cv. Festival) were treated with POS (at 0, 2, 5, and 9 g L^-1 ) and evaluated for firmness, weight loss, color, soluble solids, titratable acidity (TA), total phenolic and anthocyanin content, antioxidant capacity, decay, and some defense-related enzyme activity during storage at 2 ± 0.5 °C for 14 days.

RESULTS

Treatment with POS significantly delayed (P < 0.05) strawberry decay, and reduced the water loss and softening of fruit during storage. Strawberries treated with POS showed a significant increase in total phenolic and anthocyanin content, and antioxidant capacity when compared with controls. Interestingly, POS induced higher activity of phenylalanine ammonia-lyase (PAL), chitinase, and β-1,3-glucanase in strawberries. Compared to the control, the activity of enzymes was markedly increased in fruit treated with all tested POS concentrations, particularly chitinase, and β-1,3-glucanase activities, but 5 and 9 g L^-1 POS were the most effective treatments for maintaining the quality attributes and improving anthocyanin accumulation and antioxidant capacity of strawberries.

CONCLUSION

These findings suggest that POS treatment could potentially be applied to maintain quality attributes, reduce decay, and further enrich the anthocyanin content and antioxidant capacity of strawberries during postharvest storage. The results also suggest that the positive effects of POS on strawberries could be associated with the rapid accumulation of chitinase and β-1,3-glucanase activities, and the increase of PAL enzyme activity leading to the synthesis and accumulation of anthocyanins. © 2019 Society of Chemical Industry.

Ethyl pyruvate (EP) suppressed post-harvest blue mold of sweet cherry fruit by inhibiting the growth of Penicillium oxalicum

BACKGROUND

The shelf-life of fresh sweet cherry is relatively short due to fungal decay during post-harvest storage. To investigate the effect and the mechanism of action of ethyl pyruvate (EP) against blue mold of sweet cherry fruit caused by Penicillium oxalicum, the spores were treated with 25 mg L^-1 EP. The spore germination rate of P. oxalicum, the integrities of the cell wall and plasma membrane, reactive oxygen species (ROS) and malondialdehyde (MDA) were evaluated.

RESULTS

EP treatment significantly suppressed post-harvest blue mold of sweet cherry fruit. We found that the treatment of 25 mg L^-1 EP significantly suppressed blue mold of post-harvest sweet cherry fruit by directly inhibiting germination and the mycelial growth of P. oxalicum. After co-inoculation with EP for 30 min, the spore germination rate of P. oxalicum was reduced by 83.5%. In addition, the pH of the EP solution was found to affect its antimicrobial activity. After treatment with EP, the cell surface structures of the spores of P. oxalicum were much more incomplete, and higher ROS and MDA values were recorded in the spores.

CONCLUSIONS

The results suggested that EP treatment destroyed the integrities of the cell surface structures and caused oxidative damage of the spores of P. oxalicum. © 2019 Society of Chemical Industry.