Sodium alginate coating of Ginkgo biloba leaves extract containing phenylpropanoids as an ecofriendly preserving agent to maintain the quality of peach fruit.

Plant constituents are of great interest in the food processing industry as potential natural preservative agents for controlling foodborne pathogens. In this study, the 95% EtOH/H2 O extract of Ginkgo biloba leaves was separated using polarity extraction solvents with petroleum ether (PE), ethyl acetate (EA), n-butanol (nB), and water (W) by the principle of similarity and compatibility. Through TLC and NMR analysis of these extracts, it can be concluded that the main component of PE extract were organic acids, for EA extract were flavonoids, for nB extract were phenylpropanoids, and water extract were oligosaccharides. Twelve monomer compounds were separated from the extracts to verify the composition of each extraction stage. Results of morphological and molecular identification revealed that Monilinia fructicola and Rhizopus stolonifer were the main fungi causing peach rot. After evaluating the antifungal activity and peach quality of the four extract/sodium alginate coatings, it was found that the n-butanol extract/sodium alginate coating containing phenylpropanoids had the lowest decay index and the best preservation effect, providing a sustainable alternative to reduce the harm to the environment of synthetic preservatives. PRACTICAL APPLICATION: The abuse of synthetic preservatives poses a threat to the ecological environment and physical health. Therefore, this study developed sodium alginate coating of Ginkgo biloba leaves extract containing phenylpropanoids, which has good effects on the preservation of peaches. The agent is a promising environmentally friendly alternative for synthetic preservatives.

Effects of Bacillus Subtilis CF-3 VOCs Combined with Heat Treatment on the Control of Monilinia fructicola in Peaches and Colletotrichum gloeosporioides in Litchi Fruit.

In order to study the effect of volatile organic compounds (VOCs) produced by Bacillus subtilis CF-3 combined with heat treatment on Monilinia fructicola in peach and Colletotrichum gloeosporioides in litchi fruit, fruits were treated with B. subtilis CF-3 VOCs and hot air alone or in combination. The quality indexes of peach and litchi fruit after treatment and the changes in defense-related enzymes were measured. The results showed that the B. subtilis CF-3 VOCs combined with heat treatment could significantly reduce the rot index of peach and litchi fruit, and effectively maintain firmness and soluble solids content, as well as reduce weight loss of fruits. The combined treatment effectively enhanced the activity of peroxidase (POD), polyphenol oxidase (PPO), catalase (CAT), and superoxide dismutase (SOD) than either treatment alone, and enhanced the resistance of fruit to pathogenic fungi by activating disease-resistant enzymes (phenylalanine ammonia-lyase [PAL], chitinase [CHI], ß-1, 3-glucanase [GLU]) activity. In this study, B. subtilis CF-3 VOCs combined with heat treatment maintained the quality and delayed the decline of peach and litchi fruit, providing a theoretical basis for future applications. PRACTICAL APPLICATION: The combination of B. subtilis CF-3 VOCs and heat treatment reduce the extent of M. fructicola and C. gloeosporioides. The combination maintain the quality of peach and litchi better. The combination obviously improve the activity of defense-related enzyme in fruit.

Effects of hot air treatment in combination with Pichia guilliermondii on postharvest preservation of peach fruit.

BACKGROUND: Antagonistic yeast and hot air treatment are two promising methods for conferring resistance to pathogenic fungi. The study assessed the effectiveness of hot-air treatment (45 °C, 4 h) and antagonistic yeast (Pichia guilliermondii at 108 CFU mL-1 ) alone or in combination on the two major postharvest diseases (Rhizopus stolonifer and Penicillium expansum), as well as the quality and antioxidant parameters in harvested peaches. RESULTS: The combination of hot-air treatment and Pichia guilliermondii had notable inhibitory effects on infections in peach fruit wounds. In addition, the individual hot-air treatment or Pichia guilliermondii could improve quality indexes to varying degrees, but the combination of the above two treatments could achieve the highest efficacy. Furthermore, compared with other groups, the combined treatment induced the highest activities of superoxide dismutase and catalase, improved the content of total phenolics and reduced glutathione most obviously. Lastly, the most significant reductions in malondialdehyde content and relative electrical conductivity were observed in the combination-treated fruit. CONCLUSIONS: The combined treatment could control fungal diseases, besides delay the decline of quality and antioxidant parameters, so as to achieve the purpose of fresh keeping for harvested peach fruit. © 2018 Society of Chemical Industry.

Effects of postharvest oligochitosan treatment on fungal diseases and defence responses in Dongxue peach fruit.

In this study, the effects of oligochitosan treatment on controlling postharvest diseases in Dongxue peach ( Prunus Persica L. Batsch, cv Dongxuemi) were examined and the possible underlying mechanisms were discussed. Results showed that the disease incidence and lesion area in peach fruit inoculated with Monilinia fructicola and Penicillium expansum were all remarkably reduced by oligochitosan treatment. Oligochitosan treatment inhibited spore germination and mycelial growth of the two fungi in vitro. Oligochitosan treatment also induced upregulation of the salicylic acid signalling pathway-related genes (NPR1, PR1 and phenylalanine ammonia lyase) and enhanced the levels of total phenolics, flavonoids and lignin in peach. Meanwhile, enzymatic activities of superoxide dismutase, catalase, polyphenoloxidase, ascorbate peroxidase and phenylalanine ammonia lyase also increased. These findings suggest that the effects of oligochitosan on the disease control of peach fruit may be associated with its direct antimicrobial effects as well as increasing antioxidant, phenylpropanoid metabolism and accumulating antifungal compounds by activating the salicylic acid-dependent pathway.

Antifungal activity and mechanism of tea polyphenols against Rhizopus stolonifer.

OBJECTIVE: To investigate the antifungal activity and possible mechanism of tea polyphenols (TPs) against Rhizopus stolonifer, the agent of rotting in nectarines and peaches. RESULTS: TP inhibited both mycelial growth and spore germination in vitro in a dose-dependent manner, and the morphological changes of the treated hyphae with TP, such as irregularly swollen, increased branching, wrinkled, entwining, collapse and breakage, and of the treated spores, such as swelling of germ tube tips, exfoliation of the surface layer and disorganization of cell organelles, were observed using optical microscopy, scanning electron microscopy and transmission electron microscopy. TP also significantly decreased rhizopus rot on inoculated nectarines and induced the activities of phenylalanine ammonia lyase, polyphenol oxidase, peroxidase, chitinase, and ß-1,3-glucanase. CONCLUSION: The mechanism of action might be attributed to direct damage of the mycelium and spore and indirect induction of defensive enzyme activities. TP has the potential to be developed as an alternative to control post-harvest disease of fruit caused by R. stolonifer.

Antifungal Activity of Some Constituents of Origanum vulgare L. Essential Oil Against Postharvest Disease of Peach Fruit.

Plant essential oils (EOs) can potentially replace synthetic fungicides in the management of postharvest fruit and vegetable diseases. The aim of this study was to evaluate in vitro and in vivo effectiveness of thymol, carvacrol, linalool, and trans-caryophyllene, single constituents of the EO of Origanum vulgare L. ssp. hirtum against Monilinia laxa, M. fructigena, and M. fructicola, which are important phytopathogens and causal agents of brown rot of pome and stone fruits in pre- and postharvest. Moreover, the possible phytotoxic activity of these constituents was assessed and their minimum inhibitory concentration (MIC) was determined. In vitro experiment indicated that thymol and carvacrol possess the highest antifungal activity. Results of in vivo trials confirmed the strong efficacy of thymol and carvacrol against brown rot of peach fruits. The thymol MIC resulted to be 0.16 µg/µL against M. laxa and M. fructigena and 0.12 µg/µL against M. fructicola, whereas for carvacrol they were 0.02 µg/µL against the first two Monilinia species and 0.03 µg/µL against the third. Results of this study indicated that thymol and carvacrol could be used after suitable formulation for controlling postharvest fruit diseases caused by the three studied Monilinia species.