Effect of the moisture content of forced hot air on the postharvest quality and bioactive compounds of mango fruit (Mangifera indica L. cv. Manila)

Hot Air Treatment Elicits Disease Resistance against Colletotrichum gloeosporioides and Improves the Quality of Papaya by Metabolomic Profiling

Forced air heat treatment could induce defenses to protect fruit from pathogen attacks and has been applied as an alternative to methyl bromide for phytosanitary treatment before exportation. However, few studies were reported on the regulation mechanism of antifungal effect and delayed physiological disorders of papaya by heat treatment. Therefore, we aim to explore the fruit's resistance to pathogens and the inhibition of physiological disorders by metabolomic profiling. In our study, papaya fruits were treated with 47.2°C for 30, 60, and 90 min by forced hot air treatment. The disease resistance against Colletotrichum gloeosporioides, quality parameters, and metabolites of papaya fruits were measured during 10 days of storage after heat treatment by metabolomic profiling. Papaya fruits after 30 and 60 min heat treatment had higher firmness, a delayed degreening and yellowing (lower a value) process, and a higher lightness (L) and hue angle (h) during storage. Heat treatment also delayed ripening, inhibiting the growth of C. gloeosporioides and softening of papaya. Metabolites and enzymes inhibited ROS scavenging, depressed ABA-regulated respiratory, and activated phenylpropanoid metabolism. Our study provides a broad picture of fruit resistance to pathogens and the inhibition of physiological disorders by metabolomic profiling, which is induced by heat treatment.

Supply Chain Management of Mango (Mangifera indica L.) Fruit: A Review With a Focus on Product Quality During Postharvest

Mango (Mangifera indica L.) is a widely consumed fruit in tropical/subtropical regions around the world due to its excellent flavor and taste, and valuable source of nutrients and phytochemical compounds. As a climacteric fruit, mango is easily perishable after harvesting due to the ripening process, environmental conditions, and improper postharvest handling, leading to significant quality losses as well as economic loss throughout a supply chain. Postharvest losses are attributed to harvesting at an improper maturity stage, poor postharvest pretreatment, improper packing and packaging, inappropriate storage temperature and distribution conditions. These caused mechanical damage, sap burn, spongy tissue, weight loss, fruit softening, decay, chilling injury, and postharvest diseases. Currently, each step in the supply chain has been applied many postharvest technologies to reduce the quality losses of mango fruits as well as improving their marketability with the highest retention of quality. This review documented available possible causes for the quality losses and observed the physicochemical changes of mango fruit when applying postharvest technologies at each critical step in the mango supply chain from harvesting, pre-treatment, packaging, storage, to distribution. The summarized information is expected to provide comprehensive quality changes of mango fruits and point out the proper technology at each step of the supply chain.

Hot air treatment reduces postharvest decay and delays softening of cherry tomato by regulating gene expression and activities of cell wall-degrading enzymes

BACKGROUND

Fruit softening facilitates pathogen infection and postharvest decay, leading to the reduction of shelf-life. Hot air (HA) treatment at 38 °C for 12 h is effective in reducing postharvest disease and chilling injury of tomato fruit. To explore the effect and mechanism of HA treatment on reducing postharvest decay and softening of cherry tomato, fruit at the mature green stage were treated with HA and then stored at 20 °C for 15 days. Changes in natural decay incidence, firmness, cell wall compositions, activities and gene expression of cell wall-degrading enzymes of cherry tomatoes were assessed.

RESULTS

HA treatment reduced natural decay incidence, postponed the firmness decline, inhibited the respiration rate and ethylene production, and retarded pectin solubilisation and cellulose degradation of cherry tomatoes. Enzymatic activities and gene expression of pectin methylesterase, polygalacturonase, cellulase and β-galactosidase were inhibited by HA treatment. In addition, the gene expression of LeEXP1 was reduced, while LeEXT was up-regulated after HA treatment.

CONCLUSIONS

Our findings suggested that HA treatment could inhibit cell wall degradation and postpone softening of cherry tomatoes by regulating gene expression and activities of cell wall-degrading enzymes, resulting in the reduction of postharvest decay. © 2017 Society of Chemical Industry.

Changes in Levels of Phenylethanoid Glycosides, Antioxidant Activity, and Other Quality Traits in Cistanche deserticola Slices by Steam Processing

We investigated the effect of steaming time on Cistanche deserticola Y. C. MA slices by analyzing levels of bioactive compounds, antioxidant activity, and weight loss compared with fresh, directly oven-dried, and blanched samples. Fresh samples had extremely low levels of phenylethanoid glycosides and antioxidant activity. Lower levels of weight loss and higher amounts of soluble sugars, polysaccharides, and dilute ethanol-soluble extracts were found when the slices were steamed rather than blanched. Slices steamed for 5 and 7 min contained significantly (p<0.05) higher amounts of acteoside, isoacteoside, and 2'-acetylacteoside than directly oven-dried samples. However, soluble sugars and dilute ethanol-soluble extracts decreased gradually throughout the steaming process. The concentration of polysaccharides fluctuated during the steaming process. The steaming time had a consistent effect on antioxidant properties evaluated by oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (DPPH) and ferric reducing antioxidant property (FRAP), showing a significant increase and reaching 108.62, 23.08, and 11.68 micromoles Trolox per mass of fresh slice (μmol TE/g FW), respectively. The present results suggest that fresh-cut C. deserticola can be subjected to approximately 5-7 min of steaming to improve phenylethanoid glycoside levels and antioxidant activity, while still preserving the amounts of soluble sugars, polysaccharides, and dilute ethanol-soluble extracts. These results would help to improve the production process for fresh-cut Chinese medicines, and increase the understanding of their associated health benefits.