Iranian Journal of Horticultural Science

Iranian Journal of Horticultural Science

Effect of Harvest Time on Fruit Quantity and Quality of ‘Hass’ Avocados Stored in Cold Storage with ethylene treatment

Document Type : Full Paper

Authors
Narges Ghorbanian 1
Mahmood Ghasemnezhad 2
Abuzar Hashempour 3
Jeremy Burdon 4
Malek Ghasemi 5
1 Department of Horticultural Science and Engineering, University Campus, University of Guilan, Guilan, Iran
2 Department of Horticultural Science and Engineering, Faculty of Agriculture, University of Guilan, Guilan, Iran
3 Department of Post-harvest Physiology and Technology, Citrus and Subtropical Fruits Research Center, Horticultural Sciences Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Ramsar, Iran
4 Department of Postharvest, Plant and Food Research Institute, New Zealand
5 Department of Genetic and Breeding, Citrus and Subtropical Fruits Research Center, Horticultural Sciences Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Ramsar, Iran
10.22059/ijhs.2025.385302.2229
Abstract
A primary challenge for avocado exporters is the incidence of grey pulp in fruits. This study investigated the effects of different harvest times (240, 270, and 300 days after full bloom, DAFB) and post-harvest ethylene treatments (0 and 100 ppm) on grey pulp development and other quality-related characteristics of ‘Hass’ avocado fruits during six weeks of cool storage at 5°C. Our findings indicate that delaying the harvest time increased the susceptibility of fruit flesh to graying, correlating with heightened sensitivity to ethylene. Specifically, fruits harvested at 270 and 300 DAFB exhibited 100% grey pulp when treated with 100 ppm ethylene and stored under cool conditions. Furthermore, delayed harvesting significantly enhanced fruit weight, skin weight, pulp weight, seed weight, dry matter percentage, and oil percentage. The highest concentration of oil phenols was observed in control fruits (no ethylene treatment), contrary to what might be expected when comparing with ethylene-treated fruits. The highest total flavonoid content and antioxidant activity in avocado oil were found in fruits from the second harvest time (270 DAFB) under control conditions. Enzyme activity analysis revealed that the highest POD and PPO activity (using Pyrogallol substrate) occurred in fruits from the third harvest time without ethylene treatment, or from the second harvest time with ethylene treatment. Correlation analysis demonstrated a positive association between grey pulp incidence and fruit weight, seed weight, oil flavonoid content, and PPO activity (using Pyrocatechol). In conclusion, while delaying harvest time in avocados generally improves fruit size and quality, it also increases fruit susceptibility to grey pulp, particularly in ethylene-contaminated environments during cool storage.
Keywords
Maturity
bioactive compounds
antioxidant activity
fruit ripening
dry matter
Subjects

Extended Abstract

Introduction

     The postharvest quality of ‘Hass’ avocado (Persea americana) fruit may be compromised by physiological disorders that develop during storage and ripening. The extent to which these disorders occur is significantly influenced by storage conditions, including duration and temperature, as well as the maturity stage of the fruit at harvest. In general, ‘Hass’ avocado fruit are chilling sensitive, and symptoms of chilling injury may appear in both the skin and flesh. Skin chilling injury manifests as discrete patches of discolored skin, whereas flesh injury appears as diffuse discoloration or greying. These two symptoms are not directly linked: skin injury may occur well before greying, and it is associated with the onset of ripening at storage temperatures rather than with a simple time–temperature relationship. Therefore, the main objective of our study was to examine the effect of ethylene treatment on the incidence of grey pulp in partially ripened ‘Hass’ avocados during cold storage. 

 

Materials and Methods

    This study investigated the effects of different harvest times (240, 270, and 300 days after full bloom; DAFB) and postharvest ethylene treatment (0 and 100 ppm) on grey pulp incidence and other quality-related attributes of ‘Hass’ avocado fruits during cool storage at 5°C for 6 weeks. After 3 weeks of storage, ripe fruits were treated with 100 ppm ethylene. After an additional 2–3 weeks (5–6 weeks total), fruits were cut in half and evaluated for grey pulp severity and incidence. In addition, fruit size, peel weight, flesh weight, seed weight, dry matter content, and oil percentage (on both fresh and dry weight basis) were measured, along with total phenol, total flavonoid, and antioxidant activity in the oil. Enzyme activities, including POD, SOD, and PPO, were also determined using pyrogallol and pyrocatechol as substrates. Grey pulp was assessed by determining the percentage of the cut surface affected by disorders (rated on a scale of 0–100).

 

Results and Discussion

    The results showed that delayed harvest increased grey pulp incidence in avocado fruits by enhancing fruit sensitivity to ethylene. Fruits harvested at 270 and 300 days after full bloom (DAFB) developed 100% grey pulp when treated with 100 mg L−1−1 ethylene and stored under cool conditions. Delayed harvest also increased fruit weight, peel weight, pulp weight, seed weight, dry matter percentage, and oil percentage.

The highest oil phenol content was observed in control fruits treated with ethylene. The highest total flavonoid content and antioxidant activity in avocado oil were found in fruits from the second harvest under the control treatment. The highest POD and PPO activities with pyrogallol as the substrate were observed in fruits from the third harvest without ethylene treatment and the second harvest with ethylene treatment.

Correlation analysis showed a positive relationship between grey pulp incidence and fruit weight, seed weight, flavonoid content in oil, and PPO activity with pyrocatechol.

 

Conclusion

    The grey pulp disorder can be seen when the fruit is cut, although it may darken further during storage. It is a major limiting factor for avocado production and export during cold-chain transport. Previous studies have reported that grey pulp is generally associated with senescence or ageing. In this study, we found that delaying harvest improved fruit size and quality, but increased the fruit’s sensitivity to ethylene during cold storage. As a result, delayed-harvest fruits showed a higher incidence of grey pulp than early-harvest fruits. Overall, ethylene exposure during cold storage increased the susceptibility of ripened fruits to grey pulp incidence. 

 

Author Contributions

Methodology, N.Ghorbanian., M. Ghasemnezhad., A. Hashempour,  J, Burdon and M.Ghasemi.; data curation; M.Ghorbainan.; writing–original draft preparation, N.Ghorbanian, M. Ghasemnezhad; Conceptualization, M.Ghasemnezhad; Investigation, M.Ghasemnezhad; resources, M.Ghasemnezhad, and J. Burdon; writing – review & editing, M.Ghasemnezhad and A. Hashempour; All authors provided critical feedback and helped shape the research, analysis and manuscript.

 

Data Availability Statement

The authors will make the results available if requested.

 

Acknowledgements

The authors appreciate the University of Guilan for the financial support of this research..

 

Ethical considerations

The authors avoided data fabrication, falsification, plagiarism, and misconduct.

 

Conflict of interest

The authors declare no conflict of interest.

 

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Iranian Journal of Horticultural Science
Volume 56, Issue 2
Spring 2025
Pages 357-377

  • Receive Date 18 November 2024
  • Revise Date 25 January 2025
  • Accept Date 27 January 2025