HORT*4300 Postharvest Physiology

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The following description is for the course offering in Winter 2023 and is subject to change. It is provided for information only. The course outline distributed to the class at the beginning of the semester describes the course content and delivery, and defines the methods and criteria to be used in establishing the final grades for the course. Offered in odd-numbered years

This course provides an examination and discussion of physiological and biochemical processes unique to postharvest development and deterioration. Principles and practices of storing fruits, vegetables, and florists' and nursery stocks as well as marketing pathways for horticultural crops will be considered.


Teaching Assistant:

Credit Weight:


Course Level:

  • Undergraduate

Academic Department (or campus):

Department of Plant Agriculture



Semester Offering:

  • Winter

Class Schedule and Location:

Please refer to Web Advisor for class schedule and location.

Learning outcomes:

At the end of this course, students should be able to:

  1. Have a broad knowledge about fruits, vegetables and flowers and the physiological characteristics of their development into an edible or commercially usable product.
  2. Know the physiological and biochemical changes that occur after harvest, and how such changes lead to the deterioration of the produce.
  3. Understand the strategies involved in the utilization of various technologies for the preservation of shelf life and quality.
  4. Know the impact of global trade as a consumer driven process, and its implications on the transportation and shipping of various horticultural products.
  5. Evaluate the importance of Canadian horticultural produce in global food security.  

Lecture Content:

Physiology/Biochemistry - Biological basis for postharvest practices, emphasizing biotic and abiotic factors (e.g., maturity, temperature, humidity, gaseous atmosphere, ethylene, gene action and regulation, etc.) which affect metabolism, senescence, stress-induced physiological disorders and quality of harvested horticultural products.

  • Postharvest Technology - Principles, application and limitation of methods and special techniques such as "common" and controlled atmosphere storage, pre-cooling, and high humidity storage; some modern instrumentation for assessing quality such as for volatile analysis, packing line technology; novel ethylene antagonists (e.g. 1-MCP), phospholipase D inhibition technology etc., to extend shelf-life of horticultural products.

In general, each week of the course covers a specific post-harvest topic within two 50-minute lectures. Emphasis is placed on class discussion, and background reading will be useful each week. One laboratory period of up to 170 minutes per week may include - 1) a lab demonstration or class discussion of certain post-harvest principles not necessarily covered in lecture, 2) web searches on postharvest topics or 3) a field trip, or other suitable topic of interest.

Course Schedule
  • Course Information: Course outline; Lecture Schedule; Recommended Reading Schedule; Laboratory Schedule; Laboratory organization; Contact Persons
  • Fundamental Nature of Perishable Products - Aspects of Deterioration; Introduction to Postharvest Facility; Value of Ontario Storage Industry
  • Maturation and Development - Introduction and Terminology; Deciding Harvest Maturity; Fruit Development and Maturation
  • Metabolism of Harvested Products / Metabolic Control Mechanisms - Respiratory Metabolism – Overview; Stress in Harvested Products; Metabolic Control by Temperature; Alternative Respiration; Metabolite Channeling
  • Ethylene Physiology- Biosynthesis and Measurement of Ethylene; Ethylene Biosynthesis; Role of Ethylene in Fruit Tissues; Ethylene, ACC, and the Climacteric; Exogenous Ethylene; Control of Ethylene by O2 & CO2; Stress, Auxins and Ethylene; Measurement of Ethylene; Properties of Ethylene; Developmental and Physiological Effects; Postharvest Uses of Ethylene; Sources of Ethylene; Undesirable Effects of Ethylene; Developmental Changes Induced by Ethylene; Cellular and Molecular Modes of Action; Ethylene Binding and Perception in Plants; 1-Methylcyclopropene (1-MCP); Ethylene and Biotechnology; Summary
  • Cooling Horticultural Commodities - Heat and Temperature; Need for Cooling; Cooling of Produce; Principles of Temperature Control of Postharvest Deterioration, Water relations
  • Gas Exchange and Movement - Forces Driving Movement; Movement and Exchange of Gases; Gas Exchange & Atmospheric Stress
  • Oxidative Stress Physiology - Active oxygen species; Effects of postharvest procedures on oxidative stress; Senescence and ethylene; Antioxidants; Mitochondrial electron transport – Alternate oxidase; Postharvest treatments to control oxidative stress, Physiological Disorders
  • Controlled Atmosphere Storage of fruits, vegetables and flowers
  • Phospholipase D inhibition Technology for enhancing quality and shelf life
  • Other technologies for enhancing quality and shelf life


Labs & Seminars:

One laboratory period of up to 170 minutes per week may include - 1) a lab demonstration or class discussion of certain post-harvest principles not necessarily covered in lecture, 2) web searches on postharvest topics or 3) a field trip, or other suitable topic of interest.

Lab examples:

  1. Estimation of ethylene, carbon dioxide, firmness in fruits
  2. Estimation of colour using a Minolta Colour meter
  3. Estimation of soluble solids, acidity
  4. Shelf life extension by 1-MCP, Hexanal vapour treatments
  5. Web searches for relevant topics

Seminars are expected to be 25-30 minutes duration with 10 minute question period. Seminar presentations carry 30% of the marks.

  1. Postharvest issues of cut flowers
  2. Physiological disorders in fruits/vegetables
  3. Colour components in fruits and vegetables
  4. Flavour in fruits, vegetables and flowers
  5. Production and postharvest storage of herbs
  6. Health regulatory properties of fruits and vegetables
  7. Minimal processing and marketing of fruits and vegetables
  8. Processing of fruits
  9. Processing of vegetables
  10. Microbial and food safety in fruits, vegetables and minimally processed products
  11. Stress in horticultural produce (including turfgrass)
  12. Local food

Course Assignments and Tests:

Assignment or test Contribution to Final Mark Learning Outcomes Assessed

Term Paper - a topic relevant to post-harvest physiology

30% 1, 2, 4, 5
Labs/Reports 30%

2, 3

Seminar 30%

2, 3, 4, 5

Participation 10%

1, 2, 3, 4, 5

Additional Notes:

Term paper (30%): Students may choose a topic of their interest relevant to the. The term paper should be a concise description of the topic, described in about ten pages, double spaced, including diagrams, figures, tables etc. This should be submitted by 7th February or earlier to provide an early evaluation of performance.

Labs/Reports (30%): Students are expected to write six lab reports in a format involving problem investigated, objectives, Materials and methods, results and discussion. The reports are expected to be submitted at least 15 days before the end of the classes, or preferably earlier.

Seminar (30%): Seminars will be assessed focusing on the content, clarity, quality of the slides, organization of slides and relevance to the outcomes. Students are advised to consult with the instructor about the suitability of presentation well before the actual. Slides for the seminar can be submitted well before in order to obtain comments to improve the quality.

Participation (10%): Participation of students is evaluated by regular attendance, involvement in class room discussions.

Final examination:

There is no final examination scheduled for this course.

Course Resources:

Required Texts:

Kader, A.A. (editor). 2002. Postharvest Technology of Horticultural Crops (3rd edition). University of California, Agriculture and Natural Resources, Publication 3311, 535pp.

Paliyath, G., Murr, D.P., Handa, A and S. Lurie (Eds) (2008) Post harvest biology and technology of fruits, vegetables and flowers. Wiley-Blackwell, Iowa.

Texts are available in the library

Recommended Texts:


Lab Manual:

There is no lab manual for this course. Detailed information will be provided before the labs in advance.

Other Resources:

The Commercial Storage of Fruits, Vegetables, and Florist and Nursery Stocks (Website) http://www.ba.ars.usda.gov/hb66/index.html  USDA Agricultural Handbook #66. Gross, K., C.Y. Wang, and M.E. Saltveit (editors). 2002.

Postharvest biology and technology (Article) https://www.journals.elsevier.com/postharvest-biology-and-technology/

Scientia Horticulturae (Article) https://www.journals.elsevier.com/scientia-horticulturae/

Journal of the American Society of Horticultural Science (Article) http://journal.ashspublications.org/

Field Trips:

Field trips usually involve a trip to a cold storage facility (Norfolk Apple Growers, Simcoe). The field trip is usually towards the end of the semester, dates are decided based on the convenience of the facility operators. There are no costs to the students.

Additional Costs:


Course Policies:

Grading Policies:

Late submissions will be subjected to a reduction of 5% of the total marks.

Course Policy on Group Work:

Not applicable.

Course Policy regarding use of electronic devices and recording of lectures:

Electronic recording of classes is expressly forbidden without consent of the instructor. When recordings are permitted they are solely for the use of the authorized student and may not be reproduced, or transmitted to others, without the express written consent of the instructor.

Other Course Information:

University Policies

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