Basics of Postharvest Management
Maintaining the quality and freshness of your fruits and vegetables as they move from farm to consumers’ hands involves knowing when to harvest at the correct time, proper handling, sanitation, and storage. This allows for the best product and marketability of your produce.
Knowing how and when to harvest, as well as how to handle your produce immediately after harvest in the field is a critical step towards maintaining maximum quality. From the New Entry Sustainable Farming Project, Plain Language Guide to Harvesting Your Crops is a good place to start for those just beginning their farm venture, or want a quick reference on a specific vegetable or fruit group e.g. greens, roots, tubers. The guide goes over maturity guidelines, the optimal time of day to harvest, and harvest and postharvest handling instructions. It also briefly discusses how to prepare your product to sell at market as well as recommended pricing.
For a more comprehensive look at harvesting procedures see the Roxbury Farm Harvest Manual. This manual contains an index of 53 crops. It references information on each crop’s yield, value, standards, tools needed, ready to harvest indicators and quality, harvest procedures, washing procedures, cleaning in the field, packing in the field, packing for delivery, and storage recommendations.
Although the above publications on harvesting touched briefly on postharvest handling, the following resources will cover cooling, cleaning, and sorting and packing of your crop in fuller detail. Attention to these processes will help prevent damage to your crops value and condition. Post-harvest Handling for Best Crop Quality out of the Wisconsin School for Beginning Market Growers represents a good introductory publication on postharvest handling through their Step-By-Step Post Harvest Handling guide. It briefly goes through how to best retain quality and freshness by: avoiding mechanical injury, promptly and thoroughly cooling your crop, maintaining the crops’ optimum storage temperature, and avoiding water loss.
The Post-harvest Handling Decision Tool is a more comprehensive publication. Produced out of Iowa State’s 2007-2011 Iowa Fruit and Vegetable Working Group, goes over cooling, cleaning, sorting and packing of harvested crops to ensure future quality and safety. More specifically it discusses steps to reduce field temperature to extend shelf life and protect nutrient value, minimize moisture loss/shrinkage, avoid physical damage, as well as practice proper sanitation throughout each step. The information prepared came out of a case study of three Midwestern farms. Crop types are discussed separately as they have different ideal ranges of storage temperature, humidity and equipment/cleaning considerations. Pack facility considerations are also included followed by a summary of the featured case-study vegetable farms.
For specific information regarding postharvest sanitation complying with NOP rules, see eXtension’s Approved Chemicals for Use in Organic Postharvest Systems adapted from Erin Silva of the University of Wisconsin’s 2008 piece for Family Farmed. This publication covers different cleaner and sanitizer options with chlorine, and the chlorine alternatives ozone and peroxyacetic acid in the most detail. The publication also provides a list and brief summary of usage of other allowed cleaners and sanitizers e.g. bleach and ammonium.
Proper storage of your fruit and vegetables is a critical component of every operation. Having proper cooling and packing areas as well as knowing the recommended humidity levels, storage temperatures, and ethylene sensitivity of the fruits and vegetables you are storing all need to be considered. If you are still in the construction/planning phase, see Building a Low-Cost Cooler & Packshed developed by the Madison Area CSA Coalition (now FairShare) in partnership with the Farley Center for Peace, Justice and Sustainability. These two groups underwent a 2-day workshop to teach beginning farmers how to construct a 60′ x 30′ packshed and walk-in cooler in an existing pole barn. This handout provides an overview on how to build your own structure based on the experience of the workshop for under $5000. It is complete with figures and photos to assist in the construction process.
Once your storage facilities are constructed, it is important to know the correct storage conditions of your crops. For a quick reference see the ATTRA publication Postharvest Handling of Fruits and Vegetables’ appendix of storage conditions for vegetables and fruits. The table includes temperature, relative humidity, ethylene sensitivity, storage life (days), and precooling method information for various crops. This publication also includes an appendix on constructing a Portacooler.
The 2012 Production Guide for Storage of Organic Fruits and Vegetables, out of the Cornell University Cooperative Extension, represents a more comprehensive resource on postharvest storage recommendations. The guidelines presented are an effort to translate comprehensive scientific research into practical management options focusing on postharvest storage in order to retain produce quality not immediately marketed. Specifically, this publication represents a comprehensive guide on the principles underlying storability for fruits and vegetables (e.g. maturity, respiration, ethylene), harvest and storage management (e.g. food safety, sanitation, cooling methods, ethylene management), and specific crop recommendations. Further resources are provided at the end.
Additional Resources and Citations
Bachmann, Janet and Richard Earles. 2000. Postharvest Handling of Fruits and Vegetables. ATTRA
Bittermann, Vanessa. 2007. Plain Language Guide to Harvesting Your Crops. New Entry Sustainable Farming Project World PEAS Cooperative
Blanchard, Chris. 2013. Post-Harvest Handling Decision Tool. Leopold Center for Sustainable Agriculture and Iowa State University Extension Value Added Agriculture Program
eXtension. 2014. Approved chemicals for use in organic post harvest systems. extension. Adopted from: Silva, Erin. 2008. Wholesale success: a farmer’s guide to selling, post harvest handling, and packing produce (Midwest edition).
Farley Center and the Madison Area CSA Coalition. 2011. Building a Low-Cost Cooler & Packshed. Madison Area CSA Coalition
Newenhouse, Astrid and Cindy Tong. 2001. Post-harvest Handling for Best Crop Quality. Wisconsin School for Beginning Market Growers
Roxbury Farm. 2012. Roxbury Farm Harvest Manual. Roxbury Farm
Silva, Erin. 2013. Influence of Preharvest Factors on Postharvest Quality. eXtension. Adapted from: Silva, E. 2008. Influence of preharvest factors on postharvest quality. In Wholesale success: a farmer’s guide to selling, postharvest handling, and packing produce (Midwest edition).
Silva, Erin. 2010. Respiration and Ethylene and their Relationship to Postharvest Handling. eXtension. Adapted from: Silva, E. 2008. Respiration and ethylene and their relationship to postharvest handling In Wholesale success: a farmer’s guide to selling, postharvest handling, and packing produce (Midwest edition).
Watkins, Chris B. and Jacqueline F. Noc. 2012. 2012 Production Guide for Storage of Organic Fruits and Vegetables. New York State Integrated Pest Management and Cornell University Cooperative Extension