Western Sustainable Agriculture Research & Education
(SARE) Farm Internship Curriculum and Handbook
Tom and Maud Powell and Michael Moss,
Sustainable Farmers, Jackson County, OR.
Technical advisor: Tim Franklin, Jacksonville, OR.
Curriculum advisor: Peter O'Connell, Jacksonville, OR.
Web advisor: National Center for Appropriate Technology, Butte, MT.
Harvest/Post-harvest Handling and Food Safety - Field Exercise
The learner will:
- Understand the importance of attentive harvest, packing, storage and transportation to providing quality product.
- Understanding how management practices affect post-harvest condition.
- Understanding how food safety practices begin in the field and carry through harvest & post-harvest handling.
- Provide resource access.
- Roots - carrots, beets, radish, parsnips, etc. Use digging fork or shovel to loosen soil, if necessary. Pull roots, using wooden baskets for container. Should be set in shade until washed. If this will be more than an hour and it's a hot day, remove greens from the roots to prevent dehydration.
- Fruits - nightshades, cucurbitae, etc. Determine which will be harvested based on ripeness. For nightshades, gently pull, or snip, the fruit from the plant. For cucurbitae, cut at stem with knife. Skin of fruits is more sensitive, so a lined wooden basket or a plastic container is used. Should store in shade until washing or boxing.
- Greens - lettuce, spinach, broccoli. Determine which plants to harvest based on maturity. Demonstrate proper use of harvest knife for cutting heads. Also demonstrate picking or cutting technique if only leaves are harvested. Quick cooling of greens is essential. Keep out of sun and wash as soon as possible.
Decision Making for Harvest
- Type of produce being harvested: Care should be taken to understand the ability of any given item to hold up post harvest in the field. There are some that can endure a lot of stress and go to market looking great and others such as lettuce that need utmost sensitivity.
- Time until sale: Leafy produce should be harvested and cooled just prior to distribution or market (unless refrigeration is available). Some produce like winter squash or garlic can be processed and stored for months prior to distribution.
- Weather conditions outside: The time of day a certain item is harvested, and the time that item sits in the field after harvest can differ greatly depending on the weather outside. If the temp is 50 degrees, under an overcast sky, your urgency is greatly reduced. Beans and other produce, which should be dry upon harvest, should not be harvested in the rain or first thing in the morning when dew is present.
- Cold Storage/Cool Pack resource availability: If refrigeration is available on site, taking the "field heat" out of an item is often enough cooling before going into reefer storage. If there is no onsite reefer, top icing wax boxes is often necessary to keep produce in prime condition before delivery.
- Field durability: Some items hold up just fine under the sun for a brief time. Other items like greens and lettuce should be shaded immediately after harvest and hydro-cooled as soon as possible.
Specific Handling Procedures Based on Type of Produce
- Greens and Lettuces should not spend any significant time in the field or without adequate shade. They should generally be harvested first, and cooled in cold water/ice bath immediately after leaving the field. Lettuces and greens should be inspected and cleaned before entering bath.
- Green beans should be harvested before mid-day heat is present. Beans cannot be hydro-cooled (cold bath) because of rust due to excessive moisture, therefore, should be cooled in reefer as soon as they are harvested to preserve crispness.
- Beets and Carrots should be forked, followed by simultaneous washing and hydro-cooling. Pull off any ugly greens of carrots; be slightly less critical of beets due to the fact that there greens are so widely enjoyed. They should be bunched and stored below forty degrees. Carrots do well in bins or perforated bags in cold storage.
- Broccoli and Cauliflower should be iced and or hydro-cooled immediately following harvest. Special care should be taken to insure green caterpillars are not present under the "trees."
- Cucumbers should be hydro-cooled immediately and washed down to remove any "spike" that may be present. Cucumbers can be stored in lugs or flats with lids and should be kept cool between forty and fifty degrees.
- Eggplants should be handled with delicate care following harvest. The skin shows rough treatment and punctures with ease. Eggplants should be sold as soon as possible.
- Tomatoes can be harvested at any time of the day, and should be packed gently into a box immediately following. Egg crate packaging is the best for avoiding tomato damage and layers should not be stacked more than four high in a box. Large heirloom varieties have a tendency to be VERY delicate and should be handled appropriately. Green tomatoes gleaned from vine before frost can be wrapped individually in newspaper and stored in a cool area inside a wax box. They will slowly ripen and provide you with tomatoes from your garden long after the last plants outside have died off.
- Salad Mix is generally placed in cold-water bath after harvest. This keeps temperature down while providing the farmer a good opportunity to thoroughly mix the salad for good uniformity. It is during this time in which you can pick out weeds and ugly leaves. Following the washing and mixing the salad should be thoroughly spun dried. It is important that the mix is relatively dried before being bagged, excessive moisture can lead to rot. Perforated bags are helpful.
- Melons can be harvested at your leisure although a melon harvested in the cool of morning will have a better texture down the road than a melon harvested in the deep heat. They should be stored around 45 degrees and can last for a couple of weeks.
- Potatoes can be harvested anytime of the day but should be handled carefully afterwards. It is now the accepted method of post harvest handling of tubers to either not wash them at all or give them the lightest of dustings. This reduces the chance of disturbing or tearing their skin and thus greatly reducing there storage time. Potatoes can be stored in jute bags or bins. Store in a cool dark place for optimal length of storage.
- Onions/Garlic generally need some curing after harvest. This provides an opportunity to dry the stem, making it possible to clip then store the produce. Garlic is often cured by hanging it in bunched of ten to twenty in a relatively cool dark space. Onions can be cured by laying them out on mesh wire with decent airflow above and below them. This insures good even drying of the stem and will provide the neck a good closure. This is important to promote good storability.
- Key production considerations:
- Water & irrigation
- Soil amendments - manure
- Equipment cleaning
Key harvest considerations:
- Food contact surfaces
- Soil contact
- Water used during harvest
Key processing considerations:
- Wash water
- Personal health & hygiene
- Effective sanitation practices for facility, equipment, utensils
Key storage considerations:
- Temperature/proper cooling
Food Safety Issues:
- Why have on-farm practices become a focus?
- Risk management
- Understanding pathogens
- Legal perspective/liability
- Why are all the considerations in the field, during harvest and post-harvest so imperative to the flavor, nutrient profile, shelf life, safety, texture and aesthetics of produce?
- Why are food safety considerations and regulations increasing?
This page was last updated on: May 16, 2012