Mighty Clean and Comfortable – A New Wash and Pack Shed at Mighty Food Farm

 Download this Postharvest Case Study as a PDF Here!

Lisa MacDougall has led Mighty Food Farm through start-up, relocation from rented land to owned land, and now through the construction of a brand-new 60 ft x 90 ft wash and pack shed. She’s done this all while producing a diverse mix of organic vegetables, tree fruit and berries on fourteen acres, now, in Shaftsbury.

The packshed has become the central “hub” of the farm boasting new, slab on grade construction with a large overhead door on the east side for receiving from field and packing out for market, person-door for crew access on the northeast corner, and a second person-door for retail and CSA access on the northwest corner.

One of Lisa’s primary goals in her new location was “a proper P-shed”; a pack shed where she and her crew could comfortably and safely wash, store, and pack produce for delivery to her customers year-round.  Mighty Food Farm serves retail farm stand, farmers market, CSA, and wholesale customers.

Continue reading Mighty Clean and Comfortable – A New Wash and Pack Shed at Mighty Food Farm

A Vegetable Farming “Must Have”: Harvest Tote

Every vegetable farm must have a harvest tote, and I don’t mean a basket for picking into. What I’m referring to is a box with the daily essentials in it so you’re never without, and don’t have to go back to the barn.

This “Just-In-Time” kit is taken right out of the Lean principles and works outstanding on the farm just as it does in the automotive or manufacturing industry. Lisa MacDougall of Mighty Food Farm in Shaftsbury, VT swears by this little blue box she calls the “Harvest Tote” which holds all the essentials needed for daily harvesting out of the field.

What’s should you have in the box?

  • Harvest Knives
  • Snippers
  • Scissors
  • Sharpening Stone
  • Rubber Bands
  • Harvest Log
  • Pen, pencil or marker

This box always gets placed in the truck, every morning. These essential tools are kept all together and in one place at all times minimizing time to look for tools, or trips back to the packshed because the rubber bands were forgotten. This reduces downtime and saves wasted steps leading to increased efficiencies of operation.

This kit has food safety benefits too! With all the tools stored together, they are cleaned and sanitized all at the same time and logged, usually on a weekly basis. This Friday afternoon cleaning is also an opportunity for a weekly sharpening so all tools are in good shape for the week ahead. Keeping the tools in a tote keeps the knives from getting used for other activities outside of harvest which could contaminate them and make them dirty. Keeping the knives in a tote, also ensures that they are not stored in a hard to wash sheath, tossed on the dash of the truck, cup holder of the tractor etc.

Implementing this standard has many benefits and could be a great tech-tip to consider on your farm.

Postharvest Resource Survey

We are seeking input regarding a research and education project with the goal of consolidating postharvest information in a single set of resources.

Our proposed project aims to consolidate existing knowledge, best practices, and new developments in postharvest equipment, infrastructure, and buildings into a web-based handbook, workshop curriculum / educational materials and recorded videos.

Click here or on the picture to take the survey! 

This survey is voluntary and anonymous. Summarized and anonymized results will be included in a grant project proposal and also on our website (go.uvm.edu/ageng). Please direct any questions to Chris Callahan, chris.callahan@uvm.edu, 802-447-7582 x256.

The survey should take an average of 3 minutes to complete.

Thanks for your help.

Construction Details for a Counter-top Forced Air Cooler

To learn more about forced air cooling visit go.uvm.edu/forcedaircooling

To download the PDF version of this plan click here!


Farms that need to cool smaller volumes of produce can also benefit from forced air cooling. Whether cooling stacked pallets, pallet bins or individual cartons, the same principals apply. A smaller pallet cooler was noted on the previous page, but this concept can be scaled down even further to fit your needs. Here is a prototype, that could fit on a countertop with-in a walk-in cooler.

Framing:

Constructed of 2×4’s on top of a horizontal base made from 1/2” plywood cut 24” deep and 44” wide. Angled reinforcements were needed to stiffen the assembly.

Plenum Panel:

Continue reading Construction Details for a Counter-top Forced Air Cooler

Construction Details for a Pallet Forced Air Cooler

The blower is just placed up to the cut-out hole, on a shelf. This unit has a very simple shelf and feet to add some stability.

To learn more about forced air cooling visit go.uvm.edu/forcedaircooling

To download the PDF version of this guide click here!


Framing:

2”x12” lumber to make a 43” wide x 74” tall x 11-1/4” deep plenum for suction air distribution.

Plenum Panel:

3/8” CDX Plywood with an 11-1/4” circle cut out for the blower suction inlet. Position this whole centered for even air pressure.

Plastic Wrap:

Continue reading Construction Details for a Pallet Forced Air Cooler

Forced Air Cooling On The Farm

A downloadable/printable pdf of this article is available here.

Introduction

A commercial forced air cooler in a produce distribution facility

The preservation of quality in fresh market and storage crops on small and medium-sized farms in the Northeast depends on the rapid reduction of pulp temperature and maintenance of relatively low temperatures to slow metabolic respiration.

There is strong foundational work showing that rapidly reducing the temperature at the start of the cold chain increases product quality when delivered to the consumer. Postharvest handling is critical for fresh produce farmers and the markets they sell to. Effort and expense invested in growing fruits and vegetables can be wasted without good handling practices at and following harvest (Gross 2014). Consumers expect the best from fresh produce. Quality and freshness are ranked with high importance among consumers. Farmers market respondents respectively rank quality (63% ) and freshness (59%), as highly important factors in their buying decisions. Nearly 87% of the respondents indicated that availability and quality of fresh produce affected their decision about where to purchase (Gorindasamy 2002).

Precooling involves flowing a controlled, chilled fluid (air or water) over the product to improve heat transfer for removal of field heat to depress respiration and initiate the cold chain.

Figure 1—Produce packed in cartons, lugs, or other containers will not cool rapidly even when placed in a cooler. The cold air does not have sufficient velocity or pressure to pass into the center of the pallet or even to the center of a single carton, even when the containers have vented sides. Heat removal from the produce depends on conduction through produce and cartons which is slow.
Figure 2—Using a high-pressure blower, cool air can be pulled through cartons of produce to remove field heat and reduce product temperature to storage temperature more quickly. The heat removal rate from the produce is enhanced due to increased convective cooling in addition to conduction. This lowers respiration and leads to improved quality.

Precooling

This is a 4-foot tall version of a simple, portable forced air cooler. It is being used to cool a mixed pallet of fresh picked zucchini, summer squash, and peppers.

One of the most important postharvest factors influencing quality is temperature. Temperature directly impacts the rate of metabolic respiration and associated decay. Produce which is not cooled quickly degrades in quality (Sargeant 1991). Table grapes, for example, deteriorate more in 1 hour at 90 °F then in one day at 39 °F or one week at 32 °F (Thomson et al 2008). Lower quality leads to a decrease in sales, inefficient use of storage space, and wasted labor due to the time taken to grow, clean, and store product that doesn’t sell. Coolers are a good addition to most farms but fall short of meeting optimal precooling needs. When produce is packed in boxes, stacked on a pallet and directly placed into a cooler, cooling time will be a minimum of 24 hours and may take many days. (Thompson et al 2008).

One method to reduce cooling time is through forced air cooling (FAC). In FAC systems, refrigeration cools a space and blowers are set in position to actively draw the cold air through the produce. The cooling time drops from 24 hours to 10 hours or less when using a static cold room due to the increased air flow (increased convective heat transfer) (Thompson et al 2008, Boyette 1989).

Attempts have been made at smaller scale pre-coolers to reduce field heat at harvest in absence of coolers (Thompson and Spinoglio 1996). Retrofitting a cargo container with insulation and cooling with a large capacity air conditioner was also explored (Boyette & Rohrbach 1990). This forced-air cold room offered space for many pallets of produce but it still took many hours to reduce the temperature internally, especially for the boxes on pallets in the center of the container. The key is integrating both cooling and air flow effectively (see Figures 1 & 2).

A mobile forced air cold box mounted on a trailer was constructed and demonstrated in Florida (Talbot and Fletcher 1993) aimed at farms growing produce on 5-50 acres. This unit could be self-built. Experiments showed that grapes could be cooled by 15 °F per hour. For denser produce like melons and tomatoes, the cooling times were longer. The construction cost at that time was close to $5,000.

We have built prototype FAC’s for a single, fully or partially loaded pallet (figure 2) and also a 1-3 carton (either bulb crate or 1 1/9th bushel box) “counter-top” model. The construction details of these units are provided on the following pages of the PDF linked above.

123 lbs of Watermelons will take a long time to cool, but forced air cooling removed field heat 2 times faster than ambient room cooling.

Key Points of Precooling

  • Starts the cold chain by rapidly reducing respiration.
  • Reduced respiration leads to higher quality over a longer storage and distribution time.
  • Cooling is improved with the combination of active cooling and forced air flow with a blower.
  • 1-3 CFM of airflow at 0.5 IWC static pressure per pound of product is the rule of thumb for sizing.
  • Ventilated containers (e.g. holes or slats) are necessary to ensure airflow is actually through the product.
  • Close up any large openings to prevent short-circuiting air flow.

Build Plans

Sound like a good idea to you? Build plans are available for both of these prototypes!

For the pallet-sized unit check out this post –> http://go.uvm.edu/palletcooler

This is a video from a field trial of a modified pallet sized cooler! https://youtu.be/Ccy5KxrVhPk

For the counter-top forced air cooler, take a look here –> http://go.uvm.edu/countertopfac

Acknowledgments

Funding for this publication was made possible, in part, by the USDA NE SARE program under grant #LNE16-347.

Finding a Better Way: Engineering on the Farm (Podcast)

Check out episode 10 of this podcast with Chris Callahan, and Trevor Hardy from Brookdale Fruit Farm talking about engineering on the Farm! Full series available on iTunes.


The Our Farms, Our Future podcast series brings together the sustainable agriculture community for thought-provoking conversations about the state of agriculture, how we got here, and where we’re headed. With each episode, we hope to share different perspectives within the sustainable agriculture community while tackling such topics as building resilient farming systems, farm profitability, and fostering community through local food systems.

This series is being produced in conjunction with the Our Farms, Our Future conference, held in April 2018 to coincide with SARE’s 30th anniversary.

For this episode, two agricultural engineers discuss adapting innovation on the farm.

Trevor Hardy is manager of one of New England’s largest distributors of agricultural supplies at Brookdale Fruit Farm in Hollis, New Hampshire. Chris Callahan is an agricultural engineer with University of Vermont Extension. Both guests say engineering plays a crucial role in synthesizing the newest research and technology with the diversity and complexity of farming practices on the ground.

Click the image to open the podcast page, and listen to Episode 10!

A Better Way to Pick Strawberries

Tried and tested, the Picking Assistant by Crop Care works great for picking strawberries! Using both hands to “swim” through the plants helps you become efficient and thorough at picking. This machine is also great for weeding or planting other crops as well. More information about their new model can be found here: https://cropcareequipment.com/vegetable_equip/picking_assistant.phpI have experience using a Picking Assistant, and it has been a game changer on the farm! Here is a video of it in action.