Safely dehydrating produce for school food service

Because dehydrating produce is specialized processing, you may need to request a variance. A variance is a request made by a school or other food establishment to use a food preparation method that does not have safe handling requirements outlined in the Food Code.

• The variance request must show how the preparation process and final food product will minimize the risk of foodborne illness.
• The Minnesota Food Code does not contain safe food handling instructions for dehydrating foods.

Before dehydrating produce in your school, contact your local health inspector.

• Provide the health inspector with a list of all the fruits, vegetables and herbs you plan to dehydrate and serve.
• Your health inspector will help answer questions about your HACCP (Hazard Analysis Critical Control Point) plan.
• The food service or nutrition services director must write and submit the HACCP plan.

You will need a HACCP (Hazard Analysis Critical Control Point) plan specific to dehydrating produce as part of your variance request. A HACCP plan is different from your department’s Food Safety Plan.

• A Food Safety Plan contains the day-to-day policies and procedures related to food handling, sanitation, employee hygiene and illness, training, and other topics needed to prepare and serve safe food.
• A HACCP plan pertains to a specific food preparation or handling process and outlines the specific actions needed to minimize any food safety risks not addressed in your Food Safety Plan.

To begin the process:

• Assemble your team.
  • At least one person should have completed training in HACCP principles. This may be a food service director.
  • An Extension food safety educator may be able to support your team.
  • Your local health inspector and the Minnesota Department of Health (MDH) HACCP Plan Coordinator will assist your team with questions throughout the process.
• Describe all of the produce you plan to dehydrate, its intended use, and how long it will be stored before serving.
• Map the flow that both the produce and other supplies, like packaging, will follow in the department.
  • Start with receiving and storage, then continue with the preparation steps (pre-treatment, dehydrating, post-treatment), storage, and service.
  • Physically walk through the department to verify the flow.

Your local health inspector will provide you with a plan template. There are seven principles or components of a HACCP plan. Each of these should be completed with the entire HACCP team. Your plan will be unique to your food service department and the produce being dehydrated.

To write your HACCP plan:

1. Conduct a hazard analysis. Identify all the potential food safety risks (biological, chemical and physical) at each step in the flow of the produce and supplies.
2. Determine the critical control points (CCPs). Identify which risks are not minimized by the policies and procedures in your Food Safety Plan.
3. Establish critical limits for each CCP. Set food safety parameters and processes to minimize the risks for each CCP.
4. Establish a monitoring system for each CCP. Create a plan for how each critical limit will be monitored throughout the process. This includes the specific actions that will be used to test and who will be responsible for testing.
5. Establish corrective actions. Write plans for how the produce will be handled if the critical limit is not met. This may include reprocessing or discarding the produce.
6. Establish verification procedures. Identify who will be responsible for checking the final product.
7. Establish documentation and record-keeping procedures. Identify the production logs needed, and include training plans and frequency.

Considerations for your HACCP plan

Below are considerations for determining the CCPs and the critical limits to minimize food safety risks. Use research-based recipes, and work with a food safety expert.

Pathogens of concern (biological hazards)

Your HACCP plan must include processes to minimize these biological hazards: Salmonella, Bacillus cereus, Clostridium perfringens, Hepatitis A virus, and molds that produce mycotoxins.

These are pathogens of concern related to dehydrated foods because they have been shown to survive in foods with low moisture content, such as dehydrated produce.

How to minimize the risks of biological hazards

In addition to purchasing from approved sources, inspecting produce for quality and safety, and storing foods to prevent contamination, there are strategies to minimize food safety risks when dehydrating produce.

The following strategies may be used in your HACCP plan and depend on the produce being dehydrated.

• Use an antimicrobial fruit and vegetable wash treatment before cutting and preparing produce for dehydration.
  • Research has shown that commercially available antimicrobial produce washes for use in food service settings can reduce the number of certain pathogens, like E. coli, Listeria monocytogenes and Salmonella, that may be present on produce by up to 99.9%. (Note: the produce washes formulated for use in a food service setting are different from those used on farms during harvesting).
• Prevent bare-hand contact when cutting and preparing produce for dehydration. Follow safe single-use disposable gloves recommendations.
• Specify the size cut and thickness of the produce in your recipes as this will impact dehydrating time and consistency.
• After cutting produce, keep it refrigerated at an internal temperature of 41 degrees F or below until you are ready to dehydrate.
• Use a pre-treatment process on produce before dehydrating.
  • Blanching: briefly cooking food in boiling water or steam, and then rapidly cooling.
    • This is an option for most vegetables and may be an option for firm fruits.
    • Blanching inactivates ripening enzymes and changes the structure of cell walls so water can be removed during dehydration.
    • There is also research supporting the use of a citric acid solution for blanching to aid in inactivating bacteria and preventing color changes of the dried produce.
    • Blanching time will depend on the type of produce, whether it has a skin, peel or rind, and the size of the pieces.
    • If the produce will not be immediately dehydrated, cool the blanched produce quickly by following the department’s cooling procedures.
  • Acidifying: adding an acidic component to a food to lower the pH (the measurement of acidity in a food).
    • For certain fruits and some varieties of tomatoes, bacteria are reduced when they are soaked in a specific concentration of an ascorbic or citric acid solution for a set amount of time before dehydrating.
    • Do not confuse acidifying produce with dipping produce in a lemon juice solution to prevent browning caused by ripening enzymes.
• The time and temperature needed for dehydration will vary based on the produce.
  • Use research-based recipes and processes, such as from the National Center for Home Food Preservation and educational institutions.
  • If there is no, or limited research available regarding a specific produce item, the proposed dehydrating process may need to be reviewed by a process authority. A process authority is a qualified individual who has the knowledge, training and experience in a specific food processing system.
• Incorporate visual and tactile indicators for doneness into your testing.
  • Dried vegetables and herbs should be hard and brittle when fully dry.
  • Dried fruits may remain pliable, but do not stick to themselves if folded or to other pieces.
    • Cut several pieces from each batch of dried fruit in half. There should be no dark spots (moisture) in the center, and you should not be able to squeeze out liquid.
• Use a post-treatment process after dehydrating.
  • Conditioning or sweating: cooled, dehydrated produce are placed into a food-grade container or bin with a lid to allow for any residual moisture to evenly distribute.
    • Shake the container daily to separate pieces and check for any moisture condensation. If condensation is present, return the produce to the dehydrator.
    • Conditioning decreases the risk of mold.
  • Pasteurizing: an additional heat treatment to dehydrated produce. There is some research available supporting the pasteurization of certain fruits and herbs that were not blanched before dehydration.
• Use packaging materials that prevent moisture exposure to the dehydrated produce. For example, plastic storage bags may not be appropriate as they can be permeable.
• The shelf life of the dehydrated produce will vary depending on the type and storage.

Throughout the entire process, keep notes on your conversations with your local health inspector and others assisting you. Detailed note-taking can help answer questions that arise.

Once you have finished your HACCP plan, submit it to your local health inspector and the MDH HACCP Plan Coordinator to review. Be sure to ask for a review timeline, and follow-up periodically if you do not receive an update.

Wait to begin dehydrating produce until you have received approval from your local health inspector.

Once you have received approval, you can begin to train your staff. Training should be ongoing to ensure dehydrated produce is prepared safely.

If you need to modify your HACCP plan, contact your local health inspector before making a change. A change could include purchasing a new piece of equipment or planning to dehydrate a new produce item.

Your local health inspector will verify adherence to the HACCP plan during future routine inspections.