Annalisa Hultberg Extension Educator, food safety
While not all produce should be washed during postharvest handling, many items need to be washed to remove soil or to hydrocool. It is a best practice use a food-grade sanitizer in bulk tanks of wash water to reduce the potential to spread microbial contamination via the water. If one leaf of lettuce has some bird poop on it, for example, the water will spread it to all the others. The sanitizer prevents that from happening.
We know that sanitizers are very effective at inactivating bacteria such as Salmonella and Escherichia coli O157:H7 that may be present in the water and brought in from the field, hands, compost or other sources. They also can increase shelf life, since the sanitizing agents inactivate bacteria, viruses, spores, fungi and other microorganisms that can lead to degradation of fresh produce in storage.
Read below for instructions on using sanitizer in wash water. If you are looking for an organically approved sanitizer for postharvest wash water, many growers use Sanidate 5.0 from BioSafe systems. You can find it at Johnny's, BFG or order it from Arbico Organics. Sanidate 5.0 breaks down in the environment into oxygen, water and carbon dioxide. Or, you can use plain, unscented bleach that is labeled for use in sanitizing fruit and vegetable wash. Both are used at very low concentrations. Always read the label to determine the rate and which to use sanitizers and measure PPMs to ensure you have not used too much.
Here is an overview on using sanitizers in produce wash water.
Step 1. Fill tank and measure sanitizer
Water used for washing must be clean and potable (drinkable). Add the amount of sanitizer as indicated by the label to reach the PPM for fresh fruits and vegetables to the wash tank.
If using household chlorine, use only plain, unscented household bleach without added thickeners or fragrances.
Dispensing sanitizer from bulk bottles can be a challenge! If you are struggling with your SaniDate bottle to figure out how to dispense small amounts safely, University of Vermont has a great overview of very low-cost options that can help you dispense the chemical safely. Always follow the label!
Step 2. Rinse products in the dunk tank with the sanitizer
Be very gentle with leafy greens and other items. Let the water remove the dirt, not your hands. Do not immerse tomatoes. You do not need to keep the greens in the water for too long. They have very little mass, so generally they will cool down very rapidly. After 2-3 minutes they are likely going to cool as much as possible from the cold water.
Step 3. Rinse products in fresh water if indicated by the label
Read the label carefully. Some sanitizers require a freshwater rinse, others do not (SaniDate 5.0 does not).
Step 4. Change water frequently
Empty the tank in a way to ensure that you are not standing in mud. Using gravel or pallets can help, if you do not have a concrete pad. Make sure to change the water when it becomes dirty and when a new crop is added. After dumping old water, refill the container with clean water, re-measure the sanitizer, and test for concentration.
Step 5. Monitor sanitizer levels
To maintain levels that are appropriate for your sanitizer, use test strips or another method to verify the concentration after each addition of sanitizer. Make sure the tester strip that you get tests for the chemical you are using! SaniDate needs PAA tester strips.
Sanitizers will vary - follow the instructions on the package. Also note your water pH. pH level should generally be maintained between 6.0 and 7.0 to provide for the greatest effectiveness.
Step 6. Always document the sanitizer levels on a log sheet
Keep a log sheet with the date, time, and concentration levels near your washing station. You should check the sanitizer level in the water after each addition of sanitizer and document the level on the log sheet.
For more information:
UMN Extension page on using produce wash water sanitizers
Produce Wash Water Sanitizers: Chlorine and PAA (UMASS Amherst)
Comments
Post a Comment