Why should farmers care about how their herbs are treated after harvest?
I recently read the results of a survey and study on the post-harvest care of herbs.
This is obviously an important topic for anyone buying produce. Different herbs have different needs, but most people are unaware of how those needs differ between species. This leads to mistakes that reduce shelf life or even ruin produce before it can be used.
Not only does this cost produce users, but it costs farmers.
We recently had an Upstart Farmer come to us with this story. He had sold fresh basil (harvested that day) to a restaurant owner, and the next day the restaurant reported that the basil had decayed overnight and was unusable. They didn't know that basil shouldn't be stored in temperatures lower than 55º F, and had put it in a walk-in cooler. Even though the responsibility of storing the basil properly lies with the restaurant, it may reflect poorly on the farmer.
Educating yourself and your customers can help you avoid situations like this, and at least be able to offer an explanation if something like this happens.
I highly recommend reading the full report for more information (it's about 55 pages, but not a hard read). For now, let's stick to the main takeaways.
10 tips to keep herbs fresh after harvest
1 - Keep it cool!
Respiration rates slow way down when produce is kept cool, as the plant stomates close and gas exchange decreases. Harvesting during a cool part of the day will also help.
Harvest in the early morning or in the evening to keep produce cool.
2 - But not too cool.
Some herbs (like basil, shiso, and some oregano species) are sensitive to chilling and can be damaged by over chilling. Basil should not be kept below 55º F, for example, but can attain a shelf life of 12 days at 60º F. That means that if you keep a cool kitchen, the best place for your basil might be in a pitcher on the counter.
Help your customers avoid waste by marking the packaging, like Local Greens does.
3 - Be consistent.
Temperature and moisture fluctuations are largely responsible for disease and decay issues. Reduce the number of times you move produce from one place to another, and try to keep temperatures of coolers and transport vehicles steady.
4 - Production of hormones such as ethylene generally increase rate of deterioration.
Ethylene, nicknamed "the ripening hormone", causes aging and often deterioration in plants. While this is an important part of plant life cycles, it's generally something that you want to discourage after harvest. If your crop is a type which produces a lot of ethylene, you'll want to package and provide air movement as necessary. (But watch out that you don't dry your produce out.)
Some plants are also more responsive to ethylene at certain life stages. The best way to know this is to research your crops!
5 - Dirty trick: Use CO2 to control ethylene.
As the saying goes, "the enemy of my enemy is my friend." In this case, ethylene is your enemy and CO2 is one way to control it. Ethylene generation may be inhibited by increasing CO2 levels.
6 - Decrease plant damage and use clippers.
Ethylene generation is increased by wounds. Avoid harsh treatment of plant material (such as being crushed by crate) and remember to use clippers instead of tearing when you harvest your herbs.
7 - One size does not fit all.
Harvesting and packaging practices should be specific to the herb and its age, since needs vary widely.
We're used to seeing a wide range of herbs in grocery stores and on farms, from basil to mint. It's easy to forget that most of the common herbs we use are widely different in origin, needs, and life cycles. This means that each herb should be treated differently to increase shelf life.
8 - Packaging should balance water loss with decay.
Tender herbs such as basil or chives lose less water when packaged in plastic bags, but condensation increases decay rates.
9 - Control light exposure.
Whether stored under light or in the dark may have effects on the decay rate of herbs, depending on the herb. (See more on page 33.)
10 - Use your advantages.
As an Upstart Farmer, you have advantages over other producers. Your travel time is shorter, you have control over the transport conditions and handling, and you get more face time with the people who will be managing the produce after the sale. Use these to your advantage!
Fresh produce reflects well on the farmer, so do whatever you can to keep your produce looking (and tasting) pretty after harvest. Keep temperature and humidity low and consistent, know your crops needs, and reduce ethylene if possible.