May 9, 2023

Caveats for CA storage of asparagus

It’s possible to extend the Michigan asparagus season by two weeks or more through controlled atmosphere storage.

Randy Beaudry, horticultural professor at Michigan State University, outlined some takeaways from a study of CA storage for the Millennium asparagus variety in Michigan.

Consider the pros and cons of CA storage

“You can have a good year in which you can store a little bit longer, maybe up to four weeks. On a poor year, maybe two weeks and that’s all you’ve got. If you have a resource like a CA storage, and it’s a poor year for asparagus storage and you wouldn’t venture it, that room sits empty and it’s an investment lost. It’s important to understand that.”

Store only the highest-quality spears

“You can’t rescue a spear. It’s not like apple fruit where you can take it at any stage of ripening and slow that ripening process down.”

Harvest by cutting; collect as much of the butt portion as possible

“This is more important for spears of lower initial quality. In that first (research) year, the lower quality seemed to benefit, but not like the second year, where we had really high-quality spears going in.”

Do not trim spears before storage

“Cutting might not be an option in Michigan, but it is beneficial if you have questionable spears.”

Storage past two weeks is possible, but inadvisable

“Higher quality spears translate into greater storage capacity. Spears of all initial qualities will appear saleable immediately after exiting storage, but spears of sub-supreme initial quality will deteriorate and decay very quickly in the cold chain, possibly faster than it can reach the buyer’s refrigerator, and likely faster than consumer expectations. Your CA storage doesn’t have any lingering effects. They will fall apart eventually.”

Closely monitor the atmosphere

“We recommend 1% oxygen, 10% CO₂. Keep oxygen above 3% and elevate CO₂ up to 10%.

Do not disturb the atmosphere if possible

Avoid prolonged air storage

“Consider an earlier-producing cultivar that does not compete during Millennium’s glut period.” Beaudry said. “We need diversity in asparagus seed in Michigan.

“It would be a wonderful thing to look at different varieties than Millennium to look at their response to CA storage, should this be an option that the industry wants to pursue,” he said.

For more information on controlled atmosphere storage of Michigan asparagus,  read: Taking control: CA storage for asparagus extends season.

— Gary Pullano, senior VGN correspondent

Top photo: Gary Pullano