Why are macadamia nuts sold without shells?
Written by
Olivia Mitchell
Reviewed by
Prof. Martin Thorne, Ph.D.How to grow macadamia trees explain why you've never seen the nuts sold in their shells. That 1/4-inch thick shell will require a pressure of over 300 pounds to crack open, which is roughly the same PSI of a car tire. Home methods unsuccessfully use hammers, which would yield 60-70% kernel shatter in the cracking process, which is why commercial processing is the only viable alternative for an edible product.
Shell Hardness
- Industrial crackers: Steel blades apply 300-500 psi
- Home attempts: 60% kernel loss with hammers
- Safety risk: Sharp shell fragments cause injuries
Quality Control
- Sorting: X-ray machines detect hollow/rotten nuts
- Freshness: Vacuum-sealing within 2 hours of shelling
- Cost: Shells add 30% to shipping weight
A vacuum seal keeps food fresh. Nuts that hang out in their shells oxidize much faster as the moisture is trapped inside. A study has shown that a shelled nut can retain freshness for 18 months compared to six months for nuts left in their shells. Packaging factories often flush their packages with nitrogen to prevent rancidity and oxidation of nuts; they cannot do this with nuts in intact shells.
Commercial sorting eliminates defects. Infrared scanning complements human sorting to find mold or insect damage not visible. Through my tours of various facilities in Hawaii, I'm aware that post the shelling process, at least 20% of the nuts may have been rejected. This quality control step ensures that only the plump and sweet kernels are sent to retailers.
Space dedicated for storage drives the removal of shells. They both increase the weight of shipmed nuts by 30% and the volume by 50%. Retailers save $1.50 per pound in shipping costs when shipping hulled or shelled nuts. For home growers, even cracking 10 pounds of nuts requires purchasing a hydraulic press which generally runs between $800-$1200 and is more expensive than buying shelled nuts.
Try roasting the shelled nuts at a temperature of 275°F (135°C) for about 15 minutes to enhance the flavor of them. You can store your nuts in mason jars or similar, with oxygen absorbers added to maintain freshness. My fresh 2022 batch was kept crisp for 14 months using this process. Always keep nuts in shells out of the freezer, as they will absorb odors from the freezer through microscopic pores.
Read the full article: How to Grow Macadamia Trees: A Complete Care Guide
