The macadamia had its origins in Australia and is now enjoyed as one of the premier nuts worldwide. Like all nuts and many seeds, the flavour is enhanced with roasting, but it has to be done carefully to avoid burning.
The following process should give you a delicious product to enjoy:
1. Nuts should be collected as soon as possible after falling to avoid any mould growth.
2. Remove the husk as soon as possible. Some trees will do this for you before falling but for others you will have to do it.
3. You can eliminate nuts with malformed, unsatisfactory or absent kernels by immersing them in a bucket of water. Discard the ones that float.
4. Place in a shaded location on flat trays, spreading them out to maximise air exposure, and allow to air dry for at least a few weeks depending on the prevailing temperature. The ideal time to crack the hard shell is when you can shake the nut and hear the kernel rattling inside.
5. Crack the very hard shells. Short of having a properly designed macadamia nut cracker with a hopper for cracking large quantities, this will inevitably be one by one. There are many crackers advertised on the Internet, but one of the best for the home grower is TJs, designed and made in Queensland. They sell for $40-80 according to whether you can get one second hand or new. Many others are cheaper but may not be quite as convenient if you’ve got a couple of kilos to do. The final 'no-cracker' approach of course is to use a hammer or vice, but this can be very slow and result in most kernels being broken, sometimes into many pieces. It is also hazardous, as the nuts break explosively and throw sharp shrapnel in all directions.
6. Spread the kernels out in a single layer on a flat baking tray and place in the oven or food dryer, probably on your lowest setting, hopefully to achieve about 37°C. Let them dry at this temperature for at least two days, then increase the temperature to 60°C and continue heating till kernels are crisp. The purpose of these two steps is to ensure the kernels are sufficiently dry. If not followed, the retained moisture will caramelise or brown when completing the next higher temperature roasting stage. The goal is to achieve the roasting with kernels remaining a creamy colour.
7. Roast kernels at 135°C for 20-30 minutes with occasional stirring until a creamy light golden colour is obtained.
8. They are now ready to be enjoyed as is, or by adding whatever fancies you choose. Store smaller quantities in an air-tight jar.
9. For longer term storage, you could vacuum seal or freeze.