Trudi Meyer is a member of the New Zealand Walnut Industry Group’s Promotions Committee and along with her husband Basil has a commercial walnut orchard in Canterbury.
Preparing for the Walnut Harvest
Do you graze livestock in your orchard? If you want to sell your walnuts or supply to a processing plant, sheep, cattle and other livestock MUST be removed from the orchard well before harvest (by 1st January) to minimise contamination of the walnut crop. Ground where walnuts fall should be mowed at least twice to assist the removal of faecal matter etc.
It is not acceptable to have livestock manure adhering to walnuts on the orchard floor. Even though you will be washing your walnuts, any manure washing around with the walnuts in the wash-water can potentially contaminate the shells with bacteria.
Harvesting. Depending on the region, the walnut trees will start to shed their crop at the end of March and through April and often into May. The green walnut husk surrounding the in-shell walnut will split open allowing the walnut to drop to the ground. Usually, the tree will shed any light or diseased walnuts first – clear these away and prepare for the fully formed walnuts to drop later. Remove any debris or litter and mow the grass down low.
Pick the walnuts up at least twice a week or daily in wet harvesting conditions. Walnuts will deteriorate quickly if left on the ground, particularly if the walnut shell has a weak seal, as this allows moisture to creep into the kernel and mould to develop. Nuts that have been left wet for too long with deteriorating kernel, discoloured and mouldy nuts are an unnecessary loss.
If they don’t fall of by themselves, get the green hull/husks off of the walnut. Juice from walnut hulls leaves a dark stain, so wear gloves or use tongs when you handle un-husked walnuts. Press on the skin of the walnut with your thumb; ripe nuts will show an indentation. Removal can be done by just taking a small jack knife and cutting around the hull and peeling off! Or you roll them under your foot until the hull is cracked open, pick them up and peel the hull off.
There are a number of harvesting aids, i.e. nut rollers, picker-uppers, to larger machines which will provide relief to a sore back.
Washing. Immediately after pick up, the walnuts should be washed to remove any dirt or husks still clinging to the shells. Dirt on the outside of the shells can indicate that the kernel inside may be second grade. Washing at this point of the harvest is very important to ensure that you have a fine quality nut and maximise the financial return for your crop.
Washing techniques include:
- hosing down the walnuts while they are placed on racks with a high pressure hose or a water blaster
- placing in a more advanced revolving cylinder with internal water spray
Avoid soaking walnuts in recycled water as cross contamination could occur.
- Do not wash the walnuts in an onion bag and then leave the walnuts out to dry while still wet inside the bag. The same applies for plastic buckets or any container that will not allow air to get around the walnuts – they will go mouldy very quickly and be of no value as a food item.
Drying. Drying is an extremely important part of the post-harvest care needed to present a clean and tasty walnut. At home, place the walnuts on racks to dry and turn the walnuts from time to time. Make sure the racks are placed in an area open to air movement but under cover from rain or evening dew. A hot area with no air circulation will make the walnuts go mouldy.
Air drying on racks will take up to six weeks to be efficient. To check whether the crop is properly dry, open the shell and check whether the partition that lies between the two halves is brittle. If the partition is still soft and flexible it is unlikely the walnut kernel is properly dry. Another way to check is to taste the walnut. If the kernel flesh appears translucent or waxy, the taste is sour, strong or with a distinct after taste then the walnut is still not properly dry. The dryer the nut, the easier it is to remove the kernel.
Make sure that you dry and store your walnuts in a vermin proof area. Do not lay them out where they can find them. They will take every one they can. They are the biggest enemy of walnut growers.
Storage: Storage for small amounts for personal use:
Once dried store the walnuts in onion bags in vermin free, cool and dry conditions. Keep them away from fuel, diesel, solvents etc. as these can taint the walnuts.
Correctly stored walnuts in the shell keep a long time.
Once out of their shells walnuts keep best in an airtight container in the fridge or freezer.
Using Walnuts. Once the walnuts are completely dry (about 8%) they are ready to eat, bake with, garnish etc. An easy way to judge whether the walnuts are dry enough, is to crack open a walnut and check if the partition breaks when bending it. If it doesn’t break, the walnut needs more drying.
The best advertisement for our fantastic product is to produce high quality clean, properly dried and stored walnuts!
Use a nutcracker, hammer, vice, or cracking machine etc.to pry the walnut kernel out of the shell. With a bit of practise the results are very rewarding and the walnut pieces becoming bigger and better!
Eat raw in muesli, salads, cookies, cakes, pies, meat dishes, pasta dishes, whole, cracked, ground, in smoothies! The possibilities are endless.
Do yourself a favour and have some NZ grown, fresh walnuts soon! You will not regret it!
- Wear good heavy duty rubber gloves! The staining of the walnut oil on these nuts is pretty awful. You will have yellow and black hands and fingers for quite some time if you do not heed this warning!
- Wear old clothing as any contact with the hulls will stain clothing permanently, and will also stain your hands if picked up barehanded.
Trudi Meyer, New Zealand Walnut Promotion Committee