Organic Olive Curing and Olive Fruit Fly Control

It is the end of the year and we have harvested the last of our ripe organic olives. The varieties are a mixture of Mission, Manzanilla, Piccolino, and Leucino. All of these varieties are suitable for either pressing for olive oil or water cured & brined into table olives.

UCANR has a detailed publication (Publication 8267) that gives a full treatise on all different ways to process fresh ripe table olives. https://anrcatalog.ucanr.edu/pdf/8267.pdf Publication 8267 describes four different styles of water cured table olives: Kalamata Style, Sicilian Style, Mediterranean Style, and Greek Style.

Here is my quick and easy fresh olive curing recipe:

a) rinse the ripe olives in filtered water and remove any that are moldy or soft.

b) load the rinsed olives into glass canning jars, leaving an about 1" headspace at the top.

c) mix up a salt brine in a sufficient quantity for the volume of olives you are curing, using 1 TBSP Eden Sea Salt per cup of filtered water - stir until dissolved.

d) pour the salt brine over the rinsed olives in the glass canning jars, making sure that the olives are fully submerged.

e) place a weight at the top of each jar to keep the olives fully submerged. I use Kraut Source fermentation tops to press down the olives, but a saucer with a stone, or some idea of your own could work. https://www.krautsource.com/

f) place the jars with the brine in a shady spot on your kitchen counter or in a cupboard.

g) once per week pour out the olives into a colander and give them a quick rinse. Scrape off any white yeast that may have formed a scum at the top.

h) rinse and reload the glass canning jars with the olives and fresh salt brine.

i) repeat steps b - h for at least four weeks, then start tasting an olive at each week after rinsing. Sometime within about four to 7 weeks, the olives will have released enough of the bitter oleuropein to be palatable, and absolutely delicious.

j) Load the rinsed cured olives into the jars you wish to use at the table. Top the olives off with a final brine having a mixture of vinegar, filtered water, Eden sea salt, and a few herbs (optional). Through the years, I've used all different types and mixtures of vinegars, including apple cider vinegar, red wine vinegar, balsamic vinegar, and rice wine vinegar. Use a blend of vinegars that mosts suits your palate. When I make a total of eight quart mason jars, my final brine comprises 3 1/2 cups vinegar, 7 1/2 cups filtered water, and 1/4 cup Eden sea salt. Adjust the volume of the final brine to match what you need for the amount of jars you are filling.

Another recipe for the final brine is by weight, as follows: a wt. ratio of 2:5:20 salt, vinegar, water. For example, 40 g salt, 100 g vinegar and 400 g water makes about half a liter of final brine. Examples of herbs that can be added to the jars of brined olives include rosemary, thyme, garlic, chiles, mustard seeds, mint, and coriander.

k) top off each jar of olives with a thin layer of organic Black Point olive oil; cap the jars and store them under refrigeration to enjoy for months and even years to come.

Salt-Brining in Process - small batch

Salt-Brining in Process - larger batch

Finished Jar of Ready to Enjoy Cured Olives to Keep in the Fridge

If you decide to get more committed to growing your own olives at home, you will eventually face the olive fruit fly pest.

The Olive Fruit Fly [Bactrocera oleae(Rossi) (Diptera: Tephritidae)] recently appeared in the Bay Area of California. The olive fruit flies inject their eggs into the olive fruits as they are forming and ripening. The maggots grow in the fruit and make the olive very unpalatable and unsuitable even for oil production. Our olives were heavily infested with the olive fruit fly in 2022; we ended up harvesting all of our infested olives and burying them about 3 deep in a hole away from the olive trees.

We used an experimental approach to protect our ripe organic olives from olive fruit fly damage, and I'm excited to share that it worked! Read further to learn more.

Many commercial (even certified organic) olive growers in California with the appearance of the olive fruit fly in mid-June, typically initiate treatments of an insecticidal bait formulation marketed as GF-120 NF Naturalyte Fruit Fly Bait (produced by Dow AgroSciences LLC) that contains a highly effective fruit fly attractant and a small portion of the insecticide spinosad®. Treatments are made on a bi-weekly schedule until the olives are harvested in September through December. The average olive acreage per California grower is 30 acres. The “average table olive grower” would pay between $1,920 and $3,456 in treatment costs (materials & labor) for 30 acres depending on if the individual harvested early in mid-September (10 sprays) or late in mid-December (20 sprays), respectively. Oil producers could potentially pay more because the fruit is harvested later to increase oil content, but they have a higher acceptable damage threshold. Thus, the presence of the olive fruit fly has dramatically increased production costs for California olive growers.

The GF-120 NF Naturalyte hazards in the instruction sheet gave me some pause and I thought that there must be a better, more environmentally responsible way, to deal with the olive fruit fly. https://assets.greenbook.net/L71092.pdf

At our farm we have about 10 olive trees and paying for a pesticide and labor to apply GF-120 NF Naturalyte didn't seem cost-effective.

The alternate solution I came up with is to use Torula yeast baits. Torula yeast is a traditional olive fruit fly control in organic olive orchards in Greece. I purchased the Torula yeast from Harmony Farm Supply in Sebastopol. https://www.store.harmonyfarm.com/olive-fruit-fly-torula-yeast-lure/ They also sell bait traps: https://www.store.harmonyfarm.com/mcphail-trap-for-olive-fruit-fly/

We made our own traps using 1 liter plastic water bottles and screw on hangars. Here is an example of what our bait traps look like.

Once per month we placed 2 Torula yeast pellets into each 1-liter plastic bottle and added about 1 1/2 cups of water. We hung one or two of these traps in each of our 10 olive trees, starting on July 1 and we rinsed and repeated rebaiting the traps every four to six weeks. We removed the traps at our last olive harvest of this year, December 30, 2023.

The yellow bottle tops for the traps are currently for sale at Walmart: https://www.walmart.com/ip/Fruit-Fly-Trap-Killer-Plastic-Yellow-Drosophila-Trap-Sale-2022-Catche-Fly-J5O5/2277112827

Our olive fruit fly control was excellent!

We are completely out of fresh olives to sell from our Cloverfield Organic Farm as of today. We will have more again next Winter and hope we can help you u-pick your own fresh picked organic ripe olive oils. Our farm is located at 501 La Paloma Rd., El Sobrante, California. Our regular u-pick hours in the Winter are Fridays, Saturdays, and Sundays from 11 - 4, or by appointment on our website: https://www.cloverfieldfarm.us/book-online