New recommendations for safe mesquite bean harvesting

June 23, 2013

ForageHomesteadIssue 1: Summer 2013

Do you want to produce some of your own food but don’t have time, space or water for a garden? The desert rewards those who stay here through the summer with beautiful late-June mornings and mesquite trees laden with edible bean pods. Mesquite has a nutty sweetness, is gluten free, high in fiber and protein, and is probably available in your neighborhood, if not your own yard.

Are you ready to harvest one of the most abundant, versatile, nutritious, and delicious foods of this desert? Here’s what to do.

Harvest before the summer rains, or in the dry autumn

Traditional Tohono O’odham harvested before the summer rains gathering the first ripe pods in the extreme heat of June. They placed the pods on the hot desert floor for several consecutive days, bringing them in each night (avoiding condensation) in breathable containers, before grinding or storing them. Mesquite harvesting and drying were done in the Bahidaj camp, and the coming of the rains meant the end of the harvest. Then it was back to the village to plant a summer garden. If there happened to be a second ripening of mesquite in September or October they might harvest incidental ripe pods, but it was not tradition to gather them in quantity like the June harvest.

Science is now reinforcing that traditional knowledge. A common soil fungus that thrives in hot, wet conditions can produce toxins on mesquite pods. Nicholas Paul Garber, a PhD candidate working with USDA-ARS plant pathologist Dr. Peter Cotty at the University of Arizona, assayed fungal toxins on mesquite last year and suggested that harvesters “get out there as soon as the crop is mature, and leave any pods that get wet on the trees!”

All of the mesquite collected before the summer rains was below FDA limits for aflatoxin. However, a few of the many samples collected during the rainy season at low elevations were not safe. As with corn, nuts and other crops, when rain falls on mature or nearly mature pods, the danger of contamination increases. Samples collected long after the summer rains, in dry and cooler conditions, were also safe. At higher elevations, pods may not ripen before it rains, but may still be safe, due to cooler temperatures which favor different microflora over the toxin producing fungi. In this case, the autumn harvest may be the best option, though it is not abundant every year. Keep in mind these recommendations represent only one season of testing and research yet to come may refine our harvesting.

Taste test the pods before picking

Simply chew on a ripe pod, avoiding the seeds, to determine if a tree’s fruits suit your tastes. Ripe Velvet, Honey and Screwbean pods have a nutty sweetness, pick easily from the tree, and rattle when shaken. The South American mesquites planted in Arizona seem to be selected for landscape characteristics, tasting nothing like the imported harina de algorrobo. In the urban environment, species cross-pollinate to produce trees with a confounding mix of characteristics.

Do not wash the pods 

Harvest only clean pods from the trees, not from the ground, as wetting the mature pods encourages fungi and bacteria to proliferate. Harvest away from major pollutants, such as along major roadways or where pesticides or herbicides are sprayed.

Dry the pods before storage

Spread the mesquite pods in a thin layer in the sun or in a warm (175 degrees) oven until they are brittle. Store in a dry, cool place. Dry pods snap cleanly when broken, but can reabsorb moisture from the air, or when removed from the freezer. While in storage, bruchid beetles may emerge. Allow them to escape, suspend them by freezing, or kill them in the oven.

Community millings and DIY 

Most harvesters take their pods to community milling events to be ground and sifted in a hammer mill. Only very dry pods will grind into meal. Any moisture, even from the air, creates a gooey mess and a big cleaning job for the mill.

You can grind for yourself in a molcajete, Vita-mix (not an average blender or food processor) or coffee grinder, and sift through a wire mesh strainer to remove the hard seeds and remaining bits of pod. Or cook whole pods and strain the liquid to make ice cream, toffee, syrup, atole, pudding, smoothies, milkshakes, tea or beer. ✜

For milling dates and results of further research, see and Baja AZ Sustainable Agriculture at Special thanks to the Mesquite Harvest Working Group.

Amy Valdés Schwemm makes moles for Mano Y Metate, LLC and plays with food and plants.

Martha Ames Burgess teaches workshops on traditional methods of harvesting and using wild desert foods and medicines

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