Black Mold – what is it and why does it happen?

Eat dates long enough and you will eventually encounter “black mold.” The scientific name for black mold is Aspergillus niger.  Not to be confused with the toxic black mold that can grow in homes, this particular strain is endemic to dates, but is especially prevalent in semi-soft dates like Medjool.  Scientific studies and the USDA consider this mold to be generally nontoxic and harmless for most people.  That’s the good news! The bad news is that it tastes pretty yucky if you unwittingly bite into an affected date.  Blech!  Seasoned date eaters know from experience that it’s best to inspect the inside of the date before consuming it.  In addition to black mold, we have a couple insects that love dates and are sometimes found inside them also.  The carob moth is the most common of these, so check the inside before taking a bite.

Black mold develops under the woody cap, or calyx, that attaches the date to the tree.  If the dates are exposed to moisture (hello monsoonal summer rains common in the desert Southwest) the mold can become activated and grow inside the date.  Growers don’t use fungicides to treat black mold (though research is underway to find tools growers can use to prevent the development of black mold), and rely primarily on using protective paper covers on the maturing date bunches.  These are effective, but ONLY if growers know rain is coming and have the resources to put these on their bunches before rains arrive.   Mother Nature doesn’t always announce her plans.

Because the mold develops inside the date, out of view, detection is very difficult.  Larger date processors rely on sophisticated equipment with computer optics to detect and remove affected dates, but these have limited success because they rely on physical markers for detection and have false positives.  The telltale signs (discoloration at the top of the date and of the calyx itself) are not always present.  Skilled workers sort the dates on sorting tables under lights and, with experience, can identify and remove many of the affected dates, but complete detection is impossible.  

Black mold is misunderstood and stigmatized by consumers who often view this “natural and unavoidable crop defect” as a reflection on the grower or date processing standards.  Neither is accurate, and all date growers, processors, and brands will have instances of black mold in products, most especially in whole dates that have the seed intact.  We all struggle with this issue. 

My hope is that education and information will help inform consumers to be aware the potential exists, understand its nature and why it occurs, and be conscious of checking the dates prior to eating them.  Black mold tends to occur in clusters (wind driven rain may affect the fruit on one side of the tree on the perimeter of the field for example) so it is not uncommon to find several if you find it at all.  1 or 2 affected dates from time is time is normal, but if you have a larger quantity of affected dates in a product you buy from us by all means reach out!  We’ll work with you to credit you or replace the product if necessary.