There’s a void in scientific knowledge of fermented and pickled vegetables, and scientists are just starting to scratch the surface.
“We have a wealth of chemical compositions that we still don’t fully understand,” says Dr. Ilenyz Pérez-Díaz, PhD, a microbiologist with the USDA-ARS. Perez-Diaz presented on “Development of Pickling Technologies & Products” during a webinar hosted by TFA. “I honestly think there is still a lot to do in regards to the richness of the biological functions that are present in these systems. Every vegetable is different. … It will be fantastic to be able to comprehensively understand what’s really there and how we can use it for the benefit of not only processing but also for the benefit of human health.”
The purpose of the USDA-ARS is to find solutions for agricultural challenges, domestically and globally. In 2019, the 8,000 employees of the USDA-ARS researched 660 agricultural projects, filed 85 new patents, issued 65 new patents, received 51 new licenses and wrote 3,816 peer-reviewed journal articles.
Pérez-Díaz is assigned to the food science and market quality and handling research unit. There the team develops state-of-the-art, science-backed methods that improve the post-harvest processes, food preservation, food quality and safety and, ultimately, introducing nutritious products into the food system.
“What I love about the research that she’s doing is that pickling and fermentation are these ancient, traditional technologies that people have been using for hundreds and hundreds of years, and she’s really thinking about ways that we can advance those technologies using all the amazing sequencing and all the microbiology we have today,” says Ben Wolfe, PhD, associate professor of biology at Tufts University, and the TFA Advisory Board member who moderated the webinar.
Pérez-Díaz shared the USDA’s latest technologies to reduce food waste, lessen environmental impacts, improve water/energy demand and add more health value to preserved vegetables. Here are highlights from the research presented, focused on addressing two key problems:
Eliminate Salt in Cucumber Fermentation
PROBLEM: Sodium chloride is essential to fermentation, but the salt-rich (and sometimes preservative-filled) brine shipped from overseas producers can get into local freshwater supplies. There are no growers of small cucumbers (gherkins) in the U.S., so food projects that require small cucumbers must use overseas produce. But, in order for the cucumbers to be transported, they must be fermented or pickled. High amounts of salt, acid and sometimes preservatives are added, and these potentially can damage the water supply.
SOLUTION: USDA-ARS tested fermenting pickles using three popular spices: dill, cinnamon and mustard seed. But, though salt was reduced or eliminated, “the indigenious microbiota is always there,” Pérez-Díaz explains. “The salt is modulating the activity within this population. It tends to favor the lactic acid bacteria. But what I’ve learned is it is not the main factor modulating that microbiota. The ph and the production of that lactic acid and or acetic acid is really the factor in excluding the non desirable microorganisms and favoring the fermentative microbiota.”
Reduce Food Waste by Creating Foods
PROBLEM: In the U.S., between 30-70% of fresh vegetable produce is wasted. “Those are alarming numbers,” says Pérez-Díaz. “Even though they are estimates, it is necessary to look at ways to resolve the impact of such waste.”
SOLUTION: The USDA developed small-scale fermentation systems for use in restaurants, farmer’s markets and grocery stores. These vessels make fermenting excess food more manageable by allowing easy fermentation of smaller batches.
“We can convert what was waste or surplus or defective vegetables into a value-added product,” Pérez-Díaz says. “It will be a probiotic product, it will be fermented vegetables auxiliaries that can be used as sources of flavor, colors, ingredients in a number of recipes or even dehydrated for different applications.” [This project was near completion before the pandemic and is expected to pick-up soon.]
Fermentation, she emphasized, is needed to sustain a modern food system.
“These fermentations, if applied properly, they are very powerful eliminating the organisms that are not desirable or the organisms that are not of health significance,” Pérez-Díaz says. “I think fermentation will truly be an important component as we move forward to that new era.”