Yerba mate can be so different in taste, durability and effects. If you are experienced matero — you know what I’m talking about! To realize and appreciate just how varied and nuanced yerba mate can be, it’s good to understand the manufacturing process and be aware of how different stages of yerba mate production affect its flavor and other properties. Knowing all the stages of yerba mate manufacturing will also make you a more conscious matero and will allow you to choose yerba mate with more awareness, according to your preferences, be it a smoke-free organic yerba mate or a traditional barbacuá. In this guide we’ll take a deep look at the whole process of yerba mate production, from planting seed to packaging yerba that is ready to be enjoyed.
Yerba mate plant starts from a seed. It is, however, quite difficult to germinate seeds of Ilex Paraguariensis. This quite elaborate process starts about year and a half before the planting date, when fresh yerba mate drupes are being harvested. Harvesting takes place from second half of January until April, after they have turned dark purple in color. It is a manual process, during which yerba mate cultivators, aka yerbateros in Spanish or ervateiros in Portuguese, carefully select the healthiest looking fruits. 7-8 kilos of drupes yield about 1 kg of seeds, which totals nearly 135,000. Only 20,000 seeds germinate.
After harvesting the seeds are submerged in water, to eliminate various debris and empty seeds that stay afloat. Treated seeds are then put in clean plastic bags and stored in refrigerators to preserve their germination power for a longer period.
Between March and May, seeds are planted in a moist manured soil in nursery. It may take from 100 days up to a whole year for the seeds to germinate. Young seedlings are very susceptible to fungi and various diseases, and nursery allows to grow them stress-free until the plant becomes strong enough to be first planted in pots, and later in the open field, slowly introducing it to the natural sunlight. In total, it takes about 7 to 8 months to take a newly germinated yerba mate seed to reach the plantation field.
At this stage, manufacturer also makes a choice of whether they will treat their yerba mate crops with herbicides, pesticides or artificial fertilizers in order to keep them healthy and prevent pests, insects, fungi and diseases to harm the plants. A lot of yerba mate producers opt out of those chemicals in favor of organic yerba mate, although keep in mind that obtaining the needed certifications, such as USDA Organic or Organico Argentina is a long and tedious process that only a handful of big brands can afford. There are lots and lots of smaller manufacturers and family plantations who grow their yerba mate organically without being certified to be able to prove so on their packaging.
Harvesting aka cosecha
Leaves from yerba mate plant are ready to be harvested on its third year in soil, however for commercial purposes yerba mate manufacturers start to harvest it after 4-7 years. Harvesting the leaves, aka cosecha in Spanish, is a delicate process — Ilex Paraguariensis is a perennial plant, so in order for it to remain strong and continue growing, crop should be harvested in a rational balance, leaving the plant with leaves and branches to maintain its normal biological functions.
Harvesting of leaves is also a manual process, and usually takes place every two years to allow yerba mate plant to regrow and overcome the stress of pruning. The season for harvesting can take place at any time of year, but generally it depends on the region, its climate and altitude, and the desired caffeine levels of the final product — highly caffeinated yerba mate, for instance, is harvested exclusively during summer.
Harvested leaves with branches are collected into big nylon tarps and become ready for transportation and further processing.
Searing aka sapecado
In order to avoid fermentation processes and stopping biological degradation of plant matter, yerba mate leaves must be seared no later than 24 hours after the harvest. In order to do that, yerba mate leaves are exposed to an open fire in a cylindrical rotary kiln that is about 2 meters in diameter and 6 to 9 meters long. Hot fumes reach temperature up to 600°C / 1110°F , making yerba mate leaves lose 55 to 75% of moisture content, killing protoplasm and destroying ferments in the leaf.
Drying aka secado
After the quick searing, yerba mate leaves must be properly dried, until they lose almost all of its moisture. This process also reduces the weight of yerba mate, such as 100 kilograms of freshly harvested leaves yield about 30 to 36 kilograms of dried yerba mate.
Drying consists of exposing seared yerba mate leaves to a hot air ( 80°C to 100°C / 175°F to 210°F ) for up to 24 hours, either on stationary racks, or on conveyor belts. The source of the hot air, however, varies greatly depending on the manufacturer. Standard method in the industry is drying yerba mate with air that was heated by wood, gas or electricity.
Some yerba mate producers, such as Rosamonte, are known for the barbacuá drying method, which is the oldest process used by Guaraní people. During barbacuá method, leaves are exposed to heat and smoke from wood fire, giving a final product a distinct smoky flavor, akin to lapsang souchong tea or peaty Islay whiskey.
Other manufacturers, such as Kraus, use a no-smoke drying systems that dries their yerba mate with hot air produced by indirect heat that comes from a boiler, yielding in a milder, smoke-free and delicate tasting mate.
Grinding aka canchado
Once yerba mate is completely dried, it is coarsely shredded to make it more transportable. This is not the final grinding though and is done only because they need to put yerba mate into burlap bags and move it to other facilities either for aging or straight up for proper milling and blending, depending on a regional type of yerba.
Back in the day, grinding was done by hand using machetes. Today, most of the yerba mate producers automated this process, with exception to some artisanal manufacturers like Meta Mate who preserved the original processing methods for generations.
Aging aka estacionado (optional)
After grinding and bagging, most of the Argentine, Paraguayan and Uruguayan yerba mate is then aged at special facilities with controlled temperature and humidity. Aging is another very important step that heavily influences the taste of the final product.
Yerba mate matures in burlap sacks for a period from 6 to 36 months, developing various complex flavor notes in the process. Manufacturer decides on the period of aging depending on what taste profile they intend their yerba to have.
It is actually still not completely known what kind of chemical processes happen to yerba mate leaf during aging, but it’s safe to assume that some oxidation takes place, which makes aged yerba mate less vibrant and green, although it is not clear which exact components are affected by it. Most likely the process of aging yerba mate is similar by its nature to tobacco leaf aging, which also happens for a long period of several years after it has been dried and cured.
In Brazil, the majority of producers skip this step, unless they are making a product for specific consumer, such as Rei Verde with their Rei Verde Export yerba mate that is intended for Uruguayan market. That is also why Brazilian erva is so different in terms of looks (very bright, almost neon green) and flavor (fresh, grassy, and chlorophyllic).
Milling aka molienda
During the milling process, yerba mate is finally ground into the desired consistency that is determined by its manufacturer. Using special machinery, leaves are separated with stems and then milled separately. Most of the leaves are ground into particles that are about 1 to 5 millimeters in diameter, depending on a regional variety, and the rest are pulverized very finely, which produces the powder aka polvo. Also during this step, yerba mate is inspected, cleaned from unnecessary debris, and in case of selección especial varieties — carefully selected to include only the best yerba mate leaves and stems into a final blend.
After leaves, stems and powder are elaborated, manufacturer blends them back together according to their needs. For instance, if they want to create con palo yerba mate, they blend in a lot of stems, while for sin palo yerba mate they would use not more than 10% of the smallest twigs.
In some countries, such as Brazil and Uruguay, they usually prefer much more powdery yerba mate, and even implemented yerba mate composition standards, which producers should follow while blending their yerba mate. For instance in Uruguay, there are following standards aka Padrón Uruguayo:
- P.U.1 — not less than 90% of pulverized dried leaves, and not more than 10% of finely ground dried stems;
- P.U.2 — not less than 65% of dried leaves, and not more than 35% of dried stems;
- P.U.3 — purely dried leaves and dried stems, without any powder.
Yerba mate manufacturers do the testing of the final product after it was blended. This is the time for a quality control. They want to verify that their product is safe to consume, and it complies with all the regulations.
Most of the yerba mate producers also employ tasters, who sample every new batch of yerba mate to make sure that it is up to their standards, and that their yerba mate has a consistent flavor balance batch to batch.
The final step of yerba mate production is packaging. Yerba mate is sealed in bags and is ready to hit the shelves all around the world. While aged yerba mate usually comes in a less durable paper bags, Brazilian erva mate is sold exclusively in vacuum packaging, to exclude any oxidation and ensure the freshness of erva even after many months since its production.
Yerba mate production is an interesting and unique process that managed to carry over most of the techniques and traditions over hundreds of years, making sure that we enjoy the same delicious and healthy yerba mate as our ancestors. Although the process has been influenced by the development of modern technologies, essentially it is still the same as the one used by Guaraní people hundreds of years ago, just more efficient and large-scale. If you know Spanish, I highly ecourage you to read this incredibly elaborate Yerba Mate Production Manual provided by INYM and Oscar José Burtnik, which formed the basis of this guide.
Hopefully, next time you’re drinking mate you will have a better understanding and appreciation of this beautiful and complex drink. Make sure to check out our ever growing collection of yerba mate reviews to see for yourself how diverse it can be, and decide on what to try next! And if you’re just starting out — check out my personal picks for beginner-friendly yerba mates to kick off your yerba mate journey.
What stage of yerba mate production do you care about the most? What are your preferences and dealbreakers? Is it organic, smoke-free, fresh, or smoky and aged yerba mates? Tell us in the comments below!