The Production Process
The first step in producing yerba mate is to harvest the leaves, which happens from March to October based on the region. The leaves are harvested when the tree is three to five years old and every third year after that to protect the tree. A mature tree can produce between 65 to 85 pounds of dried yerba per pruning year.
Premium blends are harvested by skilled craftsmen (Taraferos) who not only know which and how many branches to prune, but also how to make specific cuts that protect the tree and promote growth. Commercialized yerba on the other hand, is harvested using pruning machinery.
Once cut the branches sorted to eliminate unwanted branches and debris, The selected yerba leaves are gathered and bundled in burlap sacks called ponchadas, then they are hauled off immediately on trucks to the processing plant for the next step in the production process.
Sapecado (Flash heating)
Sapecado is a guarani word that means “opening the eyes” referring to opening the cells or vesicles of the green leaves using high heat (1100°F). This heat can be generated using specific types of wood or in larger manufacturers, special machines with large cylinders and temperature control.
The flash heating process only takes about 20 - 30 seconds and it must be done within 24 hours of harvest to stop the oxidation process in the leaves. The high heat causes the leaves to suddenly lose 20% of their weight and 80% of their humidity while locking in the chlorophyll and nutrients. The results are aromatic golden green leaves that are ready for the next stage in the drying process.
Secado (Drying Process)
To further remove the remaining moisture in the leaves and prevent the leaves from getting wet, the leaves are taken to large covered sheds for drying. There are two processes for drying the yerba leaves completely; barbacuá and electric drying system.
This method stems from the drying process used by the Guarani called carijó in which yerba mate branches were fanned for long periods of time over a flame. The smoke of the firewood combined with the sporadic burnt edges on the leaves created a smoky flavor in the yerba that has become one of the traditional styles of yerba mate.
The barbacuá process, also known as toasting or topitá requires burning various selected woods including yerba mate wood in chambers and pumping the heat through pipes beneath the leaf piles. The process of heating the yerba this way can take ten to twenty-four hours to finish. The end result is a well-balanced, aromatic yerba containing anywhere from 3% - 5% humidity based on the style of yerba desired.
Electric drying system
This process, known as fogueado is similar to the barbacuá process with the exception that the heat is machine generated. The air is heated between 175 to 195 degrees (80 to 100 C) and then pumped through the layers of the leaves, creating a very uniformed drying process. This drying process can be completed in two to twelve hours, making this the preferred way to dry large amounts of yerba at a lower cost.
After the yeba leaves are properly dried, they go through a coarse milling process that simply breaks up the whole leaves in to large pieces. The word canchado comes from the Quichua word cancha meaning field or designated area. Originally the indigenous people would take the yerba leaves to a field next to the drying fire and place them in between leather mats or in holes in the ground to pulverize them with rods. Today, machines are used to pulverize the leaves in to large pieces prior to the aging process.
Aging brings out complex and intricate flavors the in the yerba that green yerba (not aged) does not have. Yerba can be stored as little as three months to as much as three years. Like wine and cheese, the longer the aging process the more flavorful.
Yerba mate can be aged using natural or chamber storage. Natural storage requires placing the pulverized yerba leaves in burlap sacks and stacking them in storage units called noques (no kes), which are made to protect the yerba by keeping moisture and odors out.
Chamber storage is similar to natural storage with the exception of controlling the temperature using thermally lined walls. Controlling the temperature allows for a faster aging process (three to six months) which helps in the production of large amounts of more affordable yerba. However, the shorter aging time and the lack of temperature variations produces a yerba without the flavor characteristics of a naturally aged one.
This semi final step in the process is where the yerba is sifted using screens to separate large stems and particles, milled into smaller pieces and blended to create the various styles (with and without stems, soft flavor, intense flavor, etc.). This step in the process greatly determines the flavor of the yerba as explained in the “Type of cut” section.
The final step in the process is packaging the yerba mate. A growing style of packaging uses airtight sealed bags that help to retain the freshness longer as compared to the method of folding and gluing the ends of the bag.
It is important to note that while the freshness of the yerba may decrease slightly with time, yerba mate has a long shelf life and does not spoil, even after the industry required expiration date has passed.