Fresh Chilled Separation, a variation on the Fresh Frozen technique
In recent years, the Fresh Frozen technique has become more and more popular among hashish makers. It is a variation on the traditional way of extracting cannabis resin with water and ice in which fresh frozen plant material is used. In our article about the Fresh Frozen technique we already introduced some of the advantages of using fresh buds or trim when making water hash, such as maintaining a terpene profile much closer to the live plant or the fact that fresh plant material doesn’t contaminate the extraction as dried buds/trim do.
In this way, we get an extremely pure concentrate, both for the lack of adulterants (we’ll never add any substance to improve the texture or effect of the resin) and contaminants, since the plant material is not shredded into small particles that contaminate the extract. As we already mentioned, the flavour of Fresh Frozen hashish is much closer to that of the plant than traditional hashish, since almost no degradation of Beta-Myrcene is produced. Thus, our resins have a much wider organoleptic profile.
Fresh frozen hashish, 73 microns
As we also discussed in our post on how to make water hash, freezing the plant material highly facilitates the extraction process, since trichome heads are removed much easily when they’re frozen than when being, for example, at room temperature. This technique works well either for dry or fresh plant material, although it does have some cons when using fresh buds/trim and trying to make several runs. Let’s see now what happens when we freeze fresh buds.
The ice nucleation process in frozen cannabis tissues
Frost precedes the ice nucleation process (Picture: Jun)
As we have seen, freezing the plant material enables a faster and more efficient separation than not freezing it at all, although it does have a main disadvantage especially if we plan to make several runs with the same material. When someone uses fresh frozen buds/trim and performs successive runs, it is not strange observing how the resin collected from the second and following runs is much darker than the resin from the first one, decreasing the quality of the resin extract. But, why does it happen and how to avoid it?
When we freeze fresh plant material (this also happens in Nature with frosts) very small ice crystals are formed in the plant tissues – phenomenon known as ice nucleation process – and damage both their intracellular (protoplasm) and extracellular structures. This affects the plant tissues to a greater or lesser extent, depending on several factors: the natural resistance of the plant to frost, freezing and defrosting speeds or the minimum temperature reached. In this way, the damages do not depend as much on the minimum temperature as they do on whether if ice crystals are formed or not. Unfortunately, most cannabis strains do not tolerate frost and are specially sensitive to this phenomenon.
The surface of the plant tissue gets frosted from temperatures between -3ºC / -5ºC. Since the fresh plant material is composed of approximately 80% water, ice crystals are soon formed inside the plant tissues, in the intracellular spaces, the xylem vessels and the stomal cavities. This phenomenon causes protoplasm – the inner part of the cell including the cytoplasm and the nucleus – dehydration, being severely damaged; the cell collapses as the ice crystals expand. The cell walls are also damaged and pierced by these crystals, releasing the chlorophyll stored in the thylakoids, inside the chloroplast. But, how does this affect our fresh frozen material?
During the first run, the plant material is still completely frozen, so the ice crystals formed in the tissues of the plant epidermis actually block those piercings and no chlorophyll is released into the water. However, as this plant matter starts defrosting the crystals blocking the pierced walls disappear, so the chlorophyll stored in the chloroplasts is released into the water and mixed with our resin glands, which is “dyed” dark green. For this reason, this phenomenon is normally observed only when we perform a long first run or during the following runs; in other words, this happens as the plant matter is defrosted during the ice water extraction process.
Plant cell structure (Picture: ASPS)
How can we avoid this? Basically, we have two solutions to the problem of ice nucleation process in ice water extractions: the first one is flash freezing the plant material so very few crystals – and smaller – are formed. The second oprtion is not freezing the plant material before the extraction, but cooling it down enough to make the trichome separation easier, and more specifically the heads of the capitate-stalked trichomes. Let’s see how this techniques works.
Making hashish without freezing the cannabis buds/trim
Although it may seem that this goes against one of the basic principles of hash making (freezing the plant material), experience shows us that reaching below zero temperatures is not necessary at all to separate the trichome heads from the stalks.
Fresh chilled hashish, plant material at 4ºC
As we know, when we are looking for top grade hashish we want to isolate the heads of the glandular trichomes (also known as capitate-stalked trichomes). This heads are attached to the stalk (that can be between 150 and 500 microns tall) in the abcission zone by the basal cells, and only few of these cells need to be broken to detach the head from the stalk. Int his way, we isolate the secretory heads which store the terpenes and cannabinoids, leaving the stalk attached to the plant matter and thus getting a more pure resin.
In our test for this article, the fresh buds where frozen at -24ºC in one case (Fresh frozen) and chilled at 4ºC in the other (Fresh chilled). The experience makes it clear that a temperature of 4ºC is more than enough to obtain similar yields than with frozen plant material, but of better quality.
Second runs, fresh frozen (left) and fresh chilled (right)
Still, this technique does have a small problem. Since the plant material is not frozen but kept in the fridge, making the extraction within 3-4 days from harvest is advised, otherwise it could get spoiled.
Have a nice smoke!