Step 2 - Silting

Step 2 - Silting

Introduction

Silting is a term coined to describe a unique way of clarifying the wash of polar and semi-polar compounds. Phospholipids, denatured proteins and water soluble compounds are the unnamed contaminates in RSO that have not been discussed before. The Silting step is a modification of what the food industry does to refine cooking oils. Silting uses a simplied form of Degumming that removes these unwanted phosopholipids (gums) and water soluble compounds prior to distillation.  

Note: Phospholipids make up the cell membranes of Trichomes, the little chemical factories that produce THC, CBD and the myriad of other cannabinoids. Using an alcohol solvent, Ethanol or Isopropyl, will dissolve phosophlipids in order to access the cannabis oils. Using a cold or frozen wash does not eliminate phospholipids from the wash, you still need to deal with phospholipids somewhere in your refinement process.

There are two forms of phospholipids to be removed - Hydra-table and Non-Hydra-table. Hydra-table phospholipids are hydrophilic, meaning the material gums up with water. Non-hydra-table phospholipids are stubborn, needing to be dissolved with acid. Fortunately, heat and a small amount of Lime Juice will dissolve these lipids. With that, here is how Silting works -

An amazing discovery was made in separating these heavier compounds out of the wash. Just by pouring in Brine, AKA, saturated salt water, into the Isopropyl wash, phospholipids and other water soluble compounds immediately fall out. This is known as "Salting-Out" Isopropyl, a common high school chemistry experiment. Brine now becomes our most power tool for removing the trash from the oil.  

Here’s what you may see depending on the amount of phospholipids in the wash. The final density of the gunk is determined by the quality of the extracted material. Some washes will be thick, some thin, your mileage may vary. 

Procedure for Water Degumming 

1. Add 1 cup Brine per liter/quart to the wash. If using 91% Isopropyl, add another 30g/1oz table salt per liter/quart. Shake hard for 10 seconds. 

2. Phospholipids coagulate and form a Snow Globe effect. As the solution settles, a layer of liquid gunk forms between the alcohol and water with solids crashing out and settling on the bottom of the jar. A spectacular Snow Globe effect happens if the salt also has anti-caking additives. (Anti-caking material is not bad, but is not beneficial as it leaves debris in the alcohol.)

3. Use a Turkey Baster for small washes, or an Electric Siphon for larger washes, and draw out the alcohol leaving the trash behind.

4. Pour the alcohol through a folded paper napkin to catch any visible debris.

Science - Degumming studies

Both 99% and 91% Isopropyl alcohol work with water or acidic degumming. Salting-out the alcohol is the primary means for water degumming to work. Acidic degumming works by heating the alcohol, mixing in lime juice and letting it sit for 10 minutes. One or both forms of degumming might be needed for the different cultivars. So far, Water Degumming has been observed to be the fastest and simplest means to degum the solution. Here are some of the many references on water and acidic degumming -

Enzymatic Degumming of Rice Bran Oil Using Different Commercial Phospholipases and Their Cocktails [Link]

Degumming Alternatives for Edible Oils and Biodiesel Production [Link]

Physical Refining: Electrolyte Degumming Of Nonhydratable Gums From Selected Vegetable Oils [Link]

Establishment Of An Effective Refining Process For Moringa Oleifera Kernel Oil [Link]

Minor Components in Canola Oil and Effects of Refining on These Constituents  - A Review [Link]

A kinetic study of phospholipid extraction by degumming process in sunflower seed oil [Link]

Tips and Tools

Tip: Use anti-caking free, non-iodine salt. Anti-caking material may add to the source of the Snow Globe effect. Pickling and Kosher salts are available without anti-caking compounds.

Troubleshooting

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