Background

With the recent cold and rainy weather, I finally had time to try out making my own sunflower oil. Using the press I built (see the older post on sorghum syrup), I followed the instructions on this site:  http://journeytoforever.org/biofuel_library/oilpress.html

I used oilseed purchased on Amazon, spendy but I got a load of seed for experiments and for fridge saving over a few years. There’s enough to sow a large plot with enough plants to generate a years supply of oil. My biggest issue was pests, mostly finches but also deer and squirrels. Once you have a large enough plot, there’s not enough pests to get the whole thing, assuming you put up a fence to keep the 4-legged critters out. Birds will eat as much immature seed as they possibly can, they are voracious pests so plan on loss unless you can add plastic mesh overhead.

The process

Starting with cleaned black oilseed, use a kitchen blender to shred the whole seeds until it turns into coarse flour. You can only do about a half quart at a time, once the flour forms the whole seeds stop getting to the blade.  Heat the flour up in the oven until it gets to about 150 F, this allows the oil to become less viscous and flow out of the slug inside the press. Don’t be afraid of overheating it, it cools down quickly and you really need a hot press to get the oil out. It will help to preheat the press itself, it will keep the slug warm. You will also want to add heat to the press with a heat gun, to keep it from cooling off.

Load the press full, then compress it by hand to pack as much in as you can. The sleeve will compress 3-4 times in volume, so expect that. You will also need a very large force, I used a 2 ton hydraulic press for the pressure. This was just adequate, the press was binding and at the limit of what I felt comfortable with. Still, it worked very well but could use refinement.

Towards the end of the pressing

I initially got nothing out of the slug, I was thinking “this is a bust” but it finally began flowing out the ports. It took a while, applying heat, cranking the press, and letting it rest. It eventually compacted to an end stage where no additional oil flowed, that’s time to collect and filter the oil.

The spent slug (turd to some LOL)

Looks like wood ash, but it’s just the flour. It is as hard as a rock, and requires a large screwdriver and mallet to break free from the press sleeve. Lots of people complain about this, the little screw presses are really tough to clean from what I hear. I’m also not sure they generate enough force to clear all the oil from the “cake”.

Collecting and filtering

I heated the pan, and poured the hot oil into a coffee filter lined funnel on top of a 25 mL graduated cylinder. I wanted to accurately measure the yield, and I got just about 50 mL from a quart of loose seed (not flour). This seems to be about the right yield, looking at reference site’s numbers. It looks great, nice and clear but took overnight to clear the last of the oil through the paper filter. Coffee filter are around 15 microns, this is too small for a gravity filter and especially oil. I will get a 25 micron mesh and see how that goes, I don’t recommend paper for an oil filter unless you pressurize. Next steps are to fry some stuff in the oil, it’s in the fridge waiting for the test. Supposedly oil will turn rancid quickly at room temps, so I’m being cautious.