I've been tinkering around with LCs for a while. I really liked the idea of using grain soak water, or other carbohydrate/nutrient sources for the solution, but the risk of not noticing contamination always concerned me. I discussed the issue with a bartender friend of mine who slings expensive high-end drinks in Manhattan. I didn't know this was a "thing", but you can clarify fruit juices, and pretty much any aqueous solution using the following method.
I pinched the details of the method from this site: https://cookingdistrict.com/cd/general.nsf/blogbydate/852578CF000187B9852578CC005537D5?opendocument
What I wanted was a solution similar in composition and concentration to my agar plates, but crystal clear and not viscous. The method relies on agar-agar being a hydrocolloid. Very small amounts of agar can dramatically increase the viscosity of a solution. Then, using a property called "syneresis", we can separate the water solution from the gelling agent (agar), while the cloudy materials (little bits of undissolved colloidal materials) stay suspended in the gelatinous matrix. A simple filtration at the end yields a solution that is very clear, but with the same dissolved nutrient profile as the parent liquid. I tested the method in the web site--clarified OJ tastes identical to regular OJ, but clear. Even coffee tastes like coffee, with only a slight color.
It turns out, we are only using a 0.2% agar concentration here. I'm making a quart of broth, so it comes out to 1.9g agar.
First, place the materials you want to use in a pot and cover with about half a quart of water. Here I'm using a small sliced potato and a small carrot, and a few grams of mixed grain (barley, brown rice, cracked corn). Simmer these at a very low boil for about 15 minutes. Pour off the water into a quart jar, then add another portion of water, and again simmer for 15 minutes. Collect that fraction too.




During the second simmer, 1g of yeast was added (I just used regular bread yeast). I also added added light Karo. Karo and honey both have a density of about 1.45g/ml. I added 10g ~ 7ml ~1.5tsp. It's not exact science--I prefer the solutions a bit on the lighter side of concentration. I went light on this. A standard PDA recipe calls for 200g potatos infused into 1 liter of water and 20g dextrose. I'm using potatoes mixed with carrots (some simple and complex carbs, some minerals) and only 10g of sugar.
Clarification: Here is the interesting part. The broth is cooled to room temperature, and the required amount of agar is dissolved. (remember, 0.2%--in this case, 1qt=950ml, so we need 1.9g agar). When dissolved, bring to a gentle boil, then allow to cool for about an hour in the fridge, or even the freezer. It doesn't need to be frozen, but cool enough that it sets.
Use a fork or whisk, and gently mix the gelatinous results. Then, with a colander lined with cheesecloth, a smooth rag, or even an old t-shirt, pour the gel in and let it drip. Extracting the liquid will take some time--I let mine go for a couple of hours.

And here we go before and after:


It worked pretty well. A bit of a pain, but not too bad, and very cheap to do. I'm not suggesting that this is an idea everyone needs to be pursuing. I just personally have been interested in using nutrient systems derived from grains and other foods. I read Fast Fred's collection of agar recipes, and figured, what the heck? Why not formulate a crystal clear water solution and get around the cloudiness problem? My bartender friend told me that they prepare various juices in bulk very frequently (lime, pineapple, tomato....). It's worked so far with several mixed I've tried. Simmered WBS, simmered oats, oatmeal, corn meal, carrot/potatoes. It seems pretty general.
Hope you found it useful. It was a fun way to tinker around this morning.
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My LC is crystal clear just using lme and water like mushboy, but if you have time, materials, and energy to burn, why not I guess.
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