Corn steep liquor is an additive that is under-produced by fermenting corn for a variety of purposes, from brewing beer and spirits, to culturing yeast for industrial purposes or making bioethanol.
It is a bait and soak product offered by virtually all carpfishing companies for one very simple reason: it is cheap and actually has a good fishing performance.
It is sold by large feed and processing companies in 10000-litre tanks and then re-bottled by fishing companies.
It can be found in different densities, flavours and colours because a lot depends on the production process from which it is redeemed, the lightest are those of corn beers, the darkest those of corn molasses, in any case for fishing all are good, what changes is the taste more or less sour or sweet, but all variants are very popular with carp.
The cost of this ingredient can vary from 10 to 3 euros per litre, depending on the quantity purchased, (3-4 euros is usually the price you get for 50 or more litres), so it can be defined as a cheap product with a very affordable price. This is one of the reasons that have never encouraged me to try home production as the process takes at least a couple of weeks and requires constant monitoring.
But I understand that self-maker might be very stimulated by this curious ingredient and that perhaps the pleasure outweighs the advantage.
At the kind request of some enthusiasts, I try to hypothesize a homemade process, bearing in mind that there are different methods all adaptable, first of all those used for the home production of whiskey, for which there are many tutorials to follow step by step until the distillation phase (which of course is skipped because our csl is what is formed in the first step)
In our case the process starts from broken corn or whole corn, (more difficult to blend) and I recommend you to try with a kilogram for a test, and then optimize and correct the process in function of larger quantities.
As a first step we will put in soak 1 kg. of broken corn having the foresight to cover it with at least 3-4 cm. of water and let it rest for 24 hours, at this point we will proceed to boil everything for at least a couple of hours, adding 100 grams of sugar, then we will let it rest until it returns to room temperature.
At this stage we will blend everything and add 30 grams of lacrtobacillus, 50 grams of active dry brewer's yeast, mix everything well and then put it to ferment in a dedicated container for at least 10 days, checking it daily to release the excess gas that will have formed in the vessel.
At the end of fermentation (when the typical foam and bubbles of carbon dioxide will no longer form) we will boil everything again for at least 5 minutes or more if we want to obtain a more or less dense product (the process stabilises everything, kills the bacteria and eventually evaporates the watery phase making it creamier).
At this point, you can keep it hermetically bottled away from direct light as it is, or, if you want more adhesiveness and stickiness, you can add 300 ml. of corn syrup for every litre of CSL, stirring well with an electric whisk, and then bottle it.
A product thus fermented and with added sugar does not present particular problems of preservation.
In my book Boilies you will find descriptions of all ingredients of both plant and animal origin.