TLDR: I'm naive and overconfident enough to try my hand at ghee soap for complex reasons that don't apply to most people. Maybe I'll learn something new and maybe I'll just confirm what everyone knows.
I'm new to soapmaking, but have quite a bit of experience in similar hobbies like cheesemaking, brewing and winemaking, and I have a background in biochemistry/molecular biology. I've made soap before, but only as an incidental byproduct during lab scale analytical trans-esterification (I've never made biodiesel, though the idea has always intrigued me). My goal is to settle on 100-200 acres in East Texas, and I have been looking for lower effort, high value added ways to ultimately make the land produce an income stream (with the main financial benefit being an ag exemption and maybe a tiny bit left over at the end; I'm a physician by trade and I don't need or want to make much money from this). I'll plant a vineyard, but also wanted something else which I can hopefully continue doing well into retirement. Soapmaking came up as a value added product that meets a few goals: 1) physical labor is limited to things that a 60 year old can do 2) doesn't compete with massive ag commodities markets 3) provides a decent ROI on time and money and 4) uses inputs that I can grow in East Texas (rainy all year, hot in summer, cold enough to kill tropical plants in winter). This informs a lot of my choices and might explain why my decisions differ from most folks.
To that end the huge challenge is finding an oil with sufficiently saturated FA profile to allow for hard soap. Oil palms will grow in Galveston, but won't survive anywhere else but the southern tip of the state. Likewise with coconut plams, and nobody has even bothered to try shea trees. The historical solution to this issue in the Northern hemisphere before globalization was tallow, and that may be where I ultimately wind up. People have done pure olive soaps, and I have considered trying a castile soap, but again olive trees just won't survive in the northern half of Texas. If I want soap production to be divorced from the number of animals that I slaughter, then my one real option is milkfat (commonly referred to in discussion here as ghee, though ghee is typically cooked on the butter solids whereas I'll just warm it long enough to separate the oil). The other source of oil, pecan trees, is very similar to olive oil save that it has less stearic acid and as such would have no hope for making a solid bar.
The overwhelming issue with milkfat is the presence of C4-C10 fatty acids, particularly C4 and C10. While sodium caprylate is just goaty and potentially tolerable, the odor of odium butyrate is pretty universally hated by humans. Some of us are less sensitive, but we all detest it, and 2-4% of the fatty acids in milk are butyric. Any effort to make "ghee" based soap will have to deal with that in some way. My proposal is as follows: VFA are, by definition, volatile, with the shorter chains being far more so. Indeed, that volatility is how the odor reaches the olfactory plate and allows us to smell them at all. Humans can detect sodium butyrate at ~10ppm, so we need to reduce the amount given off. Hydrolysis of the oil and column distillation of the fatty acids prior to saponification would work, but the capital investment required to do that isn't practical at even a light commercial scale.
So I have two ideas. First, I'm going to make soap using pecan oil and ghee (I worked out the recipe using the wonderful calculator on this site) with 0-0.5% superfat, or just enough to ensure that I've completely reacted out the NaOH). I will then cast it into flat sheets sized to fit in a dehydrator. That will allow a constant stream of heated air, which should drive off the sodium butyrate at an accelerated rate, leaving less smelly soap that I can then recast along with whatever flavor compounds I want to use (I'll add that after since the process would be just as if not more effective for driving off the smells that I wanted). The levers to pull there are temperature, time, and sheet thickness. Time is pretty easy to test (yank a slab and sniff it at time T then put it back and keep going or call it good), but the other two will require some pseudoscientific guess and check. If that doesn't work, then my next idea is heating similar flat sheets but in a vacuum chamber. In that setting, we replace a constant stream of semi-inert gas (air) with a vacuum, wherein the partial pressure of EVERYTHING is very low. That has the benefit of keeping hot oxygen away from the soap (i.e. the key driver behind soap going rancid), but the downside is that a vacuum chamber costs more than a drying rack.
I'm also going to experiment with using salt to reduce the glycerine content of my soap, but I'll just use coconut palm and olive oil for those experiments to keep the number of variables down. If anyone has helpful hints, please chime in, otherwise I'll share what I learn in the hope that someone can learn from my errors.
Thanks again.
I'm new to soapmaking, but have quite a bit of experience in similar hobbies like cheesemaking, brewing and winemaking, and I have a background in biochemistry/molecular biology. I've made soap before, but only as an incidental byproduct during lab scale analytical trans-esterification (I've never made biodiesel, though the idea has always intrigued me). My goal is to settle on 100-200 acres in East Texas, and I have been looking for lower effort, high value added ways to ultimately make the land produce an income stream (with the main financial benefit being an ag exemption and maybe a tiny bit left over at the end; I'm a physician by trade and I don't need or want to make much money from this). I'll plant a vineyard, but also wanted something else which I can hopefully continue doing well into retirement. Soapmaking came up as a value added product that meets a few goals: 1) physical labor is limited to things that a 60 year old can do 2) doesn't compete with massive ag commodities markets 3) provides a decent ROI on time and money and 4) uses inputs that I can grow in East Texas (rainy all year, hot in summer, cold enough to kill tropical plants in winter). This informs a lot of my choices and might explain why my decisions differ from most folks.
To that end the huge challenge is finding an oil with sufficiently saturated FA profile to allow for hard soap. Oil palms will grow in Galveston, but won't survive anywhere else but the southern tip of the state. Likewise with coconut plams, and nobody has even bothered to try shea trees. The historical solution to this issue in the Northern hemisphere before globalization was tallow, and that may be where I ultimately wind up. People have done pure olive soaps, and I have considered trying a castile soap, but again olive trees just won't survive in the northern half of Texas. If I want soap production to be divorced from the number of animals that I slaughter, then my one real option is milkfat (commonly referred to in discussion here as ghee, though ghee is typically cooked on the butter solids whereas I'll just warm it long enough to separate the oil). The other source of oil, pecan trees, is very similar to olive oil save that it has less stearic acid and as such would have no hope for making a solid bar.
The overwhelming issue with milkfat is the presence of C4-C10 fatty acids, particularly C4 and C10. While sodium caprylate is just goaty and potentially tolerable, the odor of odium butyrate is pretty universally hated by humans. Some of us are less sensitive, but we all detest it, and 2-4% of the fatty acids in milk are butyric. Any effort to make "ghee" based soap will have to deal with that in some way. My proposal is as follows: VFA are, by definition, volatile, with the shorter chains being far more so. Indeed, that volatility is how the odor reaches the olfactory plate and allows us to smell them at all. Humans can detect sodium butyrate at ~10ppm, so we need to reduce the amount given off. Hydrolysis of the oil and column distillation of the fatty acids prior to saponification would work, but the capital investment required to do that isn't practical at even a light commercial scale.
So I have two ideas. First, I'm going to make soap using pecan oil and ghee (I worked out the recipe using the wonderful calculator on this site) with 0-0.5% superfat, or just enough to ensure that I've completely reacted out the NaOH). I will then cast it into flat sheets sized to fit in a dehydrator. That will allow a constant stream of heated air, which should drive off the sodium butyrate at an accelerated rate, leaving less smelly soap that I can then recast along with whatever flavor compounds I want to use (I'll add that after since the process would be just as if not more effective for driving off the smells that I wanted). The levers to pull there are temperature, time, and sheet thickness. Time is pretty easy to test (yank a slab and sniff it at time T then put it back and keep going or call it good), but the other two will require some pseudoscientific guess and check. If that doesn't work, then my next idea is heating similar flat sheets but in a vacuum chamber. In that setting, we replace a constant stream of semi-inert gas (air) with a vacuum, wherein the partial pressure of EVERYTHING is very low. That has the benefit of keeping hot oxygen away from the soap (i.e. the key driver behind soap going rancid), but the downside is that a vacuum chamber costs more than a drying rack.
I'm also going to experiment with using salt to reduce the glycerine content of my soap, but I'll just use coconut palm and olive oil for those experiments to keep the number of variables down. If anyone has helpful hints, please chime in, otherwise I'll share what I learn in the hope that someone can learn from my errors.
Thanks again.
Good luck!
