Having previously produced ethanol by fermentation, and being in possession of a couple of gallons of sour milk, I decided to try something a bit
smellier. Following is an account of my production of calcium lactate via lactic acid fermentation. While it was not very well executed and will
probably serve more as a cautionary tale of various things not to do than as a template for others to imitate, I still met with some success and
thought the details might be interesting.
In the 'Cyclopaedia of practical receipts and collateral information' by Cooley and Tuson (1872), there are instructions for production of lactic acid
on p674. They give no fewer than six recipes. I used the 'wholesale' recipe as it used materials I had on hand, and I had the ingredients on the
necessary scale:
Cane sugar, 7 lbs
Dissolved in milk, 2 gallons (skimmed or stale)
Add 1/2 pound moist or putrescent cheese
Chalk, 4 pounds, rubbed to a cream with water, 1.5 gallons
2-3 weeks at 80-86F, with occasional stirring
At this point I made my first deviation from the instructions: I didn't have chalk, rather I had pulverized aragonite (bought as a feed supplement).
It's fairly fine, but being more or less limestone can't really be 'rubbed to a cream' with water. I used it regardless.
After combining the ingredients in a large stockpot (20 liters), I set it on my hotplate and turned it to a very low setting. Although I had
previously experimented with controlling temperature fairly closely this way, that was in an indoor environment, and this pot was outside in my barn
where the ambient temperature ended up varying from -5C to 25C during the course of the fermentation. As a result the temperature, far from being kept
between 30 and 32C, varied from 25 to 40C with a couple of excursions to even lower temperatures. Ultimately I partly insulated the pot to limit the
temperature variation. I stirred the pot twice a day, which agitated the grit on the bottom and would release a large amount of carbon dioxide as the
lactic acid was neutralized by the carbonate.
After 18 days (on April 8), the fermentation was unfinished; gritty aragonite remained on the bottom of the pot, though noticeably less than when I
began. I realized that the reduced surface area of the grit (in comparison to really fine chalk) was probably slowing down the fermentation by
allowing it to become more acidic than it otherwise would. Or maybe my poor temperature control was to blame... regardless, it was going, but only
slowly.
After 24 days, I decided to work up what I had and see where I had gotten. I cranked up the heat to kill the bacteria and dissolve all the calcium
lactate (which had begun to show up as a white material in the solution). Unfortunately, there was enough grit on the bottom of the pot that this
created a hot spot, which was sufficiently higher than 100C to turn some of the remaining sugar in the solution into brown caramel.
After noticing this, I filtered while still hot, boiled again, and then reduced the liquid volume by evaporation at about 70C over a couple of days.
Once it was about 2/3 of the original volume I cooled pot and contents. A large quantity of light tan material precipitated - calcium lactate, but
also a large amount of unreacted sugar and brown caramel contamination.
I filtered, then recrystallized the precipitate twice - dissolving in hot water and precipitating from cold, using first two liters and then one liter
of water. Finally the last precipitate was washed (after filtering) of a little bit of remaining brown gunk using ice cold water.
Net result, 1391g of (presumed) calcium lactate pentahydrate. Still a little crude. Recrystallization is actually fairly easy and results in low
losses if done properly (I estimate that the two recrystallizations I did together lost less than 10% of the product). So I may do one more.
Observations, cautions, and recommendations:
- if you want to use a recipe for this fermentation that uses milk, make sure to use well-skimmed milk; better yet, find a recipe that uses whey. The
butterfat and protein in milk lead to needless goo and smelliness, including the delightful smell of butyric acid as the butterfat breaks down.
- if you use calcium carbonate to neutralize the acid as it is produced, you need very fine particles. There are recipes that use continual addition
of sodium (bi)carbonate instead - if I were to do this again, I'd use one of those.
- temperature control is nice. Yet it's not really essential. Lactobaccillus can grow (slowly) at lower temperatures and survive up to 50C at least.
Overall, a smelly preparation, but fortunately forgiving of missteps.
Polverone - 26-4-2012 at 19:33
Nice work. Have you acidified some of your calcium salt and smell-tested that it is (at least largely) free of butyrate? Further conversion of lactate
to butyrate is common even if the starting material is free of fat and protein.bbartlog - 27-4-2012 at 07:43
Not yet. Based on my experience with the pre-recrystallized product (which did indeed smell faintly of butyric acid), the calcium salts of lactate and
butyrate slowly give off small amounts of the free acid as they react with atmospheric CO2. Since calcium butyrate is both more soluble in water than
the lactate (at all temperatures) *and* is less soluble in hot water than in cold, I think the butyrate that was no doubt produced has been almost
entirely removed.
However, I still intend to take a sample of the material and obtain free acid; at the very least I can measure the density and see if it matches what
would be expected.
As an aside, I think that the use of the coarse CaCO3 that I had, while it slowed the fermentation down a great deal, also suppressed the butyric
fermentation. Lactobacillus tolerates slightly acidic pH better than clostridium. I wish I had measured the pH as I went along - I had planned to but
my children misplaced my pH test strips.
[Edited on 27-4-2012 by bbartlog]Paddywhacker - 27-4-2012 at 14:59
A great writeup, entertaining and informative.
I wonder about all that cheese. It would include a lot of fat and protein, so there would be no point in using skimmed milk or whey instead of whole
milk. It would be nice if the fat and protein could be avoided and just use whey.
Do the other recipes that you have also require such a smelly fermentation mixture?White Yeti - 27-4-2012 at 18:35
Very nice! I've attempted to do something similar, but my results have not been great. I will try to use calcium instead of sodium and see how things
turn out.
Next step: mix with sodium bisulphate and dry-distil for food grade lactic acid bbartlog - 27-4-2012 at 19:19
Thanks all! Yes, the cheese surely contributed to the odor - although the instructions say to mash it up, which I did, there were still lumps floating
on top. But if you're actually going to do the fermentation, the bacteria need some source of nutrients beyond just limestone and cane sugar.
Some of the other recipes in the Cyclopaedia of Practical Receipts do use just milk instead of cheese, and they also give some instructions
(originating from Scheele, apparently) for simply extracting the lactic acid from sour whey. But the thing is, I *had* a couple of gallons of sour
milk and a lump of cheese gone bad...
Quote:
dry-distil for food grade lactic acid
Near as can tell from my reading, it doesn't distill well at all. Some passes over while a lot ends up dehydrated to the lactide instead. But there
are other methods of purification that aren't terribly difficult.bbartlog - 27-4-2012 at 19:24
Thanks all! Yes, the cheese surely contributed to the odor - although the instructions say to mash it up, which I did, there were still lumps floating
on top. But if you're actually going to do the fermentation, the bacteria need some source of nutrients beyond just limestone and cane sugar.
Some of the other recipes in the Cyclopaedia of Practical Receipts do use just milk instead of cheese, and they also give some instructions
(originating from Scheele, apparently) for simply extracting the lactic acid from sour whey. But the thing is, I *had* a couple of gallons of sour
milk and a lump of cheese gone bad...
Quote:
dry-distil for food grade lactic acid
Near as can tell from my reading, it doesn't distill well at all. Some passes over while a lot ends up dehydrated to the lactide instead. But there
are other methods of purification that aren't terribly difficult.
