| When you make ethanol on an industrial scale corn is ground to make mash, perhaps first being boiled in ethanol to extract the corn oil for the making of biodiesel. This plant in Superior, Iowa belonging to Green Plains Renewable Energy cranks out fifty million gallons of ethanol annually. The black rail cars are ethanol tankers with a capacity of 30,000 gallons each and the three beige cars at the end of the string are grain carriers with a capacity of roughly 4,000 bushels each.
Once the corn is ground the next step is making 'beer'. The corn is mixed with water and amalyse enzyme which converts the starch in the corn to glucose/fructose. The yeast is added after this and the fermentation process begins. If bacteria get into the mix they convert the sugar to lactic acid rather than ethanol and it can poison the whole batch.
The yeast grow until they've converted all the sugar to ethanol, then the distillation process begins. The solids are separated with a centrifuge and the liquid is then heated, driving the ethanol off and leaving a mixture of water and organic material behind.
The recovered solids are high in protein and perhaps in oils. These are part of the economic output of the plant and they're sold to feed lots. If the feedlot is nearby the distiller's grain is left wet but if shipping or storage is required it must be dried. The drying process consumes nearly 40% of the energy that is input to make ethanol and if it's possible to sell the distiller's grain wet there is a tremendous economic reason to do so.
The recovered solids contain the bacteria that invaded and survived the fermentation process ... as well as the antibiotics used to control them. There are four commonly used antibiotics, penicillin, virginiamycin, erythromycin and tylosin. Some distiller's grain samples from ethanol plants in the Midwest already contain E. Coli that is resistant to these antibiotics.
I happened to send the link to the AgWeb post that got me started on this to Kossack Nb41 and he came back with a quick industrial chemist's response:
The other way around this problem is to use sterile facilities - and small quantities of NaOH are very good disinfectants. Then a new batch of corn and water are cooked with amalyse enzyme (converts starch to glucose/fructose) after the pH is adjusted slightly, and this hot (too hot for bacteria) mix is then cooled down via a heat exchanger and the yeast are added. By and largge, the yeast propagate like crazy at 95 F, and go to town on the sugar in this O2 free environment. Then after the batch is transferred to the holding tank, the next batch is started.
It is always important to keep O2 away from this beer - and a blanket of CO2 can do that, or N2. But, if air sits on the top of the batch...that's asking for trouble. Which is evidently what has happened, and partly why they are using antibiotics. That should be banned, outright.
But all the preventative and sterilizing steps add some small amount of money to plant cost - antibiotics are probably cheaper.
So there you have it. For want of a few cents more per gallon instead of doing it right the ethanol industry may be setting us up for another horror like Methicillin-resistant Staphylococcus Aureus. There is some talk, as yet unconfirmed, that MRSA is traveling in our feedlot hog population. This will be the subject of further research before any definitive statement can be made, but the path of E. Coli in distiller's grain later turning up in the cattle and hogs eating it is clear cut.
Oh, and the FDA is the organization to regulate this, so I think we ought to be getting after them on this point.
(UPDATE:
A real live meat inspector that I've known for 20+ years dropped me a note after seeing this. She says this is not yet a scientifically solid thing - she easily found one study that confirmed it and another the repudiated the idea. She is all over this stuff as it's her daily work and if she says it's still on the fence I'll take it to heart. The potential is there and I'd prefer we fix it before it becomes a huge public health problem.) |
