It looks like this: http://cheeseforum.org/forum/index.php/topic,13810.msg104618.html#msg104618
Late blowing is caused by clostridium tyrobutyricum spores in the milk. Pasteurisation kills clostridium but not the spores.
If cows are fed with ensilage the risk of clostridium is higher than if fed on grass/hay. I use something called Lysozyme when not using grass-/hay-milk. This minimizes the risk of late blowing.
I feel like I am running around CheeseForum posting little tidbits about Lysozyme as I learn more.
I learned this morning that it is all made in Europe from parts of chicken egg whites and that the rest of the egg is used to make ice cream, etc. It takes about 10,000 eggs to make a kilogram. It is available in the US from several sources including Scott Laboratories in Petaluma, CA (
scottlab.com) and several wine and beer making suppliers offer it in small quantities. Scott Labs calls their version Lysovin as their market is wine making. I talked with a biologist there this AM who had heard of its use in cheese making but knew nothing more about it. It is used in winemaking to kill lactic acid bacteria following malolactic fermentation. She had no idea how it could kill clostridium tyrobutyricum and not effect thermophilic cheese bacteria as lysozyme goes after gram positive bacterial and both of these are gram positive. But, it is widely used in Europe and especially Italy to help prevent blowing in long aged hard cheeses. Lysolac, a Dutch company, has a web page showing how to use it and a little calculator to compute how much should be used. (
http://lysolac.com/products.html). The US and Eurpoean granular versions are the same (lysozyme hydrochloride) and are likely made in the same plant.
Other than possibly affecting thermophillic bacteria I see no downside in using lycozyme as directed above. In fact, at a cost of about $40 per 150 grams I think it might be cheap insurance to make sure your long aged hard cheeses don't undergo late blowing. The dosage level is about 1 gram per 4 gallons of milk so the cost works out to be about $ .08 per pound of cheese.
I'm still on a quest to learn how it can kill the bad guy without harming the good guys.