Although I have never been to Naples, I understand that if you want a DOC pizza in a Naples pizzeria--with buffalo mozzarella cheese--you have to specifically ask for a DOC pizza. Otherwise, you will get cow's milk mozzarella cheese on your pizza. The Naples pizzaoli claim that the buffalo mozzarella cheese is too watery for pizza but I'm not certain that that is the real reason. With oven temperatures in excess of 700 degrees F, and with bake times under a few minutes, I would think that the water contributed by the buffalo mozzarella cheese would be burned off by the time the pizza is done. Cow's milk mozzarella cheese is cheaper than buffalo mozzarella cheese, which may be the real reason that it is used by Neapolitan pizzaoli instead of buffalo mozzarella cheese. In the U.S., because home ovens don't achieve the temperatures of wood-fired ovens, it will usually be necessary to drain fresh mozzarella cheeses before using to reduce the water content.
Jeffrey Steingarten, a writer for Vogue magazine and an oft-quoted food guru, wrote an article in the September 2003 edition of Vogue magazine in which he thoroughly investigated Italian buffalo mozzarella cheeses. Two brands of imported buffalo mozzarella cheeses he particularly favors are Caseificio Cooperativa La Garofalo, Capua, Caserta, and Industria Lattiero Casearia Mandara, Mondragone, Caserta. But, unless you live in or around a major metropolitan area, like New York City, you will have a hard time finding those particular brands. You will have to be satisfied with whatever brand your local specialty store offers--if it even offers any brand. Also, whatever brand you find will not be quite as good as what is availalable in Italy, since the buffalo mozzarella cheeses destined for U.S. markets must undergo special processing to ensure that they survive the rigors and delays in the journey across the Atlantic from Italy to the U.S. (by air), and that they arrive in fresh enough condition to be used before the quality starts to degrade, which is usually within a matter of a few days.
Because of the unavoidable drawbacks inherent in the importation of buffalo mozzarella cheese from Italy, there has been a recent movement on the part of a few entrepreneurial domestic companies to produce fresh buffalo mozzarella cheese for local consumption. To date, I am aware of only two domestic producers of buffalo mozzarella cheese: Star Hill Dairy, a farmstead dairy in Vermont and Bubalus Bubalis, Co., a cheese producer in California. They may well be the only domestic producers in the U.S. at this time. Only time will tell whether their domestic buffalo mozzarella cheeses will match the quality of the imported varieties, but early indications are that the quality is reasonably good but not yet up to the standards of a good buffalo mozzarella cheese imported from Campania, Italy. For those who may be interested in the domestic versions of buffalo mozzarella cheese, I have provided links below for the two domestic producers mentioned above. I live outside of Dallas and was able to find the Bubalus Bubalis brand in Central Market, and I was able to find the Star Hill product in a Whole Foods store in Massachusetts while I was there on a visit. I found both brands quite good, and even did a side-by-side test of the Star Hill cheese and an imported buffalo mozzarella cheese on pizzas, and no one could tell the difference.
As with any mozzarella cheese product, whether buffalo mozzarella cheese, cow's milk mozzarella cheese, whole-fat, low-moisture, part-skim, sliced, crumbled, shredded, diced or minced, you will have to experiment to get the desired texture, flavor, meltability and coloration on your pizzas. There are just too many variations among types and brands of mozzarella cheese to lay out specific rules.
Here are the links to the two domestic producers of buffalo mozzarella cheese:
Star Hill Dairy (Vermont): http://www.starhilldairy.com/products.shtml
(with online ordering capability)
Bubalus Bubalis, Co. (California): http://www.farmersmarketonline.com/mozzarelladibufala.htm
(with online ordering capability)