A recall of 4,000 half gallons of potentially contaminated ice milk mix turned up only 20, and a distributor's spokesman said the rest was apparently consumed. But neither they nor state health officials had any reports of illnesses traced to the mix. State health and agriculture officials announced that Listeria monocytogenes, a bacteria that can cause serious illness and stillbirths, had been found in a sampling of Adohr Milk Farms' vanilla ice milk mix. Adohr recalled all of the mix with the code number Dec 02, but was able to find only 20 half gallons, Gary San Filippo, division manager of Adohr's Santa Ana plant, said. "Unfortunately most of the product was already consumed. There's no notification from anyone of any illness," he said. The mix was sold to restaurants, mostly in Southern California, to make soft-serve ice cream and milkshakes.