Why is it important to drink pasteurized apple juice?

Pasteurization is a heat process the product goes through to kill harmful bacteria, enzymes, and naturally occurring spoilage organisms in the juice.  Most refrigerated juice sold in bottles or cartons at grocery stores is pasteurized.  Unrefrigerated juice in bottles, cans, and laminated paperboard boxes has been heat-treated and generally considered safe.  Frozen, concentrated juices are pasteurized during the concentration process.  But resist buying apple juice or cider from farmers’ markets and cider mills, which often sell unpasteurized product.  Fresh squeezed or pressed juice, as in some juice bars and restaurants, may also pose some risk, as it probably has not been processed to kill pathogens.  If these beverages were made from ground-tagged apples (apples that fell to the ground and lay there awhile), these apples might have become contaminated by dirt or manure With unpasteurized apple juice or cider, you could be buying (and drinking) dangerous germs as well as juice. 
 
Source(s):
USDA, Food and Rural Economics Div., Economic Research Service, “New Juice Regulations Underway.”
Food Alert! by Morton Satin, 2008.