Fifty years of bland beer have saddled lagers with an image problem. When most people think of lager, they can only conjure images of the pale-yellow, low-calorie, mass-market varieties or perhaps a skunk-scented Mexican brand with a piece of fruit crammed into the neck. But this sorry reputation is undeserved.

The main difference between lager and ale is the type of yeast and the temperature of fermentation. When yeast does its thing, it produces a number of chemicals that give beer flavor and aroma. Ale yeasts work at higher temperatures that promote production of these byproducts, infusing ales with interesting fruity and spicy flavors. The low temperatures at which lager yeasts ferment inhibit the production of those chemicals. This gives lagers their distinctive crisp, clean character.

The best-known lager style is pilsner -- in my view the perfect beer. Poured into a tall, tapered glass, a true pilsner is a thing of beauty; deep golden, crystal clear and sporting a creamy cap of white foam. Its flavor is a subtly complex interplay of sweet malt and perfumed hops.

There are two types of pilsner. The drier German pils highlights hops with sharper bitterness and more pronounced spicy flavors. The Czech version has richer malt profile that balances the moderate bitterness.

One of the best German-style pilsners is Prima Pils from Victory Brewing Co. It's sharp and peppery with the faintest hint of citrus floating in the background. Minnesota-brewed Schell's Pils has a spicy, bitter bite set on a bed of soft, bready malt. It finishes refreshingly crisp and dry.

For a Czech-style pilsner, I like Lagunitas Pils from California. It's fuller-bodied and a bit sweeter, but still provides a great showcase for the earthy/floral flavors of Czech hops. It's a great session beer for summer or winter.

Munich-style dark lager, or "dunkel," is one of my favorites. This malt-centric, dark-brown brew showcases bread-crust flavors, with only a hint of hops to keep it balanced. One of the best examples available locally is Ayinger Altbairisch Dunkel from Germany. Its light bitterness and subdued, spicy hop flavor really let the toasty malt shine through. In April look for the draft-only Schadenfreude from Surly.

Doppelbock is the big-bopper of the lager world. These are rich, malt-forward beers that feature luscious caramel and raisin flavors, sometimes with hints of chocolate thrown in. Double Bock from the Sam Adams Imperial Series is worth checking out. It's smooth and creamy with huge burnt-sugar and dark fruit flavor. Alcohol that warms all the way down makes it a great sipper during the winter months.

Michael Agnew is a certified cicerone (beer-world version of sommelier) and owner of A Perfect Pint. He conducts private and corporate beer tasting events in the Twin Cities, and can be reached at michael@aperfectpint.net.