Essentially this enzyme preparation  breaks the glucoside bonds in starches--including malt dextrins-- forming glucose and fructose, either of which can be fermented-- i.e. eaten-- by yeast.  Amyloglucosidase is made by fermenting special strains of Aspergillus Niger, a black fungus that causes black mold on fruits and vegetables. The fungus is then processed to remove the enzyme. Amyloglucosidase is now a ubiquitous product in the food and beverage industry, used for example, in the production of high fructose corn syrup from corn.

Gablinger's Diet Beer may have flopped, but Dr. Owades was onto something.
A lot of people who drink mainstream, American style lagers, worry about their weight. They also dislike the full  feeling that one can get from drinking a couple of pints of a normal beer, laden with malt dextrins, which are carbohydrates. More
than that, American palates have been shaped increasingly by the hugely successful soft drink industry. A lot of people, especially younger people, simply dislike the bitterness, the malty body and the hops smell of real beer.

There are three possible ways to make a very light style of lager beer with as few calories as possible. The first is to simply water it down. But this produces a watery tasting product that is simply unappealing.

The second is to brew from a very lean wort, with a low Original Gravity, and accept low alcohol levels, say 2% alcohol. This has never been a popular approach in the United States, although in Germany some brewers make a Leicht style, that has some body, flavor, hoppiness and low alcohol content. Since the alcohol contributes even more calories than the malt dextrins, this is a fairly low calory beer.

The third is to use Amyloglucosidase to convert the non-fermentable carbohydrates that remain in beer and give it body and flavor. By converting these dextrins to sugars the brewer can ferment them out to alcohol and carbon dioxide, achieving a respectable 4.2 ABV  whileremoving about 50 calories of carbohydrate from a bottle or can of beer.

That, in a nutshell is Light Beer.

Dr Owades took his brainchild to Chicago Brewer MeisterBrau, who tried
out Meister Brau Lite beer in Chicago. That didn't work either. The stuff was being marketed to women, it even had a woman pictured on the can. While American women do drink beer, those who do are a distinct minority.

Enter Philip Morris, the giant tobacco company. They bought Miller Brewing in 1969 for $130 Million from W.R. Grace and Co. To run Miller they put John
Murphy, a tall, hefty Irish American in charge. The story goes that in 1972, on a business trip in Germany, Murphy, was dining out with George Weissman the chairman of Philip Morris. Weissman was trying to diet. The waiter introduced him to Diat Pils-- a german brew designed for diabetics, where a low OG brew was fermented out as far as the yeast could take it, to render every scrap of sugar into alcohol. While not actually low on either calories or carbs, due to the alcohol content, Diat pils tastes light.  Murphy tried it too and told Weissman
There's room for something like this in America.

Miller bought Meister Brau that same year and picked up Meister Brau
Lite in the package, as it were. The Philip Morris people were marketeers, with skills honed in the cut throat world of cigarettes. They identified a better way to market Lite, and set the brewers to tinker with the recipe and then released Miller Lite on an unsuspecting world in 1975.

They positioned it as a beer for sports guys who didn't want to get all filled up with
heavy, old fashioned beers, but still wanted a real, ie, alcohol above 4% ABV, beer.

The American Premium beer market--e.g. Budweiser, Miller High Life,
Coors, Strohs,  was already one for very .light tasting lagers. Hop bitterness levels were generally in the 11-13 IBU range, in other words almost indetectable. Rice and corn were used to supplement, or even supplant, more expensive barley malt to provide fermentable sugars.

Miller Lite simply opened the way to a mass market for even less flavorful brews. And, it goes without saying, since less went into them, but the price remained the same as that for Premium brews, these were considerably more profitable products.

In 1978 Coors came out with Coors Light, their first response to Miller's onslaught.  Then, in 1982, after long thought and considerable internal debate, Anheuser Busch finally responded by launching Bud Light. Thence began the Beer Wars, as AB slowly took share from Lite, until by the early 90s, Bud Light was preeminent. There began a long decline in the fortunes of Miller Lite, until that brand was eventually overtaken by Coors Light. About then, Philip Morris, to whom Miller represented a mere 4% of revenues, sold the brewer to South African Breweries (SAB) who soon began an aggressive campaign to recapture market share. The Beer Wars heated up again, and Miller's assault on Bud Light paid off to the extent that Lite recaptured the Number 3 position in US beer brands, behind Bud Light and Budweiser in 2005.

Take a look at this little collection of stats.

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                             ABV       Cals          Carbs
Bud Light               4.2          95              6.6
Budweiser              5.0         143            10.6
Michelob                5.0         155            13.3
Coors Light             4.2         102             5.0
Coors Original        5.0          148            11.3
 Heineken              5.4          166             9.8
 Miller High Life      5.5          156              11
 Miller Lite             4.2           96              3.2
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For all the marketing, plus all the clever, expensive and malicious advertising that this highly profitable and very popular market segment is known for, the arguments all come down to two or three carbs and one or two calories, per serving. In other words, from the perspective of those who drink ales, bocks, stouts, or even full bodied European lagers, like Pilsner Urquell (4.3 ABV 160 cals) almost nothing.  Indeed, the beers in this category barely qualify as beer.

And, by classical standards they aren't, since real beer is only made
with water, hops, barley malt and yeast, leaving no room for Amyloglucosidase.
However, that said, this style is rapidly becoming the world's favorite, which says a few things about popular taste, advertising and the power of marketing.