Long chain sugars are basically starch. They're polysaccharides. It can be considered carbohydrates. Wrapped in the starch are monosaccharrides that can be converted to disaccharides, called maltose. Glucose, a monosaccharide, makes up about 10% of starch. After a-amylase liquifies the starch, turning it into carbohydrate soup, it begins chopping up the long chain. A reducing and non-reducing end are formed everywhere the chain is cut. Then, beta chops off two molecules of glucose from only the non-reducing end of the chain, mixing with one water molecule, resulting in maltose. When b-enzyme cuts off three molecules of glucose and blends with one water molecule, maltriose is formed, an trisaccharide. There's something called amylopectin thrown in the mix, too. Disaccharides should make up 55% of the starch. The left overs should be reduced to maltriose and small limit dextrins. In a nutshell, long chain sugar, remains long chain sugar until mashing. Then, a-amylase cuts the chain up. When a and b enzymes can not reduce the sugar/carbo chain any farther, a-limit and b-limit dextrins are formed. The limit dextrins are not fermentable. Long chain sugar remain as such in crystal and cara malt, as enzymes cannot reduce the sugars. A 145 F rest is done, because starch hasn't gelatinized. Beta, slowly produces maltose, the low temp preserves enzymes. If you look at a step mash process for German style ale, wheat, lager and pils. There is usually, a 140-145 F rest. Then another beta rest above gelatinizing temp. Starch gelatinizes at 149 F. Both rests take advantage of a-amylase chopping up the chain, producing many non-reducing ends for b-amylase to work on. Then, a short rest is done at 155-158 F and at 162 F, until conversion. When testing for conversion, unconverted gelatinized starch will cause iodine to be deep red to mahogany. Carried over gelatinized starch reduces the quality of the finished product. During conditioning phase it can open the door for gram negative bacteria. None of that matters if the product goes from boiler to belly in four or five weeks. A decoction method brewer is able to vary the conversion temps in each decoction as well as in the mashtun. Why boil water for infusions, when mash can be boiled? There is much to brewing beer and so little time to drink it all.