During mas- tication, salivary α-amylase acts briefly on dietary starch and glyco- gen, hydrolyzing random α(1→4) bonds. [Note: There are both α(1→4)- and β(1→4)-endoglucosidases in nature, but humans do not produce the latter. Therefore, we are unable to digest cellulose— a carbohydrate of plant origin containing β(1→4) glycosidic bonds between glucose residues.] Because branched amylopectin and glycogen also contain α(1→6) bonds, which α-amylase cannot hydrolyze, the digest resulting from its action contains a mixture of short, branched and unbranched oligosaccharides kown as dextrins (Figure 7.9) [Note: Disaccharides are also present as they, too, are resistant to amylase .] Carbohydrate digestion halts temporarily in the stomach, because the high acidity inactivates salivary α-amylase .