Question on Biomolecules

The Kiliani-Fischer synthesis is a method for synthesizing monosaccharides. It proceeds via synthesis and hydrolysis of a cyanohydrin, thus elongating the carbon chain of an aldose by one carbon atom while preserving stereochemistry on all the old chiral carbons. The new chiral carbon is produced with both stereochemistries, so the product of a Kiliani-Fischer synthesis is a mixture of two diastereomeric sugars, called epimers. For example, D-arabinose is converted to a mixture of D-glucose and D-mannose. so basically it can be considered a step up reaction .