Strecker industrial applications

Beer, on the other hand, is produced by more complex biochemical and technological processes, which all affect its flavor. Yeast amino acid metabolism, a key to the development of beer flavor as described earlier, is affected by process temperature and use of cell immobilization techniqnes. Therefore, technologies based on these features as well as other process conditions and strain selection have been developed to control beer flavor. The combination of immobilized yeast and low-temperature primary fermentation was found to produce beers with low diacetyl amounts, therefore indicating potential of low-cost industrial application since maturation is a high-energy-consuming process. Finally, Perpete and Collin showed that during alcohol-free beer production, the enzymatic reduction of worty flavor (caused by Strecker aldehydes) by brewer s yeast was improved by cold contact fermentation. 

An a-amino acid 3 can be prepared by treating aldehyde 1 with ammonia and hydrogen cyanide and a subsequent hydrolysis of the intermediate a-amino nitrile 2. This so-called Strecker synthesis - is a special case of the Mannich reaction-, it has found application for the synthesis of a-amino acids on an industrial scale. The reaction also works with ketones to yield a, a -disubstituted a-amino acids. 

At DSM a very efficient and universally applicable industrial process for the production of both optically pure l- and D-amino acids has been commercialized [25, 271. Pivotal in this process is the enantioselective hydrolysis of D,L-amino acid amides. The stable D,L-amino acid amides are prepared efficiently under mild reaction conditions starting from simple raw materials (Fig. 12.2-1). The reaction of an aldehyde with hydrogen cyanide in ammonia (Strecker reaction) affords the amino nitrile. The amino nitrile is converted in a high yield into the D,L-amino acid amide under alkaline conditions in the presence of catalytic amounts of acetone. The... 

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