Cereal Chem 46:189 - 195.  |  VIEW ARTICLE
Preparation and Properties of 1, 4, 5, 6-Tetrahydro-2-Acetopyridine, a Cracker-Odor Constituent of Bread Aroma.

I. R. Hunter, M. K. Walden, J. R. Scherer, and R. E. Lundin. Copyright 1969 by the American Association of Cereal Chemists, Inc. 

A pentane extract of a reaction mixture of proline, dihydroxyacetone, and sodium bisulfite has a strong odor reminiscent of freshly baked soda crackers. The compound responsible has been found to be 1, 4, 5, 6- tetrahydro-2-acetopyridine, which was isolated by vacuum distillation. Structure of the compound was determined by means of functional group reagents and by infrared, Raman, nuclear magnetic resonance, and mass specra. Gas-chromatographic analysis of the fresh liquid showed it to be a single substance that coincided with the aroma peak prepared from an extract of freshly baked bread.The compound is an unstable, colorless liquid that undergoes both physical and chemical changes on standing in air. It is stable as the bisulfite complex, or when hermetically sealed under nitrogen. A pentane solution remains stable for several weeks. It has a distinct odor of crackers. As little as one part in 100,000 in an extract of fresh bread is easily detected and imparts a pleasant crusty overtone to the extract. Spraying week-old bread with an aqueous solution containing 6 p.p.m. of the sodium bisulfite complex of the tetrahydropyridine compound returned a desirable fresh-bread odor to the crust after it had dried.