Monitoring Chemical Changes in Cheddar Cheese During Aging by High Performance Liquid Chromatography and Gas Chromatography Techniques

Abstract

The concentrations of several chemical metabolites in Cheddar cheese were monitored by various chromatographic techniques during the aging process to learn which metabolites were the best predictors of the glycolytic, lipolytic, and proteolytic age of the cheese. Pyruvic, lactic, acetic, and propionic acids were measured by ion-exchange high performance liquid chromatography; acetone, 2-butanone, ethanol, 2-pentanone, 2-butanol, and n-propanol were monitored by headspace gas chromatography; free fatty acids were quantitated (without derivatization) by gas chromatography; and free amino acids were determined as their o-phthaldehyde derivatives by high performance liquid chromatography. The best predictors of the glycolytic age were propionic acid and acetic acid; the best predictors of lipolysis were the free fatty acids C10, C12, C14, and C16; and the best predictors of proteolysis were the free amino acids leucine, methionine, and glutamic acid. The volatile metabolites determined by headspace gas chromatography were not good indicators of aging; however, they did provide useful information related to flavor problems. Cheddar cheese aged at elevated temperatures produced propionic acid, acetic acid, and free amino acids at significantly faster rates than the other chemicals that were monitored.