Effects of pH and Temperature on the Carbonyls and Aromas Produced in Heated Amino Acid‐Sugar Mixtures

Abstract

SUMMARYSolutions of glycine, glutamic acid, lysine, methionine, and phenylalanine adjusted to pH 6.5 were reacted separately with glucose, fructose, maltose, and sucrose at 100 and 180°C. Some of the aromas generated were reminiscent of foods, whereas others were distinctly unpleasant. Ethanal, propanal, acetone, isobutanal, aerolein, butanal, 2‐butanone, 2,3‐butane‐dione, erotanal, 2‐pentanone, and heptanal were identified as end products in one or more of the 20 mixtures. The glutamic acid‐glucose mixture was also heated at 100 and 180°C after being adjusted to pH 5.0 and 8.0. Of the compounds above, isobutanal and heptanal were not formed. Pentaual was formed at 100° but not at 180°C. A synthetic potato medium containing glucose and glutamic acid heated at 100°C yielded ethanal, propanal, acetone, butanal, 2‐butanone, 2,3‐butanedione, and crotonal. A potato extract heated at 180° differed from the synthetic potato medium heated at 100° in the products formed. Not formed were 2‐butanone and 2,3‐butauedione; pentanal, heptanal and hexen‐l‐al were formed. In all, 85 carbonyls were detected in the various mixtures or substrates.

POTATO FLAVOR GENERATION‐AN APPROACH To THE FLAVOR IMPROVEMENT OF DEHYDRATED POTATO PRODUCTS

“…A similar observation was made byEl'Ode et al (1966) as they reported that heating an aqueous solution of methionine and sugars to 100" and 180°C yielded a cabbage-like odor..…”

Free Amino Acids in Ham Muscle During Successive Aging Periods and Their Relation to Flavor

“…Ockerman et al (1964) have isolated a number of volatile carbonyl compounds, bases and sulfides in an attempt to characterize the flavor of dry-cured hams. It has been well established that amino acids can give rise to various volatile compounds and that heating synthetic mixtures of sugars and amino acids gives rise to odors reminiscent of certain foods (Hertz et al, 1960;Casey et al, 1965 ;El 'Ode et al, 1966 ;Pearson et al, 1966). It would be expected that the amino acids in dry-cured hams are an important source of volatile compounds when the ham is heated.…”

“…It has been suggested that certain amino acids are important precursors of the flavor components released when foods are heated and several studies have been conducted to determine the free amino acids present in different foods (Wood et al, 1957;Bender et al, 1958Bender et al, , 1961Herz et al, 1960 ;Macy et al, 1964 ;Casey et al 1965 ;El 'Ode et al, 1966;Pinto et al, 1966).…”

Isolation and Characterization of Ether Soluble Sugar‐Amino Acid Interaction Products

“…Their presence would be expected because most of the sugar fission products and decomposition products of mono-and di-ketoseamines are carbonyls (Hodge, 1953 ;Reynolds, 1963). Other recent studies have also implicated carbonyl compounds (El'Ode et al, 1966;Sugisawa, 1966).…”