Chemistry of non-enzymic browning. II. Reactions between Amino Acids, Organic Acids, and sugars in freeze-dried Apricots and Peaches

Abstract

The water-soluble constituents of apricot and peach purees were examined qualitatively and quantitatively before and after storage for 4 to 16 months at 25 °C and 70 per cent. R.H. All samples contained all the amino acids, organic acids, sugars, and polyols previously detected (Reynolds 1967 ; Anet and Reynolds 1955a, 1966b ; Ash and Reynolds 1955a, 1955b) in the two species of fruit. The stored samples also contained the following compounds : eleven 1-(N-amino acid)-1-deoxyfructoses, traces of two 2-(N-amino acid)-2-deoxyglucoses, nine by-products of unknown constitution formed from the reaction between glucose and aspartic acid and glucose and asparagine, three compounds formed from ammonia and glucose, two series of sucrose, glucose, and fructose mono-esters of malic acid, traces of a sorbitol mono-ester of malic acid, and some sugar mono-esters of citric acid. The free amino acid or organic acid lost was equal, on a molar basis, to the amino acid-deoxyfructoses (and related compounds) and sugar esters formed. After allowing for these derivatives as much as 7 per cent. of the total sugar (calculated as hexoses) originally present could not be accounted for.