Food Biochemistry and Food Processing (2 edition)

BLBS102-c04 BLBS102-Simpson March 21, 2012 11:59 Trim: 276mm X 219mm Printer Name: Yet to Come

64 Part 1: Principles/Food Analysis

Maillard browning reactions

O C C C C C

H

H

H

H

RN C

H C

H

OH

HO H

HOHHOHO

O

OH

NH–R

β-Pyranosyl

β-Furanosyl

β-Pyranosyl

O OH

HO

Ch 2 OH

HO Ch 2 NH–R

R–NH CH 2

CO

HO C H

H C OH

C

CH 2 OH

Amadori product

HOH OH

OH CH 2 NH–R

HO

Advanced glycation products

O

Schiff's base

Amadori rearrangement

HOH

C

C

C

CH 2 OH

CH 2 OH

OH

H 2 N

NH 2

O

O

Asparagine D-Glucose

OH

HO

HO

HO

Heat

OH

OH

OH

OH

H

N

OH

O

O

N-(D-glucose-1-yl)-L-asparagine

Several

steps

O

Acrylamide

NH 2

O

NH 2

HO

HO HO

O

OH

OH

CH 2 OH

Glucose

R-NH 2

amino acid

or protein

HO

+ +

H

Acrylamide formation

Figure 4.5.Initial stages of the Maillard reaction and acrylamide formation (Friedman 2003).

loss of glycine was faster at high phosphate buffer concentration

(Figure 4.6), showing its catalytic effect on the Maillard reaction.

The effects of salt concentration on the rates of browning reac-

tion of amino acid, peptides, and proteins have also been studied

by Yamaguchi et al. (2009). High concentration of sodium chlo-

ride retarded the reaction rate of glucose with amino acids but

did not change the browning rate of glucose with peptides.

The type of reducing sugar has a great influence on Mail-

lard reaction development. Pentoses (e.g., ribose) react more

readily than hexoses (e.g., glucose), which, in turn, are more re-

active than disaccharides (e.g., lactose; Ames 1990). A study

on brown development (absorbance at 420 nm) in a heated

model of fructose and lysine showed that browning was higher

than in model systems with glucose (Ajandouz et al. 2001).

A study using heated galactose/glycine model systems found

that the rate of color development in Maillard reaction fol-

lowed first-order kinetics on galactose concentration (Liu et al.

2008). The effects of tagatose on the Maillard reaction has been

also investigated in aqueous model systems containing various

sugars (glucose, galactose, fructose, and tagatose) and amino

acids through volatile Maillard products determination (Cho

et al. 2010).