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3: ) Maillard Reaction in Microwave Heating
Maillard Reaction in Medicine
As was
introduced before, the Maillard reaction between amino acids and reducing
sugars were first described by Louis Maillard in 1912. For the next
few decades, effects of the Maillard reaction in food processing were extensively
studied by food scientists . In recent years, the reaction between
glucose and amino acids in living organisms was recognized to have an important
role in human health. The term Advanced
Glycosylation Endproducts or AGEs is then introduced to describe
Maillard reaction products that form under normal physiological conditions
in living organisms. Results from recent studies have shown that
AGEs are responsible for a number of medical complications among diabetic
patients and the aging populations.
AGEs and Cataract
AGEs can accumulate on long-lived proteins in living organisms such
as the crystallin proteins of the ocular lens. Monnier and Cermai
(1981) first reported that yellow-brown pigments
accumulated in the lens with age and at an accelerated rate in diabetic
patients.
The graph on the right showed the fluorescence-excitation spectra of
bovine and human lens protein. It indicated that the intensity
of yellowish increased in the bovine lens after incubation with sugar.
Also, human cataractous lens had higher intensity than young normal lenses.
Accumulated AGEs such as pyrraline, carboxymethyllysine, and pentosidine
can crosslink with proteins and eventually lead to cataract formation.
AGEs and Aging
In addition to crystallin
proteins in the ocular lens, AGEs were also found in other long-lived proteins
such as the extracellular matrix in the brain, cartilage between joints,
and renal basement membrane. Furthermore, serum albumin, LDL, and
immunoglobulins have been found to be trapped in the AGEs-protein matrix,
leading to thickening of basement membrane and tissue damage as seen in
aged tissue.
Results from animal studies
have shown that feeding caloric-restricted, starch-restricted, or glucose-restricted
diets to animals led to decreased AGEs and lowered level of AGEs-protein
matrix in diabetic animals. The effects on normal healthy animals
were not as obvious. Further studies on the presence of AGE receptor,
structure of AGE epitope, and the mechanism of collagen crosslinking are
required to fully understand the effects of AGEs in aging.
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3: ) Maillard Reaction in Microwave Heating