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

74 Part 1: Principles/Food Analysis

Polyunsaturated fatty acids

Lipid hydroper oxides

Short chain secondary

products

4,5-Epoxy-2-

alkenals

Amino

compounds

1-Substituted-2-

(1’-hydroxyalkyl)pyrroles

Propanal

hexanal

1-Substituted-

pyrroles

Polymerization

Color

fluorescence

Oxygented fatty acids

Figure 4.13.General pathways of pyrrole formation during polyunsaturated fatty acids oxidation (Zamora and Hidalgo 1995).

functional lipids in the maintenance of cellular integrity, most

of the studies have been conducted in biological samples

(Bucala et al. 1993, Requena et al. 1997, Lertsiri et al. 1998, Oak

et al. 2000, Oak et al. 2002). The glycation of membrane lipids

can cause inactivation of receptors and enzymes, cross-linking

of membrane lipids and proteins, membrane lipid peroxidation,

and consequently, cell death. Amadori compounds derived from

the interaction between aminophospholipids and reducing car-

bohydrates are believed to be key compounds for generating

oxidative stress, causing several diseases.

In foods, this reaction can be responsible for deteriora-

tion during processing. Although nonenzymatic browning of

aminophospholipids was detected for the first time in dried egg

by Lea (1957), defined structures from such reaction were re-

ported later by Utzmann and Lederer (2000). These authors

demonstrated the interaction of PE with glucose in model sys-

tems; moreover, they found the corresponding Amadori com-

pound in spray-dried egg yolk powders and lecithin products

derived therefrom and proposed the Amadori compound con-

tent as a possible quality criterion. Oak et al. (2002) detected the

Amadori compounds derived from glucose and lactose in several

processed foods with high amounts of carbohydrates and lipids,

such as infant formula, chocolate, mayonnaise, milk, and soy-

bean milk; of these, infant formula contained the highest levels

of Amadori-PEs. However, these compounds were not detected

in other foods due to differences in composition and relatively

low temperatures used during the processing.

As an example, Figure 4.14 shows a scheme for the formation

of the Amadori compounds derived from glucose and lactose

with PE. Carbohydrates react with the amino group of PE to

form an unstable Schiff’s base, which undergoes an Amadori

rearrangement to yield the stable PE-linked Amadori product

(Amadori-PE).

On the other hand, similar to proteins, phospholipids, such

as PE and ethanolamine, can react with secondary products

of lipid peroxidation, such as 4,5-epoxyalkenals. Zamora and

Hidalgo (2003b) studied this reaction in model systems, and they

characterized different polymers responsible for brown color

and fluorescence development, confirming that lipid oxidation

products are able to react with aminophospholipids in a manner

analogous to their reactions with protein amino groups; there-

fore, both amino phospholipids and proteins might compete for

lipid oxidation products. Subsequent studies, besides to corrob-

orate these findings (Zamora et al. 2004, Hidalgo et al. 2006b),

showed the capacity of amino phospholipids to remove the cito-

and genotoxic aldehydes produced in foods during lipid oxida-

tion when its fatty acid chains were oxidized in the presence of

an oxidative stress inducer. These results suggested that, in the

presence of amino phospholipids, the oxidation of polyunsatu-

rated fatty acid chains is not likely to produce toxic aldehydes in