BLBS102-c04 BLBS102-Simpson March 21, 2012 11:59 Trim: 276mm X 219mm Printer Name: Yet to Come
4 Browning Reactions 67Escherichia coliand emulsifying properties. Recently, Corzo-
Mart ́ınez et al. (2010) observed an improvement in gelling and
viscosity properties of glycosylated sodium caseinate via Mail-
lard reaction with lactose and galactose.Control of the Maillard Reaction in FoodsFor a food technologist, one of the most important objectives
must be to limit nutritional damage of food during processing.
In this sense, many studies have been performed and found use-
ful heat-induced markers derived from the Maillard reaction, and
most of them have been proposed to control and check the heat
treatments and/or storage of foods. There are many indicators
of different stages of the Maillard reaction, but this review cites
one of the most recent indicators proposed to control early stages
of this reaction during food processing: the 2-furoylmethyl
amino acids as an indirect measure of the Amadori compound
formation.
Determination of the level of Amadori compounds provides
a very sensitive indicator for early detection (before detrimental
changes occur) of quality changes caused by the Maillard reac-
tion as well as for retrospective assessment of the heat treatment
or storage conditions to which a product has been subjected (del
Castillo et al. 1999, Olano and Mart ́ınez-Castro 2004).
Evaluating for Amadori compounds can be carried out
through furosine [ε-N-(2-furoylmethyl)-l-lysine] measurement.
This amino acid is formed by acid hydrolysis of the Amadori
compoundε-N-(1-deoxy-d-fructosyl)-l-lysine. It is considered
a useful indicator of the damage in processed foods or foods
stored for long periods: milks (Resmini et al. 1990, Villamiel
et al. 1999); eggs (Hidalgo et al. 1995); cheese (Villamiel et al.
2000); honey (Villamiel et al. 2001, Morales et al. 2009); in-
fant formula (Guerra-Hernandez et al. 2002, Cattaneo et al.
2009); milk-cereal-based baby foods (Bosch et al. 2008); jams
and fruit-based infant foods (Rada-Mendoza et al. 2002); fresh
filled pasta (Zardetto et al. 2003); prebaked breads (Ruiz et al.
2004), cookies, crackers, and breakfast cereals (Rada-Mendoza
et al. 2004, Gokmen et al. 2008); fiber-enriched breakfast cereals ̈
(Delgado-Andrade et al. 2007); flour used for formulations of
cereal-based-products (Rufi ́an-Henares et al. 2009); and sauces
and sauces-treated foods (Chao et al. 2009). Erbersdobler and
Somoza (2007) have written an interesting review on 40 years
of use of furosine as a reliable indicator of thermal damage in
foods.
In the case of foods containing free amino acids, free Amadori
compounds can be present, and acid hydrolysis gives rise to
the formation of the corresponding 2-furoylmethyl derivatives.
For the first time, 2-furoylmethyl derivatives of different amino
acids (arginine, asparagine, proline, alanine, glutamic acid, and
Υ-amino butyric acid) have been detected and have been used as
indicators of the early stages of the Maillard reaction in stored
dehydrated orange juices (del Castillo et al. 1999). These com-
pounds were proposed as indicators to evaluate quality changes
either during processing or during subsequent storage. Later,
most of these compounds were also detected in different foods:
commercial orange juices (del Castillo et al. 2000), processed
tomato products (Sanz et al. 2000), dehydrated fruits (Sanz et al.2001) and carrots (Soria et al. 2010), commercial honey samples
(Sanz et al. 2003), and infant formula (Penndorf et al. 2007).CaramelizationDuring nonenzymatic browning of foods, various degradation
products are formed via caramelization of carbohydrates, with-
out amine participation (Ajandouz and Puigserver 1999, Ajan-
douz et al. 2001). Caramelization occurs when surfaces are
heated strongly (e.g., during baking and roasting), during the
processing of foods with high sugar content (e.g., jams and cer-
tain fruit juices), or in wine production (Kroh 1994). Carameliza-
tion is used to obtain caramel-like flavor and/or development of
brown color in certain types of foods. Caramel flavoring and
coloring, produced from sugar with different catalysts, is one
of the most widely used additives in the food industry. How-
ever, caramelization is not always a desirable reaction because
of the possible formation of mutagenic compounds (Tomasik
et al. 1989) and the excessive changes in the sensory attributes
that could affect the quality of certain foods.
More recently, Kitts et al. (2006) also observed the clastogenic
activity of caramelized sucrose, this property being mainly due
to the volatile and nonvolatile compounds of LMW derived from
sucrose caramelization.
Caramelization is catalyzed under acidic or alkaline condi-
tions (Namiki 1988) and many of the products formed are similar
to those resulting from the Maillard reaction.
Caramelization of carbohydrates starts with the opening of
the hemiacetal ring followed by enolization, which proceeds via
acid- and base-catalyzed mechanisms, leading to the formation
of isomeric carbohydrates (Figure 4.8). The interconversion of
sugars through their enediols increases with increasing pH and
is called the Lobry de Bruyn-Alberda van Ekenstein transforma-
tion (Kroh 1994). In acid media, low amounts of isomeric car-
bohydrates are formed; however, dehydration is favored, leading
to furaldehyde compounds: 5-(hydroxymethyl)-2-furaldehyde
(HMF) from hexoses (Figure 4.9) and 2-furaldehyde from pen-
toses. With unbuffered acids as catalysts, higher yields of HMF
are produced from fructose than from glucose. Also, only the
fructose moiety of sucrose is largely converted to HMF un-
der unbuffered conditions, which produce the highest yields.
The enolization of glucose can be greatly increased in buffered
acidic solutions. Thus, higher yields of HMF are produced fromHCO
HC
(CHOH) 3 (CHOH) 3 (CHOH) 3
CH 2 OH CH 2 OH CH 2 OHAldose 1,2-Enodiol KetoseOHHCOH CH 2 OH
C OH COFigure 4.8.The Lobry de Bruyn-Alberda van Ekenstein
transformation.