BLBS102-c04 BLBS102-Simpson March 21, 2012 11:59 Trim: 276mm X 219mm Printer Name: Yet to Come
66 Part 1: Principles/Food Analysis1995). The effect ofaw(0.33, 0.43, 0.52, 0.69, 0.85, and 0.98)
on the rate of loss of lysine by mild heat treatment or during
storage of milk powder was only significant at highawvalues
(Pereyra-Gonzales et al. 2010).
Because of the complex composition of foods, it is unlikely
that Maillard reaction involves only single compound (mono- or
disaccharides and amino acids). For this reason, several studies
on factors (pH, T,aw) that influence the Maillard reaction devel-
opment have been carried out using more complex model sys-
tems: heated starch–glucose–lysine systems (Bates et al. 1998),
milk resembling model systems (lactose or glucose–caseinate
systems) (Morales and van Boekel 1998), and lactose–casein
model system (Malec et al. 2002, Jim ́enez-Castano et al. 2005). ̃
Brands and van Boekel (2001) studied the Maillard reaction
using heated monosaccharide (glucose, galactose, fructose, and
tagatose)–casein model systems in order to quantify and iden-
tify the main reaction products and to establish the reaction
pathways.
Studies on mechanisms of degradation, via the Maillard reac-
tion, of oligosaccharides in a model system with glycine were
performed by Hollnagel and Kroh (2000, 2002). The reactivity
of di- and trisaccharides under quasi water-free conditions de-
creased in comparison to that of glucose due to the increasing
degree of polymerization.Study of Maillard Reaction in FoodsDuring food processing, the Maillard reaction produces desir-
able and undesirable effects. Processing such as baking, frying,
and roasting are based on the Maillard reaction for flavor, aroma,
and color formation (Lingnert 1990). Maillard browning may be
desirable during manufacture of meat, coffee, tea, chocolate,
nuts, potato chips, crackers, and beer and in toasting and baking
bread (Weenen 1998, Burdulu and Karadeniz 2003). In other pro-
cesses such as pasteurization, sterilization, drying, and storage,
the Maillard reaction often causes detrimental nutritional (ly-
sine damage) and organoleptic changes (Lingnert 1990). Avail-
able lysine determination methods has been used to assess the
Maillard reaction extension in different types of foods: breads,
breakfast cereals, pasta, infant formula (Erbersdobler and Hupe
1991), dried milks (El and Kavas 1997), heated milks (Ferrer
et al. 2003), and infant cereals (Ram ́ırez-Jimenez et al. 2004).
Sensory changes in foods due to the Maillard reaction have
been studied in a wide range of foods, including honey (Gonzales
et al. 1999), apple juice concentrate (Burdulu and Karadeniz
2003), and white chocolate (Vercet 2003).
Other types of undesirable effects produced in processed foods
by the Maillard reaction may include the formation of mutagenic
and cancerogenic compounds (Lingnert 1990, Chevalier et al.
2001). Frying or grilling of meat and fish may generate low (ppb)
levels of mutagenic/carcinogenic heterocyclic amines via the
Maillard reaction. The formation of these compounds depends
on cooking temperature and time, cooking technique and equip-
ment, heat, mass transport, and/or chemical parameters. Tareke
et al. (2002) reported their findings on the carcinogen acry-
lamide in a range of cooked foods. Moderate levels of acrylamide
(5–50μg/kg) were measured in heated protein-rich foods, andhigher levels (150–4000μg/kg) were measured in carbohydrate-
rich food, such as potato, beet root, certain heated commercial
potato products, and crisp bread. Ahn et al. (2002) tested dif-
ferent types of commercial foods and some foods heated under
home cooking conditions, and they observed that acrylamide
was absent in raw or boiled foods, but it was present at signifi-
cant levels in fried, grilled, baked, and toasted foods. Although
the mechanism of acrylamide formation in heated foods is not
yet clear, several authors have put forth the hypothesis that the
reaction of asparagine (Figure 4.5), a major amino acid of pota-
toes and cereals, with reducing sugars (glucose, fructose) via
the Maillard reaction, at temperatures above 120◦C, could be
the pathway (Mottram et al. 2002, Weiβhaar and Gutsche 2002,
Friedman 2003, Yaylayan and Stadler 2005). Other amino acids
have also been found to produce low amounts of acrylamide,
including alanine, arginine, aspartic acid, cysteine, glutamine,
threonine, valine, and methionine (Stadler et al. 2002, Tateo et al.
2007). Over the years, much work have been done to study the
factor influencing the acrylamide formation during processing
(Granda and Moreira 2005, Gokmen and Senyuva 2006, Tateo ̈
et al. 2007, Burch et al. 2008, Jom et al. 2008, Carrieri et al.
2010), the mechanism of acrylamide formation (Elmore et al.
2005, Hamlet et al. 2008, Zamora et al. 2010), the development
of robust and sensitive analytical methods that provide reliable
data in the different food categories (Zhang et al. 2005, Kaplan
et al. 2009, Preston et al. 2009), and the content in different
processed foods (Bermudo et al. 2006, Tateo et al. 2007, Burch
et al. 2008, EFSA 2010). On the basis of the large number of ex-
isting studies, the International Agency for Research on Cancer
(IARC 1994) has classified acrylamide as “probably carcino-
genic” to humans. Currently, researchers are looking around for
other strategies to obtain finished foods without acrylamide. In
this sense, Anese et al. (2010) have proposed the possibility to
remove acrylamide from foods by exploiting its chemical and
physical properties. Thus, processed foods were subjected to
vacuum treatments at different combinations of pressure, tem-
perature, and time. Removal of acrylamide was achieved only in
samples previously hydrated atawvalues higher than 0.83, and
maximum removed amount was between 5 and 15 minutes of
vacuum treatment at 6.67 Pa and 60◦C.
Beneficial properties of Maillard products have also been de-
scribed. Resultant products of the reaction of different amino
acid and sugar model systems presented different properties:
antimutagenic (Yen and Tsai 1993); antimicrobial (Chevalier
et al. 2001, Rufi ́an-Henares and Morales 2007) and antioxidative
(Manzocco et al. 2001, Wagner et al. 2002, Rufi ́an-Henares and
Morales 2007). In foods, antioxidant properties of MRPs have
been found in honey (Antony et al. 2000) and in tomato purees
(Anese et al. 2002). Rufian-Henares and de la Cueva (2009) ́
found antimicrobial activity of coffee melanoidins against dif-
ferent pathogenic bacteria.
On the other hand, the Maillard reaction is one of the safest
and most efficient methods to generate new functional proteins
with great potential as novel ingredients. Miralles et al. (2007)
investigated the occurrence of the Maillard reaction between
β-lactoglobulin and a LMW chitosan. Under the studied condi-
tions, MRPs originated improved antibacterial activity against