BLBS102-c30 BLBS102-Simpson March 21, 2012 13:56 Trim: 276mm X 219mm Printer Name: Yet to Come
30 Non-Enzymatic Browning in Cookies, Crackers and Breakfast Cereals 587considered a reliable marker of the extent of the thermal treat-
ment for comparison of different products or processing plants.
In these cases, the measure of lysine availability is a better index
of protein quality.
Similarly, the variable amounts of dried milk used in manu-
facture of cereal-based products and the different levels of free
GABA in unprocessed cereals appear to be the major drawback
for the use of furosine and 2-FM-GABA as suitable indicators to
differentiate between commercial cereal-based products. How-
ever, in the cereal industry, where exact composition is known,
measurement of 2-FM-GABA and furosine formed might be
used as indicators to monitor processing conditions during the
manufacture of cereal products.
Finally, the effect of the addition of common bean flour (15%
and 30%) to semolina on furosine content, total phenolics and
other parameters related to quality evaluation (moisture, optimal
cooking time, cooking loss, water absorption capacity, colour
and firmness) was determined by Gallegos-Infante et al. (2010)
in spaghetti pasta obtained at different temperatures (60–80◦C).
Although an increase in furosine and phenolic contents was
observed in pasta fortified with bean flour and dried at high
temperature, further research is necessary to elucidate the actual
phenolic content and the antioxidant capacity related to the MR
products or polyphenols.Hydroxymethylfurfural and FurfuralHydroxymethylfurfural (HMF) and furfural are intermediate
products in the MR, originated from the degradation in acid
solution of hexoses and pentoses, respectively (Hodge 1953,
Kroh 1994).
HMF is a classic indicator of browning in several foods such
as milk (van Boekel and Zia-Ur-Rehman 1987, Morales et al.
1997), juices (Lee and Nagy 1988) and honey (Jeuring and
Kuppers 1980, Sanz et al. 2003). HMF has also been detected in
several cereal-based foods, including dried pasta (Acquistucci
and Bassotti 1992, Resmini et al. 1993), baby cereals (Guerra-
Hern ́andez et al. 1992, Fern ́andez-Artigas et al. 1999b), cookies
(Ait-Ameur et al. 2006) and bread (Ram ́ırez-Jim ́enez et al. 2000,
Cardenas-Ruiz et al. 2004). ́
In a study on the effect of various sugars on the quality of
baked cookies, furfural (in cookies elaborated with pentoses)
and HMF (in cookies elaborated with hexoses) were detected
(Nishibori and Kawakishi 1992). HMF has also been found
in model systems of cookies baked at 150◦C for 10 minutes
(Nishibori and Kawakishi 1995, Nishibori et al. 1998).
Garc ́ıa-Villanova et al. (1993) proposed the determination of
HMF to control the heating procedure in breakfast cereals as
well as in other cereal derivatives. Birlouez-Aragon et al. (2001)
detected HMF in commercial samples of breakfast cereals (corn-
flakes), in samples before and after processing using traditional
cooking and roasting, and in a model system of wheat, oats and
rice with two levels of sugars submitted to extrusion. Although
only traces of HMF were detected in the raw material, HMF
formation during extrusion increased proportionally as sugar
concentration increased. Among all the analysed samples, the
highest content of HMF was found in commercial samples.The effect of recipe composition in terms of leavening agent
(ammonium and sodium bicarbonates) and sugars (sucrose and
glucose), and baking conditions (temperature and time) on HMF
formation in cookies has been recently studied by Gokmen et al. ̈
(2008b). The type of leavening agent, affecting both pH of for-
mulation and degradation of sugars, appeared as one of the most
important parameters from the viewpoint of HMF formation.
Water activity, which has also been reported to be highly influ-
ential on HMF formation, must reach levels lower than 0.4 for
allowing a significant formation of this indicator in commercial
cookies (Ait-Ameur et al. 2006).
Together with HMF and furfural, glucosylisomaltol (GIM, an
intermediate product of the MR that is generated principally
from the reaction between maltose and glutamine) has been de-
termined by HPLC as a control index of the MR development in
breakfast cereals (Rufian-Henares et al. 2006a), with the advan- ́
tage over HMF that the MR, and not the addition of thermally
damaged ingredients, is the sole pathway of formation of GIM.
Recently, Rufian-Henares and Delgado-Andrade (2009) stud- ́
ied the effect of digestive process on the bioaccessibility of
furosine and HMF and on the antioxidant activity of corn-
based breakfast cereals. Digestion allowed liberation of HMF
and Amadori products (furosine) and increased the solubility of
antioxidant compounds.ColourColour is an important characteristic of cereal-based foods and,
together with texture and aroma, contributes to consumer pref-
erence. Colour is another indication of the extent of MR and
caramelisation. The kinetic parameters of these reactions are
extremely complex for cereal products. As a consequence, the
colouring reaction is always studied globally, without taking into
account individual reaction mechanisms (Chevallier et al. 2002).
Colour depends both on the physico-chemical characteristics of
the raw dough (water content, pH, reducing sugars and amino
acid content) and on the operating conditions during processing
(Zanoni et al. 1995, Gokmen et al. 2008b). ̈
Brown pigments (melanoidins) formation occurs at the ad-
vanced stages of browning reactions and, although is undesir-
able in milk, fruit juices and tomatoes, among other foods (De
Man 1980), it is desirable during the manufacture of cookies,
crackers and breakfast cereals. Colour development has been
studied in cereal-based foods such as baby cereals (Fern ́andez-
Artigas et al. 1999b), bread (Ram ́ırez-Jimenez et al. 2001), cook- ́
ies (Kane et al. 2003, Gokmen et al. 2008b), breakfast cereals ̈
(Rufi ́an-Henares et al. 2006b, Moreau et al. 2009) and gluten-
free biscuits (Schober et al. 2003).
The formation of melanoidins and other products of the MR
darkens a food, but a darker colour is not always attributed to
the presence of these compounds, since the initial composition
of the mixture can also afford colour. In a study on the protein
nutritional value of extrusion-cooked wheat flours, Bjorck et al.
(1984) determined the colour of the extruded material and found
a correlation between the reflectance values and total lysine
content of extruded wheat. As the reflectance of the raw flours