Food Biochemistry and Food Processing

24 Nonenzymatic Browning of Cookies, Crackers, and Cereals 561

processing of cookies, crackers, and breakfast cere-
als. Maltulose (Fig. 24.2), an epimerization product
of maltose, has been found in the crust of bread
(Westerlund et al. 1989). Maltulose formation is
also observed during the heating of maltodextrin
solution at high temperatures (180°C) (Kroh et al.
1996). García Baños et al. (2000, 2002), detected
maltulose in commercial enteral products and pro-
posed the maltose:maltulose ratio as a heat treat-
ment and storage indicator of enteral formula.
In cookies, crackers, and breakfast cereals, Rada-
Mendoza et al. (2004) detected maltulose (from
traces to 842 mg/100 g) in all commercial samples
analyzed. Figure 24.3 shows the gas chromatograph-
ic profile of the oxime-trimethylsilyl derivatives of
mono- and disaccharide fractions of a cookie sam-
ple. Similar patterns were obtained for crackers and
breakfast cereals. The formation of maltulose de-
pends mainly on initial maltose content, pH, and the
heat treatment intensity of the processes. Since
cookies, crackers, and breakfast cereal samples may
contain variable amounts of maltose, the usefulness
of maltulose as an indicator of heat treatment may be
questionable. Previous studies on the formation of
maltulose during heating of enteral formula (García-
Baños et al. 2002) pointed out that values of the
maltose:maltulose ratio were similar in samples with
different maltose content submitted to the same heat
treatment. Therefore, the maltose:maltulose ratio is

an adequate parameter for comparing samples with

different initial maltose contents. Because maltose

isomerization increases with pH, differences in the

maltose:maltulose ratio can be due to different heat

processing conditions only in samples with a similar

pH. These results, shown by Rada-Mendoza et al.

(2004), seem to indicate that the maltose:maltulose

ratio can allow differentiation among commercial

cereal-based products and may serve as an indicator

of the heat load during its manufacture.

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Figure 24.3.Gas chromatographic profile of the oxime-trimethylsilyl derivatives of fructose (1,2), glucose (3,4),

sucrose (6), lactulose (8), lactose (9,10), maltulose (11,12), and maltose (13,14) of a cookie sample. Peaks 5 and 7

were the internal standards myo-inositol and trehalose, respectively. (Taken from Rada-Mendoza et al. 2004 with per-

mission from Elsevier.)