Chemistry Reference
In-Depth Information
Maillard reaction products have been shown to increase the intestinal
absorption and urinary excretion of calcium and magnesium (O'Brien and
Morrissey, 1989), which resemble the action of poorly digestible carbohy-
drates, such as lactose and polyols. However, while calcium absorption has
been shown to be higher in a bottle-sterilized liquid infant formula, calcium
retention was significantly lower in a study on suckling rats (Sarri´ et al.,
2001). Casein subjected to a Maillard reaction with reducing sugars impairs
the uptake of zinc by Caco-2 cells in culture, suggesting a reduction in
bioavailability compared with untreated casein (Seiquer et al., 2000). By
contrast, Sarri´ and Vaquero (2006) reported higher percentage copper
absorption and erythrocyte copper concentrations despite lower food intake
and body weight in in-bottle-sterilized formula compared with a reconsti-
tuted powder formula.
Dietary Maillard reaction products of a glucose-glutamate system have
been reported to reduce zinc retention in rats as a result of increases in both
faecal and urinary zinc losses (O'Brien and Morrissey, 1989). Furniss et al.
(1989) reported a large increase in urinary zinc in rats fed a heated case-
in-glucose mixture. Urinary zinc was also increased in animals fed a reacted
casein-lactose mixture, although the effect was not as pronounced as for the
casein-glucose system. However, there were no changes in faecal zinc or in
zinc retention and the authors concluded that an increased loss of urinary zinc
would have little significance for individuals consuming a diet adequate in
zinc.
7.8.2.
Milk Protein Allergy
There is an increasing volume of scientific literature on the influence of
processing, in particular thermal processing, on food protein allergy (Davis
et al., 2001). This research has been driven by increased awareness and better
risk management of food allergens. However, an additional consideration has
been to ensure that novel foods and processes do not increase allergenic risk
for sensitized consumers. It was long known that the allergenicity of
-lactoglobulin could be enhanced by the Maillard reaction. Matsuda et al.
(1985b) found higher antibody titres in mice immunized with a
-lactoglobu-
lin-lactose adduct than animals injected with native
-lactoglobulin. The
increased allergenicity of lactosylated
-lactoglobulin was demonstrated by
Bleumink and Berrens (1996). Matsuda et al. (1990) reported that the lactose-
ovalbumin adduct induced a stronger antibody response when injected into
mice than the adducts of other sugars (glucose, galactose, melibiose, maltose
or cellobiose). The authors suggested that the immunodominancy of the
lactose adduct was due to some feature of its stereochemical configuration.
The effect of Maillard reactions on the epitopes of native proteins was
