Chemistry Reference
In-Depth Information
Reducing sugar +
α
-Amino acids
-H
2
O
N
-substituted glycosylamines or
N
-substituted fructosylamines
Amadori rearrangement
Hydroxymethyl-5-furfural
(from hexoses)
-3H
2
O
1-Amino-1-deoxy-2-ketose or 1-Amino-2-deoxy-2-aldoses
Amadori and Heyns intermediates
&
Furfural
(from pentoses)
Strecker degradation
Reductones and Dehydroreductones
Amino acids
NH
3
H
2
S
Retro-aldolization
Hydroxyacetone
Cyclotene
Dihydroxyacetone
Hydroxyacetyl
Glyoxal
Pyruvaldehyde
Glycolaldehyde
Glyceraldehyde
Aldehydes +
α
-amino ketones
Methional from MET
H
2
S and NH
3
from CYS
Acetoin
3-Furanone
4-Pyranones
Pyrroles
Thiophenes
Heterocyclization
Pyridines
Thiazoles
Pyrazines
Pyrroles
Oxazoles
Imidazoles
Figure 14.3.
Formation of aroma compounds via Maillard reaction/non-enzymatic browning
(modified from Singh et al., 2007).
Microfiltration (MF) using cross-flow membrane separation has shown
promising results in eliminating bacteria from milk and increasing shelf-life
without the development of off-flavours (Elwell and Barbano, 2006; Rysstar
and Kolstad, 2006).
High hydrostatic pressure processing (HPP), a new technology to the
food industry (Torres and Velazquez, 2004), can destroy microorganisms by
high hydrostatic pressure without heat (Berlin et al., 1999; Velazquez et al.,
2002). This technology has been gaining commercial acceptance in the man-
ufacture of food products with 'fresh' flavour that are not possible with other
preservation technologies. To retain the 'fresh' milk flavour, HPP has been
studied as a potential alternative to the pasteurization of milk. A microbio-
logical reduction and significant extension in the shelf-life of milk compared
to that of pasteurized milk has been achieved using pressure treatments. HPP
can reduce the size of casein micelles in milk at pressures above 230 MPa,
resulting in a decrease in whiteness and turbidity and an increase in the
viscosity of milk (Buchheim and El-Nour, 1996). High pressure can also
affect the crystallization properties of milk fat. It is generally assumed that
