Chemistry Reference
In-Depth Information
Non-thermal treatments
High pressure treatment,
Pulsed electric field and membrane processing
Production/Processing
Unit Operations
MILK
Storage
Homogenization
Thermal Processing
Pasteurization
UHT
Concentration/evaporation
Drying
Separation
Centrifuge
Membrane-UF, MF
Fermentation
Lactic acid bacteria
Mould
Primary aroma
Secondary/
process-induced aroma
Figure 14.1.
Main sources of aroma components in dairy products.
parameters, i.e., heat treatment, pH, water activity, salt concentration and
ripening temperature, necessary for the right balance of biochemical changes
are set during manufacturing (Figure 14.1). In case of deviation of any of
these parameters, cheeses or other dairy products could potentially develop
texture and/or flavour inconsistencies or defects. The degradation of milk
constituents during the manufacture of dairy products involves a concerted
series of chemical and biochemical reactions. Reactions and/or pathways
involved in the production milk and milk products can be sub-divided into
three major categories:
(1) Lipid oxidation
(2) Process-induced changes
a. Heat-induced changes
b. Changes induced by non-thermal processing technologies
(3) Fermentation by lactic acid bacteria and other cultures.
14.2.1.
Lipid Oxidation
Auto-oxidation of fat in milk and milk products occurs initially in the
polyunsaturated phospholipids fraction of the milk fat globule membrane,
followed by the main triacylglycerol fraction. It has been reported that
different milks vary widely in susceptibility to oxidation. The oxidative
