Chemistry Reference
In-Depth Information
mechanisms outlined below (see Table 14.9 for possible causative chemicals/
mechanisms involved):
Off-flavour transferred to milk during lactation
Feed off-flavours (e.g., from green forages, silage, etc., consumed
by the animal a few hour before milking)
Weed off-flavour (e.g., volatiles formed from certain weeds during
digestion)
Cowy flavours (related to ketosis and acetonemia in cattle resulting
in an increased concentration of acetone)
Stable off-flavours (e.g., transferred via the respiratory system from
stable/feed to cow)
Lipid oxidation—most widely implicated in the defects in milk and
milk products
Microbial action
Contamination (e.g., compounds from sanitizers)
Thermal abuse
Adsorption/permeation of aroma compounds with/through packa-
ging material
Some of the mechanisms of off-flavour development, in particular lipid
oxidation and microbial metabolites, have also been responsible for the
development of a whole variety of off-flavours in milk and milk products
(Table 14.9). Specific flavours like nutty or brothy flavours were also char-
acterized in Cheddar cheese (Table 14.9), which may or may not be consid-
ered as an off-flavour depending on the consumer preference.
14.5.
Taste Compounds in Milk and Milk Products
Research on taste compounds in dairy products is fairly limited but there
seems to be an increasing interest in this area in recent years. In food systems
such as milk and milk products, study of taste compounds in isolation or in
matrices devoid of contribution from volatile aroma compounds is difficult
due to complex nature, in terms of both number of food constituents and their
competing/synergistic effects on taste and/or aroma. Compounds which con-
tribute to the taste of milk and milk products can originate from three
possible sources:
(1) Naturally found in milk, e.g., lactose
(2) Added/produced during the manufacturing process (e.g., NaCl, lactic acid)
(3) Produced by many biochemical reactions occurring during fermentation.
