Chemistry Reference
In-Depth Information
good flavour quality has a bland but characteristic flavour (Badings, 1991).
Products made from this basic raw material vary in flavour from mild/weak
(e.g., yoghurt, Mozzarella cheese) to intensely flavoured (e.g., Blue cheeses,
hard Italian cheeses). For dairy products, three elements comprise the overall
sensory experience:
(1) The mouthfeel from the constituents of the milk, especially milk fat and
proteins which are essential for viscosity and/or texture
(2) Taste components, e.g., slight sweet/salty taste from lactose, milk salts and
added salt (NaCl) to bitterness in cheese caused by peptides
(3) Aroma
caused
by
a
proper
balance
of
numerous
volatile
organic
compounds
In the past, the stability of milk and milk products was the primary
consideration but is no longer the principal objective due to the evolution of
modern sanitary practices, as well as pasteurization. Today, the manufacture of
dairy products of consistently good flavour and texture is crucial. In early flavour
studies, researchers identified hundreds of volatile compounds, with little or no
attention paid to their sensory contribution to the overall flavour of the products.
The availability of powerful chromatographic separation techniques, like high-
resolution capillary gas chromatography in combinationwithmassspectrometry
and olfactory detection techniques (use of olfactory detection ports), has revo-
lutionized work on the characterization of flavour compounds. Advances in
instrumental/chemical analysis have paralleled the developments in sensory
methods for the analysis of flavour compounds. Recently, published reviews
by Parliment and McGorrin (2000), McGorrin (2001), Singh et al. (2003a, 2007),
Cadwallader (2007) and Drake et al. (2007a) described various sensory-directed
analytical flavour techniques used in the evaluation of key aroma compounds in
milk and dairy products. A recently published text, 'Sensory-Directed Flavour
Analysis' edited by Marsili (2007a), is highly recommended to readers who may
be interested in more details on flavour analysis techniques.
This chapter presents a discussion on the aroma/taste compounds in
various dairy products and reactions involved with their production.
Mechanisms involved in the production of odorants responsible for the
specific flavour notes and off-flavours in dairy products are also discussed.
14.2.
Reactions Involved in the Formation of Flavour
Compounds in Milk and Milk Products
The volatile flavour and taste compounds in milk products originate from the
degradation of the major milk constituents, namely lactose, citrate, milk
lipids and milk proteins (particularly the caseins). The physico-chemical
