Chemistry Reference
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diacylglycerols (DAG) produced from sunflower oil or rapeseed oil. The interest
in DAG is due to the finding that DAG has been able to reduce body fat mass in
animals (Kristensen et al. 2006). Moreover, a DAG cooking oil has won large
market shares in Japan (Kristensen et al. 2006). Butter blends with sunflower oil
or DAG made from sunflower oil had a lower oxidative stability and more
rancid odour and flavour than butter blends made with rapeseed oil or DAG
produced from rapeseed oil. This was expected since sunflower oil has a higher
content of polyunsaturated fatty acids than rapeseed oil. For the sunflower oil
butter blends the DAG version tended to be more rancid throughout the storage
period, whereas no difference was observed between the butter blends made
with rapeseed oil or DAG produced from rapeseed oil (Fig. 6.2). Interestingly,
the biggest difference between the butter blends made with DAG or the
traditional oils was that the DAG butter blends had a significantly lower
intensity of butter and salty flavours (Fig. 6.2). This was despite the fact that all
four butter blends had the same salt content. However, the difference in butter
aroma between the butter blends with DAG and the traditional oils was much
less pronounced. Dynamic headspace analysis of the volatiles in the butter blend
showed significantly higher levels of 2,3-butanedione (diacetyl) in the blends
with the traditional oils than in the blends with DAG. 2,3-butanedione is one of
the most important compounds in butter flavour (Lund and Hùlmer 2001).
Moreover, butyric acid has been suggested to play a very important role for the
butter odour, but this compound was found in similar concentrations in all four
butter blends. Hence, differences and similarities in the intensities of butter
odour and flavour in the four butter blends could at least partly be explained by
their contents of these two volatile compounds. The physical structure of the
butter blends was evaluated by droplet size measurements and microscopy. Both
analyses clearly showed that the DAG butter blends had smaller droplet sizes
indicating a high physical stability of the droplets. A good flavour release is
obtained when the water-in-oil emulsion is broken down easily in the mouth.
Hence, the perception of saltiness is influenced by the stability of the emulsion.
The smaller droplet size and higher stability of the DAG butter blends was
therefore suggested to be responsible for their less intense salty flavor
(Kristensen et al. 2006). The small droplet size of the DAG butter blends was
suggested to be due to the emulsifying properties of DAG and also to the low
levels of monoacylglycerides present in the DAG oil. It is interesting to note that
physical structure of the butter blends mainly seemed to influence the saltiness
and to a lesser extent rancid aroma and flavour. At least the physical structure
was not able to prevent the perception of the DAG sunflower oil blend as being
the most rancid.
Several studies have also been carried out on the enrichment of milk with
omega-3 fatty acids (Let et al. 2003; 2005; Venkateshwarlu et al. 2004b). Lipid
oxidation gave not only rise to an intense fishy off-flavour, but also to a strong
metallic off-flavour. These off-flavours were found even when fish oil of a
relatively good quality was used. Thus, even when a fish oil with a PV of 1meq/
kg was used a sensory panel could clearly distinguish the fish oil enriched milk
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