Biomedical Engineering Reference
In-Depth Information
This results in fi rm and discrete pieces of fruit for application in products
like yoghurt (Degraeve et al. 2003). Future applications for specifi c and
purifi ed pectin degrading enzymes may be directed towards production
of pectic oligosaccharides.
Lactases
One of the few carbohydrate molecules present in food from animal
origin is lactose in milk. As the majority of the world population is
not able to digest lactose and milk is an important food component in
providing protein, calcium and vitamins in the human diet, an enzyme
to pre-hydrolyse the lactose in milk of commercial interest (reviewed by
Dekker and Daamen 2011). In milk pre-hydrolysis mainly the lactase of
Kluyveromyces
species is applied. Fungal (acid) lactase, originating from
A. oryzae
or
A. niger
is available as dietary supplement when lactose
containing products are consumed by lactose intolerant people. Fungal
lactase can also be applied in yoghurt and in whey processing, e.g., to
produce sweetener for soft drinks from concentrated whey, as hydrolysed
lactose has a higher sweetness than lactose syrup as such.
The use of lactase in production of galacto-oligosaccharides, which have
a prebiotic effect, is an alternative application of this enzyme. In this case
it is not hydrolysis, but synthesis, resulting from the transferase activity
of the enzyme. The synthesis of oligosaccharides using lactose and lactase
is highly dependent on the type of enzyme, the concentration of lactose
and temperature of the reaction. Further development of hydrolysed
whey applications may open up more opportunities for lactases in food
application. A fi eld currently being explored is the use of immobilized cold-
active lactase, which will allow processing of milk and whey below 5°C, as
well as immobilized thermostable lactases, which will make the processing
less prone to microbial contamination (Panesar et al. 2006).
Further development of enzymes for new applications, such as
oligosaccharide production and coffee processing is of interest. New or
improved enzymes may be derived from screening biodiversity, but also
by means of adaptation of existing enzymes using directed evolution or
protein engineering techniques.
Lipases
Lipids can be divided in
apolar
and polar lipids. The former are the
triacylglycerol lipids and the latter consist of phospholipids and
galactolipids, which contain a polar group, consisting of phosphate or
galactose linked to a hydroxyl of glycerol, whereas fatty acids are linked
to the other two hydroxyl groups.
