Chemistry Reference
In-Depth Information
et al., 1993). Heat sterilization is a common step in food manufacture.
Lactulose is stable and little decomposed when heated to 1308C for 10 min
at low pH. This relatively high stability makes it a suitable ingredient for
normal food processing.
5.7.3.
Properties of Lactosucrose
Lactosucrose is very soluble in water (up to 3670 g/L at 258C). It has
a sweetness relative to sucrose of 0.3. It is stable for 1 h at pH 4.5 and 1208C.
It is most stable at neutral pH and remains fairly stable at pH 3 at 808C.
As a powder, it has a high moisture-retaining capacity and is highly
hygroscopic.
Lactosucrose acts as a prebiotic carbohydrate and is not readily
digested by intestinal enzymes in the stomach and small intestine. It is
selectively fermented by Bifidobacterium in the human colon.
5.7.4.
Properties of Lactitol
Lactitol is an odourless, colourless, sweet, non-hygroscopic and stable
sugar alcohol. As it lacks a reactive carbonyl group, which is characteristic of
sugar molecules, it does not participate in Maillard browning reactions with
amino groups. It occurs in both monhydrate and dihydrate crystalline forms
as pure products with good flowability. Lactitol is stable under both alkaline
and acid conditions and at high temperatures likely to be encountered during
food processing. Its melting point is 1468C and it is very soluble in water. The
sweetening power of lactitol is about 40% of sucrose and the calorific con-
tribution of lactitol after it is metabolized by colonic bacteria is less than
2.4 cal g
-1
(10 kJ) compared to 4.0 cal g
-1
(17 kJ) for sucrose.
Lactitol is not hydrolysed or absorbed in the small intestine and passes
through to the colon. Lactitol also acts as a prebiotic carbohydrate and
enhances the growth of certain groups of bacteria (e.g., bifidobacteria) in
the colon.
5.7.5.
Properties of Lactobionic Acid
Lactobionic acid is best described as a natural polyol acid with a formula
weight of 358.30 Da and a pK
a
of 3.8. It is soluble in water as a free acid or as a
salt. The molecule possesses multifunctional groups and thus acts as a metal ion
chelator and can sequester calcium (Abbadi et al., 1999). Lactobionic acid
inhibits the production of hydroxyl radicals as a result of its iron-chelating
capacity and it functions as an antioxidant in tissues. It has a sweet taste despite
being a weak acid. Lactobionic acid can be dehydrated to a lactone.
