520 Chapter 20
low birth weight (and even very low birth
weight) as well as other neonatal intensive
care unit (NICU) products. These are avail-
able in different caloric density and nutrient
distribution forms and a variety of conve-
nient packages. These product innovations
have enabled better outcomes for infants in
the NICU environment. The metabolic disor-
der formulas include those for inborn errors
of amino acid metabolism, which deserve
special mention because of the unique protein
source, free purifi ed amino acids. Their use
also presents some limitations on acceptable
carbohydrate sources, because high reduc-
ing sugar content can result in signifi cant
Maillard browning. These reactions can gen-
erate product acceptability issues (fl avor,
color, and odor) as well as potential clinical
impacts. Such considerations also affect for-
mulas with heavily hydrolyzed protein sys-
tems, which have similar reactivity. Finally,
free amino acids are absorbed by the body
in a different fashion than peptides, which
increases the total protein requirements for
optimal growth. Thus, a completely free
amino acid (or elemental) formula is only
used when physiologically demanded.Comments on Manufacturing
Commercial infant formulas are primarily
available as ready - to - feed or concentrated
liquids and powders (Figure 20.2 ). Manufac-
turing of infant formulas is based on either
complete integral processes or a base mix
preparation, consisting of main components
combined with a blending operation to spe-
cialize the recipes for target groups. The
manufacturing process typically consists of
reconstitution of ingredients (such as milk
or milk solids, and whey protein materials,
lactose or maltodextrins, corn syrup or other
carbohydrate sources, minerals, lipids and
fats, emulsifi ers and stabilizers, and vitamins
and trace nutrients) in a specifi c sequence to
enable heat and shelf stability, followed byCombinations of vegetable and tropical
oils have been used to approximate breast
milk fat. Butter fat (relatively high in satu-
rated fat and cholesterol) is not a good
approximation of the lipids in breast milk;
they are high in shorter chain unsaturated fats
and essential oils, with moderate levels of
cholesterol and saturated fats. Research con-
tinues into the potential physiological bene-
fi ts of the phospholipids in bovine milk fat.
Interesterifi cation of oils allows for the more
appropriate placement of the palmitic fatty
acid on the C - 2 position, which has substan-
tial impact on digestion and absorption
routes. More recently, long - chain polyunsat-
urated fatty acids (docosahexaenoic acid and
arachadonic acid) are routinely added to
infant formulas, because studies indicate a
positive effect on brain development as well
as other health benefi ts.
Probiotics are defi ned by the Food and
Agricultural Organization (FAO) and the
World Health Organization (WHO) as “ Live
microorganisms, which when administered
in adequate amounts, confer a health benefi t
on the host, ” and their use is gaining great
interest. Milk and whey proteins offer good
encapsulation properties that could allow for
delayed release of these probiotics. Further
work is in progress to develop encapsulation
technologies to allow introduction of live
microorganisms into ready - to - use liquid for-
mulations. Alternatively, interesting packag-
ing developments allow mixing of the
probiotics with the liquid nutritional product
at use, but this currently adds signifi cantly to
packaging costs. Introduction of these live
bacteria into liquid formulas is still very tech-
nically challenging, but can be achieved via
dry blending into powder products. Develop-
ment of technologies in the near future is
anticipated, which would allow use even in
liquids.
Major infant formula manufacturers offer
products for infants with various metabolic
disorders such as signifi cant prematurity and