Proteins as clean label ingredients in foods and beverages - Natural Food Additives, Ingredients and Flavourings - page 196

animal sources. They have been consumed for millennia and regarded as safe and
do not need to be identifi ed by an E number on the label of the food or beverage
(though there is one exception, gelatin has an E number: E441). Despite this
positive aspect, proteins have some points that have to be taken into consideration:

1 Allergenicity.
2 The presence of possible anti-nutritional components.
3 Source-related issues such as those around animal protein and those associated
with soy and corn proteins (due to genetic modifi cation of these crops).

The fi rst two topics, allergenicity and anti-nutritional factors, are considered in
more detail below.
In general, there is the risk that every protein could be allergenic, i.e. capable
of causing an allergic reaction. This relates to the digestibility of proteins in the
stomach of infants and the immaturity of their gastrointestinal mucosal barrier.
Under conditions that prevail in the stomach of infants (pH > 4), the degradation
of proteins is less effi cient than under conditions present in the stomach of adults
(pH 2). As a result, immunoreactive epitopes (part of an antigen that is recognized
by the immune system) of proteins are not completely eliminated (Schmidt et al.
1995; Alting et al. 1997). This may lead to an increased risk of developing
immunological responses, since the immature gastrointestinal mucosal barrier of
infants will allow the passage of antigenic fragments into the systemic circulation
(Matthews 1991; Kuitunen et al. 1994). Therefore, although differences in
allergenicity exist between food proteins, allergenicity is also related to other
factors such as the history of food intake (e.g. breast fed) and digestibility
(elimination of immunoreactive epitopes). Legislation requires that proteins
identifi ed as bearing a higher risk factor for developing or causing allergic
reactions (see, for example, http://foodallergens.ifr.ac.uk/search.lasso or http://
fermi.utmb.edu/SDAP/sdap_ver.html) are labeled as such.
Protein preparations applied as food ingredients never consist solely of protein.
Depending on the source and the extraction process, the protein ingredient will
contain other components. In addition to carbohydrates and salts, these components
can also be anti-nutritional factors. The latter are components which, when
present in human or animal foods, affect the absorption of nutrients and may
reduce growth. Pulses are especially known for their content of anti-nutritional
factors.
Examples of anti-nutritional factors are phytate, protease inhibitors and
fl avonoids. Phytate can form insoluble complexes with calcium, zinc, iron and
copper, thereby affecting their absorption and causing defi ciency syndromes. The
presence of protease inhibitors, such as trypsin inhibitors, reduces the digestibility
of protein by affecting digestive proteases. Flavonoids are a group of polyphenolic
compounds which includes tannins. In addition to reported benefi cial effects,
these compounds can display multiple effects as chelating of iron and zinc ions
(reduced absorption), and inhibition of digestive enzymes by complexing and by
precipitation of proteins. Current production processes for protein ingredients aim
to eliminate the presence of anti-nutritional factors in the fi nal product.

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