Proteins as clean label ingredients in foods and beverages - Natural Food Additives, Ingredients and Flavourings - page 205

crucial role. The most active peptide obtained from lactoferrin is lactoferricin,
which displays an activity 40 times higher than that of lactoferrin. Despite this
higher activity, the estimated cost in use of this specifi c hydrolysate is the major
drawback for its application as a natural or clean label preservative.
Two strategies can be applied to reduce the cost in use of antimicrobial peptides.
The fi rst is to select cheap protein sources as the raw material for hydrolysis. The
sequences of several food proteins, including caseins, are known to comprise
cationic sequences that can be liberated upon hydrolysis. A common feature of
known antimicrobial peptides is their cationic character, which will facilitate their
extraction and purifi cation with commonly applied separation techniques. Hence,
starting from protein-rich by-products, such as rice bran, canola protein and so on,
will allow the development of commercial attractive antimicrobial peptides. The
second approach is found in the synergistic interaction between antimicrobial
peptides/proteins and natural antimicrobial compounds, such as those found in
essential oils extracted from herbs, including cinnamon (cinnamaldehyde), clove
(eugenol) and thyme (thymol). This synergistic interaction results from the
different modes of action of the two classes of ingredients. For example both
lactoferrin and thymol show an antimicrobial activity against Escherichia coli
(Fig. 9.4). The combination of both showed an enormous synergistic effect with
almost complete inhibition of the growth of this bacterium (Lambers 2010). Thus,
the synergistic interaction between different classes of natural antimicrobial
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Fig. 9.4 Synergistic interaction of the protein lactoferrin with the natural compound
thymol in their action against E. coli . Copyright NIZO, 2012.