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immunomodulatory (Nelson et al. 2007) and hypoglycemic activities (Nasri et al.
2015). These functions are related to biopeptides of 3–50 amino acid residues in
length, present in the protein hydrolysates. Therefore, they may be used as alternative to artificial drugs. Indeed, most food proteins contain bioactive peptides that are
inactive within the sequence of their parent proteins, and can be released by enzymatic hydrolysis, either during gastrointestinal digestion in the body by endogenous
proteases or during food processing or by proteolytic processes using appropriate
exogenous proteases (Clare and Swaisgood 2000).
Chemical Hydrolysis
Chemical hydrolysis is hydrolysis of peptide bonds with either acid or alkali solutions. However, chemical process is ecologically undesirable due to the involvement
of strong acids and bases. Further, products obtained by chemical hydrolysis have
less nutritional qualities and biological activities, since unwanted products could be
produced during nonspecific chemical treatment. In addition, acid hydrolysis treatment oxidizes cysteine and methionine, destroys some serine and threonine, and
may convert glutamine and asparagine to glutamate and aspartate, respectively
(Bucci and Unlu 2000). On the other hand, chemical hydrolysis cannot be controlled to obtain reproducible bioactive protein hydrolysates, since cleavage of peptide bonds by chemical reagents is not specific. Hence, high variations during
cleavage lead to high variations in bioactivity. These drawbacks significantly limit
the high-value applications of these protein hydrolysates. However, acid hydrolysis
is used in the production of flavor enhancers (Pasupuleti and Braun 2010).
Enzymatic Hydrolysis
Among the methods and according to the literature, in vitro hydrolysis of protein
substrates is the most widely used process for the production of protein hydrolysates by using appropriate exogenous proteolytic enzymes. These methods produce
peptides with desirable biological properties (Kristinsson and Rasco 2000).
However, enzymatic hydrolysis is a valuable approach to produce protein hydrolysates compared to chemical hydrolysis due to milder process conditions required
(pH 6.0–8.0; temperature 40–60 °C) and better control than enzymatic hydrolysis.
On the other hand, bioactivities of protein hydrolysates obtained by enzymatic process can be reproducible as compared to chemical hydrolysis. Furthermore, in contrast to chemical process, the overall amino acid composition of enzymatic protein
hydrolysates is nearly similar to that of the protein substrate, with slight modifications depending on the applied enzyme(s). Additionally, enzymatic digestion is suitable for the food and pharmaceutical industries due to non involvement of organic
solvents or toxic chemicals (Kim and Wijesekara 2010). A schematic representation
Advances in the Application of Food Proteins and Enzymes
immunomodulatory (Nelson et al. 2007) and hypoglycemic activities (Nasri et al.
2015). These functions are related to biopeptides of 3–50 amino acid residues in
length, present in the protein hydrolysates. Therefore, they may be used as alternative to artificial drugs. Indeed, most food proteins contain bioactive peptides that are
inactive within the sequence of their parent proteins, and can be released by enzymatic hydrolysis, either during gastrointestinal digestion in the body by endogenous
proteases or during food processing or by proteolytic processes using appropriate
exogenous proteases (Clare and Swaisgood 2000).
Chemical Hydrolysis
Chemical hydrolysis is hydrolysis of peptide bonds with either acid or alkali solutions. However, chemical process is ecologically undesirable due to the involvement
of strong acids and bases. Further, products obtained by chemical hydrolysis have
less nutritional qualities and biological activities, since unwanted products could be
produced during nonspecific chemical treatment. In addition, acid hydrolysis treatment oxidizes cysteine and methionine, destroys some serine and threonine, and
may convert glutamine and asparagine to glutamate and aspartate, respectively
(Bucci and Unlu 2000). On the other hand, chemical hydrolysis cannot be controlled to obtain reproducible bioactive protein hydrolysates, since cleavage of peptide bonds by chemical reagents is not specific. Hence, high variations during
cleavage lead to high variations in bioactivity. These drawbacks significantly limit
the high-value applications of these protein hydrolysates. However, acid hydrolysis
is used in the production of flavor enhancers (Pasupuleti and Braun 2010).
Enzymatic Hydrolysis
Among the methods and according to the literature, in vitro hydrolysis of protein
substrates is the most widely used process for the production of protein hydrolysates by using appropriate exogenous proteolytic enzymes. These methods produce
peptides with desirable biological properties (Kristinsson and Rasco 2000).
However, enzymatic hydrolysis is a valuable approach to produce protein hydrolysates compared to chemical hydrolysis due to milder process conditions required
(pH 6.0–8.0; temperature 40–60 °C) and better control than enzymatic hydrolysis.
On the other hand, bioactivities of protein hydrolysates obtained by enzymatic process can be reproducible as compared to chemical hydrolysis. Furthermore, in contrast to chemical process, the overall amino acid composition of enzymatic protein
hydrolysates is nearly similar to that of the protein substrate, with slight modifications depending on the applied enzyme(s). Additionally, enzymatic digestion is suitable for the food and pharmaceutical industries due to non involvement of organic
solvents or toxic chemicals (Kim and Wijesekara 2010). A schematic representation
Advances in the Application of Food Proteins and Enzymes