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    ABSTRACT: There are many examples of biologically active food proteins, with physiological significance beyond the pure nutritional requirements that concern available nitrogen for normal growth and maintenance. Moreover, there are many physiologically active peptides, derived by protease activity from various food protein sources; however, relationships between structural properties and functional activities have not been completely elucidated. Many bioactive peptides have in common structural properties that include a relatively short peptide residue length (e.g. 2-9 amino acids), possessing hydrophobic amino acid residues in addition to proline, lysine or arginine groups. Bioactive peptides are also resistant to the action of digestion peptidases. Antihypertensive peptides, known as Angiotensin I converting enzyme (ACE) inhibitors have been derived from milk, corn and fish protein sources. Peptides with opioid activities are derived from wheat gluten or casein, following digestion with pepsin. Exorphins, or opioid peptides derived from food proteins such as wheat and milk (e.g. exogenous sources) have similar structure to endogenous opioid peptides, with a tyrosine residue located at the amino terminal or bioactive site. Immunomodulatory peptides derived from tryptic hydrolysates of rice and soybean proteins act to stimulate superoxide anions (reactive oxygen species-ROS), which triggers non-specific immune defense systems. Antioxidant properties that prevent peroxidation of essential fatty acids have also been shown for peptides derived from milk proteins. The addition of a Leu or Pro residue to the N-terminus of a His-His, dipeptide will enhance antioxidant activity and facilitate further synergy with non-peptide antioxidants (e.g. BHT). We also show herein, that the tryptic digests of casein yielding caseinophosphopeptides exhibits both hydrophilic and lipophilic antioxidant activity due to both metal ion sequestering and quenching of ROS. The separation and purification of bioactive peptides which will involve development of automated and continuous systems is an important field for Food chemists. Much effort has been given to develop selective column chromatography methods that can replace batch methods of salting out, or using solvent extraction to isolate and purify bioactive peptides. Advances here will enable recovery of bioactive peptides with minimal destruction thus enabling utilization by returning these active peptides to functional food or specific nutraceutical applications.
    Current Pharmaceutical Design 02/2003; 9(16):1309-23. DOI:10.2174/1381612033454883
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    ABSTRACT: Milk proteins exert a wide range of nutritional, functional and biological activities. Many milk proteins possess specific biological properties that make these components potential ingredients of health-promoting foods. Increasing attention is being focused on physiologically active peptides derived from milk proteins. These peptides are inactive within the sequence of the parent protein molecule and can be liberated by (1) gastrointestinal digestion of milk, (2) fermentation of milk with proteolytic starter cultures or (3) hydrolysis by proteolytic enzymes. Milk protein derived peptides have been shown in vivo to exert various activities affecting, e.g., the digestive, cardiovascular, immune and nervous systems. Studies have identified a great number of peptide sequences with specific bioactivities in the major milk proteins and also the conditions for their release have been determined. Industrial-scale technologies suitable for the commercial production of bioactive milk peptides have been developed and launched recently. These technologies are based on novel membrane separation and ion exchange chromatographic methods being employed by the emerging dairy ingredient industry. A variety of naturally formed bioactive peptides have been found in fermented dairy products, such as yoghurt, sour milk and cheese. The health benefits attributed to peptides in these traditional products have, so far, not been established, however. On the other hand, there are already a few commercial dairy products supplemented with milk protein-derived bioactive peptides whose health benefits have been documented in clinical human studies. It is envisaged that this trend will expand as more knowledge is gained about the multifunctional properties and physiological functions of milk peptides.
    International Dairy Journal 09/2006; 16(9-16):945-960. DOI:10.1016/j.idairyj.2005.10.012
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    ABSTRACT: Whey protein concentrate was hydrolyzed using the technical food-grade enzyme Corolase 7092 in order to abolish the allergenicity of whey proteins. The immunological properties of the hydrolysates were tested in vitro with a human-immunoglobulin E (human-IgE) enzyme-linked immunosorbent assay (ELISA) using sera obtained from children allergic to milk proteins and in vivo with a mouse-rat heterologous passive cutaneous anaphylactic test and an anaphylactic shock test in mice. The protein efficiency ratio, determined in young growing rats, was compared to that of casein. Ultrafiltration of the hydrolysates appeared to be necessary to obtain a hypo-allergenic product. The minimal molecular mass to elicit immunogenicity and allergenicity of whey protein hydrolysates appeared to be between 3,000 and 5,000 Da, so the molecular weight cut-off value of the filters required must be in this range. Although there was no evidence that extensively hydrolyzed whey protein is nutritionally inferior to casein, the slightly bitter taste might reduce food intake.
    Journal of food protection 06/1994; 57(7):619-625.